GoodSoundClub - Romy the Cat's Audio Site

In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET

Post Subject: Yes, that is right...Posted by anthony on: 7/29/2016

Romy the Cat wrote:
anthony wrote:
My transformer winder has completed the first prototype DSET bass OPT. He was quite excited when he called me and used the word "phenonomenal" to describe its performance into a reflective 1R load. At 4Hz it is down 0.5dB and at 10kHz and 20KHz it is down 1dB and 3dB respectively.

That all make sense ONLY if we are taking about max power. You will not get from your transformer 0.5dB at 4Hz and 3db at 20KHz at max power and the fact that your guy gives you the numbers at a fraction of power does not make me too happy about him….

That was all data given to me over the phone in real-time as he measured the setup late at night. He did some more testing today and it turns out that there is a bit more there than 9.5watts at 5% distortion...it was not the opt running out of puff but the the amplifier he was using for the signal generator...the tube and opt were still quite accurately passing the signal as it came to it from the generator. With that rectified and some full power testing for bandwidth it became clear that the tube is too stiff when loaded at 2kOhm and that the grid clips before the opt does, but at 5.1w into 1R (which is where the grid was clipping) the output was down 0.6dB at 4 Hz, so at full power it still should be well under 10Hz

So, after all that and studying the tube curves the decision made is that the tube definitely needs to be loaded closer to 1500R as was originally intended and to do that we need to go up two core sizes (no inductance gain if we go up only one core size) and use larger diameter secondary wire.

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