Liverpool Amp - Xtra Small Platform

[Thomas_H]

Awesome build!
this last mod made this amp so versatile, are you using always the same cathode resistor?

You could use different tubes for different sounds, and power scaling to have different output levels.

Thomas

[Zippy]

Now I have a max B+ of 180 volts which ultimately comes down to about 70 volts on the plate of the first preamp stage. To my surprise, it still sounded good and was still pretty loud... gives you an idea of how far down in voltage you have to go for a power scaling unit to do it's thing.

The EL95s still sound awesome. I then tried some 6AN5 tubes... they also sounded awesome and the clean to mean thing worked well. Finally I tried some 9001 "acorn" sized tubes. They sounded kinda cool but there is almost no headroom. Tube distortion at Bedroom levels - kinda cool! There are a ton of options for 7 pin output tubes and they are generally dirt cheap.

RJ - You rock!

Have you considered redoing the dropping string to bring the preamp voltages back up a bit? Maybe go parallel vs series?

You might also consider hardwiring an orange 12' power cord to that. It's so small that it needs a tail so it does't get lost!

[RJ Guitars]

Awesome project! What signal caps did you use?

Signal caps are all either 400 or 630V Panasonic polyester caps. They come in a pretty small package and are pretty common. All the resistors in the signal chain are either 1/4 watt with a few 1/2 watt mixed in.

I have also swapped out a NOS 12AY7 into the V1 socket and I picked up a little more headroom.

I'm debating but sorta leaning toward putting this into a combo cabinet... lightweight grab and go amp that might weigh less than your Les Paul - you won't even need a roadie but it will sound best if you have a 4-12 cabinet.

[RJ Guitars]

Now I have a max B+ of 180 volts which ultimately comes down to about 70 volts on the plate of the first preamp stage. To my surprise, it still sounded good and was still pretty loud... gives you an idea of how far down in voltage you have to go for a power scaling unit to do it's thing.

The EL95s still sound awesome. I then tried some 6AN5 tubes... they also sounded awesome and the clean to mean thing worked well. Finally I tried some 9001 "acorn" sized tubes. They sounded kinda cool but there is almost no headroom. Tube distortion at Bedroom levels - kinda cool! There are a ton of options for 7 pin output tubes and they are generally dirt cheap.

RJ - You rock!

Have you considered redoing the dropping string to bring the preamp voltages back up a bit? Maybe go parallel vs series?

You might also consider hardwiring an orange 12' power cord to that. It's so small that it needs a tail so it does't get lost!

Has me wonderin' what the true solution to lower volume but great tone requires? I know that at some point the B+ gets so small that the electrons can't really tell which way they want to go or at least their enthusiasm is lacking... eventually the amp will get fizzy sounding. If I did pump up the B+ on the premap tubes I expect that to increase thier output and I am curious if I would have to throw away more signal going into or out of the phase inverter to keep from overwhelming the power tubes... any thoughts?

[jelle]

Awesome project! What signal caps did you use?

Signal caps are all either 400 or 630V Panasonic polyester caps. They come in a pretty small package and are pretty common.

Great, thanks!

Jelle

[jtn191]

I'd love to hear clips too. One big thing with these little amps is how they sound clean!

[RJ Guitars]

I can take that a couple ways but I think both are valid. The easy thing is to just consider that the volume is reduced in some proportionate relationship to the difference in size between this and a full blown Wreck. Because of the way our ears work this can be tricky business and reducing volume evenly across the frequency spectrum doesn't always sound equivalent but smaller... so with the limited amount of clean that a Wreck has to begin with I sorta expect it to sound a little thin to my ears. I'm not sure if I think this because it makes sense or if it's because I've experienced it many times.

The other way I could hear your statement would have something to do with a lower onset of the clean to mean threshold. Its kinda hard to get enough clean headroom in several of the Wrecks I've built so I would again anticipate that a good loud clean tone might be a bit of a challenge with a scaled down version... also it's reasonable to expect these power tubes to have a lower distortion threshold based a bit on their size but more so at the operating voltage I've got them at. I did anticipate this and changed some circuit values to knock down the signal just a touch. After the fact I swapped in a 12AY7 into V1 and it really sounds good!

Clips - I have just setup some recording gear and have plans for clips to be forthcoming. I think that is the real way to share how any amp sounds since our own objectivity can be compromised by any number of issues. Look for these to show up soon !

[RJ Guitars]

I can take that a couple ways but I think both are valid. The easy thing is to just consider that the volume is reduced in some proportionate relationship to the difference in size between this and a full blown Wreck. Because of the our ears work this can be tricky business and reducing volume evenly across the frequency spectrum doesn't always sound equivalent buy smaller... so with the limited amount of clean that a Wreck has to begin with I sorta expect it sound a little thin to my ears. I'm not sure if I think this because it makes sense or if it's because I've experienced it many times.

The other way I could hear your statement would have something to do with a lower clean to mean threshold. Its kinda to get enough clean headroom in many of the Wrecks I've built so I would again anticipate that a good loud clean tone might be a bit of a challenge with a scaled down version... also it's reasonable to expect these power tubes tubes to have a lower distortion threshold based a bit on their size but more so at the operating voltage I've got them at. I did anticipate this and changed some circuit values to knock down the signal just a touch. After the fact I swapped in a 12AY7 into V1 and it really sounds good!

Clips - I have just setup some recording gear and have plans for clips to be forthcoming. I think that is the real way to share how any amp sounds since our own objectivity can be compromised by any number of issues. Look for these to show up soon !

[jtn191]

Yeah I mostly meant it to be interpreted the 2nd way. I've been really intrigued by little amps...but ones like the Zvex Nano amp aren't very clean/articulate. I've been really impressed by JTM1 demos. As much as I like overdrive sounds, I'm really into funk now...so anything that could pull of strong cleans with a mic live/recording is a winner!

[RJ Guitars]

I entirely agree, little amps that sound cool are usually challenged to have any useful headroom. This one accomplishes it pretty well - I'll keep trying to make some progress on recording a clip.

This amp is deceptive because it is a very small package size but it's actually a bit more amp than it might seem at a glance... I'll bump it up to a 12" x 6" chassis in the next iteration so I can use bigger filter caps and bump up the B+ voltage to 300+. This is still a bit of a deception because it will make 8 or 10 watts and would easily fit into a Fender Champ sized cabinet.

I learned what I needed to make this little amp successful in a long term project with a similar one documented here... http://ampgarage.com/forum/viewtopic.php?t=11528. Same tube compliment but entirely different layout and higher B+ across the board.

In the last pages of that thread I get down to a few fixes that were required to make it useable. These can be applied to any high gain Wreck circuit and I think I mention in the other post that I felt like I actually went a bit past the ideal in taming the Wreck. It didn't draw much comment at the time but to me it is the ultimate tool kit for bringing a Wreck from nasty instability to extremely well behaved. I applied many of them to this build but left off a few...

[RJ Guitars]

I bought some equipment so I could start doing some recording... if I only knew anything about recording and subsequently could play guitar well enough to do the amp justice.

I used Zippy's Hamer SuperPro Monico (sweet guitar) and pushed the amp through my open back 2-10 cabinet. I was getting some great tones out of the rig but I struggled to get what I was hearing to come out of the amp. I set all the tone controls on max with the bright switch on and the volume just a tad above 9 O'Clock. I hadn't used the amp outside of the shop (lots of fluorescent lights) and I was surprised at how quiet it was. It got even a bit better when I used to a nice "Monster" input cable.

I used two microphones in stereo into a Focusrite 2 channel USB interface then into my Laptop. I tried a few different mic locations, and overall I worked at it a couple hours... most of it was in the steep part of the learning curve... I have much yet to learn.

So I haven't got anything professional gear wise but I am hoping with time I figure out how to get a decent representation of the tones the amp puts out. I wasn't too displeased with the clean sounds, although I think it lost some of the crispness and sparkle. As soon as the amp started to break up I could hear something starting to compress and the recording wasn't really true to reality... but, I think it is good enough to hear what's going on overall.

Among other things I hope some of you will share some of the secrets of how to record guitar amp clips.

[xtian]

Your clip sounds great!

Of course there are tons of creative ways to record guitar amps. But in creating demos, I think the most important thing is to use a common recipe that everyone knows what it sounds like, so you have a point of reference for comparison. A SM57 a couple inches from the grill, a bit off axis away from the center of the dust cap. That's it!

[Zippy]

I used Zippy's Hamer SuperPro Monaco (sweet guitar) and pushed the amp through my open back 2-10 cabinet...

So I haven't got anything professional gear wise but I am hoping with time I figure out how to get a decent representation of the tones the amp puts out. I wasn't too displeased with the clean sounds, although I think it lost some of the crispness and sparkle. As soon as the amp started to break up I could hear something starting to compress and the recording wasn't really true to reality... but, I think it is good enough to hear what's going on overall.

That sounds promising, RJ. What did you do to vary the sound in the clip? Switching pickups (neck/bridge), changing guitar volume, changing amp volume?

Some of those autoleveling recorders will hose ya. Do you have manual control of the level? It is often better to go manual, run through a clip, and then determine where best to set the level. Autolevel will often compress and get muddy on ya. Have you tried the SM57? 421? No need to go stereo, if you can get GOOD mono results.

Like I've said before, You Rock! Nice work.

[RJ Guitars]

... That sounds promising, RJ. What did you do to vary the sound in the clip? Switching pickups (neck/bridge), changing guitar volume, changing amp volume?

Some of those autoleveling recorders will hose ya. Do you have manual control of the level? It is often better to go manual, run through a clip, and then determine where best to set the level. Autolevel will often compress and get muddy on ya. Have you tried the SM57? 421? No need to go stereo, if you can get GOOD mono results.

Like I've said before, You Rock! Nice work.

All the recording was done with the amp at one setting as defined above. The differences you hear in the clip - starting from clean to mean - are all due to turning up the signal at the guitar. I used both pickups and dialed in the amount of each I liked, although generally it was a balanced amount of each. The final part of the clip was done with the guitar output maximized.

These clips were done with your MD 421 U-5 sennheiser mic and a shure SM-58. Hopefully I'll get some help with the recording end of things... would love to get a real player just to demo amps!

[jtn191]

Sounds great! Yeah that first clean sound is much more full than other mini-amps. And that recording sounds good, anything with a good soundcard and mics will sound a lot better than built-in laptop/camcorder recordings.

Some engineer advice: if you use 2 mics, make sure they're phase coherent. Flip the phase on one and flip it back. Keep the setting that sounds best (ie usually has the most bass). The brightest sounds are recorded by miking the center of the speaker, the mellowest from the ridge. Move mics around until you get the balance you want. Usually for me, near center but not quite. Angled off axis a bit.

cool trick:
-send some white noise through your amp and mic it up. Move your microphones around until the recorded noise sounds like the noise in the room. Now your guitar will sound equally realistic.