Channel imbalance

schweigc · 13733

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Offline Beefy

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Reply #15 on: February 23, 2012, 10:12:46 AM
Quote from: Noskipallwd on February 23, 2012, 06:29:38 AM
Yes, Desmond is right the TKD model that sells for $100 is an improvement over the cheaper one. I've felt that if I am going to spend 100 might as well go an extra 30 or so dollars and get a goldpoint mini-v or other equivilant stepped attenuator. I have found the cheaper TKD to be quiet and smooth from bottom to top. It is trickier to solder than the alps as it is a bit smaller.

I'm a big fan of the TKD 2CP-2511, which is the more expensive TKD model. However I bought my TKDs when the base price was $72, and PCX had a 20% off sale - at $100 full price it is a big ask.

Not a fan of steppers like the Goldpoint in very brief listens. My perfect listening level is always between steps.


Offline schweigc

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Reply #16 on: March 04, 2012, 05:48:05 PM
Hello,
I just got back from out of town. While I am waiting for another pot, I thought I would look at voltages again. I bought a better DMM, and got some strange readings (expected value):
1:  5  (90)
2:  .5  (170)
4:  0  (170)
5:  0  (90)
6:  86  (0)
7:  85  (100)
9:  85  (100)
10:  88  (0)
A6:  136  (90)
B1:  135  (90)
B3:  140  (100)
I also got -2 readings on 12, 14, 16 (not sure if negative voltage means anything).

Thanks,
Chris

Sorry, I was measuring some of the wrong terminals (1-10 I *was* measuring the transformer terminals). The out of tolerance readings for 1-10 are as follows:
T1:  135  (90)
T7:  138  (100)

Terminals 6 and 10 jump around from .5 to -50


« Last Edit: March 04, 2012, 07:08:40 PM by schweigc »

Chris Schweigert

Offline Laudanum

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Reply #17 on: March 05, 2012, 02:49:47 AM
Just double checking here ... what do you measure at T2, T4 and T5?

Desmond G.

Offline schweigc

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Reply #18 on: March 05, 2012, 04:53:23 AM
Laudanum,

T2: 165  (170)
T4: 165  (170)
T5: 90  (85)

Thanks,
Chris

Chris Schweigert

Offline Laudanum

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Reply #19 on: March 05, 2012, 07:25:26 AM
Would you happen to have another 12AU7 tube to swap in and re-check voltages?   Im not one of the gurus here, but a tube swap and then re-checking voltages would be a quick way to rule a bad tube out.  I think the voltage will be high if the tube isnt drawing enough current and that can be an issue with one side of the tube itself.

Desmond G.

Offline schweigc

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Reply #20 on: March 05, 2012, 04:16:42 PM
I have a couple on the way along with another pot. Thanks for all your help!

Chris Schweigert

Offline schweigc

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Reply #21 on: March 09, 2012, 03:52:07 PM
New tube fixed it. Sounds absolutely amazing!

Chris Schweigert

Offline Laudanum

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Reply #22 on: March 10, 2012, 04:20:13 AM
Quote from: schweigc on March 09, 2012, 03:52:07 PM
New tube fixed it. Sounds absolutely amazing!

Great that I got one right :-)  ... Better that you got it sorted out.  Enjoy.

Desmond G.

Offline .Sup

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Reply #23 on: June 29, 2012, 10:57:38 AM
Hey guys, I finished building my Crack and have the same issue with the right channel having lower volume output. All measurements checked out. Should I order both tubes or just the front one?
thanks


Offline Laudanum

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Reply #24 on: June 30, 2012, 02:49:59 AM
Quote from: .Sup on June 29, 2012, 10:57:38 AM
Hey guys, I finished building my Crack and have the same issue with the right channel having lower volume output. All measurements checked out. Should I order both tubes or just the front one?
thanks

Channel imbalance with any rotation of the volume pot or just at the lower end, say below 9 or 10 O'Clock?

Desmond G.

Offline Jim R.

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Reply #25 on: June 30, 2012, 04:09:41 AM
.sup,

It's the front tube that will efffect channel balance the most (unless the large one is really, really bad), but why not get replacements for both?  Some folks have also had some issues with the large, output tube, and why not play it safe, plus it gives you another flavor to try -- say try something like a 6as7 in place of the 6080 -- the presentation is bound to be slightly different and may sound better to you.

Just a suggestion.

Welcome to the BH club!

-- Jim

Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline .Sup

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Reply #26 on: July 02, 2012, 03:39:01 AM
Thank you for the replies and welcome Laudanum and Jim! It doesn't matter how loud I turn the volume the channel imbalance is always there.

The back tube seems to be in really poor condition - oxidized and very old. I will get both it they are not too expensive. Any recommendations as where is the best place to purchase them? Is ebay alright?

Thanks!


Offline patm

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Reply #27 on: July 02, 2012, 05:33:47 AM
.sup,

Try here for crack tube info http://www.bottlehead.com/smf/index.php/topic,663.0.html .

Welcome to BH. This Forem is what separates this company from anything else I have encountered. There is no way that I could be involved in DIY Audio without the help of these guys.

Pat

In the beginning there was nothing, then it blew up!

FP III, Paramount 300b (Takatsuki TA-300B), both with Mundorf S/O caps, Mikes iron, HFBG Eros,Oppo 103,Rega RP6 2m black ,Vaughn Triode JR II

Offline .Sup

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Reply #28 on: July 08, 2012, 04:19:22 AM
Thank you for the welcome and you reply Pat and at the same time apologies for late reply, I have been very busy for the past two weeks.
I have purchased 2x 12au7A/ecc82 RCA Tube CL Top *Test NOS* from ebay. I will first test the front tube and if that doesn't provide an answer I will order 1 power tube. Will report back. Thanks again everybody!


Offline .Sup

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Reply #29 on: July 18, 2012, 10:33:32 PM
Hello guys, I just got the tubes and guess what - channels are now balanced! I am so proud of myself right now as this was my first DIY project and I was really thorough when building and refused to admit to myself I could have done something wrong. I am ecstatic right now as I got the tubes a day before I go on vacation till the end of the month and now I will be able to enjoy myself there even more. I am writing slightly under influence because after last night's live Buena Vista Social club concert I am still sobering up but could not wait to thank everybody who offered help here and the Bottlehead family. I just hope tubes are properly tested before shipped in the future as I was unable to listen to the amp for weeks because of the faulty tube. Thank you again!

Will be working on Speedball next month.
« Last Edit: July 18, 2012, 10:42:44 PM by .Sup »


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