not a liverpool anymore...well never was a proper one anyway

[zambo]

Latest mods to my 1/2 power Liverpool, switched out the el84's for a pair of JJ 6v6's and added a vvr from Dana Hall. Man what a difference! I love the 6v6 swap. Used a 260R cathode resistor unbypassed. Left 1.5k screen resistors and liverpool PS the same. I am guessing its still around 17 or 18 watts but not quite sure. The vvr is sweet and is going to be an addition to every amp I build at this point. I scaled the whole amp and its working just dandy. Its getting pretty hot as I used a steel chassis ( an old steel framing member from a construction sight.....ghetto fab ). So do I add a typical ratshack heat sink to it? On the inside of the chassis or just on the outside with the mounting bolt? Any thoughts are appreciated.

[ampmike]

Ive been scratching my head on the vvr thing,Some love it and others dont.Sounds like its working for you,I might put it in the liverpool Im building.
Thanks for the post,Illm let you know how it goes,Mikey

[passfan]

Latest mods to my 1/2 power Liverpool, switched out the el84's for a pair of JJ 6v6's and added a vvr from Dana Hall. Man what a difference! I love the 6v6 swap. Used a 260R cathode resistor unbypassed. Left 1.5k screen resistors and liverpool PS the same. I am guessing its still around 17 or 18 watts but not quite sure. The vvr is sweet and is going to be an addition to every amp I build at this point. I scaled the whole amp and its working just dandy. Its getting pretty hot as I used a steel chassis ( an old steel framing member from a construction sight.....ghetto fab ). So do I add a typical ratshack heat sink to it? On the inside of the chassis or just on the outside with the mounting bolt? Any thoughts are appreciated.

If you can touch it without letting go your probably okay. That would put you under 30 deg. C. If not get a sink and, I would orient it so the fins were facing up in order to dissipitate the heat properly. Preferable on the outside of the chassis to keep as much heat as possible outside. Use thermal grease between the chassis and sink for max thermal conduction. Try to estimate the temps your running and calculate the dissipitation properties of the sink you buy to get one big enough.

[UR12]

A heat sink needs to be where a free flow of air can get to it so it needs to be on the outside of the chassis. Install it right over top of where the mosfet is mounted on the inside so that the heat the mosfet radiates into the chassis gets transfered from the chassis to the heatsink and the heat dissipated from the heatsink to the surrounding air. You are probably going to need something a little bigger than what you can buy at radio shack. The one I use is about 2" square and about 1" tall but that is on higher wattage amps.

[zambo]

@ ampmike - I love the vvr. If I were to build a full on real liverpool I would put in a switch to shut off two of the tubes and a vvr. Do the extra cap and resistor mod while building.

@ Dana and Passfan - I can touch the chassis without moving my hand or getting burned but it feels like I should get a heat sink. I will look for the right one. Im sure something is better than nothing so at worst its the ratshack variety. I guess if it fails I will just have to help pay Dana's mtg. payment and buy more parts Thanks for all the help guys and thank you Dana for the parts and prompt attention. I will do business with you anytime !

@ all - The 6v6's are really sweet in this amp. I know its not traditional but if you are looking for something a little different its sweet. I guess I need to build an express now!

[Gee]

zambo - Very interesting amp.

Do you have a schematic or what specific schematic did you base it on?

[zambo]

I dont really have a schematic. It started life as a stock blues jr which developed a few problems and i thought, hmm i will do a little mod here and there....next thing i know I am using those transformers to build a half power liverpool. Didnt like the el84s as much as I could so I tried the 6v6's instead but left all the stock liverpool voltages. I also left the cathode unbypassed as it gives a bit more compression. I added the vvr just because its still to loud. I did keep some notes as I built it and plan to build another one soon. I have a Hammond organ that i gutted for parts as it wasnt working anymore and it used a 2 6v6 power section. i will probably use the tube rectifier from it as well.

[Buschman]

A Liverpool with 6v6s is an............Express.

[zambo]

well, only kinda. Cathode biased ( un bypassed ) and much lower voltages. so its not really an express or a liverpool, kinda in between.

[Reeltarded]

It's a Liverpress!

I swear I'd make a 100wt amp with 6v6s if I could get great pairs of matched quads.

[zambo]

The Liverpress!!! I was going to call it chopped liver but yeah thats good!

I may make my next one with a quad of 6au6's I just finished a project with two in push pull and it sounds sweet! cant wait to put a wreck type preamp in fron of them!

[Gibsonman63]

It's a Liverpress!

I swear I'd make a 100wt amp with 6v6s if I could get great pairs of matched quads.

Does it really matter in a cathode biased amp? For fixed bias, you can just install separate bias adjust.