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Electro Harmonix KT88 ?

#2
My last purchase was for a set of cryo winged C's for my old simms watts ap 200 I took the original GEC's out as one had just started to red plate at optimal bias to the other tubes.
Two of the winged C's drifted a little so after about eight months
use in the busy rehearsal room being thrashed by all.
I put the two best GEC (date code oct 1971). back in because they bias well with the two best winged C's.
Two Years later same set in still running fine.
JJ would be my next choice but the real best ones are still the
old GEC Genalex type.
They last for absolute ages and sound fooking great!.
Trouble is all the single ended tube hi-fi nerds have put the prices for NOS GEC sky hi.
I don't know if the Cryogenic treatment helps reduce the
drift in new production tube sets.
But my feeling is new production tubes need all the help they can get.
:bassist:
 
#6
I actually "borrowed" a set of JJ KT88 from a buddy and put them in my Orange Ad200. A BIG difference over the SED6550 that were in there. Much better mids, less boomy in the low end...just much more clear and defined. Before it sounded mucky, now it sounds clear and punchy.
Not sure if JJ's are the best for the application, but it sure seems to like KT88 ( either that or it really doesn't like the SED's)


Perhaps the thread title should be "best current KT88"
 
#7
CL400Peavey said:
I would love to see a run down on 6550's and KT88's. Retubing my Classic 400 is in the future and I need an octet. :bawl:
Click to expand...

Check these links out, there mostly views from guitar players, but there are some views, from bassists..... a few years ago a friend of mine installed 8 GEC KT-88's in his tweed 400 and when we scoped it .... it was a clean 426 watts ... his comment was it's a clean sounding amp, and it breaks-up much latter than an SVT

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#9
jastacey said:
Check these links out, there mostly views from guitar players, but there are some views, from bassists..... a few years ago a friend of mine installed 8 GEC KT-88's in his tweed 400 and when we scoped it .... it was a clean 426 watts ... his comment was it's a clean sounding amp, and it breaks-up much latter than an SVT
Click to expand...

Thanks for the links. The CL400 is a beast. Tons of clean head room, and yeah you have to push it really hard to get it to break up. I blend in a bit of the second channel to get some grit at lower volumes.
 
#10
bassboysam said:
In my experience any tube can sound good or bad. You need a tech that knows how to test and match tubes and know how to properly bias them for optimal performance. If installed properly there should be very little difference, and likely nothing noticable in a band mix.
Click to expand...

I can tell you that there is a HUGE difference with the KT88's and the SED 6550 in my Orange. And both quads are matched and both sets properly biased in the amp. The 6550 were mucky uncontrolled in the low end, and it didn't "cut" at all. With the KT88's it cut through the mix and was clear and punchy.

I have also changed the stock Mesa EL34 tubes in my Mesa guitar amp to SED El34 with significantly better results (and also with my Marshall Plexi) So, in my experience, tubes do make a difference. But everyone's experience is different I suppose.
 
#11
Dallyd31 said:
I can tell you that there is a HUGE difference with the KT88's and the SED 6550 in my Orange. And both quads are matched and both sets properly biased in the amp. The 6550 were mucky uncontrolled in the low end, and it didn't "cut" at all. With the KT88's it cut through the mix and was clear and punchy.

I have also changed the stock Mesa EL34 tubes in my Mesa guitar amp to SED El34 with significantly better results. So, in my experience, tubes do make a difference.
Click to expand...

Quesiton: From what I have read your clean head room increases a bit with the KT88's versus the 6550's. Did you notice this with your Orange?
 
#12
CL400Peavey said:
Quesiton: From what I have read your clean head room increases a bit with the KT88's versus the 6550's. Did you notice this with your Orange?
Click to expand...


To be honest, I didn't as I didn't turn it up that loud...only to jam levels ( which is actually pretty loud). I just noticed much more clarity and more cutting cutting mids. Much less mucky and boomy. A great improvement in my eyes.
 
#13
Dallyd31 said:
To be honest, I didn't as I didn't turn it up that loud...only to jam levels ( which is actually pretty loud). I just noticed much more clarity and more cutting cutting mids. Much less mucky and boomy. A great improvement in my eyes.
Click to expand...

Im torn on power tubes right now. The CL400 already has a huge bottom end, but I dont think I need to add there, but if its going to add to already expansive head room I dont know if I want that either. I want some tube break up from the power section, but we are talking war volume at this point.

If I could I would buy a set of each to compare. But when a matched octed + tech time is considered its a fair bit of coin just for some tube rolling.
 
#15
bassboysam said:
Either way you will need lots of volume to get power tube breakup out of the Peavey. The difference between tubes will not have any significant impact on volume. If you can't turn it up you need to get a lower powered amp in the 50-100 watt range probably. 200 watts+ means quite a bit of volume to get power tube breakup.
Click to expand...

I understand this. I hit a 1515/66 with it right now and it will knock your teeth out standing right in front of it. Its more of a question about where the tubes will break up in reference to volume, and the trade offs in tone. Im not looking to get more volume out of the head, if I need more SPL I have a pre/power rig bridged at 1,600 watts.
 
#19
As i understand it 6550s in general will breakup sooner than true KT88s. i say true because the distinction between the two is not as clear as it used to be. for example the EH6500 and EHKT88 are very similar and I doubt you will notice an difference.

Between the JJ KT88 and EH KT88 i do not notice any increase in volume, the JJ has a bit more top end and a slight scoop in the low mids, but nothing that is noticable once any other instrument gets involved.
 
#20
Hi.

The Fame (Smarvo) BVH300 came with EHKT88's from the "factory".

Since the mica doesn't quite touch the glass (how could it, AFAIK 6550 internals in a different bottle) a few of the tubes were shorted in the transit.

Tapping the tube onto the palm of your hand realigns the innards nicely though.

1 of the 6 tubes didn't hold its bias after about 24 hours of operation, so it got swapped.
If the amp in question doesn't have individual bias test points & adjustment, You'll never know, and one such tube can ruin the whole set of tubes.

I have 4 EH's still in the amp and 2 Sovteks and it runs as strong as it did on day one, approximately 2 hours a week, so if You get a good set it's a decent low cost alternative for those of us who are on tight budget.

Would I spend money on a set of EH KT88's, NO.
Would I use 'em if someone gave some to me for free, YES. After testing of course.

Regards
Sam
 

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