POT upgrades

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virtue

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Re: POT upgrades
« Reply #40 on: 9 May 2010, 04:09 am »
They all have the same pin-out.  3 pins map to the board... middle is ground, I think but please see for yourself.

littletree76

Re: POT upgrades
« Reply #41 on: 9 May 2010, 06:14 am »
how about this one? http://cgi.ebay.it/ws/eBayISAPI.dll?ViewItem&item=200460914264
It should last longer, and is very cheap.
I'm going to buy a zerodac for my headphones and i want to upgrade the volume control to this.
I mean, if i'm going to put it on the zerodac, i think it would be even better on the virtue two.2 that i'm going to buy next year.

This is sold as stepped potentiometer frame without any resistors (hence the low price), you have to source and solder all resistors on to the frame on your own. Good for someone who are particular on quality of the resistors and have the skill and patience to solder all resistors. Many stepped potentiometers sold in eBay come in this form so be careful to avoid any surprise.

I used to own Zero DAC (sold it within a year) and it is notorious for poor quality control and workmanship for later batches particularly for the potentiometer. Upgrading the potentiometer certainly help in improving its reliability and sound quality (it sounds decent when working well). Right now I am using Audio-GD's FUN DAC/Pre-Amp with its buffered output to feed Virtue One Classics. I will certainly consider upgrade if Virtue Audio ever launch simple DAC product (without headphone amplifier) with multiple digital input interfaces (SPDIF coaxial/optical whereas USB is secondary) and multiple analog output interfaces (balanced XLR/TSR and unbalanced RCA). Reason being design of analog circuits is the most critical factor in designing good DAC and even more important than selection of DAC chip, thus those who design good amplifier should be competent for good DAC design. Too bad Virtue Audio has decided not to launch any DAC product in near future.



Cyan

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Re: POT upgrades
« Reply #42 on: 9 May 2010, 05:21 pm »
This is sold as stepped potentiometer frame without any resistors (hence the low price), you have to source and solder all resistors on to the frame on your own. Good for someone who are particular on quality of the resistors and have the skill and patience to solder all resistors. Many stepped potentiometers sold in eBay come in this form so be careful to avoid any surprise.

I used to own Zero DAC (sold it within a year) and it is notorious for poor quality control and workmanship for later batches particularly for the potentiometer. Upgrading the potentiometer certainly help in improving its reliability and sound quality (it sounds decent when working well). Right now I am using Audio-GD's FUN DAC/Pre-Amp with its buffered output to feed Virtue One Classics. I will certainly consider upgrade if Virtue Audio ever launch simple DAC product (without headphone amplifier) with multiple digital input interfaces (SPDIF coaxial/optical whereas USB is secondary) and multiple analog output interfaces (balanced XLR/TSR and unbalanced RCA). Reason being design of analog circuits is the most critical factor in designing good DAC and even more important than selection of DAC chip, thus those who design good amplifier should be competent for good DAC design. Too bad Virtue Audio has decided not to launch any DAC product in near future.

Thank you for letting me know  :). So, is this a FULLY working one? http://cgi.ebay.it/24-Step-Serial-Type-Stereo-Volume-Attenuator-50K-New-/150441711863?cmd=ViewItem&pt=UK_AudioTVElectronics_HomeAudioHiFi_Amplifiers&hash=item23070658f7
What is the difference between 50k and 100k? Does it mean that the 50k can lower the volume less than the 100k? If so, it would be the best choice for me, as my computer volume is set to 70%.
That audio gd dac is nice, but too expensive for just the heapdhones (the deluxe version).
Btw, what version of the zero dac did u have? The 2007 or the 2009? The 2009 has many improvements, and  for 160 euros you can get a version with very nice opamps on ebay, so i wonder if that is still the best choice for the price.

dvenardos

Re: POT upgrades
« Reply #43 on: 10 May 2010, 02:21 am »
You want to match the impedance of the pot to the input impedance of the amplifier. According to Micheal Mardis 20K is ideal. I believe the input impedance is around 18K. Personally, I wouldn't use such a cheap pot with the Virtue, but then again it is so cheap you don't have much to lose in trying it out.

These are very similar to what we will be using.  100K is not a great value for the Virtue, tho.  20K is ideal.

If I ever get the time, I'll do a little photo essay on how to wire them in.

littletree76

Re: POT upgrades
« Reply #44 on: 10 May 2010, 04:17 am »
I have made resistance measurement with original potentiometer and it showed 20K resistance value. So I suppose you should match the 20K value in selecting stepped potentiometer. As for what stepped potentiometers are available through online stores, please refer to my previous post in this forum. To make your effort worthwhile (bare in mind it took quite some effort to remove the original one), I would suggest use stepped potentiometer of higher quality.

I was using 2007 version of Zero DAC with op-amp rolling done on my own (for headphone output), adjusting potentiometer generated noise at output in stock condition. With 160 Euros (about USD 205 using today exchange rate), you can purchase latest DAC/headphone amplifier product version A-USB Sparrow from Audio-GD. Sparrow has sound signature close to FUN as they share identical modules. Vendors in China have started to realize their audio products can not compete on price advantage alone.

Thank you for letting me know  :). So, is this a FULLY working one? http://cgi.ebay.it/24-Step-Serial-Type-Stereo-Volume-Attenuator-50K-New-/150441711863?cmd=ViewItem&pt=UK_AudioTVElectronics_HomeAudioHiFi_Amplifiers&hash=item23070658f7
What is the difference between 50k and 100k? Does it mean that the 50k can lower the volume less than the 100k? If so, it would be the best choice for me, as my computer volume is set to 70%.
That audio gd dac is nice, but too expensive for just the heapdhones (the deluxe version).
Btw, what version of the zero dac did u have? The 2007 or the 2009? The 2009 has many improvements, and  for 160 euros you can get a version with very nice opamps on ebay, so i wonder if that is still the best choice for the price.

envisionelec

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Re: POT upgrades
« Reply #45 on: 10 May 2010, 06:18 pm »
The input impedance is ~20k ohm. dvenardos is correct, the input impedance of the Tripath controller is 20k, and since there is no impedance buffer before the controller it is essential that the volume pot is matched to this figure. A high impedance source, such as trying a 100k pot, will not match well to a low impedance input. The result is significant gain loss and increased noise. The quick fix is to use a buffered input or preamplifier if you feel the levels are too low.
 If you feel the amplifier is too sensitive, the input gain on the Tripath controller must be changed for optimal performance. However, these parts are difficult to swap without damaging the PC board. This modification is not recommended over simply using a separate, high quality buffer or preamp.