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Old 12th March 2010, 04:30 PM   #1
Gobble is offline Gobble  India
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Default What Volume pot and selector?

Hello

This is my first post to DIY audio. I have no skills beyond soldering, and no foundation in electronics.

My existing setup is a Marantz CD6002 into a NAD 325 driving a pair of Fostex 166E Bookshelves

I recently built a GG clone preamp from a ready kit and want to "upgrade" the volume pot and selector switch.

I am thinking Goldpoint mini-v 100K for volume pot and the selector switch 4P-3T-1D = 4 Pole, 3 Positions, 1 Deck.

Currently I am pulling one pair of RCA-in's into the balanced input on the pcb because I found hum was reduced by joining the RCA earthing into the balanced-in and subsequently leading into earthing wires of volume pot. I would like to continue using the balanced connector on the input PCB with the new selector/pots.

Will the Goldpoint selector support a balanced channel + 2 single ended?
What about the DACT CT3?

CT3-5-4/wire
4-pole switch. Solder lugs for wire connections. Non-shorting. Switches up to either:
- 2 channels with signal and ground simultaneously
- 4 channels, signal only
- 2 balanced channels, + and - signal only (excl. ground)

I am confused. I hope this volume pot has extra connect points for balanced signals (earthing)? I only soldered mine per instructions without understanding too much of anything, hence pardon my stupid questions after having seemingly built a great sounding preamp.

Also the Goldpoint does not appear to be break-before-make. How critical is that?

To state my objective - I am very happy with the preamp, but along with everything good including immense amounts of new detail and dimension to the sound I experience a loss of the quality of mellifluousness ( exactly as put down in the dictionary word) in midrange - esp vocals. I want the "midrange magic" back. I am reluctant to change the Shugang 12AU7s as they bested the Telefunken diamondback smoothplates hands down and unwilling to lose more money on NOS tubes.

Keeping in mind I am happy with everything else about the preamp, will changing the volume pot add this factor back? For the money spend will it be worthwhile? Currently the volume pot uses Vishay/Dale resistors which is a 100K version of this one: Assembled Dale Resistor 23 Steps Ladder Type Attenuator 250K (Stereo)_Volume Control_Accessories Kit_Analog Metric - DIY Audio Kit

TIA
Regards
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Old 16th March 2010, 03:55 PM   #2
Gordy is offline Gordy  United Kingdom
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With respect, you asked too many questions in one post - it makes answering very difficult. So, some answers...

Goldpoint seem to be an unreliable company. DACT have a similar product and seem to be a reliable company.

Stepped attenuators need to be make-before-break, so that the new step is engaged before the old step is disengaged.

Changing the volume control is very, very, very, very unlikely to change the mid-range, especially as you already have a good quality stepped attenuator / volume control.
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Old 31st March 2010, 02:03 PM   #3
Gobble is offline Gobble  India
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Thank you. I decided to skip the upgrade thinking along the same lines - my existing pot is not bad at all. Good that you clarified my question about midrange too. Helped me rid of that nagging what-if suspicion.

Regards
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Old 2nd April 2010, 03:20 AM   #4
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I never had a volume pot (or stepped attenuator) that worked with a value of more than 1kohm. I use 500 ohm pots in my pre. For selectors Grayhill makes some nice sealed gold ones designed for telecom which last a very long time and have a nice feel.
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Old 2nd April 2010, 03:27 AM   #5
doorman is offline doorman  Canada
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Hi Gobble!
FWIW, the "LDR" (optocoupler) mod on the Grounded Grid pre. is a stunning improvement over a conventional volume pot, though I hasten to add, I've obviously not heard all the various permutations.
Check it out--
Don
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Old 16th July 2010, 03:58 PM   #6
Gobble is offline Gobble  India
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Just saw this.

Thanks will definitely try that one day when I am infected with the upgrade bug

Cheers
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Old 20th July 2010, 09:37 PM   #7
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Quote:
Originally Posted by sumaudioguy View Post
For selectors Grayhill makes some nice sealed gold ones designed for telecom which last a very long time and have a nice feel.
Do you have a make and model you like? I find the selection daunting.

As for Goldpoints unreliability, i've never had problems with Arn Roatcap. He's quite helpful. I'm purchasing a Goldpt attenuator to go with the DC B1 board from the group buy. Unfortunately, the Goldpoint selector switches are more than i'm willing to spend.
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Old 21st July 2010, 07:35 PM   #8
Gobble is offline Gobble  India
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Quote:
Originally Posted by doorman View Post
Hi Gobble!
FWIW, the "LDR" (optocoupler) mod on the Grounded Grid pre. is a stunning improvement over a conventional volume pot, though I hasten to add, I've obviously not heard all the various permutations.
Check it out--
Don

Hmm it looks like this LDR needs a source with 100ohms Zout and 100K ohms Zin in order to really shine. Mines a budget CDP marantz cd6002 with a possible Zout of 300+ ohms? Just a guess comparing other budget CDPs like NAD ... dont have the specs published actually.

-Ragool
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