[guest1632]

Hi everyone,

I've got a question about volume pots in general. Gonna pick up one of those GGP kits from Transcendentsound. Now the question.:

Apparently, it comes with a 50K pot. Now, Bruce also makes a 100K stepped atenuator. My question is the two resistances. So I take that 50K Ohm pot out and put in another pot with 100K ohms. Obviously, I would guess the points on the volume control would change? and any other advantages/disadvantages?

Ray Bronk

[*Scotty*]

Ray I would stick with the 50k pot value as supplied with the kit. If I was building it myself I would use a 50k DACT pot. It avoids the lead inductance
of the resistors used in the kit and my time is worth the 60 dollar difference in price. A lot of tube preamps have a 100k pot in them and are designed
to work this value pot. Also a 100k input value does not load down other tube gear like a tube DAC used with the preamp and maintains a good ratio of output source impedance to input impedance for good RF rejection. You might ask the kits' designer if there is any advantage to using a 100k pot
over a 50k pot in the kit or if there any incompatibility that would prevent using a 100k pot in the kit. As always it is probably advisable to seek specific technical information about a product directly from the manufacturer rather than relying on second hand information or conjecture.
Scotty

[guest1632]

Ray I would stick with the 50k pot value as supplied with the kit. If I was building it myself I would use a 50k DACT pot. It avoids the lead inductance
of the resistors used in the kit and my time is worth the 60 dollar difference in price. A lot of tube preamps have a 100k pot in them and are designed
to work this value pot. Also a 100k input value does not load down other tube gear like a tube DAC used with the preamp and maintains a good ratio of output source impedance to input impedance for good RF rejection. You might ask the kits' designer if there is any advantage to using a 100k pot
over a 50k pot in the kit or if there any incompatibility that would prevent using a 100k pot in the kit. As always it is probably advisable to seek specific technical information about a product directly from the manufacturer rather than relying on second hand information or conjecture.
Scotty

Hi Scotty,

Yeah, I plan to get a goldpont atenuator. i understand the new Dacts are pretty much the same as the goldpoint and 30 bucks cheaper. i have an email on his message board about the pot situation. no reply yet. He has this stepped atenuator which is a 100K for the GGP. So I would figure it would work out fine. The goldpoints start at 62 DB down from 0. So just not sure what the advantage of the extra 50K besides loading down the circuit.

Ray

[*Scotty*]

The circuit board traces on the Goldpoint pot are considerably longer from the surface mount resistors to the switch contacts than the DACT pot which means more lead inductance. This may or may not be a problem sonically, cautious soul that I am I would stick with DACT pot because it is the evil I know.
Scotty

[guest1632]

The circuit board traces on the Goldpoint pot are considerably longer from the  surface mount resistors to the switch contacts than the DACT pot which means more lead inductance. This may or may not be a problem sonically, cautious soul that I am I would stick with DACT pot because it is the evil I know.
Scotty

Hi Scotty,

Well, on that one you might be splitting hairs. Sonics from what I read are very good to excellent on the Goldpoints. Now that Dact has SMR's on there pots, probably the same sonics, or very close to it.

Ray

[pbrstreetgang]

Besides cost any reason not to do a TVC?

[*Scotty*]

pbrstreetgang, Here is an example of the Sonic Euphoria's ultrasonic behavior which can cause partnering amplifiers to become unstable and oscillate
as well as exhibit other problems. This is typical behavior of all TVCs which makes matching up with partnering amplifiers an exercise with  unpredictable consequences.


 
Fig.2 Sonic Euphoria PLC, frequency response at 1V with Volume control at (from top to bottom at 1kHz): maximum, –2dB, unity gain, –6dB, –8dB, –10dB, –12dB, –14dB, –16dB, –18dB, –20dB, –22dB, –24dB (5dB/vertical div.).
See complete measurements and text at this link   http://stereophile.com/solidpreamps/106sonic/index4.html
Scotty

[mgalusha]

I've used both the DACT and GoldPoint in a GG preamp and both were great. The GoldPoint was a Mini-H shunt attenuator, which they no longer sell. It sounded great but would occasionally create pops when changing levels, even with no DC on the input. The DACT, being a series attenuator, was dead quiet. I'm sure the new GoldPoint series models are just silent as well.

[poseidonsvoice]

I've listened to DACT, Gold points and TVC's. They are all great. However, how each one behaves in an individual circuit is difficult to predict. Before splurging on the above, I would first try a PEC carbon pot from either DIYhifisupply or from Digikey. Its really the only pot I would use. If cost is no object then try the DACT, Gold Points or TVC's. But...you may be happy with just the PEC. The PEC is about $23 from Digikey and a little more expensive from DIYHifiSupply since he hand picks them for lowest noise, etc...

Best,
Anand.

[guest1632]

I've listened to DACT, Gold points and TVC's. They are all great. However, how each one behaves in an individual circuit is difficult to predict. Before splurging on the above, I would first try a PEC carbon pot from either DIYhifisupply or from Digikey. Its really the only pot I would use. If cost is no object then try the DACT, Gold Points or TVC's. But...you may be happy with just the PEC. The PEC is about $23 from Digikey and a little more expensive from DIYHifiSupply since he hand picks them for lowest noise, etc...

Best,
Anand.

Hi Anand,

So how does the Peck sound? Does it track ok on lower levels? That's the main reason for replacing the pot that's in there.

I don't know how the Transcendentsound atenuator is. I heard somewhere that his atenuator somehow restricts dynamics. Don't know if that's true or not.

Ray

[pbrstreetgang]

Interesting I was looking at this Audio Mangus selection and wondering how it would be in the TGG but dismissed it, is this the same one you are suggesting? http://www.audio-magus.com/product_p/peckka.htm

[guest1632]

Interesting I was looking at this Audio Mangus selection and wondering how it would be in the TGG but dismissed it, is this the same one you are suggesting? http://www.audio-magus.com/product_p/peckka.htm

I saw the pot there. I think I've seen the Peck pots cheaper elsewhere. Just can't at the moment remember where.

Ray

[poseidonsvoice]

I've listened to DACT, Gold points and TVC's. They are all great. However, how each one behaves in an individual circuit is difficult to predict. Before splurging on the above, I would first try a PEC carbon pot from either DIYhifisupply or from Digikey. Its really the only pot I would use. If cost is no object then try the DACT, Gold Points or TVC's. But...you may be happy with just the PEC. The PEC is about $23 from Digikey and a little more expensive from DIYHifiSupply since he hand picks them for lowest noise, etc...

Best,
Anand.

Hi Anand,

So how does the Peck sound? Does it track ok on lower levels? That's the main reason for replacing the pot that's in there.

I don't know how the Transcendentsound atenuator is. I heard somewhere that his atenuator somehow restricts dynamics. Don't know if that's true or not.

Ray

Ray and pbstreetgang, I sent you both a PM.

Best,
Anand.

[pbrstreetgang]

Please share!! If its bad its bad no harm done. Also I was just looking for info and a site of your products. Could you point me to some info?

[Occam]

For those not adept at finding Poseidensvoice's recommended logarithmic dual (stereo) potentiometers, at digikey -
http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=262966;keywords=kka
click on the 'D' on the far right and you can download the PDF specification sheets.