paul_5 Posted May 30, 2011 Share Posted May 30, 2011 I've just taken delivery of an Ampeg SVP1500 power amp, which is the perfect amp to compliment my SVP PRO pre. I've noticed that the power amp is picking up the tiny amount of valve noise coming out of the pre. Currently I'm using 4x 12AX7s and a 12AU7 (in V4). Is there any benefit to attenuating the outut ofthe amp by using say, a 5751 tube at V5 (main output) to reduce the (incredible) amount of gain provided by this pre? I've tried a 12AU7 in this position, but the output was reduced by too much altogether. Any thoughts / advice / concubines appreciated. Cheers, Paul Quote Link to comment Share on other sites More sharing options...
Dood Posted May 30, 2011 Share Posted May 30, 2011 First of all, what valves are in the preamp? If they include the usual quartet of Sovtek valves - or indeed any that have seen better days, then purchasing some low noise & drive tested valves will be a great benefit. (The Sovteks are just stock valves and I'm yet to find a set that I like the feel or sound of) Yes, dropping in a quality 5751 in the output section will help to reduce noise, but obviously you are also limiting the amount of output swing you can get to drive you poweramp with. Having a word with HotRox or Watford Valves will give you an idea what is available. My favourites for the SVP and well.. pretty much any valve pre actually are the Harma Diamond STR 12AX7 or the premium JJ ECC83S (Which is exactly the same valve) and Philips ECG 12AU7 for the other position. I've only ever owned one 5751, a GE with a ridiculously long title: GE "JG5751 Triple Mica Black Plates" - but it is described as built like the proverbial out house and certainly has the least amount of hiss or nose of all the valves I have put in the same pre position. Ok, rambling over heh heh! Quote Link to comment Share on other sites More sharing options...
paul_5 Posted May 31, 2011 Author Share Posted May 31, 2011 Cheers for the response Dood. I retubed last year with Harmas from Watford Valves. They've not seen an awful lot of use (just home recording), so shouldn't be that noisy. I also found that the 'balanced' DI out is quite noisy until I switch it to 'post EQ', then the noise (through the XLR output) disappears. Could be a transformer problem? I hope not, as that was also replaced last year with a spare from Panic Music. Hmm. Quote Link to comment Share on other sites More sharing options...
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