Pre amp tubes tests

rgalpin · Post by **rgalpin** » Tue Apr 03, 2007 11:15 pm

These are samples of various preamp tubes in V1 V2 and V3.

http://www.soundclick.com/bands/pagemus ... dID=684549

They are tung sol 12AX7s, electro harmonix 12AY7, and 12AU7 and an NOS 5751 brand? (i'm not sure).

i named them with a convention: V1_V2_V3

i accidently labeled the 12AX7s as A. should have been X.

so the clip called A_A_Y is:
12AX7 in V1
12AX7 in V2
12AY7 in V3

i prolly coulda fixed it in the time it took to explain it... anyway... hope the results are interesting. please excuse the playing - i think some of the clips might even be in tune.

rgalpin · Post by **rgalpin** » Wed Apr 04, 2007 8:02 am

as i was doing these i was 2nd guessing using the VH Dr. Riff - because although my current "wood" quest partly comes from hearing ed use it - it's obviously not a classic ED tone - but i used the DR. riff anyway because that's what i have been using on previous tests and it allows me to compare apples to apples - but i think i'll start incorporating some other riffs in the tests from now on.

the .1PI has zero knock. duuuude - that is what i have been using for like 2 years or something... i couldn't believe it when i hooked it up and heard that paper-ish fizz.

i need to try a Y-A-5751 with the .02 v1 coupler. the Y-A-5751 was my favorite. there was a cool color to the high mids - i think you could "hear the fingers."

actually i think i will go through the whole range again with the 02 coupler to see how they compare.

Tone Slinger · Post by **Tone Slinger** » Wed Apr 04, 2007 9:19 am

Man, great , very informative post! I think the A-A-5751, has the most gain, grind and heft. The Y-A clip did sound unique. the last clip,U-A-5751, had a lot of that natural wood tone, but also sounded the least gainy. So these clips all were done with the .1 PI caps ?

rgalpin · Post by **rgalpin** » Wed Apr 04, 2007 10:04 am

Tone Slinger wrote:So these clips all were done with the .1 PI caps ?

no, they were all done with 022 PI caps - except for the one that indicates .1 PI caps in the title. and it's the one that sounds like somebody pulled the cork and it's sliding downhill in wrapped in old newspaper. could be the combo of .1PI with 12AU7 in v3 - maybe the big caps need to be pushed harder - dunno.

I got some KT-88s to test in the power section tonight.

harddriver · Post by **harddriver** » Wed Apr 04, 2007 10:20 am

rgalpin wrote:
Tone Slinger wrote:So these clips all were done with the .1 PI caps ?
no, they were all done with 022 PI caps - except for the one that indicates .1 PI caps in the title. and it's the one that sounds like somebody pulled the cork and it's sliding downhill in wrapped in old newspaper. could be the combo of .1PI with 12AU7 in v3 - maybe the big caps need to be pushed harder - dunno.

I got some KT-88s to test in the power section tonight.

So you still feel the .1uf caps aren't doing it? I will be curious to your finds on the KT-88 which are the Europeon version of the 6550. I am curious if they will provide the wood tone I suspect they would especially since you can drive them harder with the weber. The KT-88's tend to be a tad warmer than the GE6550 which is good thing.

Remember you need to increase your negative bias about 10 volts for the 6550 wiht a bias range of -44V to -55V and they recommend changing the the feedback wire to the 4 ohm leg. I am not sure how you have your NFB wire hooked up in your current configuration.

Lets us know how it goes, gotta get back to the bench fianlly wiring the 12 series heaters.

harddriver · Post by **harddriver** » Wed Apr 04, 2007 10:30 am

I liked the AA-5751 gave you the most wood tone. It reduced your gain in the direction you want to go. You ma want to go back to a 12ax7 for the kt-88's.

I say whatever gets you to the tone you like, if eddie did everything the way it was supposed to be done he wouldn't have had the tone he did, LOL!

Thats weird that the .1 would make it thinner sounding since it is a Super Bass spec. I thought the .022 was the evolution to making Marshalls brighter for guitar(super leads).

The .1's did sound thinner, are they sozos or mustards caps? I have read if you solder the sozos to many times close to the body they tend to leak and lose bass response. Could this possibly be the case? There was a thread on it somewhere.

rockstah · Post by **rockstah** » Wed Apr 04, 2007 10:37 am

my take is the .1u give the amp the full drum sound so to speak.
.022 are the head of the snare and .1u are the full drum. going for evh i hear the drum. going for someone like lynch or rhoads i hear the .022u.
for ed i hear a dialed 12 series with .1u's. and this is my basis for the tones. to me they both knock.

going for which ever superlead/superbass i start there in the output and tweek the circuit around them.
its my experience... and for the record i disgree with all y'all that say evh is .022u in the PI
my 2 cents.

Mark

Tone Slinger · Post by **Tone Slinger** » Wed Apr 04, 2007 10:43 am

Well the kt-88's as well as the true 6550's, have a different string of harmonics than a EL-34, so they may not sound the right way in the mids. The 6ca7, to me, is the furthest departure one can take, without completly losing that EL-34 type tone.

Tone Slinger · Post by **Tone Slinger** » Wed Apr 04, 2007 10:49 am

I agree with Mark about the PI caps. I think the tone stack may be the part that is more confusing, like 56/250 .1 PI may be too much, but the 33/500 .1 PI might be better. I definatley wouldnt use the 33/500 with the .02 caps, as that is too far the other direction.

rockstah · Post by **rockstah** » Wed Apr 04, 2007 10:51 am

Tone Slinger wrote:I agree with Mark about the PI caps. I think the tone stack may be the part that is more confusing, like 56/250 .1 PI may be too much, but the 33/500 .1 PI might be better. I definatley wouldnt use the 33/500 with the .02 caps, as that is too far the other direction.

+1

harddriver · Post by **harddriver** » Wed Apr 04, 2007 11:02 am

Tone Slinger wrote:Well the kt-88's as well as the true 6550's, have a different string of harmonics than a EL-34, so they may not sound the right way in the mids. The 6ca7, to me, is the furthest departure one can take, without completly losing that EL-34 type tone.

Rgalpins is trying for that super woody knock in the Largo MD show. The Sylvania 6ca7 did have 6550 plates in their internal construction. There was definable difference in ED tone in that show or a least the clip he posted. Probablt the cleanest/distortion amp tones I have heard out of ED compared to other shows I have heard. Just my opinion.

There is a guy who posted a 1959HW with Kt-88's into a hotplate set to load then fed a Marshall El-34 power amp. Sounded pretty good. I wish hea had not used a ZW wylde overdrive though I think the EQ would have been enough but it sounded good regardless.

harddriver · Post by **harddriver** » Wed Apr 04, 2007 2:30 pm

Hey Mark(Rockstah) hows the type II master sound since you moved it up front into your presence pot location?

Any extranious noise compared to it's original location?

zaphod777 · Post by **zaphod777** » Wed Apr 04, 2007 2:51 pm

Excellent post rgalpin.

Thanks!!!

rockstah · Post by **rockstah** » Wed Apr 04, 2007 3:06 pm

harddriver wrote:Hey Mark(Rockstah) hows the type II master sound since you moved it up front into your presence pot location?

Any extranious noise compared to it's original location?

funny you mention that. i not only moved it but didnt use shielded wire this time around. it sounds different in that i hear PO. may shield from the pot to the tubes.

oh also the 250k dual Log pot as Larry suggested is much better - many more usable lower volume levels. the log is more gradual sweep than the Lin which in comparison is on or off it seems.

Mark

rgalpin · Post by **rgalpin** » Thu Apr 05, 2007 9:00 am

harddriver wrote:Remember you need to increase your negative bias about 10 volts for the 6550 wiht a bias range of -44V to -55V and they recommend changing the the feedback wire to the 4 ohm leg. I am not sure how you have your NFB wire hooked up in your current configuration.

Lets us know how it goes, gotta get back to the bench fianlly wiring the 12 series heaters.

i posted KT88 clips in the Clips forum. i forgot about this info. i biased them for 35W dissipation at my plate voltage which measured 390. i didn't chnge the NFB wire. where did you hear that they recommend this change? any add'l info you have would help.

the clips sounded way more similar to the 6CA7s than i had hoped - and they sounded like they were biased too hot. i didn't get the WOOD i was hoping for - but maybe it's a matter of correct setup... dunno.