Re: Show off your tube amp!
Steve Conner, Mon Jul 24 2006, 10:37PM

I've messed around with tube guitar amps a lot, mostly when I was a student and had loads of time and no money. The first one I tried was the "Toaster" made from parts of an old 50 watt tube PA (that I was given for free) rehoused into a 19" rack chassis. I was into metal at the time and really wanted a Mesa Dual Rectifier but couldn't afford one, so I tried to make mine sound like that with mixed results. :-/ Pics here

The next one was the "Nifty Fifty" which was a conversion of an old Selmer Treble'N'Bass 50, that I was able to buy cheap because it was incredibly ugly looking and faulty. (The fault turned out to be one loose wire.) I rewired it to have clean and dirty channels, and changed the reverb send/return to be compatible with the newer digital reverb units. I also gave it a bit of a new look with exposed tubes, a brass front panel, and a magic eye tube driven off the speaker output signal. The pics show before and after.

I built these about 5 years ago but they're still in working order and pretty loud. I mostly use the Toaster for practice because it has a master volume control, so you can get as distorted a sound as you like without deafening volume. I think a mini tube amp like joe's is a better solution for practicing guitar at home, not to mention looking very cute. Although I have had complaints from my neighbours when playing through a 3 watt tube amp with a single 8" speaker.

Joe, how does it sound if you turn the tone control on your guitar down? Whenever anyone says "Thick lead" i think of Eric Clapton and his "Woman Tone"

Re: Show off your tube amp!
Hazmatt_(The Underdog), Tue Jul 25 2006, 12:10AM

guess ill show it off again.

Here it is. ~100W Farshall Mender through 2V30 Celestians. I'm slowly working on getting a better natraul distortion going, but I have other projects that need more attention right now.

I did have an acoustic feature on this amp for a while. It was a cap bypass to take off mid's and highs, which was pretty cool actually. So now that I've spilled that secret, you can do the same.

Re: Show off your tube amp!
Dr. Shark, Tue Jul 25 2006, 11:45AM

You guys are playing in a different league designing and building your own designs, where I am just copying / modding stuff.
Steve, your "Nifty Fifty" looks really cool in that last picture, I like it how you left the wood unfinished. Maybe that's the reason it doesn't sound like a mean recto? Well, actually I am slighly shocked that you, the Steve, the uber-geek did not manage to get the Mesa sound from your amp (which was actually your third one, I read your homepage!). I've got a strong habit of thinking that things are easier than they actually are, but tube amps are really stone-age, there cant be any secrets
Maybe I should rethink this whole approach of sticking a few tubes together to get my dream tone, and just go with digital modelling, lacking the 2000€ for a real amp Ah, regarding the tone-pot: My guitars have it disconnected, since I never used it anyway, maybe I should change that

Matt, your "Farshall Mender" inspires me to build a "Reldano Soctifier". Just the high gain channels and a 50W power section, who needs more than that. But I seriously doubt I would get it to work.
Did you use the original channels from Fender / Marshall in your amp, or did you come up with your own?

Re: Show off your tube amp!
Steve Conner, Tue Jul 25 2006, 12:38PM

Hi Joe, all,

The Nifty Fifty was never meant to sound like a recto, I had got fed up with metal by the time I built it. As for the Toaster, it does have a pretty mean distortion sound on account of having 4 gain stages and an EQ that lets you scoop out the midrange. I'm sure being made out of metal and held together with big socket head screws makes it sound heavier too.

But I can't claim that it sounds like a dual rectifier, since I never had access to a real one to compare it with. (and still don't)

I actually built two amps before these, one solid-state and one hybrid tube/SS, but they both sucked so bad I keep quiet about them. >.<

Re: Show off your tube amp!
Jorrit, Tue Jul 25 2006, 03:32PM

Here is a picture of one of my tube amps.

I've copied some things of a marshall jcm 2000.
The other part I designed myself.
The amp is nearly finished I`m just waiting for new tube sockets and 2 new ecc83's.
And then I still have to finish some last parts of the chassis

Btw.
Steve I like the looks of your Toaster amp

ps.
first post on the new forum

Re: Show off your tube amp!
Dr. Shark, Thu Jul 27 2006, 03:08PM

Jorrit, for some reason I think of a coffin when I see your amp What are you going to call it? Any chance to see your other amps?

I'm planning to start work on a SLO-Clone with a smaller power section, e.g. push-pull 6V6 for 15W, soon. Well usually I don't complete my projects, but bragging about it here will hopefully give me some incentive. It's going to be a combo, and I am considering making it an avant-garde actylic design.
I wonder if anybody has tried acrylic speaker enclosures, of if there is a really obvious reason not to do it...

As I appreciate real technology, I am considering to replace the power transfomer by a switching supply, surely that would save a few kilos of weight, and I could easily regulate B+. Just kidding.

Re: Show off your tube amp!
Hazmatt_(The Underdog), Fri Jul 28 2006, 04:39AM

Well....I had plans for blues tones, but I was toying with the preamp front end to see what I could do with it. Basically its a Twin without the reverb and the front ends from Marshall and Fender. The biggest difference is the preamp post volume control which I added to level both channels. I needed to make sure that when switching, one wasn't much louder then the other.

Tip 1. Bias is KEY! make sure your bias is from 28-35mA per tube. Otherwise it sounds like crap.
Tip 2. Do NOT use a 12AT7 for the phase splitter. Man does that KILL the tone!
Tip 3. Be really careful if you use 2 250V caps in series insted of 1 500V cap. The cans are LIVE! Ouch that really hurt one time >.<
Tip 4. Keep leads as short as possible
Tip 5. DC for filaments is silly. Okay so you don't have 60 Hz hum on the filaments, but now you have 120Hz hum! which is even more audible! Just use a Hum balance pot.
Tip 6. Filter your bias voltage and keep the ripple really low. This will reduce hum.


Here's another job I did. A friend wanted me to re-crate his Crate because he wanted a 4x12 stack insted of his crummy combo. So I did the woodwork and staining. Enjoy.

Re: Show off your tube amp!
Dr. Shark, Fri Jul 28 2006, 06:27AM

Wow, that wood-job looks fantastic! Probably wouldn't fit my tentative acrylic design too well, otherwise I would sure copy it.

Btw, that could easily be my gear, the Ibanez RG and the pick with the hole punched through. Are you my evil twin by any chance?


My µAmp from the first post is really giving me pain now: I made some _small_ changes, and now it oscillates like crazy at 15kHz and hums even more like crazy when I plug in a guitar

Re: Show off your tube amp!
Hazmatt_(The Underdog), Fri Jul 28 2006, 08:37AM

No. Like I said, this isn't my rig. This is Mike's rig. He liked my 2x12 Celestian 1/2 slant back cabinet so much that he wanted a box for his Crate.

The only thing left to do was to get some small Brass plaques made for my trademark logo. We were going to do that, but never got around to it.

Since my mom thought I would be a doctor, my initials were M.D.K., and that was going to carry over into my amps. "M.D. Overkill " is my trademak, but I've only done the 2 projects so far, excluding the unfinished foot-controller.

Re: Show off your tube amp!
Steve Conner, Fri Jul 28 2006, 10:41AM

Wow nice job hazmatt, I like the Crate crate M.D.K is cool too, "Maximum Decibel Killage"

I totally agree with your tips too, except maybe one: I used a 12AT7 in the phase splitter on my Toaster amp. I used a different phase splitter circuit to the usual guitar amp design, too. The Toaster always tends to sound muddy and sludgy when it's cranked up, whereas my other amp (that has the usual long-tailed pair splitter with a 12AX7) sounds quite mean and snarly. So maybe I should change it.

I tried KT88s in the Toaster but they draw too much current at high volume. The power supply just sags to nothing. I put a protection circuit i was messing around with in this amp, that was intended to save the tubes if the amp were cranked with no speaker. But what happens is that if the power supply sags too much, it triggers this circuit and turns the amp completely off. I don't know what I was thinking when I put that in. An amp that turns itself off before it gets to "11" isn't very rock and roll.

I went to the Marshall Amps roadshow this week. They had a rock band demonstrating their amps. The guitarist had a huge wall of different Marshalls that he plugged into in turn to show them off. They all sounded great, although the handwired tube ones pwned the solid-state models IMO. The climax of the evening was when they plugged in the new Jimi Hendrix signature stack. It sounded awesome for 10 seconds and then broke.

Re: Show off your tube amp!
Steve Conner, Sun Jul 30 2006, 06:42PM

Joe: Tube circuits can be very sensitive to small amounts of stray capacitance between wires and components. Especially in high gain guitar amp circuits. In the Toaster I had to cover the first preamp tube with a metal shield, or capacitive coupling between its anode and the anode of the nearby power tube made the amp oscillate when the volume was cranked on the high gain settings.

One tip I often saw on the Ampage forums was to poke the wiring around with an insulating stick of some kind and look for places that change the frequency or amplitude of the oscillations. The places that change it most are probably what's causing the trouble. If you get stuck, I bet you'll find someone with experience modding the Cream Machine over on Ampage.

The Toaster went on tour this weekend! The band I play bass in was playing at a music festival. There was no bass amp... damn folk musicians... so I brought the Toaster along with a 2x12" guitar cabinet. (There was no room in the car for the 2x15" that appears in my avatar.) It actually worked great! The other cool thing was that the stage was a truck trailer parked in the middle of a field.

Re: Show off your tube amp!
Dr. Shark, Mon Jul 31 2006, 12:14PM

Doh, I accidentially disconnected the ground on the µAmp, that's why it was buzzing like crazy
But with a tidy layout like this:


it can take a while to figure that out.

Now I really want to get going on that Soldano SLO Clone, but all that talk about converting old tube PAs into guitar amps has made me curious: Maybe I can save around 200€ in parts by not buying the power- and output-transformer and other bits and pieces from my favorite online store (), but looking for an old tube PA on eBay instead?

I spotted this one which might be interesting, it has 2x EL34 and 4 x ECC83 and looks old and shitty, so nobody would buy it except for parts.
On the other hand, these things seem to be quite expensive, here a similar one sold for more than 100€.

Re: Show off your tube amp!
Steve Conner, Mon Jul 31 2006, 12:49PM

That Dynacord PA looks nice! It looks like a nice case too, you could keep it and just change the front and back panels. Great that it has 4, 8 and 16 ohm taps too, my Toaster PA only had 16. I think you could have it snarling like a SLO in no time.

If you do win it, for goodness' sake tell the seller to remove the large tubes and pack them separately. Or wrap them in bubble wrap and put them back inside the chassis. Otherwise they're bound to come loose in transit and get smashed. :(