Recent content by Roctal-Amps

Haven't had much progress, but I have started working on it again. The upgraded transformers should be good for 1200v at 900w continuous power. The tubes are being upgraded from 4cx250b to 4cx350b because they are easier to drive and requires less bias voltage allowing me to cathode bias for a...

All done, ended up using a 6sl7 for phase splitter to get a bit more drive. It dirties up pretty good with active pickups.

Here are the pair of Antek toroids that will be replacing the current power transformer...

The datasheet says 1500v should deliver 450 watts at fairly clean level, at 2000v 750 watts is possible but an output transformer is extremely hard to design for that.

The output transformer is running at about 5,000 ohms reflected impedance which is a bit high for 4cx250b at 850 volts. But at 1100v to say 1400v 5,000 ohms is a good match.

Well, I am at it again and can't leave well enough alone. I will be starting a power supply upgrade. Original supply was sagging to about 850 volts with about 400 watts draw to produce a clean 175 watts. The output transformer should be clean to 300 watts. So the new power supply should...

Both the original transformers were trashed so they are getting upgraded. The output transformer is a Hammond 16xx series (20-watt, 6.6K) and the power transformer is from old HP signal generator. It is huge but it is the only one I had would fit the cut out in the chassis. The output stage...

I don't have a great deal of experience with their kits, but I do buy parts from them frequently and have had no issues with their parts. How many watts do you need? What features do you need? One possibility is to look at a marshall 100w kit and replace the output transformer with something...

The limiting factor for the marshall is going to be the output transformer. The sunn model is equipped with an output transformer that would most likely span the home audio bandwidth of 20hz to 20khz. The Marshall output will most likely start roll off below 70hz and usually is designed with...

I have one of these beasts, the single 15 is an Electra Voice evm-15l with 200 watts rms power handling, it does the job. I split the cabinet and the head up. From the phase splitter forward it is a killer amp, but the preamp is lacking. Mostly because the EQ actually kills the tone.

As for the Ceriatone kits, all of the fenders seem to be tweed bass, probably not what he wants. They do have a Plexi50 Bass clone, which may fit the bill. With modern transformers and upgraded cathode bypass caps it will probably perform well in the lower registers.

Add me to list please.

I was originally shooting for 180 to 200 clean watts. I was looking at a few things on the scope and I think I can get there running the tubes a little colder at idle and closer to class B but still A/B.

You are correct, it is a bit counter productive. It is only for practicing, but it allows the cranked sound of an overdriven tube amps (like an SVT) without having to deal with the 300 watts of deafness that comes along with it. You might be suprised how loud a small tube amp with a single...

Thinking about building up a 10 to 15-watt single ended KT100 bass head for some easy over-driving.