cytania Posted December 31, 2011 Share Posted December 31, 2011 The saga of my buzzy SWR/Compact goes on. Like watching an Agatha Christie whodunnit my suspicion goes from the amp to the cab, from the cab to the amp and back again. Last night I theorised it might be the internal cable to the driver sagging onto the speaker cone. So tried the compact upside down this morning, but no difference. I also managed to rig up something Alex suggested before christmas - playing a regular music source through the SWR amp. So in goes my cheap ipod-shuffle and some adaptors and bingo! no buzz, no fuzzy distortion, no matter how hard I drove up the volume or gain. Full bass brought out a little rasp but different from the bass buzz problem. A great demonstration of the quality of the Eminence Professional Series 3015 driver that Alex uses. the music wasn't muffled, the mids and highs were pretty darn decent. This suggest to me (having scoured Alex's excellent notes that go out with every Compact) that the problem is Crest Factor, the peaks from my two basses are much higher than recorded music. Does this suggest I should go back to the amp as the main culprit? One thing that bugs me is that particular notes provoke the buzz, usually A and G in the upper registers. I was considering switching out the valve anyway but the range of 12AX7options on Watford/Hot Rox is bewildering. Most of their remarks are oriented on guitarists who want edge and clarity. Can anyone recommend a current production tube in stock at either of these sites that is good for bass? I'd like mellow and smooth. PS. Two great things about Barefaced 1) Alex answers emails promptly with solid ideas and 2) the Compact takes apart with simple tools, the insides are accessible and straightforward. Quote Link to comment Share on other sites More sharing options...
cytania Posted December 31, 2011 Author Share Posted December 31, 2011 Ooh, like the look of this 12BH7A/Sylvania, as used in early Ampegs. http://www.watfordvalves.com/product_detail.asp?id=19 What do you reckon? Compatible? Quote Link to comment Share on other sites More sharing options...
Prime_BASS Posted January 1, 2012 Share Posted January 1, 2012 Hey man. I'd like to know what this crest factor is?????? If I understand it a buzz is cuased by an overload in signal? if so you could try a compression? Are you sure its nothing internal on the amp? At some volumes I've had old valve amps rattle a fair bit, and some notes make my room rattle like buggary where as others dont, even at low volume. Quote Link to comment Share on other sites More sharing options...
cytania Posted January 1, 2012 Author Share Posted January 1, 2012 [size=4]Hi PB, if you imagine you monitored the output from your amp on a graph the recorded music would be a flat ribbon with a slightly ragged top, except maybe for total drop outs and quiet passages. Your bass would be a series of spikes way above it. Bass is asking the speaker to move alot faster and harder. At least that's how I understand it.[/size] [size=4]Today I played with the bias of the amp (a tiny wheel pot component, being careful to go nowhere near the power sections) but no payoff. An ECC83/12AX7WC/SOV-CRYO valve is on order from Watford, so we'll see if that's the chap.[/size] [size=4]Pretty sure it's not room rattle, cab is not really as loud as it used to be. Could be a sympathetic rattle inside the cab but I've been inside and given everything a poke, nothing obviously lose. If the valve don't fix it then I have to conclude it's the speaker...[/size] Quote Link to comment Share on other sites More sharing options...
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