ned Posted July 20, 2019 Share Posted July 20, 2019 Hi everybody. I am in a transitional period while my st-70 is getting serviced. Tonight I am running a Fisher 400c into a Teac A-L 700p into KHorns. Funny thing, It sounds great at volume, but at polite levels, not so much. No bass, no umph, and the sweet details are pretty well buried in the mix. Some of this could be explained by loudness curves, but I wonder if something more is a play. The loudness controls on this pre are too drastic to be useful but some bass and treble adjustment seems to help. Could this be a symptom of an impedance mis-match between the old pre and the modern amp? I don't find the input impedance listed anywhere, but surely it is above 20kOhms or something safe like that. I may switch out the amp for transistor based SS to see if that makes me happy. Most recently I ran an Adcom 555 into the st-70 and it sounded pretty nice. In my opinion, one thing that really sets the KHorn apart is that it typically sounds great at lower volumes. Not tonight. Any thoughts? thank you, Ned Quote Link to comment Share on other sites More sharing options...
Marvel Posted July 20, 2019 Share Posted July 20, 2019 The 400c probably has a high impedance output, and plugging it into a pice of ss gear with a 20 kohm input can cause a huge loss of bass. Going the other way - ss pre into the high input z of the st-70 will work fine. Bruce Quote Link to comment Share on other sites More sharing options...
ned Posted July 20, 2019 Author Share Posted July 20, 2019 Thanks Bruce, another question, the Fisher has phono inputs for RIAA 1 and RIAA 2. The RIAA 2 seems to sound a bit better. Any idea which became the standard we enjoy today? N Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 3, 2019 Share Posted August 3, 2019 @ned Got busy and then had to dig. Between the info in the two pics it may help answer your phono input questions Bruce Quote Link to comment Share on other sites More sharing options...
ned Posted August 3, 2019 Author Share Posted August 3, 2019 Wow. You found the words of Avery himself. Thank you! Nice digging. I hope the 400c goes back in service when the temperatures drop and the pair of 200s (the last of the famous 50a line) go back in service. I just went SS with a new preamp and am loving the glassine quickness. I look forward to a languid winter. You are a great member of this community. Thank you. Ned Quote Link to comment Share on other sites More sharing options...
Marvel Posted August 3, 2019 Share Posted August 3, 2019 Just thinking... you have the 400c preamp? This is from the 400C integrated. I find the manual for the pre and send it to you. Quote Link to comment Share on other sites More sharing options...
ned Posted August 3, 2019 Author Share Posted August 3, 2019 Yes, it’s the pre. It was the first stereo item fisher produced. The manual would be a kick. Including the phono stage it has 7 tubes and a honking power transformer. This stuff was super expensive in its day. 1 Quote Link to comment Share on other sites More sharing options...
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