Quad preamp tube replacement

[ak47]

Hey,

Just thought I would share my recent Quad preamp re-tube with you.... it sounds better than the day I bought it (going on 17 years ago!!). This is such an easy way to breath new life into your sound. It is also really cheap considering that you can do it all yourself and experiment with different tubes in different positions until you find what you like. Now it is as if every frequency is fully represented with a perfect balance and when I select a note, those frequencies open up a sweet spot that unites every particle in the room... awesome!!

Big plug.... Many thanks to Doug at http://www.dougstubes.com/ for his advice and good prices! He is a really knowledgable and helpful enthusiast if you want to check him out....

I made the following selection after some painstaking experimentation (all 12ax7's):

V21 input tube for channel 1 clean.. GT 12ax7C with balanced triodes at plate voltage.. 90/90 clean and headroomy with some woolyness if pushed.

V23 channel 1 lead.. GT with 100/100 balanced triodes... more gain and that type of harmonic content that bites in a juicy way... think brown without the mud

V11 input channel 2 rhythym.. tung sol balanced 110/110 makes for a nice hot signal and is deep and toneful. Great to put through my Mesa strategy 500 power amp flat out on half power with the grindier channel selected!

V13 channel 2 lead.. tung sol balanced 105/105 lots of shred tones here!!! Doesn't need to much drive as single notes just sing out and again, are fully represented harmonically. No mosquitoes here! Plus it is huge for riffing!

V12 channels 1+2 to the fx loop.. electro harmonics russian 12ax7 110/110 giving a nice push so as to drive the effects loop

V22 effects return and output.. tung sol 105/105 to push the output along and keeping the signal rich and intact

V14 EQ and reverb mixer... electro harmonics russian 12ax7 unbalanced plate voltage 105/110

V24 reverb driver and return.. tung sol 100/100 this thing has two reverb tanks and the depth is now suprizingly big and organic... enourmous depth available!

As you can see, I am running channel 1 (clean and lead 1) with groove tubes and channel 2 (rhythym and lead 2) with tung sol's. This really opened up the tonal spectrum for me and I would highly recommend it to others using the Mesa Quad. I run the Quad into a Mesa Strategy 500 which has grey Mesa 6550-A's and yellow Mesa 5881-6L6's with GE JAN 12ax7WA's for the two different channels. This drives a Marshall 4x12 and Marshall 2x15. I can pull pretty much any sound I want now and not only is everything noise free it is dynamic and toneful. Not so portable but set it up and it does the job marvelously!

It certainly works for me but of course everyone has their own vibe... so I'm interested in what other experiences people have as good alternatives.

 

[MetalMatt]

Very helpful. Thanks!

 

[rigmarole]

I registered here just to thank you ak47!

I've owned around four Quads over the last thirteen years.
I buy them, then especially when younger, I'd sell them when I moved out-of-state or was low on funds.
But, they are fantastic preamps and thanks to Ebay, about a year ago I got a keeper.

The Quad has a retube in it's future and the only spare tubes that I have around are 2 old JAN 12AX7s...
I believe the stock tubes in the Quad I bought are Sovtek chinese.
(which have always seemed harsh and brittle)

Ch 1 Rh/Ld actually sounds OK, but I can't get creamy distortion that I remember out of Ch2 Rh/Ld.

I may just call and order the same driver tubes as you to try them out.
Thanks for the guidance!

One final note for anybody lusting after the old Simul-Class 295 Power Amp:
I played one for years in the mid-90s and never warmed up to it.
(then again, it had the original tubes that I never changed)
After years with that one, I used three different Rocktron amps that I didn't so much care for either.
When I got this Quad, I bought a used TubeWorks to hold me over until I could get a "real" power amp
and I like better than any other power amp that I've tried.
It's smooth, not grainy... warm & taut bass, not compressed or flubby.
For a "cheap" power amp, I highly recommend it.

Regards...

 

[ak47]

Wow!

It feels good to know that these forums really are helpful... I've certainly picked up loads of info and hope that others pass on their constuctive thoughts also...

Of course there are some argumentative egos out there too (you know who you are...!!) but that usually just makes for funny reading anyway!

I used to use my quad with a Mesa 50/50 ... a formidable combination! Usually pretty cheap these days and easily maintained. Would love to try it through one of the newer Mesa power amps with EL34's though.... anyone tried this???

Rigmarole... 4 Quads?!? Yep... changing gear is like changing girlfriends isn't it... usually you find the favourite (...and sometimes keep something on the side!!)

For a creamier sound I usually roll off the gain a bit and use an old Boss super overdrive which also gives my picking a nice attack. Push up the gain again and it really shreds!

Also, you may wish to check out the 'new sensor' produced Mullard 12ax7's. I couldn't get them last time I was in the states, but they might be worth a look. Again... anyone tried these ones out??

 

[crane]

I'm testing a couple of tubes for my Quad. I'll let you know my perfect setup for this little one (is 3U "little" ? :roll: )

 

[crane]

Ok, made a few tests with a couple of tubes.

V21 (channel 1 input) : Rythm 1

12AX7

Tungsol 12AX7 reissue: original tube here when I bought the Quad. Good definition, power, but too much compression for my taste, and with my active pickups too much gain when using powerchords.

JJ ECC83S: Just for testing it. EEeeeeekkkk...... few bass harmonicaly poor. I stopped the test here.

12AT7
These tubes are often my favorite for input, they are clear, good definition and more dynamic that the 12AX7, adding 3D space to the sound. But for sure you loose a bit gain. But it won't tell that there won't be enough, or even more when engaging the drive tube. AT7 tend to saturate further stages a bit more.

JJ 12AT7: Good tube. Good bass response (maybe a bit too much), clear sound. Unfortunnately this tube seems microphonic so it can't be a real candidate...

EH 12AT7: Clear sound, less bass than the JJ. Seems microphonic too.

JAN Philips 12AT7 (blackplate/greyplate): very good definition, cristal clean, but they are very focused on highs, especially the greyplate. Tend to sound funky like a strat even with my PRS/EMG60.

JAN GE 12AT7: More equilibrate than the previous JAN, but sounds a bit "thin".

NOS Mullard 12AT7WA: Definitely a winner for me. Very good balanced sound, good bass, mids and trebs, sparkling without being aggressive. High dynamic and good definition. Clean sound even at full range volume !


V11 (channel 2 input): Rythm 2

Tungsol 12AX7 reissue: original tube when I bought the Quad. Good power and attack but lacks definition and has a too big "grain". Sorry for my english ^^ : it's like the overdrive texture looks like big rocks more than sweet sand.

JJ ECC83S: Again, this tube is very poor harmonicaly speaking. Clean 2 definitely lacks something with that tube.

Ei 12AX7: Good tube, approaching what I'm looking for: better definition, good attack and not too raw. Not the best one for me but interressing ! Good choice when coupling to another one in V13 for a brutal and raw Lead 2 !

EH 12AX7: My favorite here. Good attack and less muddy bass, a bit more high mids too, leading to a better definition. Perfect for a good crunch coming out of the mix !


Overdrive tubes

This place is critical for "the overdriven sound you want". Overdrive texture and gain amount depend essentialy of this tube and the input tube. So every tube can sounds good to your ears. I personnaly choose my favorite input tube and then find the better choice for the drive tube.


V23 (channel 1 drive tube): Lead 1

Tungsol 12AX7 reissue: Good gain, a bit fuzzy. Much more "big rocks" than "sweet sand" ^^

JJ ECC83S: I personnaly hate these tube that comes with when I bought the Quad. Good gain, a bit more full/dark than with the Tungsol, but lacks something. Harmonicaly poor again ?

Ei 12AX7: Well this tube is pretty cool for that kind of position. Lacks bit "bump" when palm mutting, but makes the sound cut through the mix and add a lot of gain to the Quad. My favorite.

Ruby 12AX7C5: Lot of gain. Makes the sound less raw, more "sweet" without attenuating it.

EH 12AX7: Lot of gain, cuts due to the high mids boost. A bit fuzzy.


V13 (channel 2 drive tube): Lead 2

I find that sound muddy, definitely lacking precision, so I tried to find a tube combination that can remove it.

Tungsol 12AX7 reissue: same as for Lead 1

JJ ECC83S: same as for Lead 1

Ei 12AX7: Pretty good here. Add some definition, good amount of gain.

EH 12AX7: The winner. Lot of gain, very good definition, remove that mode's muddyness. Cutting sound too.

----------------------------------------------------------------------------------------------
Well, I still have some tubes to test (sovtek 12AX7A, Mullard reissue, ...) for this emplacements, and of course the other 4 tubes in the Quad (reverb driver, EQ/rev. mixer, output tube and channels to EQ). Hope I do have some time soon to do it !

 

[HSL]

Old thread but this is due for a bump, very helpful.

I just placed a big order at Doug's Tubes. Here's what I got:

1x Tung Sol 12AX7 re-issue
2x Ruby 12AX7AC5 HG+
1x Penta 12AX7M
1x Penta 12AX7
2x JJ ECC83 standard
2x JJ ECC83 high-gain
1x Mullard 12AX7
1x Electro-Harmonix 12AX7


Swapping all of these around and giving tests is going to make me vomit! I'm not sure what will be going where. I'll have a field day and see what happens, but chances are that I'll spot a big difference in one tube compared to the next. I'll probably end up placing another order for trying out those tubes in other spots in the Quad pre

 

[rick quad]

how do you know which tube socket is lead 1, rhythm 1 or whatever? sorry if this is a dumb one, but i couldn't figure it out.

 

[crane]

Get the schematic at tubefreak