HELP - Something Blew on my Stereomour

drewh1 · 2358

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Offline drewh1

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on: March 27, 2013, 02:09:52 PM
My Stereomour has been working great since Sunday -Now everything sounds distorted, like a fuzz tone.

All resistances and voltages check out fine - except that I have no voltage when I test the hum pot outputs.

It started when I switched to my Shunyata Power cord. I plugged it in with power off and when I powered on, the problem started. I checked the cord and everything seemed fine.

Any ideas what fried?

J-River on Custom built Music Server in Silverstone Case
Ayre QB-9 USB DAC
Kaiju
Stereoumour
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Offline Doc B.

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Reply #1 on: March 27, 2013, 02:30:11 PM
It doesn't seem likely that all the voltages would be OK except what you are referring to as the hum pot output, which I presume is the center lug of the hum pot that connects to the 2A3 cathode resistor. Check the resistance reading from that center lug to ground (should be around 1200 ohms), and also recheck the voltage at A1 and A4 which should be around 57VDC.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline drewh1

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Reply #2 on: March 27, 2013, 02:40:30 PM
I checked the hum pot output at the speaker terminals per the manual - it had been set with the hum pots to .9 mv. 

I just happened to have a new driver tube waiting to be installed. I tried it and everything is fine. Apparently the stock tube failed.

Is that a coincidental failure?  I don't see how switching power cables could have caused it.  Please let me know so I don't blow another one.


J-River on Custom built Music Server in Silverstone Case
Ayre QB-9 USB DAC
Kaiju
Stereoumour
Diy Cotton wrapped wire interconnects and speaker cab!es
Green Mountain Audio EOS HDx speakers
Crack with Beyerdynamic T1
Shunyata Diamond Back Power Cable
DIY Sub with Seas L26Roy Driver


Offline Paul Birkeland

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Reply #3 on: March 27, 2013, 02:50:22 PM
It is very unlikely that the power cord adversely affected your amp, this is more than likely just a coincidence. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Doc B.

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Reply #4 on: March 27, 2013, 03:15:17 PM
OK, you were talking about measuring the hum level at the speaker output, got it. If voltages are all good the problem is not in the power cord, power connection, power supply or the tubes. That leaves the signal path, that is the signal is not making it out to the speaker for some reason. Check to make sure the input selector switch is set to the correct source and that your speaker cables are making good contact with the binding posts.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline drewh1

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Reply #5 on: March 27, 2013, 03:21:33 PM
Hey Doc - I bypassed the switch, only use one set of inputs.

Anyway - it was definitely the driver tube - I replaced it with a JJ ECC81 Gold Pin - Not a subtle difference, my bass is back in spades, I have more volume, everything sounds more defined.

i am guessing that driver tube was faulty from day one and was causing me to have less fidelity - This amp just keeps getting better and better.

Any chance you can send me a replacement tube, just so I have a spare?

thanks,

drew.

J-River on Custom built Music Server in Silverstone Case
Ayre QB-9 USB DAC
Kaiju
Stereoumour
Diy Cotton wrapped wire interconnects and speaker cab!es
Green Mountain Audio EOS HDx speakers
Crack with Beyerdynamic T1
Shunyata Diamond Back Power Cable
DIY Sub with Seas L26Roy Driver


Offline Doc B.

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Reply #6 on: March 27, 2013, 03:37:25 PM
Yup, the best way to get a tube is to email us at [email protected]. That will get it in the queue for the next day's shipments.

Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.


Offline drewh1

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Reply #7 on: April 02, 2013, 07:31:51 PM
Got my backup tube today - thanks so much for the quick response.

In the meantime, I was trying a JJ gold pin. Now that I have the stock tube, I like it better than the JJ. Although Doc has said that tubes are really tone controls, I notice more detail with the stock tube. The JJ was a bit flat a lifeless and lost detail without providing better bass. This was my experience in any case.


J-River on Custom built Music Server in Silverstone Case
Ayre QB-9 USB DAC
Kaiju
Stereoumour
Diy Cotton wrapped wire interconnects and speaker cab!es
Green Mountain Audio EOS HDx speakers
Crack with Beyerdynamic T1
Shunyata Diamond Back Power Cable
DIY Sub with Seas L26Roy Driver