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October 17, 2021, 12:11:34 PM

Author Topic: Measuring voltages while playing a 60 Hz sine wave. [resolved]  (Read 1297 times)

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Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #30 on: August 04, 2021, 07:25:54 AM »
Thanks for your help, PB! I am unable to post pictures (site not allowing it). Do I measure across the plugs that connect to the left and right sides of the HD600 while the headphone is plugged into the Crack with the 60hz sine wave playing?
Ross

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #31 on: August 04, 2021, 07:26:40 AM »
No, you unplug the headphones from the Crack and measure across the plug on the headphones.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #32 on: August 04, 2021, 07:33:00 AM »
My bad haha. Got those measurements for you!

L headphone DCR = 0.303 K ohms
R headphone DCR= 0.302 K ohms
Ross

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #33 on: August 04, 2021, 07:53:04 AM »
Yeah, I think you could try some different tube combinations to tighten up the channel balance.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #34 on: August 04, 2021, 08:00:42 AM »
Thanks, will do! The channel imbalance does seem less noticeable when using a 12AU7 tube compared to a 6SN7. I have a new problem now though haha. I opened up a new thread.
Ross

Offline Doc B.

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #35 on: August 04, 2021, 08:03:11 AM »
Quote
That's half a dB, which is audible but not horrible

It's audible by a few with a lot of ear training, but not many.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #36 on: August 04, 2021, 08:06:27 AM »
Doc brings up a good point, I'm not sure I would readily pick up on half a dB myself!
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #37 on: August 04, 2021, 08:26:11 AM »
Right on! Doc B and Paul, it could easily be my mind playing tricks on me haha.
Ross

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #38 on: August 05, 2021, 04:24:04 AM »
That's half a dB, which is audible but not horrible.  What is the DCR of each headphone driver? 

You may find that tube rolling could yield more equal balance, or you could fit a balance control if you prefer.

PB, you mentioned that I could try fitting a balance control. I am all about modding my Crack. How much space would be required to add one? I believe space to be my limiting factor.
Ross

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #39 on: August 05, 2021, 06:26:53 AM »
You'd need to fit the 100K linear version of the volume pot we supply, and you'd want it close to the volume pot itself.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #40 on: August 05, 2021, 06:53:11 AM »
Cool! Do you have the dimensions by any chance? I can take a look at my amp to see if it would be worth the trouble. It would be a fun addition to my build.
Ross

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #41 on: August 05, 2021, 07:16:54 AM »
You have the dimensions, it's exactly the same as the stock pot but just has a different part number.
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #42 on: August 05, 2021, 07:25:09 AM »
Oh haha. I'll look into this on my end, and see if I can implement this into my amp.
Ross

Offline Colonl_Charisma

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #43 on: August 17, 2021, 06:54:42 AM »
Hi, PB! So, after looking at my amp, I think I will be able to install another potentiometer for balance control. Can I  order the pot off of DigiKey or Mouser?
Ross

Offline Paul Birkeland

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Re: Measuring voltages while playing a 60 Hz sine wave. [resolved]
« Reply #44 on: August 17, 2021, 06:59:32 AM »
Mouser has it.  We provide RV24BF-10-15R1-B100K-LA as a balance pot with our kits.  You'd need a pair of 33K resistors as well.
« Last Edit: August 18, 2021, 09:22:38 AM by Paul Birkeland »
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man