Liverpool build report

[Colossal]

I just finished a test-build of a Liverpool in a mule chassis. Fantastic sounding amplifier and I'm absolutely blown away with the tone. Although I typically base my tonal preference around Marshall amps, I gotta say that I am just amazed at how good this amp sounds. Very clear, articulate, with a 3D quality and what sounds like built in reverb through a closed back 2x12 with well seasoned Greenbacks. I have been after a Rush-meets-Tool kind of sound for a long time and this amp has it in spades. I play 7 strings and the low B stays tight and the recovery is very fast (wow!) without feeling too hard or glassy where the note dies after you play it. I really think this amp blows away most (all?) Marshalls I have heard (and even built). They have balls for sure but I think they suffer in terms of clarity and sustain. The Liverpool distortion characteristic is a smooth, tight grind, not at all fizzy. I have been after this for years. The TW sag and compression is just killer. If the Liverpool is this good, seems like I'm going to need an Express to go with it

Despite its reputation for extreme treble, the amp has great low end. The sound is very balanced with respect to lows and highs. I incorporated a Cut control which I think is invaluable and it really helps dial in the high end perfectly. I am running the amp with the Volume and tone stack dimed with a PPIMV to get the volume manageable (PPIMV does a great job). I paralleled V1a/b and used 1000pF for the treble cap since the output impedance of V1 is reduced in parallel. I also incorporated a Resonance control just to see how that affected the low end (the jury is still out on its utility). The amp is quite hissy but I will build another once I am through experimenting with this test build and expect to lower the noise floor somewhat with optimal layout and tubes.

As a curiosity, I'm wondering why Ken chose cathode bias with the Liverpool design. Perhaps he felt EL84s just sound best cathode biased or is there greater tolerance (poorer precision) in manufacture that would be forgiven with the balancing effects of split bias resistors and cathode bias? Enhanced harmonic content or a little more localized feedback?

Has anyone tried using say 1,000-2,000uF as the cathode bypass cap or tried fixed bias? As it is now (stock power amp), the compression, feel, sustain, and tone is fantastic and I don't want to mess with that but just wondering how the feel and/or tone might change with a different bias method and what Ken's reasoning might have been.

Thanks,
Dave

[loctal]

Hi Dave,

I have been reading your posts for years on this and some of the other forums. Looking forward to hearing about your results. Please post your schematic when you are done. Are you using the standard caps and output transformer?

[Gaz]

Dave,

I'm having trouble understanding your choice to make the treble cap 1000pf. Isn't the typical value 50pf? By paralleling the first two triodes and reducing the output impedance only reduces the loss slightly when modeling it in the TSC. A 1000pf cap makes the stack's response completely flat. That's cool, but I just don't get your reasoning??

[Colossal]

Hi Dave,

I have been reading your posts for years on this and some of the other forums. Looking forward to hearing about your results. Please post your schematic when you are done. Are you using the standard caps and output transformer?

Dave,

I'm having trouble understanding your choice to make the treble cap 1000pf. Isn't the typical value 50pf? By paralleling the first two triodes and reducing the output impedance only reduces the loss slightly when modeling it in the TSC. A 1000pf cap makes the stack's response completely flat. That's cool, but I just don't get your reasoning??

Hi Gaz and Loctal,

Yesterday, my hard drive failed so while I am rescuing it, I can't provide a drawing. Here is what I have for the moment. Keep in mind that this build is a test bed to let me experience a Wreck design first hand and to help me decide if I liked the tone. I definitely do! I used a Rocket build as the foundation (the amp was built for a client to hear/record with) so I converted the amp to Liverpool specs. The Rocket is a beautiful amp for sure but for my personal use I am after a high gain tone with a grinding/growling clear distortion, not the buzzy/fizzy distortion some high gain amps have.

The PT is a typical dual secondary Trainwreck type PT so 260-300-0-300-260VAC secondary. I have the amp wired with a GZ34 tube rectifier. I'm running it at the higher voltage (300VAC) setting which results in voltages that are about 10% higher than a stock Liverpool running solid state rectification on the 260V tap. I have about 365V on the plates and 11V on the cathodes. However...the amp does exhibit ghosting at higher volume so I don't think the tube rectifier (and the 50uF reservoir cap) I have in there is going to cut it. I do have some Mullard GZ34s but will just use the prescribed amount of filtering and SS rectification. I'm sure Ken tried every combination to arrive at the Liverpool "formula" and it is configured the way it is for a reason; nothing left to chance. The tube rectifier sounds pretty fantastic but it also causes sag across the whole amp and the Trainwreck design relies on stiff filtering and steady plate voltage while sagging the screens (and to some degree the preamp). I will change over to solid state and the standard 80uF for my 'final' build.

Second, I paralleled V1a/b using a 56k load resistor (3W metal film) and two paralleled 1k5 resistors on a common cathode (22uF bypass), grids are connected of course. I also used an Express tone stack, not the stock Liverpool stack or 50pF treble cap. I halved the Express pot values and doubled the cap values to get the tone stack response to match the Express' with the lower output impedance of a paralleled V1a/b.

Third, since I had the pots in place in the test chassis, I added a Cut control (left over from a Rocket), a post phase inverter master volume, and a Resonance control. I used the stock 100k NFB resistor mounted on the 8R tap with 0.1uF in front of the NFB resistor (just to keep DC off the resonance pot). The resonance pot is the usual 1M/0.0047uF. With the cut control I used the usual 250kB/0.0047 however I think somewhere between 0.0022-0.0033uF is actually usable. If the pot is maxed it really muffles the tone like a wet wool blanket over the amp, so a bit too much to be usable. The point of this is to see what works well.

So far, I am running the amp with Volume and Tone Stack dimed but I am using the PPIMV and Cut control to dial in the tone and they do work extremely well in this regard. It is a freakishly loud amp if you crank the PPIMV out of the picture. With the preamp wide open it is a beast to control but what a beast it is! My test amp is not laid out per TW spec so I did not expect to get full stability with a point-to-point setup. It is only for me to try ideas. The amp is stable with a shield plate in place. I feel pretty lucky being able to shotgun a TW design together and getting a working amp, not a howling mess. The next one will be the real deal.

The output transformer is a Dynaco. The usual Liverpool spec is 6k6 and the Dynaco is 4k3 which adds to the aggression. This also shifts the load line to put out more power too. It sounds very, very good though and the wide dynamic range of the Dynaco I think plays very well with the EL84s. The low end response was surprising to me and it is very good. Plenty punchy but the clarity is fantastic. I'm using a PRS Singlecut SC245 (standard and dropped D tuning) and Ibanez Prestige 1527 7 strings (both basswood bodies, one with a maple neck, the other with maple/rosewood). I use Dimarzio PAF7s in the 7 strings an the PRS has the stock 245 (PAF) pickups. I think that lower power pickups are the key to good clarity and I picked this up from reading Allan Holdsworth.

The tone sounds very much like Van Halen I in a way but with a different kind of clarity. The amp is dynamic and very touch sensitive. If you like Tool, the distortion reminds me a bit of Jambi off 10,000 Days. You can hear the compression but it stays tight even on the low B. If you hit say a big chord, you get the initial attack followed by a yyyyyeeeeeeeoooooowwww grind on top of it. The grind is very horn-like and musical in that respect. It just keeps sustaining and will bloom into feedback easily. Honestly, I think this amp blows away every Plexi I've heard. It's quite shocking really. It's just so much clearer and the separation with arpeggiated or wide chords (sus2, sus4, Lydian 1-5-9-add#11) is killer. I really like a progressive sound. I can see how these amps would sit well in a live mix.

Hope this helps.

Regards,
Dave

[Gaz]

I also used an Express tone stack, not the stock Liverpool stack or 50pF treble cap. I halved the Express pot values and doubled the cap values to get the tone stack response to match the Express' with the lower output impedance of a paralleled V1a/b.

Gotcha!

That's very cool info, and sorry about your computer!

[Decko]

Hey Dave,

You like what I like. Based on your experience building Marshall's versus this Liverpool, what can you say attributes to the overall difference in tone? The preamp design? The EL84 power compliment?

Danny

[Colossal]

Hey Dave,

You like what I like. Based on your experience building Marshall's versus this Liverpool, what can you say attributes to the overall difference in tone? The preamp design? The EL84 power compliment?

Danny

Hey Danny,

With the Wreck designs (specifically the LP and the Express) it's "everything" that contributes to the overall difference in tone. Yes, the preamp is definitely generating a LOT of gain. If you look at it, you have center biased first stage, so, 100k plate load, 1k5 cathode resistor and fully bypassed at 22uF. It really resembles a Fender gain stage. So there is very little clipping unless the front end is overdriven with very hot pickups. Then you have the tone stack which is plate-loaded so you get the tone shaped and signal attenuation out of the way, early in the circuit. Following this is a 2k7 biased staged, fully bypassed stage and a small coupling cap (0.0022uF) to minimize the possibility of blocking distortion as gain is further increased. Finally you have the 10k, unbypassed cold clipping stage which gives an asymmetrical clip (lots of 2nd order harmonics). As you go through the preamp, each gain stage has less gain but overall is a lot of gain and there is very little attenuation between stages.

Then there's the power section which is designed to clip, then the PI. The power supply is the key to the TW dynamic qualities. There is a stiff plate supply at 80uF followed by the 1k 25W power resistor which causes the screens to sag dynamically under load. The screens have the most control over the output tubes. This gives the sag/compression while allowing the clean tones to sound almost as apparently as loud as the fully distorted tones. It also gives the sustain. The output coupling caps (0.022uF) and 220k grid leaks give a similar bias excursion recovery as a Marshall so it's pretty tight.

So summarily, *everything* is critical to getting the whole Trainwreck physical response and sound. If you compare a JCM800 topology to an Express, they are similar and the power amp on the Express is pretty much verbatim Marshall but there is no cathode follower and tone stack late in the amp as with the Marshall. This really helps to push the PI which pushes the power amp. So an Express picks up where a JCM800 leaves off.

I've never felt such an "alive" amp. Even when you turn the MV way, way down (heresy I know, to have a MV in the amp) the amp still has the goods for bedroom level practice. I brought it down low enough to hear my metronome over the amp and the amp still felt great enough to track scalar runs and chords. Sure it's not the full-on sound, but still inspirational enough.

In the Liverpool, the EL84s add something unique. They get the rap for being trebly but it's that added chime/swirl/spank/nasal sparkle that I think gives a kind of "hi-fi" clarity without being too clinical. For prog metal (I'm not John Petrucci) it's got that kind of separation and clarity for playing with heavy distortion. Although I have been running the Volume way up (with MV about noon), last night I backed the Volume off to about 1-2 o'clock and really increased the MV. It still keeps a very mean, girthy distortion but is more dynamic and a little less compressed. The sound reminds me very much of Drop Dead Legs by Van Halen (listen after the intro when the riff kicks in). Just huge, ballsy, and has that "fashionably late" spongey sound that feels like a much bigger amp. There is still some of that EL84 bite kind of like using a glass slide on an old guitar --- that "zing". It has a natural reverb quality which is really great, much more so than any Marshall I've played/built.

Oh, keep in mind I added a Cut control too and this is very useful I think for managing the treble. It acts like a variable "fizz cap" across the PI plates. I measured the resistance and I have about 138k on it with an 0.0047uF cap. That gives a significant cut in the high treble but it all just seems to sit right. Enough clarity to hear every note but not so much as to be fatiguing. There's a lot of low end in the amp, enough to really push the Greenbacks into that tight "whump". I think Greenbacks are THE speaker to use.

Without question one of the best sounding and playing amps I have experienced. Can't wait to build a proper one. I'll have to build an Express too and a couple of Airbrakes so I can ditch the MVs

[John_P_WI]

Dave,

I'm sure it sounds great. Something I have been toying with is how do you think a 4 x 6v6 output section would sound? Both of us have had good success with the 4 x 6v6 output sections before - maybe a pissed off plexi punch?

I think I need to scrounge up some stuff and give it a quick try.

John

[Colossal]

Dave,

I'm sure it sounds great. Something I have been toying with is how do you think a 4 x 6v6 output section would sound? Both of us have had good success with the 4 x 6v6 output sections before - maybe a pissed off plexi punch?

I think I need to scrounge up some stuff and give it a quick try.

John

Hi John,

Yes, I think a 4x6V6 section would be an interesting experiment. My 6V6 Plexi very much had the plexi vibe and was quite punchy. I used a 5k 5W resistor in series with a choke on that one and it had great compression and noticeable sag. It too felt great under the fingers. It was a bit more muddy that the Liverpool though and had more of that Marshall high-treble hash with the huge, boomy bottom end. Still a killer sounding amp.

[Clyde]

Awesome sounding amp Dave, and well-described too. It's very far from a Liverpool though, perhaps better. I like it when people try to put their own spin on designs rather than trying to replicate them down to the smallest detail. Way to go.
I am rather surprised about the PPIMV. I use a master in front of the PI in my spin and find it works very well in retaining the character and transparency of the circuit. I did a 4x6V6 amp last year in the Marshall-type circuit with a PPIMV, great sounding for sure.

[surfsup]

Dave, pardon my ignorance here. Isn't a cut control used to reduce bass and pass highs?

Oh, keep in mind I added a Cut control too and this is very useful I think for managing the treble. It acts like a variable "fizz cap" across the PI plates. I measured the resistance and I have about 138k on it with an 0.0047uF cap. That gives a significant cut in the high treble but it all just seems to sit right.

f=1/6.3*138000*.0000000047 = 245Hz

Also you said you have it between the PI plates? So is this instead of the 100pF cap across the plates? Or is it between the two 220k/220k to ground?

[M Fowler]

It is called a treble cut by putting a .0047 or so cap across the pot you can adjust the amount of treble being cut in the power section.

On some amps such as Dr Z Stangray this functions as the tone control.

[Colossal]

Awesome sounding amp Dave, and well-described too. It's very far from a Liverpool though, perhaps better.

Thanks Clyde. I listened to a few clips of LP clones and yes, this amp, although similar, does sound different than what I've heard. My amp has more of a beefy grind where in a real LP, I hear more chime. My amp still has some of the chime (it's in there) but sounds wider in a way, even with the distortion tuned down. There is also less clean headroom which might turn some guys off. Glen K (Geetarpicker) has also noted that his own Liverpool had less clean in it than he preferred compared with his Express.

I like it when people try to put their own spin on designs rather than trying to replicate them down to the smallest detail. Way to go.

My thinking was to try to the Trainwreck preamp almost verbatim in values just so I could taste test and hear for myself what the buzz is about. But no, it is not a true clone by any stretch. For my "permanent" build, I do plan to go with a SS rectifier and additional filtering up front. My goal was to voice the amp to stay tight using 7 string guitars and while it does sound phenomenal, I do think it could benefit from SS rectification (I have a GZ34 in there now). The low end response is very, very good though but I need to confirm whether I'm hearing ghosting in the lower registers when playing it loud. It does not have any blocking distortion though which is great.

I am rather surprised about the PPIMV. I use a master in front of the PI in my spin and find it works very well in retaining the character and transparency of the circuit. I did a 4x6V6 amp last year in the Marshall-type circuit with a PPIMV, great sounding for sure.

The PPIMV does seem to work quite well in this amp as it is cathode biased. PPIMV does mess with the NFB loop at lower settings and that's just a cost of doing business. Perhaps a bootstraped PI or other method might be more useable. But I had a PPIMV already wired so I just left it. There is so much gain and harmonic content on tap though, even at low settings of PPIMV there is enough to retain the low end and feel when practicing at low volumes. Of course it doesn't sing like it does at high volume; we know there's gonna be some compromise, but the tone is still usable. Great job on your 4x6V6 Marshall (bet it sounds great). Others been wondering about that so good to know it's a viable option.

[Colossal]

It is called a treble cut by putting a .0047 or so cap across the pot you can adjust the amount of treble being cut in the power section.

On some amps such as Dr Z Stangray this functions as the tone control.

Hi Surfsup,

Mark's got it right in that it is a Treble cut circuit. Just refer to the AC30 scheme and you'll see the traditional setup there just past the PI load resistors. It acts to shunt high frequency signal with the opposite phase across to the other side that is conducting so as to cancel the high end to the desired level. I did not add the typical PI fizz cap as defined by the Liverpool schematic because I knew I'd have to see firsthand how much high end the amp ended up with and wanted to be able to have an active control. The Cut is very much like a tone control. If I max the pot (zero resistance) then there is a huge cut and the amp gets very dark and muffled. Also, right now I just have the tone stack controls wide open (dimed) so I'm letting everything through and shaping the tone (via PPIMV, Cut, Presence, and Resonance controls) on the back end. I need to play more with the PPIMV out of the picture, bring the Volume down to the usual 1-2 o'clock "zone" and use the tone stack. The Treble control does work well, but I can hear the drop in overall gain at lower levels of PPIMV. I'm not using the amp the way a traditionally built Trainwreck is intended to be, but need to in order to understand the foundation. But man, what a tone.

Dave

[surfsup]

It is called a treble cut by putting a .0047 or so cap across the pot you can adjust the amount of treble being cut in the power section.

Hmm, I thought the cap and pot were in series and looking at the AC30 and TW Rockster schemos, they are in series after the caps. I had this in my X10 clone off the 220ks with a 0.0047 and 82k in series. As far as I can tell, when in series, they boost treble but at low frequency so really its cutting bass.

So just to clarify what Mark said, is the cap in parallel (across the pins 1 and 3 on the pot) or in series with the pot?

Since the X10 is basically a liverpool and I took out the VVR, I'm looking to use the faceplate hole I have for something else.

It acts like a variable "fizz cap" across the PI plates

I have a 100pF across the plates now. Wondering if I should try something else or a presence control? What do you think will give me more bang for the buck?