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  1. tri-comp

    Yamaha C-2a hifi heater restoration

    Thanks a lot. Having spend a lot of time checking and switching around the two 2SK101 I couldn't make heads or tails out of what was causing the large difference in volume between the two channels. It didn't occur to me that a capacitor of this kind could short out in a low voltage circuit. In...
  2. tri-comp

    Does anyone know of any stereo amps that use the "QQE03" tube?

    About time don't expect it to get any better once you retire. If you already did you'll know what I mean:D Motivation is something else. Has to be there... For me it works knowing that I can, it usually ends up sounding very good and the face of friends when they hear what homemade tube-amps are...
  3. tri-comp

    Does anyone know of any stereo amps that use the "QQE03" tube?

    My amp is based on a Chinese kit for a reason. It's a gamble of course to order anything Chinese but don't be wrong. It may go both ways on performance and durability and it seems this time I got lucky. I don't have access to unlimited funds and buying the chassis, transformers and hardware for...
  4. tri-comp

    Does anyone know of any stereo amps that use the "QQE03" tube?

    No, I'm using a 6DT8, rather similar in characteristics to ECC81/12AT7. The China-kit chassis was pre-punched with 3 tubesocket holes for each channel. The choice was between paralleled PP QQE's and a FET source-follower or the cathode-follower option with a tube. I wasn't sure the power...
  5. tri-comp

    Does anyone know of any stereo amps that use the "QQE03" tube?

    Hi, I just came across this thread on doing LF amps with QQE03/12. It most certainly can be done and it shouldn't be a big surprise to anyone. The spec's from Philips and Telefunken tells the story on how to do it in either class AB or AB2. I choose the latter because the improvement in bass...
  6. tri-comp

    Marantz Service Manual error thread

    Just repaired a 1060(e) amp. (S/N: 528709) with no sound from right channel. With external signal supplied to Main-In RCA sockets the problem persisted so clearly had to be on the P700 board. DC check on the pre-amplifying transistor H701 shows zero Volt on all pins so evidently it's not...
  7. tri-comp

    Anyone ever use those Chinese socket savers from eBay?

    I'm using the cheap Chinese ones. The pins are not the same diameter as tube pins, just a tad smaller. Enough though, to make the socket saver wobble a lot in the original 9-pin socket in my B&K 667 tester. I'm also using Chinese 7-pin savers featuring a ceramic socket. The holes are so small...
  8. tri-comp

    Fisher 500c Insufficient Negative Bias Voltage

    Hi, Did you stop to think that you yourself is actually the problem ? Your voltmeter is loading the biasvoltage and causing a low reading. If you want to take a reliable reading you should use a voltmeter with a very high internal resistance. Not that you really need to know the exact...
  9. tri-comp

    6L6 Push-Pull amp - too much hum,need solution

    You're right, it's elevated and it should be. But is it ? Check DC-voltage across C21 (around 1/4 of the voltage across C17) and confirm that this DC-voltage is also present when measuring from any ECC83 heater-pin to ground. If there's no DC voltage across C21 suspect a bad R24 or a shorted C21...
  10. tri-comp

    Straange triodes

    Hi jazbo8, Sorry, I got into reading this thread rather late and have first noticed your request today. Here's the article you asked for. About doing an 6AS7-PP amp., that's been on my to-do list for some time. I actually don't have 6AS7's but I do own some NOS Svetlana 6H13C's that should...
  11. tri-comp

    Identify this tube...__

    6AS7 is a VERY good tube for Audio. Something that was discovered back in the 40'ies. Try Googling McProud + 6AS7 .... Hard to drive but here's a reasonable simple suggestion for an PP-amp that will sport an output of around 8 Watt with a standard 5Kohm P-P OPT. This construction is w/o any NFB...
  12. tri-comp

    Help me fix my whistling tube amp?

    This is a troublesome construction regarding the 12AX7 'Folament' I can't really imagine someone misspelling the word 'Filament' twice unless they actually think it should be spelled 'Folament'. Anyway, the cathode-voltage of the cathode-follower section is quoted at +161V DC. This is way above...
  13. tri-comp

    Checking Russian Tubes on a B&K 707

    Hi, Over time I've collected quite a few Russian tubes and I needed a way to check them easily. Since many Russian tubes are 1:1 copies of Western tubes that's not too difficult provided you know which are equivalents. I own a B&K 707 tube tester that has been renovated and resonably calibrated...
  14. tri-comp

    Anyone Have a Schematic or Know This Circuit?

    Put a more precise date on your amp. and get some spec's in the process. Have a look at page 42 of this publication: http://www.americanradiohistory.com/Archive-Catalogs/Allied-Catalogs/Lafayette-1968-Summer.pdf It's on sale so I'm guessing this is probably late in the marketing of the...
  15. tri-comp

    Hi Loomis, Back in 2011 you did a scan of the 1975 tube-chart for the B&K 707. Would it be...

    Hi Loomis, Back in 2011 you did a scan of the 1975 tube-chart for the B&K 707. Would it be possible for me to receive a copy, thanks ? My e-mail address = tricomp@europe.com Best regards from Denmark, /Torben
  16. tri-comp

    What to do with Red Plated Tubes?

    FG. I red-plated a few 6AD10-A compactrons in a Class AB2 P/P amp. I had to let them eat 28W each (Rated at 12W) to force red-plating. The still perform as new, absolutely no difference to be heard or measured. Obviously they shouldn't be run continously at red-plating conditions but the...
  17. tri-comp

    What to build?

    This is how I do it. ...sorry, couldn't resist :D Best regards, /tri-comp
  18. tri-comp

    What to build?

    In the output-range you're suggesting not a lot of tubes are available today within reasonable cost. Obviously 6L6 will get you there and so will EL34. The more interesting, from my point of view, is the 807. With a top-cap yes, but also with the 'looks'; sound/spec's like the 6L6. Exotic...
  19. tri-comp

    Rescued Phillips

    Well, good for you he choose the lesser evil and didn't butcher the amp. Getting hold of the original speaker-plugs (DIN Speaker, Male) isn't really a problem. In my drawer are severel brand new ones; they are still manufactured and sold in Europe. So are the 5-pin DIN male plugs. I imagine...
  20. tri-comp

    Please show your pics of tube amps

    I wish it was possible to buy some of this famous vintage equipment featured here. In my country it just wasn't sold in massive volumes to secure some will still be around. Also, EL34, 6L6 or 2A3 in Class A or AB, SE or PP is most always a hit and as such didn't present a real challenge when I...
  21. tri-comp

    Pioneer SX-2000

    This pdf should be close to the RF & MPX-sections. I would replace all those grey cap's with blue print. They may not be the only ones that needs to go; I'm just sure it's where I'd start. Congratulations on a very nice receiver. rgds, /tri-comp
  22. tri-comp

    sylvania amp

    I would suggest starting to measure some voltages. What are the anode-voltages on all triodes? What about the screen-grid and anode-voltage of the pentodes? Measure at the tube-sockets to see if voltage from the power-supply really arrives. The channels don't have anything in common that...
  23. tri-comp

    6AN8, 6AN8A tube recommendations please!!

    I while ago I built an amp with 6AN8A as input-amp/phase-inverter and was very pleased ...for a while. After about 2 months of use the tubes would develop a mechanical 'whine' that is very annoying. It's a high-pitched tone that would disappear for a while when touching or re-seating the tube...
  24. tri-comp

    Seul 807

    I have a quad of NOS CSF-5933/P17W. Exactly the same as 807W. Sylvania even labels their straight-side version with both typeno's. rgds, /tri-comp
  25. tri-comp

    Filamentsupply 6.3V Stabilized DC from 6.3VAC

    If you look at the broader view the switching-regulator gives you an easy and fairly simple access to using either non-standard transformers for filament-supply and even for using cheap tubes. You could take a 9VAC or a 15VAC transformer and run 6,3V tubes without dropping a lot of heat in a...
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