I always thought breakup specifically referred to crossing the threshold between audibly clean, and audibly distorted? I know I'm splitting hairs at this point, but knowledge is power, and power is my drug. 
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EL34 vs 6550 vs KT88
- Thread starter MarshallLaw
- Start date
- Feb 16, 2008
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- John K Custom Basses
- Apr 3, 2003
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- Editor-in-Chief, Bass Gear Magazine
And here I thought it was the point at which you can sleep with other women, and it doesn't count as "cheating."
- Feb 16, 2008
- 21,240
- 23,636
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- John K Custom Basses
And here is my $1000.000.00 question, then I can live happily ever after..
So if I want to have nice fat punchy lows, strong low mids, decent highs but not extemely high (the crystal sparkle is too much for me), but obtain distortion without having to blow the roof off, what would be my best choice for power tubes on the SVT?
Sounds to me that the KT100 is still what I want, just not sure about the breakup/distortion part... John?
So if I want to have nice fat punchy lows, strong low mids, decent highs but not extemely high (the crystal sparkle is too much for me), but obtain distortion without having to blow the roof off, what would be my best choice for power tubes on the SVT?
Sounds to me that the KT100 is still what I want, just not sure about the breakup/distortion part... John?
- Feb 16, 2008
- 21,240
- 23,636
- Disclosures
- John K Custom Basses
In my two monophonic power amps in my home audio system, the Gold Lion KT88s are far superior to 6550s.
And present a sound stage with my Magnepan MG3a with subwoofers that the 6550s can't.
And present a sound stage with my Magnepan MG3a with subwoofers that the 6550s can't.
I think the main difference between the use of 6550 and KT88 tubes comes down to where the amp was designed. The 6550 is an American tube and was used in amps designed in the states. The KT88 was originally made in the UK by Mazda Octal and thus used in British designed amps. Though the two types are similar Beam Tetrodes they are not interchangeable.
The EL34, a pentode with a suppressor grid, does not have near the plate dissipation of the other two. You would need double the tube count for the same power out.
The EL34, a pentode with a suppressor grid, does not have near the plate dissipation of the other two. You would need double the tube count for the same power out.
I have tried them but wouldnt use EL-34 in a bass amp. I put the JJ EL-34L's into my Dual Rectifier (was thinking more midrange etc) and they were fine, didnt love them. They are a little greasier to me than 6L6.
I love KT88's and 6550s in any kind of amp (guitar or bass). For bass amps I find the JJ KT88 to be pretty distinctive. On guitar amps I like the slightly flatter response of 6550's. I find they are flatter on midrange than 6L6.
Nobody is selling KT100s anymore, but they were just robust Shuguang KT88s. IMHO there is not really a perfect answer. I compared some JJ KT88s to Winged C 6550s in one amp and I could not hear any difference. In another amp I compared JJ KT88s to Ruby KT88V-STRs and there was a pretty noticeable difference. So it could come down to the specific brand and model of tube.
For those who are curious, I preferred the JJs. They seemed more open and lively. The Ruby's required a totally different quiescent current to sound their best.
Given the specific question I would suggest 6550s. I have done a lot of reading on the subject and often people who have compared KT88 to 6550 say when they are run clean, they sound pretty similar. The KT88 is perceived to have slightly more headroom but the 6550 is perceived to produce sweeter distortion.
Supposedly Russia is re-manufacturing the Genalex Gold Lion KT-88s, at one time were noted as the best KT88s on the market.
Why not? Many, many 50/100W bass amps were designed and marketed in the UK built around 2 or 4 EL34s.
Per Wikipedia GEC brought the KT88 to market. Their KT88s were labeled IEC Mullard in UK and Genalex Gold Lion in the US. You can hunt down a better source if you like.
Here is an image of some NOS Gold Lions from Viva tubes that sold for $3,200 for the quad. Pretty sure these are the real deal, and what was noted as the best KT88 on the market.
If you look closely you will see that the Russian tube is not a true reissue because the construction is totally different. Here is a close up of a current production Gold Lion. It bears a striking resemblance to other New Sensor KT88 models. There is some variance from model to model of course. AFAIK these are not widely regarded as the best KT88. They are rather pricey though.
You may enjoy this read: GEC KT88 …”The King Of Power Tubes” – Part 1
Even closer shots of the tube guts: Genalex Gold Lion KT88 Tube
I believe the GEC was pretty much the same tube. There is a really clear shot on this page: GEC KT88 Tube
The Sadowsky SA200 uses six EL34s. I believe Peavey and Traynor have also made bass amps with six EL34s.
Sadowsky currently recommends KT88 for the SA200 to enhance reliability, as the amp pushes the screens pretty hard.
I also have a Hiwatt DR201 that runs six EL34s. I believe it has the highest plate voltage of any amp in my collection at 711V. But it has a dual rail power supply so the screens are run at a much lower voltage.
Kinkless Tetrode or KT88 and 6550 are both kinkless Tetrode or Beam Tetrode.
The names are just more associated with British or American.
The KT88 has slightly higher power rating. Or more heat disapation. Also can handle more voltage. Doesn't mean your amp gets magically more powerful if you put in KT88. Just means if you wanted to design a amp with higher plate voltage to get more power it's a option. The KT88 has a bigger plate / bigger bottle for heat disapation. And 6550 and the kt66 KT88 and kt100 are somewhat notable for better bass response. Which still depends on actual amp design and transformers. But if your shooting for low frequency design. Probably go for a kinkless/ Beam Tetrode with larger plates for such a design. It doesn't mean amp just gets magic bass if you toss one in. But even with realatively limited frequency response transformers in some guitar amps. The limited bass response seems to be described as being" tighter " when pushed into distortion
EL34 is pentode completely different plate structure. Also known to go into distortion earlier and is unique for some for distortion character. Or otherwise for designers it's just a typical go to British pentode. And can be tortured a little bit if you want to push max plate voltage to squeeze some more power.
If your familiar with some early Traynors or Music Man amps. They torched the hell out of them with high plate voltage for more power. And they survived very well.
Otherwise it is a typical go to tube for the earlier distortion character if you want a high gain distortion type head.
Otherwise if you really need more voltage you don't waste time pushing tubes at max plate and just move up to a bigger tube with higher plate ratings. Hence...KT88
Biggest problem with beam Tetrode is the screen plate. Anode can be pounded with high voltage. Screen cannot be hit with high current or voltage in some topology and typically is the failure point. Usually screen voltage is recommended to be lower, and likewise if using DC voltage must be very clean voltage with no AC ripple. Usually doesn't happen and typical failure point for many musical instrument amplifiers. RCA discovered if you use AC or a modulated screen plate or otherwise known as ultra linear topology. Then the screen is capable of higher voltage. Very few seem to get it and countless KT88 amps get discontinued for
" bad tubes" or other beam Tetrode high voltage amps keep melting screen resistors or failing. And realatively horrible goober designs and diodes and fuses or other pointless garbage to try and make a screen grid survive with too much voltage and too much current.
The names are just more associated with British or American.
The KT88 has slightly higher power rating. Or more heat disapation. Also can handle more voltage. Doesn't mean your amp gets magically more powerful if you put in KT88. Just means if you wanted to design a amp with higher plate voltage to get more power it's a option. The KT88 has a bigger plate / bigger bottle for heat disapation. And 6550 and the kt66 KT88 and kt100 are somewhat notable for better bass response. Which still depends on actual amp design and transformers. But if your shooting for low frequency design. Probably go for a kinkless/ Beam Tetrode with larger plates for such a design. It doesn't mean amp just gets magic bass if you toss one in. But even with realatively limited frequency response transformers in some guitar amps. The limited bass response seems to be described as being" tighter " when pushed into distortion
EL34 is pentode completely different plate structure. Also known to go into distortion earlier and is unique for some for distortion character. Or otherwise for designers it's just a typical go to British pentode. And can be tortured a little bit if you want to push max plate voltage to squeeze some more power.
If your familiar with some early Traynors or Music Man amps. They torched the hell out of them with high plate voltage for more power. And they survived very well.
Otherwise it is a typical go to tube for the earlier distortion character if you want a high gain distortion type head.
Otherwise if you really need more voltage you don't waste time pushing tubes at max plate and just move up to a bigger tube with higher plate ratings. Hence...KT88
Biggest problem with beam Tetrode is the screen plate. Anode can be pounded with high voltage. Screen cannot be hit with high current or voltage in some topology and typically is the failure point. Usually screen voltage is recommended to be lower, and likewise if using DC voltage must be very clean voltage with no AC ripple. Usually doesn't happen and typical failure point for many musical instrument amplifiers. RCA discovered if you use AC or a modulated screen plate or otherwise known as ultra linear topology. Then the screen is capable of higher voltage. Very few seem to get it and countless KT88 amps get discontinued for
" bad tubes" or other beam Tetrode high voltage amps keep melting screen resistors or failing. And realatively horrible goober designs and diodes and fuses or other pointless garbage to try and make a screen grid survive with too much voltage and too much current.
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Maybe so...... I have Gold Lions KT88s in my two amps. They have been in there since the early 80s.
I found a reference at Antique Electronic Supply that says GEC produced the Gold Lions through the early 80s, so I am going to assume your tubes were made by GEC, rather than New Sensor
.
Not sure if this is a good example but I liked it.
I ordered the KT88 one from Sweetwater for guitar but I'll use at home for bass too.
I ordered the KT88 one from Sweetwater for guitar but I'll use at home for bass too.
