Quieten the Express

Express, Liverpool, Rocket, Dirty Little Monster, etc.

Moderators: pompeiisneaks, Colossal

User avatar
67plexi
Posts: 780
Joined: Sun Apr 09, 2006 8:34 pm
Location: Juneau Alaska

Re: Quieten the Express

Post by 67plexi »

I never used can capacitors but on the Mallory's I used silver 16AWG
for my ground to the chassis no hum or hiss looks like a ground loop to me.
andresound
Posts: 701
Joined: Mon Dec 01, 2014 8:48 am
Location: Durban South Africa

Re: Quieten the Express

Post by andresound »

No Hiss? :shock: I'm suprised. Especially, if your express is loaded with AX7's
If it sounds good, it is good! Trust your ears
User avatar
donzoid
Posts: 497
Joined: Mon Mar 11, 2013 2:22 am
Location: Salem, Oregon

Re: Quieten the Express

Post by donzoid »

I got a *lot* of mileage from what BobS suggested-- I had my volume pot rotated toward the brite caps already, BUT the location of them is critical and chopsticking them around made a pretty huge diff.

Note I still have some hiss, but not intolerable, and I use a 12at7 as my PI.

Cheers!

doh! edit: changed presence pot to corrected "volume" pot...
Last edited by donzoid on Fri Jun 17, 2016 3:52 pm, edited 1 time in total.
https://www.facebook.com/trialbyfirerocks

Be sure your tinfoil hat has a good low impedance ground.
User avatar
Colossal
Posts: 5038
Joined: Sat Oct 20, 2007 9:04 pm
Location: Moving through Kashmir

Re: Quieten the Express

Post by Colossal »

donzoid wrote:I got a *lot* of mileage from what BobS suggested-- I had my presence pot rotated toward the brite caps already, BUT the location of them is critical and chopsticking them around made a pretty huge diff.

Note I still have some hiss, but not intolerable, and I use a 12at7 as my PI.

Cheers!
Don, how do you find the tonal change with a 12AT7 versus a 12AX7 for your phase inverter?
User avatar
donzoid
Posts: 497
Joined: Mon Mar 11, 2013 2:22 am
Location: Salem, Oregon

Re: Quieten the Express

Post by donzoid »

Dave,
I have a lot more precise control over the level of grit in the sweet spot (around 10:30 to 11:00 on the amp vol) on the guitar vol. pot; to dial in the most versatile range across my guitar volume.

Then I clamp down on the amp with the airbrake 2 clicks, AND have a VVR installed trimming about 20% of the volts - always using 6v6's. That is the closest I can get to "unbridled" for the tone and the behavior and retain the "in yo face" fairly clean tone at about 2.5 on guitar vol. on up to a real nice high gain at 7, I just tried a 5751 at the last gig, but as with the 12ax7 it's just too much gain - I can't dial it as precise, so I'm back to my old stock military Sylvania 12at7.

I run g12h30's in a 2-12, and when its 4-12 its two g1230's and 2 g1265 circa 1980 in an angle. It rips pretty good. :twisted:
https://www.facebook.com/trialbyfirerocks

Be sure your tinfoil hat has a good low impedance ground.
andresound
Posts: 701
Joined: Mon Dec 01, 2014 8:48 am
Location: Durban South Africa

Re: Quieten the Express

Post by andresound »

FWIW, I too use a NOS MULLARD (old shield) 12AT7 in v3. I think this is the best my express has ever sounded. I find, like Don, I have more control. I can get more clean headroom. I have a VVR3 installed to cut volume. I have tried 12AT7 in V1, but the sound tends to "thin" out. Too clinical. It does however decrease hiss (obviously).
If it sounds good, it is good! Trust your ears
User avatar
Colossal
Posts: 5038
Joined: Sat Oct 20, 2007 9:04 pm
Location: Moving through Kashmir

Re: Quieten the Express

Post by Colossal »

donzoid wrote:Dave,
I have a lot more precise control over the level of grit in the sweet spot (around 10:30 to 11:00 on the amp vol) on the guitar vol. pot; to dial in the most versatile range across my guitar volume.

Then I clamp down on the amp with the airbrake 2 clicks, AND have a VVR installed trimming about 20% of the volts - always using 6v6's. That is the closest I can get to "unbridled" for the tone and the behavior and retain the "in yo face" fairly clean tone at about 2.5 on guitar vol. on up to a real nice high gain at 7, I just tried a 5751 at the last gig, but as with the 12ax7 it's just too much gain - I can't dial it as precise, so I'm back to my old stock military Sylvania 12at7.

I run g12h30's in a 2-12, and when its 4-12 its two g1230's and 2 g1265 circa 1980 in an angle. It rips pretty good. :twisted:
andresound wrote:FWIW, I too use a NOS MULLARD (old shield) 12AT7 in v3. I think this is the best my express has ever sounded. I find, like Don, I have more control. I can get more clean headroom. I have a VVR3 installed to cut volume. I have tried 12AT7 in V1, but the sound tends to "thin" out. Too clinical. It does however decrease hiss (obviously).
That's great! Sounds like it added some more versatility.
User avatar
David Root
Posts: 3540
Joined: Fri Aug 04, 2006 3:00 pm
Location: Chilliwack BC

Re: Quieten the Express

Post by David Root »

Anyone ever try a 12AY7 in the PI? Or would that be too little gain?
Current draw would be closer to a 12AX7 and a triple mica 6072 should absolutely minimize noise.
When I was a boy I was told that anyone could become President. I`m beginning to believe it--Clarence Darrow
User avatar
donzoid
Posts: 497
Joined: Mon Mar 11, 2013 2:22 am
Location: Salem, Oregon

Re: Quieten the Express

Post by donzoid »

The only thing that's prevented me from trying the 12AY7 is ...you guessed it...not having one on hand but I have also been curious about this for more 'n a year. Maybe someone reading this thread has tried it...?
https://www.facebook.com/trialbyfirerocks

Be sure your tinfoil hat has a good low impedance ground.
User avatar
RJ Guitars
Posts: 2662
Joined: Tue Nov 14, 2006 3:49 am
Location: Los Alamos, New Mexico
Contact:

Re: Quieten the Express

Post by RJ Guitars »

I have built a few of these amps and despite the fact that I occasionally push back against the purist approach to Trainwreck building, I have found that I get the best sound with a 12AX7 in every preamp hole as well as the PI hole, in a standard EL34 Express build. It takes a willingness to use the guitar volume control liberally to make it work but I have grown comfortable with that over time.

However, in my lower wattage variants of these amps I've found the 12AY7 to be critical in the V1 hole. I also tend to do a few other things to knock down the signal going into and out of the phase inverter so that the smaller output tubes are not hit too hard.

So far I haven't found a 12AT7 that I like the sound of in an Express... these seem to mess with the voltages so much that it would probably require some tweaking before I could say I've given it a fair shot.
Good, Fast, or Cheap -- Pick two...

http://www.rjguitars.net
http://www.rjaudioresearch.com/
http://diyguitaramps.prophpbb.com/
User avatar
donzoid
Posts: 497
Joined: Mon Mar 11, 2013 2:22 am
Location: Salem, Oregon

Re: Quieten the Express

Post by donzoid »

RJ,

I am shocked.... :lol: taking up sides with the purists now are ye?

Yeah I tried a few flavors in V1 and when I reversed the at7 (in V1) and the ax7 in PI, it was .. well...Pewwww. Way too surgical and thin as andresound said.

I have done a couple other things besides the AT7, but that one in that position works best on both the 6v6 and el34's - I think the selection of this tube is really, really important - I've had great results from using Telefunken, RFT, Sylvania's and RCA's. If it's old stock, its been good so far.
https://www.facebook.com/trialbyfirerocks

Be sure your tinfoil hat has a good low impedance ground.
User avatar
donzoid
Posts: 497
Joined: Mon Mar 11, 2013 2:22 am
Location: Salem, Oregon

Re: Quieten the Express

Post by donzoid »

...For David and those who may have been curious ...

Last weekend I came into a 12aY7, and was a pretty skeptical as the gain on this tube is 44 vs. the aT7 at 60-61% (and of course the ax7 being 100%).

Its a good one, old stock GE so I ran it in the PI for about a half hour.


Well, its still in there. I am surprised by how good it sounds. Initial impression is this is as good and as functional in terms of control over gain structure (from the guitar volume pot) as the aT7. I really thought it would be nasty thin and like a 12aU7 but it is worth more tests, so it will stay in until the next gig or I make a def. decision. In all its a contender for me!

Makes me wonder now, I have a 12az7 but had read that it needs higher heater volts or current ... maybe I'll try it too after I go look at the datasheet.
https://www.facebook.com/trialbyfirerocks

Be sure your tinfoil hat has a good low impedance ground.
andresound
Posts: 701
Joined: Mon Dec 01, 2014 8:48 am
Location: Durban South Africa

Re: Quieten the Express

Post by andresound »

Watching with interest 8)
If it sounds good, it is good! Trust your ears
andresound
Posts: 701
Joined: Mon Dec 01, 2014 8:48 am
Location: Durban South Africa

Re: Quieten the Express

Post by andresound »

Watching with interest 8)
If it sounds good, it is good! Trust your ears
bluesfendermanblues
Posts: 1314
Joined: Tue May 22, 2007 12:57 pm
Location: Dumble City, Europe

Re: Quieten the Express

Post by bluesfendermanblues »

donzoid wrote:...For David and those who may have been curious ...

Last weekend I came into a 12aY7, and was a pretty skeptical as the gain on this tube is 44 vs. the aT7 at 60-61% (and of course the ax7 being 100%).

Its a good one, old stock GE so I ran it in the PI for about a half hour.


Well, its still in there. I am surprised by how good it sounds. Initial impression is this is as good and as functional in terms of control over gain structure (from the guitar volume pot) as the aT7. I really thought it would be nasty thin and like a 12aU7 but it is worth more tests, so it will stay in until the next gig or I make a def. decision. In all its a contender for me!

Makes me wonder now, I have a 12az7 but had read that it needs higher heater volts or current ... maybe I'll try it too after I go look at the datasheet.
On paper 12ay7 should be "weaker" than a 12ax7. However, the 12ay7 draws a lesser amount of current, consequently the anode voltage level will be higher in comparison to a 12ax7.

All in all, the real signal diffidence between "ay" and "ax" is not that big, but the sound of the ay is IME more mellow with bigger midrange.

I've purchased a couple of ol' (not NOS) GE 12ay7's and really like their sound in a couple of Express/Bassman/Marshall 5f6a-based amps.
Diva or not? - Respect for Mr. D's work....)
Post Reply