Thank you Martin for a good explanation!
Beiträge von endresl35
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Hi,
I am looking at the schematics of the M15MK1 and the long tail pair phase inverter. My understanding is that the plate resistor on V3B should have a higher restistance than the V3A, compensating for the gain level of B, given that it is run through an extra gain stage (V3A). The schematics even show that B has (slightly) lower volt rating (206 on A vs 204 on B), but they have identical resistance (100k). Is it an error in the schematics/design (I have confirmed that in my kit it is like this), or is it something that I have missed (a very plausible explanation)? From what I understand, an uneven signal to the power amp tubes creates earlier power amp distortion. Is it that for EL 84's this doesent matter that much, or is even desireable?
Best regards,
Endre
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Thank you Martin!
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Hi,
A simple and probably silly question, what is the dimensions of the 4 chassis mounting screws on the A15MK2 kit? They where probably delivered with the kit, but I can't find them.
Best regards, Endre
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Hi,
I have finished my A15MK2 about six months ago, and the amp has been in "QA" and regular in use for a while now. I love the amp, I have decided that it is time stop procrastinating to get it installed into an enclosure now.
I have not secured the large capacitors in the power supply board yet, and a search on the web reveals that it is conflicting opinions on the subject, some use silicone, hot glue and different products. What do you guys recommend?
Best regards, Endre
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Hi,
I have just finished my first amp build. Really educational but nevrotic experience. Have been doublechecking everything about 10 times, so the build it self has taken just about forever, but better safe than sorry when you don't know what you are doing
All voltages are on the low side, but all checks out well within the 10% margin, but not the bias voltage at R51 and R52. Here I have a +-30% difference. When I have -32mv at one side I will have -22,8mv at the other. If I swap the 6V6's, the difference swaps as well, hence it seems like it is tube related. I have 265v on the socket side of both R55 and R56. I have no previous experience here, but this difference seems very substansial to me. Is this normal, or do I have a faulty tube?
Regards,
Endre
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A heater voltage of 6V AC free running is quite low, is the primary voltage from your wall outlet 230V AC?
I've got 227v AC. I will measure again when I am finished with the secondary viring.
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Hi, thank's Martin for the feedback. Makes sense now. I see the manual is rating heater voltage to 7,4, while I get ~6:
The difference was greater than the 10% difference axeptable deviation, but I judge by your answer that this is incorrect in the documentation?
Hi Endre,
One piar of it has thick copper wires soldered to them, this is the heater (6,3V).Regards, Endre
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Hi,
I am having the same problem. I can see numbers on a couple of pins, but most of them are so covered in paint they are practically invisible. I am not willing to do any guesswork on the power transformer. Could someone help me out with some kind of pin layout schematics?
Regards,
Endre