The Amp Garage

Thanks Guys, I believe the standards have been changes that any hardwired amps should use a DPDT switch, I have not checked the latest standard myself yet, but I have been told. This amp is not hardwired, but a DPDT switch is safer and easy to wire in place. No Standby on this amp anyway, but SPST i...

So Norybrook pushed me over the edge and I decided to build a Tweedle Dee at the same time, 4 evenings later and it is finished! Quite enjoyed the build, the layout is very clean and easy to work with. Anyway here are some photo's, the layout I used and a parts list that may be helpful for anyone el...

Thanks Phil, will try and figure that all out when I get there

Adjusting the trimmer compensates for PI imbalance as well as the power tube imbalance, really needs a scope and signal generator. otherwise just use your ears. it will be very subtle. Great info on the FFT with the scope, I never knew I could do that with my scope.. now I can! really wish I could g...

Depends on the manufacturer, some type test, some sample test based on qty, usually depends on the purchase specification.

Post some pictures.

Isolate where the problem is, jumper the input, just as you did with the phase invertor, to the second and third stage grids to see where the problem begins

I use ltspice for this sort of thing, gives a good idea as to what is going on

According to my US supplier yes they are technically the same.

I am a g12H fan, even before hearing these clips, but that is what I would say after listening to these clips to, they are tight and fast, great for heavy rock that smacks you in the chest, not what I would go for for clean jangly playing though.

I like polystyrene caps, plus they can be orientated for lower noise, pulled all the mica's out of a high gain amp I built and replaced them with polystyrene caps and the amp was much quieter and sounded sweet.

Nice looking built Dave

Its a 12.5w resistor, so maximum voltage it can handle is 111v, otherwise you will overheat the resistor. - when heat sinked correctly. Using Ohm law maximum current is .111A - when heat sinked correctly. This resistor will not see a 111v voltage drop across it unless there is a fault condition. i.e...

would it be OK if I put 1K/12.5W resistor instead of 1K/25W for 2xEL84 liverpool?the only thing that worries me is max.voltage rating for this resistor...btw it is chassis mount. What is the voltage rating of your resistor? What Primary impedance are you going to use? 1k/12.5w will be overkill for ...

grief three pages and not one gut shot photo to admire!

Hope you have it sorted.

If you remove V1 and all the noise goes that mean those two triodes are picking up the noise and amplifying it. it could be getting in at your tone stack grounding as it sits between the two triodes, ground the output of the tone stack to see if it get rid of the noise.

You know I am not a fan of grounding to multiple places on the chassis, but defo get rid of the bus bar on the pots. have you scoped the noise to know that it is heater noise and not 100hz hash To solve noise issues you have to divide and conquer, Start at the power tubes, ground the grids and check...