johnsonwu
Responses from johnsonwu
| Thoughts on Audio Research D70 No worries hifigeek1 I removed the 2 6FQ7s (V4V5) which are the capacitatively coupled bottom tube of the 4 triode criss cross diffamp driver subcircuit so the net filament draw of this new config is 1 pair of 6H30 vs 2 pairs of 6FQ7 ie 30% lower ... | |
| Thoughts on Audio Research D70 Ampex53: I dont have a thread on modding the D115ii.The schematics are floating around the Internet.The docs Kalvin sent me are the schematics (same) and parts list.A 1987 build would be a D115ii.Hope the fuse holder is repaired by now.Biasing is ... | |
| Review: JM Labs Diva Utopia Be Speaker It's not the caps when it comes to bass. It's the coil inductors. Changing them requires a lot of testing and measuring. Not to mention size issues esp if you use the highest end air core foils. | |
| Review: JM Labs Diva Utopia Be Speaker Interesting to see there is no "contact member" option on Audiogon. AT least I cannot find it. You can just post questions here I guess. more than happy to help. | |
| Driver/Input tubes Sorry I kept saying 12AU7 cos my personal unit is modded as a power amp not an integrated.Let be go over this again.Each channel has ONE 12AX7 as gain stage.Each 12AX7 is setup in a totem pole configuration.The output of the 12AX7 is connected to ... | |
| Driver/Input tubes Download a copy of the schematic available at many websites. The 12AU7 is an SRPP totem pole configuration voltage gain stage where the output is the midpoint between the first half triode's plate and the 2nd half triodes cathode.The 12AT7 is 2 tr... | |
| Quad 989 repair - California FIzzing and ticking upon power on may not be the dreaded panel arcing problem.It may be as simple as that 220uF Lytic right @ the input that needs a replacement. Lytics do fail over time. Mine did.Re-doing the panels of course involve expert workm... | |
| Review: JM Labs Diva Utopia Be Speaker The Diva Utopia had home theater "lifestyle" speaker in mind according to the brochures.Bad compromise. Just the cost of the inductors I put in was over $450 so figure the usual 5-7x multiple it would have increased the price of this already expen... | |
| Retubing an ARC VT100 mkll Just waiting for the first report of someone popping the filament winding. | |
| Jolida jd-502p Gentlemen,I strongly urge you to do some reading on 12AX7 tube spec regarding Max heater to Cathode Voltage.The spec says 100V. SRPP based configuration calls for a raised filment to avoid this stress.Jolida does not have raised filament, just an ... | |
| AUDIO RESEARCH-WHERE ARE THEY GOING Leonard has retired. Call and ask for Kalvin. | |
| Linn Sondek is Dead - Looking for Service Greenstreet audio. David Genther | |
| Does this amp have a problem or is it OK to buy? There is a fair price for anything less than perfect, either due to an original design flaw, or a problem with the specimen itself. Some 302s sell for up to 700+ some for the high 500s.At around $600 (going ending price on 'bay) you cant even get ... | |
| Does this amp have a problem or is it OK to buy? If " barely audible" is something acceptable when the input is shorted with nothing, no CD connected, then go for it and fix the CD player, likely a ground loop or a bad RCA cable.If "barely audible" is a buzz reagrdless of volume and it annoys yo... | |
| Does this amp have a problem or is it OK to buy? Of course, cos the hum is not from the input jack or internal wire, its from the filament supply.Most modern power amps or integrated amps with reasonably high gain have DC filaments (read: no hum)Regardless of AC or DC filament, the textbook trea... |