Can/Does the type of potentiometer on an EC Balancing act effect the overall volume or output?
Oct 13, 2014 at 12:35 PM Thread Starter Post #1 of 2

TOPnut

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I recently purchased an EC Balancing Act in great condition and it has a $300 upgraded P&G 10k pot.  I am running it with KR PX4s and an Osram B65 driver and love the sound.
 
My issue is that on a number of CDs, where they are recorded at a much lover level (yes, I am still using a CDP most of the time), - and think Reference Recordings classical CDs as an example here, I can turn the EC volume knob all they way up and it still is not anywhere near the volume I get from my EC ZDT or ZDSE.  With my ZDSE in the same configuration, for example, I get much higher output levels on the same CD at 1:00 o'clock than I do with the BA running fill tilt.
 
Also, I have noticed that the increase in volume on the BA's P&G pot over the last 1/3 of it's range only increases the volume slightly (in other words, it seems the last 1/3 of the pot's range hardly increases the output much).
 
On many if not most of my stuff, the lack of output is not a factor as I am getting the volume I want (albeit at a much higher level on the pot than on my other EC amps) but this is an issue on at least 40-50 of my CDs that I do listen to frequently.
 
I'm not as technically experienced as many here and it puzzles me because I have always heard that the BA can drive any headphone and my Sennheiser HD-800s should not be a hard phone to drive vis-a-vis other phones.
 
Am I missing something here? Is this normal for a P&G pot?  Is something wrong with my amp or a tube?
 
Thanks in advance for any help (PS, while emailing Craig back and forth a few weeks ago about another amp, I had approached this issue while asking a number of other questions on his 2A3 and 445 amps, but he may have missed it as his answer did not address it).
 
Thanks,
 
Frank
 
Dec 3, 2014 at 3:44 PM Post #2 of 2

rshuck

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So the answer is no. A pot of any type will have a little resistance at the maximum volume setting, but with a decent pot this should be negligible. The pot's rating refers to its maximum resistance, usually 10k ,20k , 50k, or 100k ohm, with an audio taper.

I have the ECBA running the stock 300B currently, with the Alps RK50 pot (earlier model with old transformers). I have read at a few places (and from Craig himself), while the amp does provide enough amplification for demanding headphones, such as my K1000, the problem exists with this amp if it doesn't receive a high enough voltage on its input, there is insufficient gain to produce enough volume for normal listening levels.

There are a few options. Craig mentioned that it is possible to use a different driver tube but did not recommend this. What he did recommend was using a source device that put out a higher voltage from the balanced output. The industry standard for this is 2V, but many sources do put out higher voltage. I am now pretty much set on the McIntosh D100 DAC for my source, which outputs 16V on the balanced side, according to their documentation.

So you have some options, but your pot is not the issue. I was unhappy with the volume level on the K1000 because the listening levels were sufficient for normal listening, but not for louder parts or for if you wanted that extra bit of volume at times.

I will have some results in the next few months (in Afghanistan for work right now) and will respond here or to you about it.
 

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