POT upgrades

virtue · « **on:** 15 Jun 2009, 04:47 am »

Many customers consider bypassing the potentiometer we have on the unit, essential for getting the best sound. If one were to not use the supplied jumpers to bypass the POT, but instead replace the POT with a 3rd party unit, what would you recommend?

rhing · « **Reply #1 on:** 16 Jun 2009, 01:36 am »

As I mentioned in the "Virtue Two" thread, I am considering a TKD conductive polymer pot to use the Virtue Two as both an integrated amp and a power amp. Parts Connexion has a 20% off sale this month, so the price is very attractive right now.

virtue · « **Reply #2 on:** 19 Jun 2009, 12:21 am »

Ok, here's a Mea Culpa. I can't find a good source for the 23-position, 2 pole rotary switches that we would need to build a stepped attenuator at a price low enough to give them away with our products. I mean, who wouldn't want one in a Virtue TWO for no extra charge, right? Can anyone help me find a low-wage nation factory who can build these things?

Please do NOT post in this thread. Please send me PMs only.

rhing · « **Reply #3 on:** 10 Jul 2009, 02:55 am »

Welborne had posted a photo of an SMD stepped attenuator on the Virtue Two thread here:

http://www.audiocircle.com/index.php?topic=68893.0

So after searching around for that cool-looking gadget, I finally found it on eBay from a seller named tube_buyer in Hong Kong.

The photo above is the photo from tube_buyer's eBay ad. I actually bought the 50kohm pot as Michael Mardis advised me to start with 50k. This little attenuator has a smooth, solid feel. Since the attenuator didn't have lead pins, I soldered on small segments of Mundorf Silver-Gold wire to the small solder pads on each channel. The SMD resistors are actually mounted on two circular shaped PCB's (one for each channel) and mechanically fastened together. The hardest part was removing the stock volume pot from the small PCB containing the pot and pot bypass jumpers. Once I removed the stock pot, inserting the small Mundorf wire leads into the mounting holes was a piece of cake as it had an identical footprint as the stock volume pot's lead pins.

So how does it sound? Better, that's for sure. It's like wiping a dusty, cloudy window clear. There's just greater transparency and clarity in the sound. The soundstage is larger in all three dimensions. Part or most of this may be due to the fact that each channel is better balanced so the image is more life-like and centered. The sound is definitely fuller, and I expect it to sound better as everything burns in. It's almost like the stock pot cast a slightly dark tone on the sound. The amp sounds more lively like a tube amp. The overall improvement is quite noticeable. I also noticed that the noise floor significantly dropped too.

For having only 21-steps, the resistor values must be a great match for this amp, because the volume level steps are perfect. The increasing volume levels are nice and gradual with plenty of room to blow the doors off, yet spaced to allow nice lower level listening. I am quite pleased with this mod. Now I just need to re-work the volume knob to fit the shaft.

I also purchased a 10kohm TKD volume pot from Parts Connexion, but the threaded portion of the panel mounting face has a larger diameter than the pot shaft opening in the Virtue Two's inner chassis. I would have to widen the hole and I really didn't want to mess up my amp in case the pot didn't work that well. That's why I choose to purchase this stepped atytenuator. I may still get brave and try the TKD pot, but this little SMD stepped attenuator is one of those bargain mods for the Virtue.

roscoeiii · « **Reply #4 on:** 10 Jul 2009, 06:53 pm »

THere's a lot of buzz at diyaudio.com about optical volume control, using LEDs. Look at the Lightspeed Attenuator. Huge thread, so sorry for sending you into that jungle.

panomaniac · « **Reply #5 on:** 11 Jul 2009, 12:15 am »

Yes, I have a couple of those. They are very nice. Small, too!

The lighwave is an interesting idea but has certain complications and limitations. Probably not something Virtue would go with, but might be great for a DIY project.

rhing · « **Reply #6 on:** 1 Aug 2009, 06:36 pm »

After listening for more than 100 hours after installing the 50k SMD stepped attenuator from eBay seller tube_man, I have to say that I am thoroughly impressed with this mod/tweak. The sound is warmer, richer and more detailed. The best way I can describe the sound quality is that it has greater weight than before with more harmonic content like a tube amp. I listened to Santana's "Caravanserai" last night and I could hear more interplay between Carlos Santana and Neil Schon on lead guitars on "Song of the Wind," since I was able to clearly distinguish the difference in tone between the two electric guitars. Percussion like the congas and Greg Rollie's Hammond organ just sounded incredible.

Before getting the attenuator, I was seriously considering a DIY tube preamp kit like a Glassware Audio Aikido or Transcendent Sound Grounded Grid, but I really like the simplicity of just having a better volume control in the Virtue Two. I don't have to be concerned with interconnect cables and another potential source of noise.

virtue · « **Reply #7 on:** 2 Aug 2009, 08:12 am »

We hear the feedback, loud and clear!!!

Cheerwino · « **Reply #8 on:** 2 Aug 2009, 01:08 pm »

Quote from: rhing on 1 Aug 2009, 06:36 pm

After listening for more than 100 hours after installing the 50k SMD stepped attenuator from eBay seller tube_man, I have to say that I am thoroughly impressed with this mod/tweak. The sound is warmer, richer and more detailed. The best way I can describe the sound quality is that it has greater weight than before with more harmonic content like a tube amp.

Thanks for the informative post rhing! I'm not a DIY tweaker-type who is likely to try this. But, I guess one could achieve similar results by following the process outlined elsewhere and installing the jumper and removing the pot from the whole circle and turn it into a power amp, right? (something I might try) And then using a preamp, of course.

I understand rhing was trying to stick with one component, though. I just haven't heard anyone say that taking the volume pot out of the loop as having the kind of impact he describes. Or perhaps they weren't as eloquent and to the point, as that was an excellent description, rhing!

Although, I can see rhing's simple solution could offer sonic advantages. In adding a pre, removing the pot may lift the "cloud" but adding in another preamp might add its own "issues". Okay, now I'm just rambling...

doorman · « **Reply #9 on:** 2 Aug 2009, 02:22 pm »

FWIW, guys, the TS GG pre is a fantastic partner to the Virtue.
Anyone else using a(good) tubed pre with theirs?
Don

rhing · « **Reply #10 on:** 2 Aug 2009, 02:41 pm »

doorman,

I am still considering a DIY tube preamp like the Transcendent Sound Grounded Grid down the road. It's a proven design from a well respected designer. The upgrading potential is tremendous. In fact, I saw a post on Audiogon for a heavily modded Grounded Grid. I thought his price was a bit steep though.

I still have to finish up my J-FET based PassDIY B1 Buffer linestage. The circuit board is completed. I just need to add the volume pots, source selector switch and RCA connectors in a chassis I need to drill out.

Welborne · « **Reply #11 on:** 3 Aug 2009, 08:57 am »

Instead of modding mine, i prefer to keep them as intact as possible, but may try a good passive like those diyparadise LSR volume or the Promitheus TVC with the virtue's volume bypassed.

al128 · « **Reply #12 on:** 18 Aug 2009, 02:23 am »

Quote from: rhing on 10 Jul 2009, 02:55 am

my eyes see a pot like this and my brain screams "a quarter"

well who of us has never sinned, wedging a coin into those cheap 1970ies car radios where the knob fell of ??? aa

TRADERXFAN · « **Reply #13 on:** 14 Oct 2009, 06:59 pm »

Quote from: rhing on 10 Jul 2009, 02:55 am

Welborne had posted a photo of an SMD stepped attenuator on the Virtue Two thread here:

http://www.audiocircle.com/index.php?topic=68893.0

So after searching around for that cool-looking gadget, I finally found it on eBay from a seller named tube_buyer in Hong Kong.

The photo above is the photo from tube_buyer's eBay ad. I actually bought the 50kohm pot as Michael Mardis advised me to start with 50k. This little attenuator has a smooth, solid feel. Since the attenuator didn't have lead pins, I soldered on small segments of Mundorf Silver-Gold wire to the small solder pads on each channel. The SMD resistors are actually mounted on two circular shaped PCB's (one for each channel) and mechanically fastened together. The hardest part was removing the stock volume pot from the small PCB containing the pot and pot bypass jumpers. Once I removed the stock pot, inserting the small Mundorf wire leads into the mounting holes was a piece of cake as it had an identical footprint as the stock volume pot's lead pins.

So how does it sound? Better, that's for sure. It's like wiping a dusty, cloudy window clear. There's just greater transparency and clarity in the sound. The soundstage is larger in all three dimensions. Part or most of this may be due to the fact that each channel is better balanced so the image is more life-like and centered. The sound is definitely fuller, and I expect it to sound better as everything burns in. It's almost like the stock pot cast a slightly dark tone on the sound. The amp sounds more lively like a tube amp. The overall improvement is quite noticeable. I also noticed that the noise floor significantly dropped too.

For having only 21-steps, the resistor values must be a great match for this amp, because the volume level steps are perfect. The increasing volume levels are nice and gradual with plenty of room to blow the doors off, yet spaced to allow nice lower level listening. I am quite pleased with this mod. Now I just need to re-work the volume knob to fit the shaft.

I also purchased a 10kohm TKD volume pot from Parts Connexion, but the threaded portion of the panel mounting face has a larger diameter than the pot shaft opening in the Virtue Two's inner chassis. I would have to widen the hole and I really didn't want to mess up my amp in case the pot didn't work that well. That's why I choose to purchase this stepped atytenuator. I may still get brave and try the TKD pot, but this little SMD stepped attenuator is one of those bargain mods for the Virtue.

I bought 2 (cheap enough that I figured if one is good 2 is better for same shipping) of these from "gigaworks" also a hong kong based ebayer.

So what size wire was it that was used? I haven't opened up the virtue yet... need to take a trip to the shack or something...

-Tony

virtue · « **Reply #14 on:** 14 Oct 2009, 07:07 pm »

We liked this POT so much that we OEM'd it for the new models on the "x1" platform (it will remain a DIY option on the ONE.2). For the lead-wire, it's so short and the current's so low, that it just doesn't matter what it is. Strands of lamp-wire or cat5 or whatever, should work in order to bridge those tabs with the solder holes that line up quite well below it. You'll need to drill out the plastic insert on the volume knob to accommodate the threaded version. Our OEM ones (20k) use the flat shaft that fits natively.

panomaniac · « **Reply #15 on:** 14 Oct 2009, 07:08 pm »

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.

TRADERXFAN · « **Reply #16 on:** 14 Oct 2009, 07:15 pm »

Quote from: panomaniac on 14 Oct 2009, 07:08 pm

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.

Quote from: virtue on 14 Oct 2009, 07:07 pm

We liked this POT so much that we OEM'd it for the new models on the "x1" platform (it will remain a DIY option on the ONE.2). For the lead-wire, it's so short and the current's so low, that it just doesn't matter what it is. Strands of lamp-wire or cat5 or whatever, should work in order to bridge those tabs with the solder holes that line up quite well below it. You'll need to drill out the plastic insert on the volume knob to accommodate the threaded version. Our OEM ones (20k) use the flat shaft that fits natively.

great news. thanks. I bought 50k though... (but planned to use the other one on another amp with stated input impedence of 50k)

-Tony

srb · « **Reply #17 on:** 14 Oct 2009, 07:19 pm »

Quote from: al128 on 18 Aug 2009, 02:23 am

my eyes see a pot like this and my brain screams "a quarter"

my eyes see a pot like this and my brain screams "$149.00? - Ouch!"
(Made in USA)

Steve

virtue · « **Reply #18 on:** 14 Oct 2009, 07:32 pm »

That little POT is a game changer. It's a bunch of resistors - a necessary EVIL - for heaven's sake! Why the million dollar scaffold???

TRADERXFAN · « **Reply #19 on:** 14 Oct 2009, 07:58 pm »

When I actually get inside there, should it be relatively obvious which is in, out, and ground on the virtue?