Only one channel through both outputs, whu happened?

Misty Vapors · 8554

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Offline Misty Vapors

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on: February 08, 2010, 09:28:13 PM
Let me start by saying that I'm really new to this. I've gone through and double checked my connections and inspected my solders. My voltages seem right.  When I plug everything in I get a lot of hum and only one channel through both speakers. Plus the ringing thing when I adjust the volume, which I kind of like. I checked for proper isolation on the posts. How could I have gotten it so wrong? When I checked the resistance without the batteries in T6-10 didn't respond across the ground bus on my meter, is this it?



Offline Grainger49

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Reply #1 on: February 09, 2010, 02:32:26 AM
Just to rephrase, you get hum in both channels, and one of the channels through both speakers?

The ringing is microphonics.  If it gets to you a different pair of tubes will cure it.  There is a thread already about microphonics and tubes that don't have it.

Hum in the Quickie is most likely an open hot lead.  Try measuring resistance from the input RCA jack center conductor to the grid of the tube.  That will trace through the volume control.  The resistance will probably change as the volume control is changed.  Post back.

If I have your other problem right above, that is that one channel plays through both, I will have to think about it.



Offline Doc B.

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Reply #2 on: February 09, 2010, 05:57:54 AM
I'll suggest starting by having someone else double check the connections for you. A fresh set of eyes can often pick out an error right away that you might be missing because you have been concentrating on the project for a while. We do this all the time in the lab, Shawn checks my work and I check his.

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


Offline Misty Vapors

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Reply #3 on: February 09, 2010, 08:50:58 AM
I'm going to go over to my father-in-laws place on thursday and have him look it over. He rebuilds old tube radios from WW2 as a hobby and should be able to help me out. I feel like I'm not seeing something and I'm sure he'll be able to spot it. Will update later this week. Thanks



Offline Misty Vapors

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Reply #4 on: February 11, 2010, 07:07:22 PM
I found the problem with my Quickie. After looking it up and down and testing everything I found the simplest problem was not even the quickie itself. Bad cables are to blame. I kick myself for not checking that right off the bat but because they are my expensive audiophile cables I didn't suspect them. Throw on a pair of cheap radio-shack cables and everything came together perfectly. Normally I would check the simple things first but because this is my first build I assumed I had failed to follow instructions properly or made a rough solder.
Anyway, I'm happy to encounter a problem if it means I get to learn something. My father-in-law has a bunch of old tube testers from the British navy and he showed me how to test tubes. The tubes I got for the quickie are top of their game it turns out. The connection pins were a little corroded but we cleaned them up nicely.
Unfortunately everyone is asleep here now so I won't get to really audition my newest piece of gear until tomorrow.