octal preamp tubes

Post by **zaphod_phil** » Thu 09/08/05 5:28 pm

markd wrote:We all know that's the poor bugger that you butchered... er, I mean improved, recently. ha!

Right, on both counts!

But you still don't know what it was/is...

And I regret to say that it contains no octal tubes - struggling desperately to keep this on topic somehow...

dartanion · Post by **dartanion** » Thu 09/08/05 5:39 pm

I wouldn't let the mu factor turn you away from the 6SN7. If it sounds good, go with it. I found them to have a very pleasing tone in my 5F1, just unreliable.

Post by **zaphod_phil** » Thu 09/08/05 5:46 pm

Yes, but I like a bit more gain than that, and there are other great sounding octal preamp tubes around to chose from.

OK, I found the thread you wanted, about how to shock mount - http://www.18watt.com/modules.php?name= ... pic&t=4744

I've also attached a close-up from a picture someone else posted of a shock-mounted EF86 - sorry, I don't remember who...

dartanion · Post by **dartanion** » Thu 09/08/05 8:24 pm

Coolio ZP!

So it is basically rubber washers between the socket bezel and the chassis and on the socket bolts.

According to Dan at 65, there is an usually high reject rate in many of the octal pres. They just buy in bulk and weed out the bad ones. They don't shock mount any of theirs. Maybe this will help, maybe it won't?

novemberrain · Post by **novemberrain** » Thu 09/08/05 10:25 pm

FWIW my two faves are the 6SC7 and the 6SL7. Low gainers like the 6SN7 don't even make my list although there are plenty of applications for 'em. Same with 6SJ7s, 6SQ7s and the like, I got tons of 'em but WHY BOTHER?!

Now the creme de la creme is the 6SC7. YES they tend to be microphonic, NO they don't make them any more not anywhere and I suspect no one has made any since around 1960 or so. YES you'll have to weed through a lot of 'em to find a good one but once you do IMHO it's worth it, can you say, "Balls like a billy goat"?! Sure you can!

12AX7s obviously have more gain but the excess gain actually thins out the tone a bit, that's why some musicians are raving about various 5751s, gain wise they're close to 6SL7s and 6SC7s.

If octal preamps weren't cool Two Rock wouldn't get over four grand for amps with 'em!

maglemer · Post by **maglemer** » Fri 09/09/05 2:43 am

I have tried some of the tubes mentioned here: 6SJ7, 6SQ7, 6SL7 and 6SN7, all with good results. I use a 6SJ7 as the first tube in a Matchless Lightning clone which is now my absolute favourite. I have a bunch of these pentodes and was surprised how different they were: my RCAs gave a harder, harsher and more evil gain compared to my Sylvanias, which I like much. And the triodes are in a separate pre-amp with parallell channels: one with the two 6SN7 stages and the other with the 6SQ7 and the half 6SL7, the second half used as a mixer. With the 6SN7 I can get an open, airy and "big" sound with crystal clear highs, and the 6SQ7/6SL7 channel is really fat and more middy, and of course has much more gain. So I think these are all very usable.

Johan

HBamp · Post by **HBamp** » Fri 09/09/05 3:02 am

When you ever have the chance listen to a Gibson GA-20 Crest amp into a good speaker cabinet and forget about TMB contols and Master volume's.

Henk

Hbamps

DutchMarco · Post by **DutchMarco** » Fri 09/09/05 3:24 am

HBamp wrote:When you ever have the chance listen to a Gibson GA-20 Crest amp into a good speaker cabinet and forget about TMB contols and Master volume's.

Henk

Hbamps

I disagree. Simplicity is important, but you just mentioned some things I've found necessary! MVs are standard issue on everything I make (mostly vintage styles so no high gain pres) simply because I have no opportunity to crank any amp, not even the Champ during band rehearsal.

I also like some form of tone shaping ability, the Champ doesn't have any and I do miss that.

But I'm not into high-gain preamps etc. Don't like Satriani's tone, in spite of some nice tunes.

I'll have a look at the GA20 schem to see what you mean

DutchMarco · Post by **DutchMarco** » Fri 09/09/05 3:27 am

zaphod_phil wrote:Right, on both counts! But you still don't know what it was/is...

And I regret to say that it contains no octal tubes - struggling desperately to keep this on topic somehow...

In spite of only using noval (preamp) tubes, I must say that's a nice karaoke machine you've made, Phil!

Helps disguise your playing?

pedro · Post by **pedro** » Fri 09/09/05 4:12 am

Phil's avatar -

looks Mercurial to me ....

but suspect its now a sleeper in disguise.

but the grill cloth looks wrong for a Mercury ?!

Pete

Post by **zaphod_phil** » Fri 09/09/05 4:25 am

deleted

HBamp · Post by **HBamp** » Fri 09/09/05 4:58 am

Marco Wrote,

I have no opportunity to crank any amp, not even the Champ during band rehearsal.

I 'am used to do it like that, so to me it's no problem at all

I also like some form of tone shaping ability, the Champ doesn't have any and I do miss that

Spend some time to redesign the champ to your own needs Marco.
Thats is what I do basicly when a amp is not sounding right.
Works fine for me and most of my customers. After that you don't need TMB controls anymore and a simple tone contol is more than enough.
Ever tryed to get the tone you realy want with a Mess a Boogie

?

Where do you live in the Netherlands Marco?
Would be nice to know.

Henk,

Hbamps

pedro · Post by **pedro** » Fri 09/09/05 5:35 am

Phil,

my guess is you've used the one EL84 already in the mercury and ripped out the solid state front end made a supercharged SE El84 combo ?

Either that or you gone all Randall Smith on us and squeezed a 50watter into the box !! ( ive just done that with the old Proamp Viper carcass )

Love to hear clips.....

Very OT now - so maybe i should mention the word OCTAL at this point.
Rgds
Pete

Post by **zaphod_phil** » Fri 09/09/05 5:51 am

Well, at one point I converted it into an AX84 P1 variant, but with tremolo. So that's pretty close to what you described. With the original speaker replaced by a vintage G12H-30 it was amazingly loud. I used to call it the doorshaker! For quite a while I've just been using it as an experimental platform, but now it's basically become a Lite IIb, again with added tremolo. It has fantastic tone and touch response.

pedro wrote:Either that or you gone all Randall Smith on us ...

Please don't associate me with that character. Just today I saw an ad for the new Meza Lonestar that had "Pat pending" written next to "Class A". So Randall wants to patent Class A now???

novemberrain wrote:Low gainers like the 6SN7 don't even make my list although there are plenty of applications for 'em. Same with 6SJ7s, 6SQ7s and the like, I got tons of 'em but WHY BOTHER?!

6SJ7s are pentodes, unlike the others you mentioned. They have plenty of gain, and provide natural compression, as well as adding a lot of richness into the tone. You should really look into them.

Hey we're back to octals again!

tubetwang · Post by **tubetwang** » Fri 09/09/05 6:31 am

I've been using those red silicone red rings for years. 50 cents each at Audioville. Some dudes pick them up at auto parts store.

I also uses Herbie's Audio Lab for my pro sound tubes.http://herbiesaudiolab.home.att.net/

novemberrain · Post by **novemberrain** » Fri 09/09/05 7:41 am

zaphod_phil wrote:
novemberrain wrote:Low gainers like the 6SN7 don't even make my list although there are plenty of applications for 'em. Same with 6SJ7s, 6SQ7s and the like, I got tons of 'em but WHY BOTHER?!
6SJ7s are pentodes, unlike the others you mentioned. They have plenty of gain, and provide natural compression, as well as adding a lot of richness into the tone. You should really look into them.

As usual Phil, you're absolutely right!

I've been avoiding EF86s 'cuz I don't have many and if I want more I'll have to spend green money for 'em! On the other hand I have a pretty good stack of 6SJ7s rattling around in my tube stash, I guess that makes 'em a "poor man's pentode"!

s2 · Post by s2 » Mon 09/12/05 10:12 pm

Here's where I am with the octals...

My stash of used and NOS 6SN7s have all gone microphonic on me after just a few hours playing time each. I'm bummed. They were 1 RCA, 3 GEs, 1 Tung-Sol, and 1 CBS. All of them went gross and I'm even going easy on them in terms of voltage and current.

I thought I had ordered a good selection of new production tubes, but it turns out I only ordered EH 6SN7s and a good selection of EL34s. One of them is pretty bad in terms of microphonics. Both of them have hum problems. The old stuff doesn't hum, so I'm a little confuzzled about these tubes. I had heard the EH tubes were very good for noise and microphonics. So much for that.

But my GOD they sound rich, fat, and smooth! Very complex. Awesome sound. Just too noisy.

So, I'm stuck at a crossroads (and really could use some hints from Mr. Macchio). Do I order a pair of every current manufacture brand and keep testing them or do I give it up and switch to 12AU7s? They have the same mu, so all I would have to do is replace the sockets for this design. Hmmm...

DonR · Post by **DonR** » Mon 09/12/05 11:04 pm

S2,

You need to borrow the tubes out of my tv front deluxe - sarge got them of some old feller 1945 issue nos fire surpression equipment mil spec.

they are not microphonic - just expensive:) and they got the sound your after-----

DonR

s2 · Post by s2 » Mon 09/12/05 11:16 pm

DonR wrote:S2,

You need to borrow the tubes out of my tv front deluxe - sarge got them of some old feller 1945 issue nos fire surpression equipment mil spec.

they are not microphonic - just expensive:) and they got the sound your after-----

DonR

Aren't you supposed to be on vacation?!

DonR · Post by **DonR** » Mon 09/12/05 11:22 pm

this is vacation-

wife and kids asleep, shot an 88 on one tough golf course on a gorgeous day in Telluride, played my s2 modded blues jr with my 56 LP, great dinner out - now, if I can just wake up the wife-----------

DonR

Donations

Links

Welcome

octal preamp tubes