The Amp Garage

Allied is back ordered on the 20uF until April. I have some on order. I am using Spraque/Atoms in the mean time. They had lots of the Mallory 40uF in stock.

PS, Allynmey, I would like a couple of the TC 80's if you would be kind enough to sell me some.

That looks weird, I'm not sure what I am looking at. You should have one main buss like a real piece of buss wire suspended off the chassis and only grounded to chassis at 1 place. Each stage should have it's local star consisting of the supply decoupling filter cap with lets say the volume pot gro...

I've been reading Aiken's article and TUT#1 (I don't have #3 yet). I've started a drawing for a grounding scheme. This version has 3 star points: power, PI and preamp. I used a "simplified" TW express layout in the drawing that shows 3 filter caps for simplicity (I realise that there are 5 B+ voltag...

Hi, I was perusing the archives and came across your Boogie post. I also have a Mk III (bought in 1988) and have been fixing/tweaking it. So far I have: * adjustable bias pot * changed the preamp to the Mk IIC+ version * added a rhythm II level control * rewired the power tube filaments (using shiel...

Hi, I was perusing the archives and came across your Boogie post. I also have a Mk III (bought in 1988) and have been fixing/tweaking it. So far I have: * adjustable bias pot * changed the preamp to the Mk IIC+ version * added a rhythm II level control * rewired the power tube filaments (using shiel...

Sounds good sir.

Thanks for the complement on my DIY.

I'll have all my parts to finish my Express build next week except for the wire (solid silver plated copper with teflon jacket) as it seems to be lost in the mail. I have lots of wire but not the nice stuff like this.

cheers - Kevin

Any pot could be used for a bias pot. Once you get the pot adjusted for the proper bias voltage (-33 VDC), you could replace it with a fixed resistor (just disconnect and measure the pot). As for the 1 ohm resistors, they are nice, but you don't need them (the Komet amps have these but the TWs did n...

A 6V6 has a max voltage of 350V. A 325-0-325 power supply will put out about 450V once rectified! Yes sir! My first DIY guitar amp was a champ (5E1) using iron from A.E.S. I ended up using a big WW resistor to drop the B+. I wouldn't go higher than 300 VDC on the 6V6. I say this because I tried a B...

I'm working on my first wreck. However, I have built a few amps with hardwood cabinets. I use a Tung Oil finish to make them a bit more gig worthy. Tung Oil can look really good and doesn't chip. If you do mark it up, you can use an abrasive pad to remove the mark and apply more Tung Oil.

The AirBrake is slightly different from a conventional L-pad in that the shunt comes before the series resistor, not after it. In the AB design, about 80% of the power is dissipated through the 100watt fixed resistor so the remaining current passed through the series resistor and rheostat is less o...

Watch your individual power dissipations, though. 1/10 the length of a 100 watt resistor is only a "10 watt resistor." I'm not so sure about that. Looking at the huge power resistors used in the airbrake pictures I've seen, it looks like the heat will spread through the entire 100W resistor, not ju...

Watch your individual power dissipations, though. 1/10 the length of a 100 watt resistor is only a "10 watt resistor." --mark That's a good point. So the series resistor in the Airbrake would be under rated? Another issue is that lower frequencies draw more power. On top of that, the impedence and ...

Doug, You're attenuator is quite cool. Have you heard/seen the transformer volume controls used in hi-fi? I would love to get a pair (from Bent Audio) for my hi-fi preamp. For a guitar amp attenuator, those kind of transformers would not handle the power. The auto-former idea may work, but I'm guess...

Here are the values for a 100W/8ohm ladder attenuator (I made an Excel spreadsheet in case anybody wants a copy): P 100.00 Z 8.00 Rin Rg Zin Zout Zin-max Zout-load W1 W2 dB 1 4.00 2.95 13.68 16.63 2.43 8.32 24.28 17.75 82.25 dB 2 8.00 4.82 5.29 10.11 2.52 5.05 25.21 47.64 52.36 dB 3 12.00 5.99 2.68 ...

No, that is not how they work. Read this http://www.goldpt.com/how.html I read it. Doesn't have anything to do with the Airbrake. If the schematic in the other thread is correct, the Airbrake is a fixed shunt, variable series. I'm glad that you read the Gold Point link. Now, if you read my original...