Liverpool Build Thread

[Raoul Duke]

Hi All,
In the spirit of trying to encourage those that are thinking about building (but like myself aren’t formally trained) to actually attempt a build - thought I’d document my first try at a TW-based circuit. Here’s how I got to this point:

I was first drawn to TAG about 4 or 5 years ago because I saw the PG YouTube video demoing 3 TWs - which led me to research the builder; Ken Fischer - which led me to acquiring a TW Express (3rd hand) built by Paul Vogel. This amp (Allison) fulfilled every expectation created by what I saw in that PG video and really hooked me - which led me to start researching how this “magic” is created - which led me here as a lurker. A couple of years later after reading many build threads and realizing how intimidatingly skilled pretty much everyone here is - I got up the courage to register and start my first build and have learned a bunch (and continue to) from the good folks here. Now with a half dozen builds experience as well as a few large scale overhauls - feel like I’m ready for a TW. My Vogel Express is a pretty amazing amp that I don’t feel needs to be replicated, so I decided to build a Liverpool.

Been planning and researching for a few months now; and now that I have a chassis - I’m ready to go.

Filter cap board (thanks to dorrisant for the inspiration and those who schooled me in the previous thread for their guidance) -

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Main board. Used AES perf board but didn’t realize the grid spacing was different and how that affected space within the chassis (because my chassis was delayed). Next time I’ll know - live and learn. I think it’ll work -

IMG_0442.jpeg

Power supply board -

IMG_0441.jpeg

And cab made of flamey Ash -

IMG_0444.jpeg

Now back to those fun heater wires…

[Raoul Duke]

Got the heaters done. I know they aren’t in the same method as KF, but the “Merlin” method has served me well thus far, so I’m sticking with it for now. I’m trying to stay relatively true to the design, but with a few small changes mainly grounding/noise reduction related - such as a heater artificial center tap and some Larry-type grounding.

IMG_0445.jpeg

Right now I’m trying to decide whether to ground the NFB circuit by itself or with the preamp.

Any suggestions anyone?

Thanks!

[xtian]

Huzzah! I have had a set of Heyboer iron for a while now, and just started my Liverpool build this afternoon! Mine is non traditional, for shore. Excited to see these projects progress!

[Raoul Duke]

Thanks xtian!

I’ve got Heyboer iron as well. I think their stuff works fantastic.

[Raoul Duke]

Did more around the pots today and got the back corner a little tidier in preparation for the power supply board. Added some leads to the main board also.

Definitely a different feel to this build vs the Dumbles I’ve built. RJs post regarding his order of assembly definitely fits this type of build pretty much right on and is a great help to a first time TW builder. Also, the Express assembly manual in the files section is probably 80-90% interchangeable for the Liverpool. I’ve found a couple of relatively small “Easter eggs” comparing the two layouts with the schematic and some gut shots - but that’s part of the learning process for me. Luckily there are enough internal pics of proven builds to help me figure it out.

[Raoul Duke]

Today I was able to get the power supply board wired in as well as the power tube cathodes and screen grids. Learned that the cathodes probably should have gone in before the heaters, but they came out fine after some fishing around. The screen grids were interesting - never done them standing straight up before.

Also figured out my grounding.
- Kept the bus bar, but didn’t solder to the pots; used homemade tooth washers for pot shield. Made a preamp star at the input jack for the bus, B+4 and 5 filters, and I decided to ground the jack as well.
- Separate independent bias ground just below the bias feed resistors.
- B+2 and 3 grounded together next to the filter board.
- B+1 and HV CT grounded together down by the IEC socket.

In the end, it looks more like “Howard” than “Larry” - but after reading a bunch of LP threads I’m thinking it will be good. The Dumble grounding hasn’t let me down and I’m familiar with it. Hopefully I don’t have to eat my words, lol.

[Raoul Duke]

Finished wiring the PI and power tube sockets and did the smoke test today. All voltages within range, no smoke, slight transformer hum - but nothing unusual, bleeder resistor works as it should. Only issue I had was the grid voltage being 25.3 for one pair and 11.6 for the other. I immediately saw that I had forgotten the jumper tying the cathode resistors together. After fixing that - everything was “kool and the gang” with both sides running at 10.7 and the plates running at 338. I’ll scrutinize the bias further once everything is wired up, but I’m in the ballpark.

Should be making noise soon…

IMG_0446.jpeg

[xtian]

Really nice lead dress, Marc!

[martin manning]

Looking good! Since the Liverpool is a stripped down AC30, and you have one of those, It'll be interesting to get your take on it.

[Raoul Duke]

Thanks guys!

Xtian - when I was wiring it, I kept thinking about a KF interview I read where he talks about building amps “3 dimensionally” - so I tried to use vertical space to keep separation as well as horizontal space. I just finished V1 and V2 the same way - I’ll put up a pic tomorrow.

Martin - I’m hoping this amp has more “blast in the shorts” than my AC30, lol.
Also, I continue to use all your “test as you go” lessons in my builds. Awhile ago I got a bench top power supply and used that to confirm OT polarity (much easier than my rigged-up wall wart) and used your power amp test process. Standard procedure now.

I also did the headphone test for the first time. Seemed to work out well. Got the quietest spot for the OT.

I used the “allynmey” recipe with the .0022 and 150k for the V2A grid (C8/R7). I’m hoping it sounds good - but I’m ready to adjust if needed. Honestly, my Vogel Express has so much harmonic content that I’m hoping I can come close with this build. I tried to be smart about the deviations from the original design in order to keep the amp quiet - I hope it all works out as intended.

I’ll be giving her a sound test tomorrow for sure. I’ll post results.

Thank you both again!

[Raoul Duke]

Ok, did the sound test and my ears are still ringing. Admittedly - I probably shouldn’t have used an EV-12L, but it was close by - so I used it. Definitely has some “blast in the shorts” to spare.

Figured out the bias and with plate to cathode voltage on both pairs at 318, cathode resistors that are right on 133R - I got 38.4 mA per tube for 12.2w/101.8%. Looks good to me.

One odd thing I experienced is that when I turn the volume all the way down, I’m still hearing a bit of signal through the speaker. Is that just part of how this circuit is?

Voltages at 120vAC:

B+1: 333
B+2: 315
B+3: 263
B+4: 249
B+5: 239
V1b plate:182
cathode:1.4
V1a (National/Yugo Ei ANOS)
plate: 160
cathode: 1.1
V2b (Philips USA ANOS)
plate: 224
cathode: 2.3
V3b (Motorola/Tung Sol LP ANOS)
plate: 201
grid: 37
cathode: 55
V3a plate:210
grid: 36
V4-7 (some old JJ Apex set)
plates: 329
screens: 312

I’ll fiddle with tubes more once I have the speaker cab sorted out. Also want to read up on the V2b grid values now that I have an idea of what the amp sounds like. Overall, pretty satisfied so far.

Final wiring pic:

IMG_0275.jpeg

[Raoul Duke]

Got everything put together (bottom shield, labels, put in the cab) and put it through my PS-2 into a 2x12 with mid 80’s Celestion G12K-85 and G12T-75. Thaaaat’s better, lol. Played it for about an hour and a half just getting to know it. Not drastically different sounding than my Express - but I know it’ll change a little as it breaks in.

Here’s the final pic:

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[martin manning]

Nicely done! I like the cap board. Much better solution than a bundle of axials.

[Raoul Duke]

Thanks Martin, I appreciate it!

[Raoul Duke]

Ok, played the amp more today and it’s pretty stable, but sounds like I need a little bit more upper mods. Did some digging around here and found a build thread from about a year ago called “Holy Agressive!!!!” where the idea of using a Marshall-style treble peaker was proposed; which sounds like something I’d like to try. Here’s a cut and paste from GlideOn’s post:

“It's likely however you really rather like this full, rich sound but just desire a bit more mid-shaping. Some teeth to it all.

To take a page from Marshall, try implementing a "Peaker."

I found that 220k/330pf value compliments the more "Fender" aspects of a Trainwreck quite well, while injecting just enough of a Marshall attitude into it.

If it were me, I would try it a V2 after the .1uf before pin 7 of V3.”

So my question is given his suggestion for implementation - should the peaker go across the .1uf cap or from the pot side of the .1uf cap down to the 1M on the left of the LTP V3 in place of the white jumper wire in Ron Worley’s layout - which goes on to pin 7?

Also thinking of putting a 33k grid stopper on V1a just to reduce hiss. The hiss isn’t THAT bad - just not sure how much is normal I guess - so trying to drop some of it if I can.

Any and all suggestions are appreciated!