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Jan Vigne

 

Silver Member
Username: Unbridled_id

ChicagoUsa

Post Number: 498
Registered: Mar-04
I have a question for you.
 

Platinum Member
Username: Nuck

Post Number: 13430
Registered: Dec-04
The meaning of life is enjoying the passage of time.
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 3038
Registered: Feb-07
Man, I love these cryptic threads.

For some reason Nuck is always a part of them.
 

Platinum Member
Username: Nuck

Post Number: 13431
Registered: Dec-04
Party crasher, like.

1,367 is the answer.
 

Gold Member
Username: Dmitchell

Ottawa, Ontario Canada

Post Number: 3041
Registered: Feb-07
I thought 42 was the answer.
 

Silver Member
Username: Soundgame

Toronto, Ontario Canada

Post Number: 980
Registered: Jun-08
The answer is the question. So shall it be written, so shall it be done.
 

Platinum Member
Username: Nuck

Post Number: 13434
Registered: Dec-04
Let me check the media for a message.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13913
Registered: May-04
.

OK




.
 

Silver Member
Username: Unbridled_id

ChicagoUsa

Post Number: 499
Registered: Mar-04
I have a passive pre-amp and have been searching online about preamps in general and what is most important in them. My focus is on the volume pot and it's importance. The pot used in my passive is the ubiquitous alps blue. Very common, reliable, good tracking and channel balance even at low volumes. I was considering (for perhaps a future upgrade) replacing the alps with a TKD pot. I have done some research and have read that they are better than the alps (both use conductive plastic but the TDK seems to have superior performance). The mfg of the pre told me with my amp to use the 50k pot though I don't know how to match amps input impedance to the pot or why.
Look, to be honest I probably cannot hear the difference even if I had it done (i am not confident with a soldering iron) and from what I can tell the passive is doing what it should do. Are you familiar with the performance of Alps pots vs TKD and does upgrading a pot really make much sense.
http://www.partsconnexion.com/tkd_64186.htmlhttp://www.partsconnexion.com/tkd_64186.html
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13914
Registered: May-04
.

I won't claim to be an up to date expert on ALPS vs TDK pots, no. But they are both high quality pieces made to reasonably good specs. That said you should expect to get what you pay for with good quality gear. The ALPS can be had in single units for what? about $15-25?

As to hearing a difference, well, the pot is (about) the only thing you have between your source and your amplifier, right? When you get down to hot rodded components such as I've seen in most passive pre amps, yes, everything counts. The connectors count, the wiring counts, any switches and the enclosure count. But I can't tell you how much each weighs into the final balance though the vc is a good chunk of that quality. If you haven't yet installed the best RCA's, switches, cabling and so forth, then I'd make certain what was around the vc was as good as the vc you intended.

The ALPS Blue is, as you say, a fairly ubiquitous vc. It's become that for its perceived high performance for the $$$ spent. The TDK is probably a better pot overall (certainly it will track better than the ALPS channel to channel over its range which can be important when you have no balance control) but you'll have to decide just how much you expect from a $60 (plus labor) upgrade. I suspect you will hear an improvement on the order of changing from ubiquitous RCA's to Eichmans or WBT's. Yep, it's there but you probably won't be writing on the forum about how this has changed your entire perspective on audio. Maybe just a note to say the change was worth the expense.

If I were going to do such a modification, I would be looking at stepped attenuators. More expensive to buy than the TDK but no more expensive to install - unless you do the DIY route and buy one you have to assemble yourself. This places one single resistor between input and output for any particular volume level. Very clean and very transparent. You can choose the degree of sophistication and the cost you prefer and get from a moderate to a quite surprising improvement in SQ. "Quite surprising" is also quite surprising cost-wise.

Loading is the bugaboo of passive pre amps. They lack an input/output buffer to ensure good electrical matches at any volume level on either side of the vc. Along with that they offer contradictory values of wanting high impedance on the input and low impedance on the output. Can't really be done in a very simple passive pre amp unit and a pot. That's why active pre amps prevail in the market.

You might want to consider a transformer based passive unit and loose the restrictions of these contradictions.


Otherwise, 50k seems like a good compromise for most passive units with a conventional pot. Keep the interconnects short and have a power amp with the highest input impedance you can find.



Does that answer your question?


.
 

Platinum Member
Username: Nuck

Post Number: 13435
Registered: Dec-04
nice!
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13915
Registered: May-04
.

Is this the pre amp you're using?

http://www.soundstage.com/revequip/ftaudio_lw1.htm


.
 

Silver Member
Username: Unbridled_id

ChicagoUsa

Post Number: 500
Registered: Mar-04
Thanks Jan. I have read about the stepped attenuators, goldpoint.com has a great mini-v with surface mount resistors, it is 200 dollars and has 24 steps. The thing is I do not use much range on the volume knob as is and a stepped volume knob really could be a problem with my limited range. I have the Nad c275 and it's input impedance is 10kohms At first the mfg of the passive said it might be too low, lowering the gain by several dbs. Future correspondence led to the belief which was shown to be true that it would not be an issue at all. The interconnect length between the passive and my amp is 2'. The passive I own claims to address the classic drawbacks of passives in it's design, and it seems to do just that.

There really isn't anything "wrong" with the sound I am getting and as you stated the difference while probably noticeable will not be earth shattering. It was just and idea I had and in the future I may go ahead and do it since the volume attenuator is so important and TKD's are superior to the alps blue.

Thanks again
 

Silver Member
Username: Unbridled_id

ChicagoUsa

Post Number: 501
Registered: Mar-04
"Is this the pre amp you're using?"

Yes that is it. I really like it for what it is and what it isn't. No power cord, 5 inputs (more than enough), 2 outputs (one for amp and one for my sub). I really don't think I could do better soundwise for the price.

I have read that many folks neglect their pre-amp and I didn't want to do that. So I felt a passive would give me quality sound at a reasonable price.
 

Platinum Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 13916
Registered: May-04
.

The 10k input on the NAD is due to the input buffer, which I assume you now know. This doesn't really indicate that should be the value of the pot in a passive pre amp and probably isn't the value of the pot in the NAD.

If the correspondence with the manufacturer has provided sufficient proof that 10k is acceptable, then that really should be your answer. I would have been concerned about stepping away from any OEM value with the passive unit you have, I don't understand the "X" circuit and how it operates passively to accomodate the variances in impedance. But, in the case of this pre amp, if the guy designing it says the lower impedance is OK, then I would stay with the lowest value possible in a replacement pot if this is being used in a modern, solid state based system. Interconnect cable length, as I suspect you've been told, should still be kept to a minimum.

If you only use a small portion of the stepped attentuator's range, only wire up a portion of the attentuator. One alternative for those of us who do not vary from quiet listening to earing bleeding blasts is to make smaller steps and/or only wire up the portion of the control that will be of value to us. This doesn't change the cost of the control by very much but makes the control more useful or allows you to use (more expensive) higher quality resistors in the average range. You can also build the unit to any taper you prefer, making smaller steps in the average range of the control and larger steps for the occasion when you want a bit more volume.

If your system accommodates a passive pre amp, it should provide the best sound quality for the least amount of cash. However, as that review I linked to claims, most passive systems have problems that cannot be resolved by short cables or impedance matching.


.
 

Silver Member
Username: Unbridled_id

ChicagoUsa

Post Number: 502
Registered: Mar-04
Thanks Jan, I will leave well enough alone for now.
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