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6550 vs kt88

6550 vs kt88 Whether your application is a hifi amp, guitar, or bass amp, the JJ 6550 tube will be up to the job. They still work 40 years later. 42 replies Jimi's problems at the Isle Of Wight. Anyway, I sure have never heard original Genalex KT88, but I know a guy in Sydney who knew them well and thought their supposed superiority was a myth. With 42 watts of plate dissipation in tetrode operation and 44 watts in triode, power is improved even over desirable vintage types. You can always sub a KT150 for a KT120 or KT90 but never the other way around. The KT88 typically needs greater bias voltage than a 6550 does in the same circuit to have the same plate current as the 6550 would. Quote: Can I replace ref5se's 6550 by kt88? These tubes are very similar and used as the The JJ 6550 tube can be used in any 6550 tube amp. Our KT88 sets are burned-in for 24 hours for maximum stability, then precision matched. In some amp designs that can make for a sonic advantage. In my main amp I have the ability to roll in El34, 6550, KT88 and a few other variations. The 6550 has a really great glassy tone to it, like when soloing you almost have a natural delay that could cut diamonds. PMG 2004-07-01 17:02:12 UTC. It isn’t used in guitar amps as often as it is in hi-fi audio amps, but that being said, I know a few guys who totally swear by the KT88. Find great deals on eBay for nos kt88. KT120 - In the spirit of Tung-Sol’s creation of the 5881 and 6550 power tubes, New Sensor Corporation released the KT120 under its Tung-Sol label in 2010. tonally, the 6550's do vary from the kt-88's in my amp. I measured the plate voltage and it read 475,the 6550 tubes are the Sovtek 6550we which I purchased from tube depot and they are marked 50 on each tube. Groove Tubes EL84 Duet (European) Install Groove Tubes EL84 tubes in 5881 vs 6L6GC Valve/Tube. This is a suitable replacement for any 6550/KT-88 tube type. This is very nearly a first production run of the 502. New Sensor Gold Lion KT-88 in Cary SLI-80 Signature. (I listen to classical music and opera. Others don't there's several varieties of all these amplifiers, since changes were made through the years of production. We carry all of the major brands in NOS, vintage and New Production vacuum tubes. KT88 The KT88 is based on the 6550 but even more refined and boosted. This tube has a tone that is warm and lively with a detailed and balance response. Early B. Above 400mA, the Rd curves over to left to 500mA and this more easily covers all my design work for UL with KT88 or 6550. That tube is known for its smoothness and maximum power. 5K for a KT88 instead of 6. Honestly I liked the SED KT88 better (with Dynaudio) but those too are out of production. It was introduced by Tung-Sol in 1964. Out of all of them, the 6CA7's sounded the best. Further research by Mullard UK for the EL34/6CA7 and EL84/6BQ5, GEC/MOV Valve Co. You will need to modify the bias circuit to obtain the correct bias for the KT88's. com. Ability to use 6L6 tubes to increase headroom. KT88's cost a little bit more than 6550's. They do sound incredible and I think it is probably the best sounding KT88 ever made. One amplifier can used wiht tube EL34, KT88 or 6550, so, you can get 3 kinds of sound from different models tubes if you buy more 2 new sets of tube. But the KT88 should be allowed greater current, and the circuit should be capable of it. It was so far ahead of anything else it was a joke. The new KT120 is a very good replacement for a lot of power amps using either KT88 or 6550, however, I must stress that it is not identical in electrical parameters and therefore there are some important differences to consider i. Test Reports 6550/ KT88 October 2005 INTRODUCTION: Object of the test To evaluate the sound quality and reliability of the new batch of 6550/KT88 and compare against the best new old stock types for use both audio and guitar and bass applications. The two tones are very close together though. PMG 2004-07-01 17:02:12 UTC. Tubes: 4-KT88/6550 output, 3-12AX7A, 4-12AZ7. Of course these are broad generalizations, but seem to hold true for amps that have good primary to secondary matching in the output trannys. It delivers a little less power than the KT88 but with a fatter tone. KT88/6550 New vs Old Stock - Tube Maze. A number of different KT tubes were later marketed by M-OV. The KT88 typically needs greater bias voltage than a 6550 does in the same circuit to have the same plate current as the 6550 would. . beam pentode Base: OCTAL Uf = 6,3 V If = 1,6 a Typical Characteristics: U a = 250 V U g2 = 250 V I a = 140 ma I g2 = max. But the KT88 should be allowed greater current, and the circuit should be capable of it. Marshall used them in their 200 watt Marshall Major amps. so, if you like power amp saturation, don't go with them. 6550. Specifications. KT88 Ra curves for Screen Eg2 vs Ia for Eg1 = 0V. Shuguang Treasure KT88-Z vs. The KT88 and 6550 are always interchangeable. Sovtek and EH 6550: These are the same tube and both are boxy. Designed to hold up in even the most punishing environment of high powered bass amps, such as Ampeg SVT. The KT88 is a beefed up 6550. AFAIK the KT88 is a lot bigger than the EL34 (>40W anode dissipation instead of about 25, depending on manufacturer and year of manufacture); moreover, it has a much lower internal resistance and is therefore used customarily with a much lower load than the EL34, say 3. I had Wing "C" 6550 which are very nice and Had some NOS GE 6550 which were very nice, But the New Golden Loin KT88 is in another league, in my opinion. And then the Tung-sol KT120 which has even more "pop" and because we run them so easy, the tube may outlive you. Group "B" consists of KT88, KT90, 6550 and their variants. Hence the assumption that the kt88 might be more durable. In the measurements and listening sections I relate the differences. In order to run 6550 or KT88 in a VTA ST-70, all you have to do is drop the value of R39 from 7. The KT88-TK is a beam-power tetrode that shares similar applications as the 61. Audio Transformer is PMF-20S,FC-20S(XE20-S),H20-3. The Hammond transformers in my Eiclones should be up to the job too. Jean Hiraga 12AX7 (ECC83) Single-Ended KT88 Tube Amplifier Schematic Jean Hiraga's single-ended KT88 tube amplifier schematic with 12AX7 (ECC83) tube input stage. 6550/KT88/KT120 Power Tube Amps. The EL34 is probably the narrowest of the medium glass octals. Pete--Hey you big ape! 1 NEW PUSH-PULL TUBE AMPLIFIERS MENNO VAN DER VEEN, AES member it. Shop with confidence. bass. Matched to perfection within 1-3mA. The KT88 will sound more extended in the top end with harmonically accurate mids and bottom end. Graph 9. KT88 posted by garymuffley@fuse. I just want to know if I would have to change capacitors, transistors, or other things. KT88 (6550 equivalent) Genalex GOLD LION reissue, new productionMATCHED PAIR: Looks and sounds like the 1960s vintage Genalex Gold Lion KT88, one of the most famous vintage power tubes in the world. If you care about tone, re-tube with Tung-Sol. BEAM PENTODE 6550 is a beam output pentode with an octal base and power of 35W. Loads failed on me. EL156 need at least 400V B+. $21. In contrast, the 6550 will sound more dynamic and warmer across the midband with a more fleshed out bloom. It has the same big and heavy glass envelope and beautifully polished metal base. Substitutes: 7D11, 12E13, 6550A, 7027A#, KT88, KT90 Type 2 or 3, KT99, KT100, KT120/KT150 (only if sufficient bias is present) Unless forbidden by your manufacturer, I would try some of the high powered goodies on the market to boost performance. The 6550 has a midrange grain that is unmistakable and frankly, annoying. KT88's generally have a little more output at the very frequency extremes (top and bottom). Can be used in place of 6550 for a more "round" bass signature. KT120+KT88 AB Po vs RLa-a, TRIODE, Ea = Eg2 = +500Vdc. com/6550a-ex. The KT90, KT120 and KT150 are all tubes that were designed in the modern era. I tend to agree with him that audiophiles cling to many myths Testing 6550 on TV-2 : Page 1 of 1 [ 8 posts ] Previous topic | Next topic : Author Message; Rockbert Post subject: Testing 6550 on TV-2. Using the beer analogy again, the 6550 is like Heineken as it would be better without the aftertaste. B. 00 Buy Now; 6550-JJ TESLA AMPEG SET JJ Tesla The JJ 6550 is a valve that is based on the famous American 6550A and since its launch it has proved an excellent valve In stock £162 A. 6550 Tubes KT88 Sensibly equivalent ¶ to: 12E13 6550 7D11 CV5220 See also: Design for a 50 Watt Amplifier - KT77 & KT88 Advert - New Audio Output Valve The GEC KT88 - New KT88 Advert - KT88 Advert - KT66 and KT88 Advert difficult to compare really as it invaribly involves different amps but I went from EL34 push pull to 6550 push pull. 95. The last valves M-OV produced after a run of 28 years (1956 - 1984) were branded Gold Lion and here this Russian tube made by Genalec carries the same branding, but this valve has been made for the modern audio market. KT88's can stand a little more voltage than 6550's and *may* be more durable in amps with a very high B+ voltage. These are excellent sounding KT-88 from China-GUI GUANG at an EXCELLENT price! Just $69. KT88’s were also used in Hiwatt Custom 200 and 400 bass amps. There are several in the sequence as manufacturers gradually improved it over the years and discovered new ways to push the tube to higher powers. The 6550’s ran for 4 years and are still fine . Questions: Have you looked at toroidals and why did you choose a 33% screen tap as opposed to 40% (more common)? What are your feelings about fixed bias vs. A pair of KT88's in a 8417 amplifier will produce a hair over 55watts. Hello Group. In today’s market, these valves are more likely to be used past failure, new but of very poor quality, or ruinously expensive New Old I had an old Consonance M100SE that came with EL34's and could run 6CA7's, KT88's and 6550's. Posts: 8,171. Marshall KT88 amp PI's. The SED 6550C is manufactured in the SED factory in St Petersburg, Russia, and is designed to be a direct replacement for any 6550. In Reply to: RE: St. Winged C 6550: We actually like this tube better than the chinese and russian KT88's. This modification will allow use of either 8417, KT88 or 6550 valves & possibly EL34. The Electro-Harmonix KT88 has excellent tonality, with a full bodied sound, and great dynamics. This had been the best sounding new production 6550 until the release of the JJ 6550. There later was released a 7581A with 35W output but most amps calling for 35W and up in the Americas would likely have been fitted with the 6550 and the 6550A. C. Platinum matched quad (4) electro-harmonix kt88/6550 tubes russia for sale is a new platinum matched quad (4) electro-harmonix kt88/6550 tubes. There is a lot of confusion in the market on Svetlana and Winged C Valves. The JJ KT88 is an excellent choice for Hi-Fi stereo equipment as well as guitar amplifiers. Great report on new and old stock tubes – View Report. That should tell you something. 這兩種膽在音色上之分別為何呢?有人說6550有勁D,高低申延好D,而KT88則較平均,中音表現較突出。但另一些人分享啲版本則剛剛同以上所說的相反。實際上大家的經驗喺點呢? Qualified orders over $99 will ship to you without incurring a shipping fee. But I have only used 6550's in my svt's. The following guidelines should be taken into account: The free shipping option allows TubeDepot to choose the most appropriate carrier and service. KT88/6550 for midrange. Derby City U. . Electro-Harmonix, being the new production tube, suffers from the same issues as its line of the preamp tubes, but since old stock is very scares and very expensive, new production for the majority of people is the only way to go. alt. 4; Brand new unopened Gui early dawn light OEM EL34M tube -generation 6CA7 /5881 fixed gate fixed screen pairing USD $11. Advanced Search Graph 8. KT88 AB Po vs RLa-a, beam tetrode, Ea = Eg2 = +400Vdc, high initial class A Po. Original Mullard KT88 Posted February 26, 2015 February 28, 2015 admin Posted in Feedback by Tube Model , - KT88 all types Comparison review by Gary S. KT88 tubes Wed, Jul 07, 2010 2:31am Are 6550 tubes less warmer and more stiff-bright sounding tghe KT88 tubes,if so then thats what im looking for . the ultimate guide to tube-rolling: 6550 / KT88 / KT120 / KT150 A range of power tubes for all tastes 6550 The 6550 is a beam tetrode that's similar and often interchangeable with the KT88 and KT90. They are not a super warm tube. Your bidding on a Used and test OK, General Electric and Tungsol - Made in USA 6550 Power Tetrodes. (Edit. on their own, i don´t like the KT88 but both tubes combined is awesome. Feb 18, 2017 - Design and construction of a pair of push-pull class-A, Ultra-Linear Mono Block Tube Amplifiers that can be used with several different power vacuum tubes including EL34, KT77, 6L6GC, 6550, KT88, KT90. Actually this Amplifier is good for EL34 and KT88(6550). and does a good job . They had the warm smooth mids and top end of a good EL34 with the balls and grunt of a good KT88. 6550's are also tight but have more low mids and an angry kind of bark to them. 99 per pair, provided in original boxes. With this in mind of the 3 6550/KT88 types I have played with in my amps - and from what I have heard from others - the JJ Electronics KT88 (copy of the Tesla but with some mods as I understand it) are about as good as it gets for non NOS stuff, sonically speaking. In other amps it makes no sonic difference so many can't be bothered. MC 275 STEREO POWER AMPLIFIER VERSIONS The Compendium MC275 CE (Gordon Gow Commemorative Edition): (1993 ~ 1998) (450 V power supply). Its European counterpart is the KT88, which is almost identical, but is rated at 40-W plate dissipation. KT88 vs 6550 wouldn't have been fair anyway Sovtek 6550 Tung Sol 6550 Of course there's no post-processing on these clips, and both brands were biased exactly the The REAL KT88's had a plate dissipation of 42 watts, wheras the 6550 had a plate dissipation of 35 watts. Never could hear any difference between them. Scroll down to see sets of 2 (pair), 4 (quad), and 6 (sextet). TYPICAL MECHANICAL AND ELECTRICAL PARAMETERS Exact replacement for: 6550, 6550A, KT88, KT90, KT99, KT100 Ea 150V always seems to have been difficult, and I have generally assumes KT88 / 6550 UL diode line to be a straight line from 0. Buy Genalex Gold Lion KT88 Power Vacuum Tube, Platinum Matched Quad, Pack of 4: 6550 equivalent sold as pack of 4 New (2) from $247. Cheap Amplifier, Buy Quality Consumer Electronics Directly from China Suppliers:PSVANE Hifi KT88 KT88/C Vacuum Tube Replace 6550 For Hifi Audio Vintage Tube AMP DIY Factory Matched Pair Quad Authorized Seller Enjoy Free Shipping Worldwide! Limited Time Sale Easy Return. EL34 vs KT88. 6550 tuic. The rating is more applicable to standard pentode operation. Tubes or Solid State: All are welcome. New & NOS power tubes from Mullard, Tung-Sol, Telefunken, Sino, GE, Telefunken & more! Electro-Harmonix KT90 The Electro Harmonix KT90-EH tube is a drop-in for any KT88 or 6550 tube bias your amp just as you would a KT88 and you're good to go! Sonically they are true to the Electo Harmonix brand; clear top end that is open but not bright or tizzy, tight bottom end, and a clear midrange that is not hard or clinical. the current 6550 tubes, whi . Why not go with 6550 tubes? They have a good track record with bass amps. It is rated at 600 V with a 35-W plate dissipation. It has a bias switc 1. Permalink. Equipment used- guitar and bass Ampeg 1972 S. Most might have used 6550, 6L6, EL34, 6V6, EL84. Hope that helps, its kinda hard to describe without actually hearing them for yourself. I had a Marshall Major with 6550's and it was only putting out about 60-80% of its power rating because it was designed for KT88's. i want to post a note about kt88s vs 6550's. The JJ KT88 delivers a powerful 42 Watts with plenty of headroom to spare. So can i go from el34 to kt88 with a just a bias? Re: KT120 vs 6550 / KT88 « Reply #8 on: 17 May 2013, 05:28 pm » Thanks for the info,, I am going to try to beg borrow or steal a few amps to hear in my system. A KT88/6550 is a pentode which is sometimes referred to a beam power tube. timeelect. The reason for the change from JA-80 to JA-80 Mk II came about because of change in the output valve world. KT88 A beam tetrode that is similar to the EL34. Hi! Well the KT88 is pretty much an upgraded 6550. However you have 3 very different construction tubes the KT (tetrode), EL (pentode) 6CA (beam) they all have subtle differences in sound. Thanks for that. I put NOS JAN and Brimars in the amp with KT88s (I cannot remember what brand) While I enjoyed the sound I prefered the overall "liquidity" of the 6550. As a drop-in to existing 6550/KT88 amps, the KT120 is impervious to overload, delivering peak power with extreme reliability and almost infinite tube life. 5" of clearance to fit the seated height of the adapter and EL84 tube. To me they reminded me of a cross between SED 6550's and KT88's. Optionally, capacitor in bias circuit may be increased (up to 220 MFD) to replace original 60 MFD 150V part. But just like speaker/amp/cables everyone has a preference of sound quality. tubestore calls these quads "Preferred" , only few bucks more . In the UK there was the KT66 invented which was a better quality 6L6. 2. Unless the filaments have changed expect reliability problems. 5% impedance. It can also be run as a triode since it and the pentode EL34 have more elements in their envelope which can be disconnected to form a semi-triode. KT120+KT88 AB Po vs RLa-a, TRIODE, Ea = Eg2 = +500Vdc. 5 ampers. 35V across a 470R resistor is 74mA. 5 105 3000 13. KT88/6550 New vs Old Stock - Tube Maze. Otherwise we don’t offer any warranty service, repair service or advice. 5 16. EL34 vs KT88. It has 6550's in it. I like the new 6550 Tung-Sol, the KT88 is just a few watts more power. All depends! But all 3 are related. 4. Flippin' Sweet!! Wonderful, sweet throated sounding like the legendary Marconi-Osram Valve Co. Any Penthodo grid bias are less than Triodo's bias so please try to use any kind of driver. f. Change bias potentiometer to 33K or 47K. V. JJ 6550 comes in a GE style straight bottle with JJ's signature dome top. Being an audiophile, there's that word again, the audiophile community uses the KT88 aka, 6550's, in half the tube based amplifier's on the market. The =C= has a nice balanced tone In general, the KT88 tube has a magical mid-range similar to the smaller EL34 tube, but with low and high end extremes that reach much further. T head , Ampeg The 6550 could be likened to a hard vacuum 6L6 whereas the KT88 is a darker and stronger KT66, which is peakier and more compex sounding. The 6550 is very full, strong and clean sounding. The 6550 has a screen rating lower than my B+, BUT I have heard many times that this rating is somewhat negotiable when running in UL. In this amplifier you can use only KT88 and KT90. Big bottom end, lean/focused midrange, articulate, little to no compression compared to 6550's, excellent touch response, increased headroom compared to 6550's with a great deal of dynamics. 1 product rating - New Current Matched Quad (4) Psvane KT88 (6550) HiFi Series Vacuum Tubes Hi-Fi KT88 JJ are awesome. 3. Petersburg Winged C 6550 vs. It can be used in place of 6550 tubes. Cheap Amplifier, Buy Quality Consumer Electronics Directly from China Suppliers:Shuguang Treasure KT88 Z Vacuum Tube Replace 6550 KT88 Black Carbon Bulb Classic Edition Factory Matched Pair Quad Enjoy Free Shipping Worldwide! Limited Time Sale Easy Return. Posted by 1 year ago. Posted on May 17, 2012 by tubemaze. Tối qua ngồi ngẫm nghĩ sao bên Mỹ người ta chuộng ampli Pushpull, nhất là 6550/KT88, trong khi anh em ta lại khoái Single end rồi New Current Matched Quad (4) Psvane KT88 (6550) HiFi Series Vacuum Tubes Hi-Fi 5. Willsenton R8 is an integrated Amplifier, it is a Power Amplifier too (there is a group Power amp input), it is a Headphones amp too. There is a subtle difference between say KT88 and 6550 tubes in sound, but the EL34 setting is where you will have the most fun, EL34/KT77/6CA7 all plug and play in the EL34 setting. Presently, most current production kt88's have the same plate voltage as 6550's, the only difference between them being a pin connection. Big gap Tesla way ahead of even that. B iasing by negative grid voltage is highly inaccurate because the same grid voltage can produce drastically different plate currents in different tubes of the same type. The 6550 itself is a more powerful valve then the EL34 (35W instead of 25W) and is usually good if you want a slightly louder and rather cleaner (slower to distort) sound from your power amp section. On the Non-Equivalence of Beam-Tetrodes vs Pentodes appears to be a very useful site that might give you reasons to interchange those devices: - The Svetlana data sheet for the KT88 says it's an exact replacement for the KT100 so I guess these can be interchanged freely. At least try KT88s! 6L6 KT88 vs 6550 wouldn't have been fair anyway Sovtek 6550 Tung Sol 6550 Of course there's no post-processing on these clips, and both brands were biased exactly the Many ppl here would not have had an amp which may have used KT88. February 2006 edited March 2006 in 2 Channel Audio. Search in titles only Search in Tubes (Valves) only. 0 out of 5 stars. They can be used as a substitute for 6550 or even EL34 tubes, if you’re looking for tighter, cleaner tone with less distortion. Here is a general blurb of how the KT88 versus the 6550 sounds. 6550-JJ TESLA JJ Tesla The JJ 6550 is based on the famous G. 10 & FREE Shipping. A. 6550: I don’t use them in my amps, but Ruby 6550 tubes are highly recommended by techs I know and trust, especially for use in amps like Ampeg SVTs that put considerable high-voltage strain on the tubes. - Nếu lấy bóng KT88 nguyên là của thực dân (Genelec) thì giải trung rất hay. 3. I only had 4 so no where near as expensive. this Amplifier good for KT88/6550 and EL34. 0V to 100mA x 400V, ie, Rd = 250r. 10. 6550 vs KT88. Let me state unequivocally that I am not a fan of 6550s as I believe the KT88 is simply a far more musical tube. Search. In 2012, I tested samples of KT120, and was keen to see how they compare with more common EH KT88 and EH 6550 Gear Talk Power Tube Comparison El34 vs El84 vs 6V6 vs 6L6 vs 6550 vs KT88 Reussenzehn Don’t settle for sets matched at lower voltages they are unlikely to be matched in your amplifier. [Note: My E-H 6550s and KT-88s have simple black and white, small print lettering, as opposed to the large yellow lettering pictured]. From what I hear, 6550's aren't the best choice for non-master volume Marshalls, but what about these older Master In KT88's the most common is the Electro Harmonix which is great, the Mullard re-issue and Gold Lion re-issue which in essence are the same tube and are superb. Declaration All items guaranteed 100% BRAND NEW in the original edition Box. These are even fatter and make more power than the JJ 6550's. The Tung-Sol KT120 (and KT150) tubes are new designs, basically more powerful versions of KT88 and 6550 tubes. There was also the max plate voltage difference as Brutus mentioned between the two, so a KT88 is better equipped to handle high plate voltages, and can bias a little hotter. The dual rectifier CAN use KT88 or 6550 tubes in the EL34 bias setting. Anyone ever compared KT77 and 6550 to KT88 and 6L6? Recently i am very curious about these TubeDepot carries a selection of 6550 / KT88 / KT90 Power Vacuum Tubes. It has even less distortion and an even cleaner tone then the 6L6 or even the 6550. The KT88 to me is a generally smoother tube. In audio amps, JJ 6550 performs similar to JJ KT88, with excellent three dimensional soundstage that JJ KT88 is known for. they will add nice high end sparkle. Since its production ceased in the early 1980s, the Genalex Gold Lion KT88 has become expensive and hard to find. But it was tested with Ea = Eg2 = 500Vdc. I know that there will be a biasing issue. Page 1 of 2 1 2 Next > writethis Well-Known Member. KT88 and 6550 use 1. i had minimal amount of time to mess around with my rig, and as i'm using something like 18 pedals front-ended on this beast i will update as i get another crack at some studio time with this. Some, but not all, were versions of existing American beam tetrode tubes or European power pentodes, such as the KT66 (6L6 similar), KT77 (EL34 and 6CA7 similar), KT88 (6550), and KT63 (6F6, pentode but almost identical characteristics). Characteristics Outline Drawing Typical Operation Class A, (single tube) Typical Performance Curves This mod can be done in most any Fender or Marshall type amp, or any amp which utilizes a pentode-style output tube, such as a 6L6, EL34, 6V6, 6550, KT66, KT88, etc. So it will be between the JJ and EH . Graph 8. 12: 6550 vs. I currently have a pair of 8417's running 6550's and again modify the bias circuit. Happy Hanukkah 2019! Where is Santa (HOho) right now? I heard that he's making his rounds The REAL KT88's had a plate dissipation of 42 watts, wheras the 6550 had a plate dissipation of 35 watts. 0 out of 5 stars. EL34 vs. KT88 is the BALLS! A 6550 is a fine tube as well, but the KT88 is less prone to failure, sounds a bit tougher and ballsier when called upon. Electro-Harmonix KT88 - Data Sheet KT66's should be fine, but there are circuit changes you might want to make if you want to run KT88's or 6550's, specifically the bias-feed resistors. KT90's will handle higher plate current compared to KT88's/6550 which means they can be biased higher. Classic vintage 6V6 tone with natural breakup. V. I’m about to buy four KT88 tubes and drop them in place of my EL34s in my home made tube amp Tung-Sol 6550 Power Amplifier Tube. KT88 are not same sound getting if Maker is different. 83. This patented Sophia Electric coke-bottle KT88-ST (long life version) tube has the most refined sounding with best high frequency extension, a cure for the dark sounding KT88 amplifiers. Quote: Can I replace ref5se's 6550 by kt88? These tubes are very similar and used as the 6550/KT88_____ Power 1W RMS 10Hz to 90Khz -1dB EL156 China_____ Power 1W RMS 10Hz to 90Khz -1dB EL156 China is both of same power but feel more powerfull than KT88/6550. 6550 vs KT88? Submitted by John Atkinson on February 19, 2013 - 1:47pm . 5K. Pricing above includes In Reply to: RE: Bob Carver on Stu Hegeman, ultralinear and 6550 vs. Note: YJS requires at least 5" of clearance and YJShort requires at least 4. A 6550 is rated at 30 Watts. . It is a single ended class A amplifier and features a tw The first issue to discuss is 6550 vs KT88. namely the Rogues, Quicksilver v4's and the ARC VS115. As far as sound goes, IMHO, most 6550's have a "tubier" sound than KT88's with perhaps a little more mid-bass content. KT88's can nearly always be substituted for 6550's and vice versa. _____ Re: All about tubes 6550/KT88 OK ! On the site "Tube Asylum" I read a lot of comments about KT88 , and a folk named Jim MacShane wrote that Svetlana SED KT88 is a turd ! He much prefers the Electro Harmonics KT88 . Nominal UL power are 10 W both EL156 and KT88/6550 and Find helpful customer reviews and review ratings for YAQIN MC-50L KT88(6550)X4 Push-pull Integrated tube amplifier at Amazon. With 16 tubes you are talking some very serious cash. 4 x. After studying the pictures of the 6550 vs the kt88 and assuming the bottle was/is the same shape, I was almost sure that the plate structure of the kt88's looked closer to the outside of the glass envelope than the 6550. 139. nl Then, I did the obvious thing for tube amps and changed the stock power tubes KT88 (actually not bad, very neutral & clean sounding) to 6550 Tungsol re-issues and right away there was an audible improvement. A new KT88 built in the style of the older British KT88's. In my experience, the best way to get tightness out of a 2203/2204 is with KT88's/6550's (I like the JJ KT88's), but keeping the master between 2 and 3. At least try KT88s! 6L6 Marconi-Osram Valve Co. Saying that KT66 and 6L6 are almost the same that leaves us with four very popular power pentodes. Quad Set Tungsol, General Electric 6550 KT88 Power Tetrodes-USED TEST OK. Twin Chassis Amp Models. Graph 9. After this in the USA from the 6L6 the larger 6550 was derived and in Europe from the KT66 the larger KT88 was derived. 74mA is the current flowing between Anode and Cathode, from a B+ supply of 380V. What is the current recommendations for 6550/KT88's tube replacements that everyone is happy with? Do i just replace the 2 pairs of power tubes only? or replace all 13 of them for each amp ( (2 matched pairs) 6550, (2) 6550 regulators, (1) 12AX7 regulator amplifier, (4) 12BH7A driver, (2) 6922 input )? The KT88 can be used interchangeably with its American rival, the 6550. Note: Our export products must be supplied by our exclusive distributor in each country. 's (Genalex) legendary Gold Lion KT88 was the heart and soul of classic tube amplifiers like the Dynaco Mark III, McIntosh MC275, and Marshall Major. You should run 6550 or KT88's at 50 milliamps each which on the original Dynaco bias system is 1. If it amplifies a signal, this is the place! 6550 and kt88 plate dissipation : Page 1 of 1 [ 8 posts ] Previous topic | Next topic : Author Message; targeteye Post subject: 6550 and kt88 plate dissipation. Jeff Day's Positive Feedback Online Review: "The Sophia Electric EL34-ST vacuum tubes remind me of a cross between 45 and 2A3 triode If you are unsure of which Yellow Jacket will work in your amp and your amp is not listed, please contact us. S. . With a number of different KT88 tube amplifiers we have had good results using new production JJ KT88 Blue Glass and Genalex - Gold Lion KT88 tubes. The Amperex 6550's were unanimously agreed upon as the best NOS 6550 by all. T head, Ampeg 1988 LTD edition S. Design and construction of a pair of push-pull class-A, Ultra-Linear Mono Block Tube Amplifiers that can be used with several different power vacuum tubes including EL34, KT77, 6L6GC, 6550, KT88, KT90. aside from the tonal differences between tube models (and individual tubes, really), you get more clean headroom when using kt88/6550's. 1 product rating - New Current Matched Quad (4) Psvane KT88 (6550) HiFi Series Vacuum Tubes Hi-Fi Power tubes, often called output tubes, can give an indication of the amount of power an amp can produce. Read honest and unbiased product reviews from our users. Very sturdy and reliable. EL34 of EH and Telefunken(Siemenz)getting very much musical sound. ONLY 2 LEFT. e. The Svetlana KT88 is made exclusively at the Svetlana Electron Devices factory in St. buro Vanderveen, The Netherlands fax: xx3l-38-4533-178, e-mail. The 6550 originated in the US and the KT88 is the European answer to the 6550. Permalink. For additional info on the GE 6550A, click on the link http://www. I think the biggest technical difference is that you can bias KT88's hotter than 6550's (28watts at idle for Kt88 vs something like 24watts at idle for 6550) As far as brands I can say this from personal experience: =C= 6550's seem to be the best value for the $. The amps can run EL34, 6L6GC, 5881, 350B, KT66, KT88, 6550, KT90 and more (some tube choices require a 5U4GB rectifier tube)" FWIW, the KT88 is not my favorite output tube. Hey all, I might be picking up a Marshall JMP 2204 (master volume). In British amps of 200W or more typically the KT88 would be the first choice, being more powerful than the US counterpart of the 6550. For me and my set up it gives the best all around detail, sound stage and separation. You may use a quad of either 6L6 or EL34. – received by email: 2. Superior high-power Octal Beam Tetrode, suitable for any amp using 6550 or KT88. F. 0 10. Share About the 6550 vs kt88 interchangeable question. The 6L6 sound kinda nasty, aggressive. amplifiers. Original Tungsol 6550 are in the same league. The KT88 is broader with less of a mid peak, the 6550 would be percieved as scooped. Posted by garf on November 8, 2016 at 02:20:20 . In 2012, I tested samples of KT120, and was keen to see how they compare with more common EH KT88 and EH 6550 The 6550 is perhaps more commonly seen as an output tube in big bass amps, and was used for a time in Ampeg’s SVT, and currently appears in models by Traynor and others. As far as sound goes, IMHO, most 6550's have a "tubier" sound than KT88's with perhaps a little more mid-bass Another great substitution is replacing the 6550’s in 800 Marshall's with the JJ KT88’s. A number of UK suppliers claiming they are selling current production Winged C valves which are made in the St Petersburg factory in Russia. The 6L6GC is rated at 500 V with a 30-W plate dissipation. Th 6L6 as you know is a very full and creamy sounding tube. 6 and El-34, and is one of the largest tubes in its class. JJ 6550. KT88 ultralinear mode connection. Jul 23, 2004 #3 Kt88's have a big tight and smooth type of sound. for the KT88, GE USA for the 6550, and RCA for the 6973 (6CZ5 hi-fi), 7027A (6L6GC), 7591, 7868 (6L6 family), also recommends 43% turns (or 43% of plate signal voltage), or 18. It has IIRC a higher permissible plate dissipation and higher voltage ratings, but in practice they are pretty close. Some of you will recall 20 years back, there was a fracas amongst valve fanciers regarding the EL34 vs the KT77, and similar battles amongst the 845 vs 2A3, and KT88 vs 6550. KT88 penthode mode connection. The large plates allow for more efficient cooling and headroom. So, to unravel this, first let’s look at the various types of 6L6 valve. A favorite among hi-fi audiophiles, provides excellent value for the price. started 2003-11-20 17:59:04 UTC. General rule is that the KT88 goes anywhere a 6550 will and usually the reverse as well, but the 88 was the more highly rated tube. Tuy nhiên đó là truyện ngày xưa. 24 FREE Delivery by Friday. Article by Ashlynne Bair/Nelson The new stock Guangxi Liuzhou old 6550 tube light , with parameters Replacement KT88, moldy screen , special USD $54. KT88 6550 Plate load OPT & 40W 6DQ6 Amplifier Vince A #64884 . EL34/6550/KT88 Single Ended Amplifier on 28th Mar 2018 in Santiago Chile. 70) Ok, I know this is a vague question and their will be many answers, however, based upon the newer versions of the Gold Lion KT88's and others KT88 tubes such as from EH vs. bar1. In bass In stock £27. 5K to about 3. This tube is a favorite of audiophiles. KT88 Ra curves for Screen Eg2 vs Ia for Eg1 = 0V. Expensive, but considerably cheaper and more available than the GEC kt88. New Current Matched Quad (4) Psvane KT88 (6550) HiFi Series Vacuum Tubes Hi-Fi 5. Bin all the output tubes and replace them with Russian built KT88/6550 (Tungsol 6550 are very good). Power tube: KT88 × 4 (Equivalant 6550) Rectifier: 5AR4 × 1 (Equivalant GZ34) (Hifi exquis 1101017) Dimension:(W × D × H): 410mm x 335mm x 198mm (Hifi exquis 1101017) KT88 triode mode connection. KT88 a. If it amplifies a signal, this is the place! 6550 and kt88 plate dissipation : Page 1 of 1 [ 8 posts ] Previous topic | Next topic : Author Message; targeteye Post subject: 6550 and kt88 plate dissipation. A KT88 is capable of a maximum dissipation of 42 watts from a single tube which is pretty hefty considering the beefy 6550 dissipation is only 35 watts and we know how loud those guys are! The KT88 also can handle larger plate voltages, up to 800 volts. The 6550 would need to have the tube pinout wired as an EL34 would be. There was also the max plate voltage difference as Brutus mentioned between the two, so a KT88 is better equipped to handle high plate voltages, and can bias a little hotter. 5U and HO-808 schematic show next. The early Russian built Gold Lion KT88 had a few issues too) There is a chance that the output transformer may have been damaged. Tung-Sol NOS 6550 next best in Air Tight ATM2. from 70mA to 75mA is more clear than large current like over 100mA. $84. for power tubes i tried kt88, el34, 6ca7,6l6gc, kt77 personnaly, I like 6l6gc best for my utopias, and el34 best for my planar hifiman arya in general i find kt88 to be hifi , almost solid state like with great bass and details,lacks a bit in refinement, and el34 more romantic and refined with emphasize on mids and rounder sound, good soundstage. JJ 6550 provides a good thick tone in guitar and bass amps. 4. The EL34s were very sweet in the midband and I felt a bit rolled at the top. ORIGINALLY the kt88 was designed to have a higher plate voltage. So I'd go with either one, you will be happy. Their tone is great and they are fairly reliable. on the subject of headroom, i feel the low end breaks up juuust a bit quicker. KT88 and 6550 are almost same charactor so you can use each other same amplifier. It was the Tesla KT88. (If you bias very cold, no re-bias Sovtek 6550 vs Tung-Sol 6550 new version Post by jahatl513 » Mon Nov 19, 2018 5:55 pm In the past I purchased a Premier 12 set that had Sovtek 6550's and had been told by another that these were not the ones to have yet my experience was that they did exactly what they say they will do. I find that 6550s, at least the ones that I have heard, have a "hardness" that the KT88 doesn't have. High possible Class A. started 2005-09-26 19:33:34 UTC. You "can" get 100W from a pair of 6550, but it needs uncommon iron. 1) has anyone compared KT88 Vs 6550 in the same amp, which did you prefer and why? 2) what brands did you like best ? I have my eye on x8 Shuguang nature Sound KT88-T but at over £500 I better make sure I'm getting something that will be good! I guess I should also consider KT120 too?? 6550 vs. Strong bottom and and a sweet, liquid top Tube choices are basically "6L6", EL34, or 6550/KT88. The results show that rather a small amount of extra Po is available if the KT120 is used to replace 6550, or KT88 as currently produced. The difference is in both the bias voltages and maximum power dissipations. on 2020 2nd Feb KT88 Author: M-O Valve Subject: JA-FP-2000-10-01 Created Date: 10/1/2000 7:35:29 PM Enter the KT120, the most powerful tube in the 6550/KT88/KT90 family. 6550. The KT88’s also sound great in the late 70’s Marshall Mark II amps in place of either the EL34’s or 6550’s. Petersburg, Russia, and is designed to be a direct replacement for any KT88, KT90, KT99 or 6550. The GE 6550A has roughly the same electrical characteristics as KT 88 (42 watt vs. They are all loosely based on the KT88 but with much more power. Introduced by GEC in 1956 specif BG286 - I get the question a lot about swapping out KT88s with KT120s or KT150 tubes in people's amplifiers. 56 VDC. For modern production, the Gold Lions are pretty good, but a definite step down from the Psvane KT88-TII vs. You need _four_ of EL34 or 6L6GC to get above 70 Watts. Change resistor between bias pot and bias diode to 10K. 6 ampers, wich is not too far from the EL34´s 1. they will take a little more current from conventional AC heater supplies [average is around 100ma once valve has Hey everyone, I'm going to be retubing my Ampeg VL-502 here pretty soon and I was wondering what kind of tubes I should put in it. So sánh "KT88 vs 6550" gần hao hao giống so sánh "KT66 vs 6L6GC" hoặc tương tự "EL34 vs 6L6GC". The KT88 was invented by Marconi-Osram Valve Co. Electro-Harmonix KT88 Vacuum Tube High power kinkless-tetrode for use in amplifiers such as the Marshall Major. 6550 tubes new vs vintage? 01-29-2012, 05:01 AM their KT88-98 is a very well-made tube and they sound great in a Leslie. They could be exchanged under certain circumstances. old simpsons vs new simpsons | KT88/6550 New vs Old Stock. Originally introduced by GEC in 1 956, it became competition for the American-made 6550, but with the ability to handle a 6550′s and custome toroidal transformers or making the transformers my self. The 6550 shown in Photo 4 is a higher-voltage, higher power tube similar to a 6L6GC. Feel free to inquire if you don't see the sets you want. 5-7K for a EL34. All KT88 tubes out of China are rubbish and have a 30% chance of failure. Reply. 1k25 = 90W, 2k5 = 112W, 3k7 = 93W, 4k9 = 77W, 7k3 = 57W, 9k8 = 45W, 12k0 = 32W, 16k0 = 24W Conclusion. 81; Guangxi Liuzhou new original print old light tube KT88 B long iron screen voice was soft and sweet USD The negative grid voltage method: This method involves measuring the DC voltage on the grid of the output tubes, and setting it to a recommended value. 6550 vs KT88? Submitted by John Atkinson on February 19, 2013 - 1:47pm . With a plate dissipation of 60 watts, the Tung-Sol KT120 is the most powerful tube in the 6550/KT88/KT90 family. The amp sounded great but was a PITA to keep biased. A KT88 is rated at 35 Watts. If all i have to do is a bias adjustment that is ok, but I like to leave my amps as stock as possible. LTP? 09-03-2007, 01:56 AM The Mk-II is the American version with 6550's and they changed that first resistor to from 220K to 150K and Re: KT88 or 6550 amp tubes? The amp you have originally came with some inexpensive 6550 tubes and preamp and driver tubes. 00 Posted in 6550/KT88 | 2 Replies KT88/6550 New vs Old Stock. Why not go with 6550 tubes? They have a good track record with bass amps. One amplifier can used wiht tube EL34, KT88 or 6550, so, you can get 3 kinds of sound if you buy more 2 new sets of tube. KT88 is rated @ 42 watts so 64mA its fine there. 5 20 to o volts volts volts volts watts watts watts ma. It needs to be checked and measured. The monster power transformer in the TU-8340VK is rated to supply the juice these tubes require. Compared to JJ 12ax7 it´s like taking a blanket of your cab. High possible Class A. In My AES-25 Super Amp the 88’s are a bit clearer which I like . Substitutes: 7D11, 12E13, 6550A, 7027A#, KT88, KT90 Type 2 or 3, KT99, KT100, KT120/KT150 (only if sufficient bias is present) Unless forbidden by your manufacturer, I would try some of the high powered goodies on the market to boost performance. KT88's/6550's want to see a maximum of 50K, but most Fender-style amps (except some silverfaces) use 220K, which is just begging them to runaway and redplate on you. Tubes or Solid State: All are welcome. 0mA x 0. Discussion in 'Tube Audio' started by writethis, May 24, 2013. This is actually the same circuit you will find in the Marshall 2550 and 2555 Silver Jubilee amps labeled as high and low power. Four EL34 are around the same price as two 6550; four 6L6 a bit more. All four are the large plate type with three getter rings. If you use KT120's DO NOT ship the amp with the tubes installed. Archived. I got a Quad of KT 88 from them few months back to replace 6550’s only to see the sound difference . A. its also recommended to use them with the Bold/Tube or Sponge/Silicon settings, so the tubes dont get too hot. Which sounds the best to my ears? For all around i use the Winged EL34 and the Sylvania 6SJ7WGT. Our tubes are always tested, matched and guaranteed. sol continued from preceding page maximum ratings design maximum values - see elk standard rs-239 plate voltage, dc grid 2 voltage, dc pentode connection triode and ultra-linear connection 660 -300 42 6. Lothar's Guitar School - Gear Talk - Reussenzehn El34In this episode I show you my Reussenzehn El34. The original GEC kt88 are better than any of the modern production. And about the tung sol 12ax7: get them. KT88 AB Po vs RLa-a, beam tetrode, Ea = Eg2 = +400Vdc, high initial class A Po. cv5220, kt88, kt88s, kt88sc, kt90 Warning: Substitutes are given as a guide only - please refer to original manufacturers data sheets to ensure that a substitute is safe and appropriate for your application. While each of these output tube types has its own characteristic tone, different makes of tubes of the same type can sound quite different, too. 35 watt), and long lasting to boot. RE: St. Instruments & vocals had more “weight” and generally more realistic sounding. Specifically designed for audio amplification, the KT88 has similar ratings to the American 6550 which was designed for use as a servo amplifier. Very powerful and great for bass, guitar and Hi-Fi amplifiers. ARC says they use them for best overall sound but the real strength of the 6550 is the bass slam. KT88 is a beam power tetreode, its anode limited dissipation power is 42W. Petersburg Winged C 6550 vs. Close. Preamp being RCA MR 6SJ7GT, Sylvania 6SJ7WGT, RCA red can 5693. Surprisingly, there is little sacrifice in going to KT88's here and the trade off in the rest of the range is well worth it. One thing that distinguishes these tubes is physical size, so if an amp was designed to be as compact as possible, substitutions could be more problematic, The KT88 is a bit wider than the 6550, so it's possible that a few amps designed for the 6550 might make the spacing of the KT88 replacements a bit tight so that they don't cool as effectively. It can take up to 650 volts on the plates if it is truly a 6550 by specification. RCA’s first version of this tube was an early ‘octal’ base tube. 6550s have an inherent grain structure in the upper midrange that is rather characteristic of the tube style regardless of manufacturer. E 6550A and this valve has proved an excellent valve for all applications. The EH KT90 or the new KT120 may be astounding in your amp. KT88 tubes (10. EL34's have terriffic midrange at the expense of LF extension. A direct replacement for 6550's. Mine have individual tube bias and they are putting out right at 55-60 watts. 7 ma U g1 = -15 V S = 11,5 ma/V R i = 12 kΩ µ-g1-g2 = 8 Triode Connected U a, g2 = 250 V I a+g2 = 147 ma U g1 = -15 V S = 12 ma/V R i = 670 Ω µ = 8 Red/Blue versions available max 125,0 max 52,0 max 110,0 Some models of Ampeg V-series specifically say on the cabinet schematic that 6550 (or KT88 or KT90, they are all interchangeable) can be used directly in place of the 7027's. 0 190 50 250 250 250 11,000 5,000 225 -16. Graph 10. mennovdv@noord. The KT90 is another similar tube, with a 50-W KT88 tubes are currently made by New Sensor, JJ and Shuguang. please try it's. guitar. The KT88 fits a standard eight-pin octal socket and has similar pinout and applications as the 6L6 and EL34. However, the tendency of the KT120 to over heat with 6550 vs 6CA7 vs KT88. kohms kohms KT88-STR TAD Premium Matched Our favourite Tube in the KT88 / 6550 Class The latest version of our TAD KT88-STR is built in the style of the early British MOV KT88. but some bias adj. On the VTA ST-70, R39 is on the BOTTOM of the driver board between the two 100 uF @100 volt capacitors. Graph 10. Article by Ashlynne Bair/Nelson Sino/Chinese Shuguang KT88 – Billington Gold Triple tested and matched. What is the current recommendations for 6550/KT88's tube replacements that everyone is happy with? Do i just replace the 2 pairs of power tubes only? or replace all 13 of them for each amp ((2 matched pairs) 6550, (2) 6550 regulators, (1) 12AX7 regulator amplifier, (4) 12BH7A driver, (2) 6922 input)? Thanks! KT88 is also upwards compatible with 6550 tubes. Why are you changing by the way? Just look online for good reviews, you will find a book full for the reissue Golden loin KT88 and maybe the odd one for the reissue 6550. Messages: 794 Location: Music 6550's are powerhouses that have full spectrum punch, KT88's tend to have great bass with slightly recessed mids. Shop our great selection of KT88, 6550, KT90, KT120, KT150, vacuum tubes now. old simpsons vs new simpsons | KT88/6550 New vs Old Stock. Gear Talk Power Tube Comparison El34 vs El84 vs 6V6 vs 6L6 vs 6550 vs KT88 Reussenzehn Don’t settle for sets matched at lower voltages they are unlikely to be matched in your amplifier. In the audio amplifier, the power can be 100W when it is used as push-pull class AB1 with double tubes, it can also be used in electronic voltage regulator circuit. Pete--Hey you big ape! Kính chào các bác. The EH KT90 or the new KT120 may be astounding in your amp. I dont know your amps - and I have a feeling tubes play differently from one amp to another. KT88 JJ are awesome. As a result, KT88's and 6550's are produce cleaner tones and have low distortion, making it popular amongst bass amplifiers and high end audio applications. cathode bias? By the way, I still have the old 6SN7 / 5881 and 6SN7 / EL34 amps. And what, to me is the audio equivalent of Guinness Stout? The Svetlana KT88 is manufactured in the Svetlana factory in St. So far i have tried GL KT88, JJ6550, Tung-Sol 6L6G, and SED Winged C EL34. I know most of us have amps that come from a factory that has predefined tubes that can be used. You can use KT88 in place of 6550 tubes in most cases. I haven't played any older Marshall's that were equipped with anything other than EL34's. Back in 1983, KT88 or the similar 6550 were all the rage, widely available, and standards were high. KT88 is similar with CV5220 and 6550,they can be replaced by each other. Petersburg, Russia, and is marketed worldwide by PM Compon ents Ltd. KT88's can stand a little more voltage than 6550's and *may* be more durable in amps with a very high B+ voltage. ANOS GE 6550 $99. 6550's a bit cooler in the mid-band (still on the slightly warm side of neutral though) and more dynamic and better controlled. and in the USA by PM of America Inc. htm The KT-90 tube in ultra linear has some strange behavior characteristics (but is better in triode). The answer isn't so straight forward and thus I kt88/6550 is a different animal, look for a little over 80 watts a pair. My concern is the voltage ratings on the 6550 vs the KT88. vs. The KT88 is one of the few classic audio output valves. 22) Posted by Audioquest4life on 2008-10-01, 00:00:06 (139. For the Bruce Moore amp, the Electro-Harmonix 6550 proved vastly superior to the JJ Tesla KT-88. At the very least they draw more filament current than KT88s. Small re-biasing. Platinum matched quad (4) electro-harmonix kt88/6550 tubes russia for sale is a new platinum matched quad (4) electro-harmonix kt88/6550 tubes. and became quick competition for the USA made 6550 tube. I have a DIY single-ended electrostatic amp that uses kt88/6550. . KT88's can take higher plate voltage and dissipate more wattage, so they are more powerful (in the right circuit). The KT90 is a beefed up KT88. The KT88 tubes that I had in there I had them biased at 64,thats from the factory. 6550. net on July 10, 2008 at 16:53:20: Here's the whole text: It was a hot mid-summer's night and I was in Chicago at the consumer electronics show. This may not give you the gain or sustain you are looking for, so you may need to experiment with pedals to augment the amp's own gain. KT88's generate a lot power, handling significantly more plate voltage than other power tubes. The new KT88 features greatly enhanced sonic performance: Increased peak cathode emission from new cathode materials; Stable operation from extended processing and There are many pentode good for audio amplifiers but the most common in the current production are the EL34, 6550 and the KT88 so follows a compare table with the main characteristics and price. 50mA +/- 5% would be fine. 's Genalex production line. 6550 vs kt88