There has been a lot of talk around here of creating a lower power Liverpool amp running 2 x el84s. Some have been trying different things like adding a LP Preamp to a 18watt Marshal PI and Power amp with mixed results. I have no idea what this amp will sound like when it's completed but thought I would share my progress and thoughts along the way for anyone interested. Any comments or suggestions would be greatly appreciated.
I had a 2 x 12 Marshall style combo cab lieing around along with a blank chassis for the cab. It should be interesting to hear a liverpool played through a open back combo cab. Speaker choices are up in the air so if anyone has any ideas on speakers or is using a open back cab on their Liverpool please let me know. So far I am drilling and punching the chassis and I have the trannys mounted and the boards mounted. The Power supply board is mounted over the PT and I devised a farady shield out of a piece of single sided copper clad board that mounts under the PS board. I hope to finish the chassis today
I used a stock Liverpool preamp board and tried to get it installed to give me as close to the original layout of tubes as I could get using a combo chassis.
This amp will also have the B+ scaled using one of my Variable Voltage Regulator boards.
Hey Dana, I'm more than a little curious about the results of your build. I have some XFMRs that should be cool for one myself. I've never read any of the O'Conner books and have no concept of power scaling. I presume that's what you're using that voltage regulator for. Will you beusing currently available tubes? I mean ones still in production or the NOS type stuff? I look forward to more reports on this spelling edit
All excellent things are as difficult as they are rare__B Spinoza
Noel Grassy wrote:Hey Dana, I'm more than a little curious about the results of your build. I have some XFMRs that should be cool for one myself. I've never read any of the O'Conner books and have no concept of power scaling. I presume that's what you're using that voltage regulator for. Will you beusing currently available tubes? I mean ones still in production or the NOS type stuff? I look forward to more reports on this spelling edit
Hi Noel
Yes the regulator makes the B+ variable but I hesitate to use the term power scaling. I also use mine to scale the whole amp not just say the power section which make make the circuit more versatile but requires adding another knob on on the front panel. This knob pretty much is the same thing as a MV which Ken didn't like in TW amps.
I probably will be using NOS tubes. I found a set of NOS GE pres and GE EL84s for my Liverpool and I am extreemly pleased with the way it sounds. I can't say it enough, tube choice is very important in these amps.
I had Heyboer make me a set of Trannys. The PT is identical to the 18watt Marshall tranny except that it was wound with a 300v tap and a 260v tap so I could run EL84s or 6V6s. The OT was wound to 10.5K to match the 5.2k used on 4 EL84s.
Hi Dana! I ended in my Liverpool 2xEL84 project to change PT to 2x250V instead of 2x300V. I posted my voltages to this forum some days ago to get comments of my voltages. It is nice hear that somebody is doing same kind of project with me. My Liverpool is like original but has aPPIMV in it. I do not know if it is useful but time will show. I have tested my amp only at bedroom level, but basic sound is promising though bright. You asked what kind of speaker is ok for your combo. I tested my Liverpool first with a 1x12" semi open Red Fang and did not like the sound. Then I changed to a 1x12" closed back Celestion G12H30 with better results. I think that a open back cab with a bright element like Red Fang is not the best alternative for this amp. Regards Harry
harryk wrote: Hi Dana! I You asked what kind of speaker is ok for your combo. I tested my Liverpool first with a 1x12" semi open Red Fang and did not like the sound. Then I changed to a 1x12" closed back Celestion G12H30 with better results. I think that a open back cab with a bright element like Red Fang is not the best alternative for this amp. Regards Harry
From hearing my Liverpool through a 4x 12 cab I am really wondering how it will take to an open back cab. I used Sammis in my last Marshall 2x12 combo and they sounded great. I was thinking of trying a set of the $20 Celestion clones . I guess I'll have to cross that bridge when I get there. It's just nice to hear comments of what people have already tried
Been working on a 1/2 Liverpool for a while now. Usually there's other things to do. IRS and so ...
So things aren't progressing too fast.
Anyway, here's a pic of the boards. Mainboard w. turrets, PS is a recycled pcb.
PT will be a 250V/120mA, several OTs to cross-check: 125ESE, Sovtek deluxe and a pretty hefty 10kOhm<-8/16Ohms.
Chassis will probably be a cannibalized 19" Telefunken device.
Other amps I have built: SE Champ w. bigger trannies (10-12W) and cascode booster, Hoffman's GA-5 variant w. diode rectis.
Sure will be learning a lot from your build!
Ciao
Martin
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I'd be working on mine, but I hardly even get to my bench. My garage is full of kitchen cabinet boxes. They should be done installing this week though, so I can get back to it...my bench and 1/2 power Liverpool. I am thinking of using a zener to limit my voltage as I have a standard 18watt PT.
Been working on a 1/2 Liverpool for a while now. Usually there's other things to do. IRS and so ...
So things aren't progressing too fast.
Anyway, here's a pic of the boards. Mainboard w. turrets, PS is a recycled pcb.
PT will be a 250V/120mA, several OTs to cross-check: 125ESE, Sovtek deluxe and a pretty hefty 10kOhm<-8/16Ohms.
Chassis will probably be a cannibalized 19" Telefunken device.
Other amps I have built: SE Champ w. bigger trannies (10-12W) and cascode booster, Hoffman's GA-5 variant w. diode rectis.
Sure will be learning a lot from your build!
Ciao
Martin
Hi Martin
Just keep on working at it and it will come. I use to own an amp parts and repair business back in the 80s and it is so nice now not to be under the gun trying to get an amp finished by a certain deadline. You can take your time and get it right without someone breathing down your neck or the phone ringing off the hook or trying to get orders out…..you get the idea. All good things take time and judging from your pics you got a great start. My brother builds a single ended Champ style amp that he calls” The Beast” and it really lives up to it’s name. He is running a 5879 pentode front end and it might be nice to compare yours with the cascode input and his with the pentode input.
dartanion wrote:Lookin' good Dana!
I'd be working on mine, but I hardly even get to my bench. My garage is full of kitchen cabinet boxes. They should be done installing this week though, so I can get back to it...my bench and 1/2 power Liverpool. I am thinking of using a zener to limit my voltage as I have a standard 18watt PT.
Hey Dartanion
Brother, have I been there. We gutted our kitchen down to the stud walls a few a few years ago and I feel for ya. Richie just went through the same thing a month or so ago. If you could only get contractors to do what they say they will do and when they say they will do it the world would be a better place. Hopefully we can get these fired up about the same time and compare notes.
Thanks man. We have been at this complete home remodel for 1 year now. We started Labor Day weekend 2006! We're nearing the end, but man has it been hard. We actually live in an RV on our front lawn for 5 months until we could move back in. That was fun
Contractors here really suck. No one is accountable for anything, especially getting the job done right and on time.
The Turbo Champ w. cascode booster is plenty loud for my livingroom. One of these days I have to compare it to one of these EF86 pentodes. Cascode and pentode should sound similar. loud&clear.
Cascode has very low noise and -guessing- probably less microphonic issues than pentodes.
El_Martin wrote:Tnx Dana, for your friendly words!
The Turbo Champ w. cascode booster is plenty loud for my livingroom. One of these days I have to compare it to one of these EF86 pentodes. Cascode and pentode should sound similar. loud&clear.
Cascode has very low noise and -guessing- probably less microphonic issues than pentodes.
Ciao
Martin
Actually the 5879 pentodes are a little better in regards to microphonics than the EF86s. There is also a EF804s which is supposed to be a low noise version of the EF86. I have heard that the cascode circuit gives you a pentode like sound. If you get a chance to make some clips of the Turbo Champ I would love to hear them sometime.
UR12 wrote:There is also a EF804s which is supposed to be a low noise version of the EF86.
You probably meaned EF806S
Larry
Hey Larry
No, I actually meant the EF804s. It has a different pinout than either the EF86 or the EF806s. The reconfiguration of the pins on the 804 was supposed to cut down on interelectrode noise and some how make for a sturdier base making the tube less microphonic. FWIW I have only tried one that was a NOS and it was still too microphonic to use
I got all of the front panel drilled and components mounted with a test faceplate. I should have my can caps and clamps in tomorrow from Mojo and will move on to drilling out the chassis for the tubes sockets, fuse holder, can caps and line cord.
spelling edit
All good things take time and judging from your pics you got a great start. My brother builds a single ended Champ style amp that he calls” The Beast” and it really lives up to it’s name. He is running a 5879 pentode front end and it might be nice to compare yours with the cascode input and his with the pentode input. 
