Cal Blacksmith Posted August 23, 2005 Share Posted August 23, 2005 I am running a VTL Ultimate pre-amp into a Sonic Frontiers Power 1 amp. The amp is a 6550 / 6922 based push pull unit rated at 55WPC. I love the sound from the combo but I am suffering from a common problem, namely, high output from the pre into a high gain amp, thus causing my Cornwalls to be driven to 100 db when the volume pot is at the 9:00 position and zero is at 7:30. It would be nice to have more adjustment in the volume department. Is there a device that can be inserted into the signal path that will help me to achieve this goal with no or minimal signal degradation? I can live with what I have but it would be nice to have more of a fine control of the volume. Ideas anyone?? Quote Link to comment Share on other sites More sharing options...
scotbuck Posted August 23, 2005 Share Posted August 23, 2005 Greetings, If it's an all-tube circuit (and assuming its got 12AX7 tubes with a gain factor = 100), you can try swapping the lower-gain 12AY7 (gain = 45), 12AT7 (gain = 60) or 5751 (gain = 70) tubes. Some folks -- including my amp tech -- advise against swapping a 12AU7 tube, even though it has still lower gain. Hope this helps... Take care, Scott Quote Link to comment Share on other sites More sharing options...
steve Posted August 23, 2005 Share Posted August 23, 2005 A few years ago I had the same problem when I ran an Adcom 565 pre..too much gain too fast. With the advice from some folks right here on this BB, I bought a Niles SV5 line level volume box in between my preamp and amp..I set the box at about 11-12:00 and then I had way more gain control..It came on a lot slower..I believe Niles has a website..I bought my SV5 at a local stereo shop in Anchorage. Good Luck! Steve Quote Link to comment Share on other sites More sharing options...
dbflash Posted August 23, 2005 Share Posted August 23, 2005 I had the same problem. Here is a possible solution to your volume control problem http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=266-242 i went with the 6db's. danny Quote Link to comment Share on other sites More sharing options...
Guy Landau Posted August 23, 2005 Share Posted August 23, 2005 2 possible solutions: 1. rotate the balance controls (feedback) fully counter clockwise. 2. wire the amp to triode operation - you'll get less power and less gain. It might sound sweeter too. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted August 23, 2005 Share Posted August 23, 2005 if you want I'll build you a little mini-box with RCA in and out, 25K stereo pot in the middle. very similar to the Klipsch mini-box. In fact, I could just build you one of those and you could ignore the center channel output. You would be able to individually adjust the attenuation per side. About $50 plus ship unless you want extra expensive hardware. Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted August 23, 2005 Author Share Posted August 23, 2005 Thanks for the help so far guys, everything is on the table. Guy, you have kept me on the straight and narrow path so far and I can not see why that would change. EDIT: The feedback is set to the center position but even all the way CC it does not buy me much in the way of adjustment. END EDIT Is the re-wire a easy operation? Can it be done with a switch like the VRDs is? I will require a tech to do the work as I have no experence inside an amp and don't want to blow anything up and would like to stay alive! I am running Tung-Sol 6550s and they are much sweeter than the Svetlanas that came with the amp. Quote Link to comment Share on other sites More sharing options...
D-MAN Posted August 23, 2005 Share Posted August 23, 2005 You might have some luck with this... Depending on the preamp, plug your cd source into a different input (aux, tape, ect.) these all have different impedance values which effect the amplitude, of course. Also, this will not hurt anything and may actually sound better! DM Quote Link to comment Share on other sites More sharing options...
Cal Blacksmith Posted August 23, 2005 Author Share Posted August 23, 2005 I wish it were that easy! It is infact ALL sources are equaly loud. The loudest of the bunch is the phono source though not by much. Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted August 23, 2005 Share Posted August 23, 2005 I see I posted almost the same time as you above. Did you see my offer? Interested at all? I'm ordering parts for another in a day or so, let me know. Quote Link to comment Share on other sites More sharing options...
codhead Posted August 23, 2005 Share Posted August 23, 2005 Try a pair of these. Beautiful construction, transparent sound, and 10dB is enough attenuation to tame all but the worst mismatches. Go to audiogon.com, and do a search on "Rothwell" to find a dealer. Quote Link to comment Share on other sites More sharing options...
NOSValves Posted August 23, 2005 Share Posted August 23, 2005 The beauty of a preamp with per channel level controls and a main volume control. They mate with anything. Quote Link to comment Share on other sites More sharing options...
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