![h.h. scott stereo master heathkit h.h. scott stereo master heathkit](https://pic2-h.avaluer.org/imgspic/e/o/w/z/e/-vintage_hh_scott_scottkit_lk48_integrated_stereo_tube_amplifie-2_1000.jpg)
Scott Stereo Master 300c Vintage Receiver (Teile oder Restauration nur!) 5 5 von 12 H.H. Scott Stereo Master 300c Vintage Receiver (Teile oder Restauration nur!) 4 4 von 12 H.H. Scott Stereo Master 300c Vintage Receiver (Teile oder Restauration nur!) 3 3 von 12 H.H. Scott Stereo Master 300c Vintage Receiver (Teile oder Restauration nur!) 2 2 von 12 H.H. Scott Stereo Master 300c Vintage Receiver (Teile oder Restauration nur!) 1 von 12 H.H. Best part is it sounds great! I've been fussin with this thing for the last month and was frustrated. Right and left output look great on the scope. It even works very good with a 5% 19KHz modulation instead of the 10% modulation. The 38KHz signal was much stronger, the decoder started working great, and I could set the R and L separation controls for excellent separation. Powered it up and viola, everything was great. Replaced the tube with a NOS RCA I had kicking around (the old Telefunken 12AX7 had tested very strong on my Heathkit TT1), replace the 2 diodes. It took out the tube and 2 germanium diodes in the stereo switching circuit. Then I accidentally shorted the grid of the 12AX7 38Khz osc. Had beautiful 19KHz signal and I thought a good 38KHz signal. Still problems with the multiplexer unit.
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Finally borrowed the right equipment to get the ratio detector set right. Couldn't get the multiplex unit to work worth a crap. I was having a dickens of a time getting the thing aligned.
#H.H. SCOTT STEREO MASTER HEATHKIT HOW TO#
I also am not sure how to adjust the R and L separation controls for best separation. I've learned a lot, though, in working with this thing!īeen working on the 350D HH Scott FM tuner that's the mate to the LK-72-B. I don't know enough about this stuff to know what to do to fix it. I need to be just off peak signal for the stereo to lock in. I seem to have trouble getting the 19khz pilot to peak at the same place as the signal. It works and I stereo is ok, but i think proper adjustment would improve separation. No procedures, so I have to adapt from other equipment without the proper test equipment. I can't find any Scott info on this unit outside of the schematic.
#H.H. SCOTT STEREO MASTER HEATHKIT GENERATOR#
I don't have a multiplex generator so getting the multiplex section aligned and adjusted properly is a bit of a problem. I have the RF and IF sections aligned using a spectrum analyzer, sweep generator, scope. I've got the matching FM tuner up and running now - A HH Scott Stereomaster 350D. It's working so good right now that I'll probably just leave it alone for now.
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The AudioKarma forum has a good bit of info that Dave Gillespie has put out on the fishers that should also work on the Scott. The active control of the bias and screen voltage as a function of the B+ apparently greatly reduces the idle current while maintaining the power and distortion characteristics of a properly biased output. I have looked seriously at the bias setup that many are adding to the Fisher amps. No fan yet, but it's fully exposed so cooling is good. The amp sounds great this way and I don't really push it that hard so I don't run into a power problem because of the lower idle current, so I'll leave it this way. Voltages are well within operating limitations of the tube. I don't think what you have done will be noticed.Īs to the B+, how does it compare with the max plate/screen voltage of your output tubes? At some point the sound becomes a bit thin and tinny. A problem? Well within the voltage ratings of all caps.I think nobody answered the bias question because it is hard to tell. Power supply voltages run about 15 volts high with the reduced output idle current. I'm just looking for maximum tube life without sacrificing sound quality. How far can one reduce idle current before a degradation in sound at lower listening levels? I would assume that getting the current too low would put the tube in an operating range where linearity would be affected. I've now reduced the cathode current to 56 ma (required a bit of circuit change to get the bias voltage where it needed to be for the reduced current), and the amp still sounds great, though I'm sure my max power output is down, but still way more than I need. Reduced current to 65ma and noticed a reduced heat factor, without affecting the sound - plenty of power in my studio. The amp generated fair heat and the trannies would get fairly warm to the touch. Normal suggested bias for the 7591A pair is 70ma combined cathode current (35ma/tube). (04-07-2018, 02:23 PM)rfeenstra Wrote: Question for you tube amp gurus: A bit of background before the question.