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GET THE PERFORMANCE of a $20k PRE-AMP for $200;

Upgrade Your Existing Pre-Amp

by W.A.J.

If I were to suggest to you that an exercise costing one or two-hundred dollars could upgrade the performance of your pre-amp, possibly, to the level of those costing over ten grand - depending on the original quality of your pre-amp, of course - would you be interested?

Yeah? Well, I just thought you'd be, so I'll keep you in suspense no longer: This is a simple upgrade, or modification, that can be done by you, or your friendly neighborhood technician. It entails the purchase of a premium volume-control, and the installation of said volume-control.

That's it!

Nothing more.

It's as simple as that!

Let's say you already own a very good pre-amp that cost you around $1000 or $2000. You're happy with the sound, yet, you wonder if it could be improved, in some way. You wonder; 'What do those 10-20-grand pre-amps do, perhaps, better than my own great pre?' Let's say it isn't among the best. Then the more expensive unit's advantages may well be along the lines of; transparency, purity, mid/high-frequency clarity, detail, 'air', imaging - perhaps, also, bass solidity, articulation, and extension.

The differences between a good pre (yours?) and a great one, are usually along these lines. And these are, exactly, the areas this upgrade addresses.

So instead of running out to buy that 10-20-grand behemoth for an upgrade in performance, consider this option. It is entirely possible that the above-mentioned $200 investment (more or less) could elicit 20-grand performance from your 1-2-grand pre - or something approaching that, at least.

Other upgrades to resistors and capacitors, etc., do elicit benefits to performance. But, by all indications, the simple upgrade of the volume-control seems pregnant with the most potential regarding any singlular upgrade. An upgrade of the coupling-capacitor(s) could also elicit another significant improvement, and should also be implemented, if possible. Other mods may not be as dramatic as either, or both, of these two (the combination of which should be even more awesome, by the way - highly recommended) but then the choice is up to you. This piece is all about the volume-control, though.

Before I continue, let me paraphrase the related experience of a poster on one of the popular audio-forums (Here's the link to the full thread at; Martin-Logan's Owners' forum):

He tells us that; some time ago his aging ARC SP9 Mk II developed a noise in one channel when the gain control was rotated. After a couple of attempts at cleaning it, he replaced the ALPS potentiometer with another ALPS pot, and all was well. Then a month ago on audioasylum.com he read about the superiority of the TKD pot from Japan, and the supposedly even better stepped attenuator from DACT, a Danish company. He located both at partsconnexion.com. The DACT was way too expensive at $190, so he bought the TKD for $68.  (The original ALPS pot would be less than $20, ordinarily, but closer to $100 from ARC, bye the way -WAJ).

Apparently a problem developed, with the TKD, during installation so he contacted the vendor who offered a discount on the replacement. He also asked about the DACT, and they did offer him a discount on it as well, so he bought it. He soldered in the DACT that day. It is not a one-for-one replacement physically for the ALPS/TKD, so he had to do some minor surgery (of the non-‘revertive’ kind) on the mounting plate of the ARC.

He was immediately stunned by the difference ! The treble is a lot more clear, and the bass was more solid. Listening to the Proprius "Cantate Domino" on LP was absolutely astounding ! On that LP and on others he heard stuff he had never heard before; There were instrumental lines that he had never heard before. And this was without the pot even broken in; He expects that it will improve dramatically after 500 hours.

The ALPS pot is standard on a lot of  high end preamps. He very highly recommends that anyone with the itch to upgrade should first look at the preamp pot.  

Some may ponder whether this could actually be true. Indeed, how could such a simple upgrade elicit such a phenomenally "stunning", or "absolutely astounding", upgrade in sound-quality? Allow me to explain by first highlighting the passive 'pre-amp', and Coincident's active line-stage pre-amp, as examples. Bear with me. In the process, I'll reprint a segment of a previous article of mine:

The existing situation is - * By all credible accounts, for nigh on thirty-years, the performance of the best active pre-amps have been at around the same (high) level, with very slight, mainly negligible, incremental improvements, here or there, despite all the 'hype' and the 'hoopla' spewed by some in industry and the press. (This is mainly why the best vintage units are still competitive with today's units). All are veiled, to some degree, at high-frequencies. This has always been their 'Achilles-heel'. Though they are significantly superior to any passive pre-amp, overall, virtually none of these mega-buck actives can match the high-frequency purity and clarity of the best of the relatively cheap passives - none that I know of - until now!...... As far as I'm aware, the Coincident is the first (certainly the first that's affordable) active pre-amp with high-frequency performance that is virtually on par with the best passives, in terms of purity and clarity..... *

The Coincident Statement active line-stage pre-amp is, arguably, the world's best pre-amp.  In truth, it's perhaps only equal to most other good pre-amps in nearly all aspects of performance. Its undeniable superiority over all others is mainly due to ONE aspect of its performance - transparency - mid/high-frequency purity and clarity virtually equal to that of the best (otherwise-flawed) passive 'pre-amps'.

One of the main reasons for this superior level of transparency, in my view, is the fact that, unlike most actives, it uses one of the very best means of volume-control. (The Coincident's dearth of resistors in the signal-path, and its uncommon tubes, are also factors, in my opinion). The transformer-based volume-control (TVC) used by the Coincident, is similar to those used in some of the world's best passive 'pre-amps'. This fact, and the quality of the Coincident's sound, is no coincidence - it's a consequence (no pun intended).

I reiterate; The quality of the VOLUME-CONTROL is one of the main reasons for the Coincident's superiority over, arguably, all other pre-amps.

Unfortunately, the passive 'pre-amp' (the cheaper alternative to an active) is flawed, in my opinion, and that of others. It's significantly flawed in one region of the audio-spectrum (see here, and here, for more on that subject). However  its performance, superior to actives at upper-mid to high-frequencies, is FACT.

In simple terms, a passive 'pre-amp' is really just a direct connection from the source-component (CD, etc.) to the power-amp, with an attenuator (volume-control) between the two. The quality of the 'volume-control' is what determines the quality of the sound the passive produces. (Other factors, to do with signal-strength, impedance, etc., are irrelevant to this simplified example). In my view, the quality and diversity of the various means of 'volume-control' available today are direct consequences of the focus and demand, by builders of passive 'pre-amps', for ever-more increased quality in their most critical component.

Coincident is the only manufacturer of active pre-amps (or one of very few) to have taken full advantage of this, by opting for one of the very best 'volume-controls' available - one of the main reasons for the quality of its sound. [darTZeel is another, among the few. For volume-control, in their $26k active pre, they use Light Dependent Resistors - arguably, comparable in potential sound-quality to the TVCs of the Coincident - Melos, also, used similar means.]

The active pre-amp, in simple terms, can be seen as similar to the passive, except that it provides an electrical-circuit which adds gain to the signal. In this context, it's blatantly obvious that the 'volume-control' is no less CRITICAL (than it is with the passive) to the quality of sound a given unit will produce.

However, paradoxically, manufacturers of active pre-amps have always 'scrimped' on the quality of volume-controls installed in their units - even some of the most expensive units are equipped with relatively cheap volume-controls. (The obvious reasons are to cut costs, and to increase profit-margins).

It stands to reason that the sound-quality of virtually ANY active pre-amp can be significantly, if not dramatically, improved (along the lines of the-above example) by simply upgrading the cheap volume-control that was originally installed.

Hopefully the foregoing clarifies the situation.

The options to better sonics thru volume-control:  Perhaps I should give some insight as to how I came to stumble upon this discovery as, like many 'activists', I never gave it much thought before. (Passive pre-amp fans - 'passivists', if I may coin a term, or two - thrive on the quality of volume-controls, though. They're the real experts on this topic, not me). My voyage of discovery began in similar fashion to that of our audiophile in the above example. My own problem is minor, and recent, so I haven't gotten 'round to actually addressing it as yet. I'll probably report on it when I do. But I couldn't wait to spread the good-news garnered in the process of my research.

To begin with, here are the relevant posts in a thread I started on a popular forum, seeking advice (yes, I don't know it all, after all) in regards to my concern(s):

WAJ - A Blue-Alps volume pot (as fitted to an ARC pre-amp) has become noisy when the knob is operated thru the three minimum notches (all other notches are fine). (1) Could cleaning with a contact-cleaner eliminate this minor problem? Specifically, where would I spray the 'cleaner, on a Blue-Alps? (Wouldn't want to muck-up anything). Or do I need to replace the pot. (2) If I do need to replace the pot, can I use a tranny - based attenuator instead, and how difficult would this mod be?

Poster A says......He would replace it. Alps Blue's are fairly inexpensive. In his experience contact sprays only help for a short amount of time.

WAJ - Yeah, I know they're reasonably priced. I'm considering my options, and that's the one I'd least like to implement. If it can be cleaned, I'd prefer to try that first. If the problem returns, as you suggest, then I'd prefer to upgrade to a tranny -based attenuator, if possible. So, to be on the safe side, I'd like to know where to spray the 'cleaner on the Blue-Alps. And I'd also like to know what a tranny-based att.-mod would entail, if that's feasible. Thanks for the headz-up though, PA!

Poster B says.....  He replaced his noisy Alps with a Precision Electronics pot. It is not expensive and is of very high quality. It is what many of the DIYers use. l PEC POT 100K OHM 2W DUAL LOG TAPER

WAJ  - The PEC pot is very interesting, PB. But in so far as variable resistors are concerned, I may as well stick with Blue-Alps, if only to keep W. Zane Johnson happy. My consideration of transformer-based attenuators is dependent on whether they actually offer a significant increase in clarity (which I don't severely lack, at the moment, to be honest). If my investigations prove those don't offer such an increase either, then Blue- Alps will prevail - whether replaced, or just cleaned. Thanks for the advice, nevertheless - I sure 'preciate it! 

Poster C says....  The Alps is widely used because it's cheap (buying one direct from ARC isn't cheap, tho') and has decent channel balance. Period. If you remove the knobs, then the screws that hold the board all the way across the inside front of early ArcS: Ls-1s and such, you can pry back the board enough to get a soldering iron on the six pot connections and remove it. Now snip the first loop from each of the solder pins of a TKD pot and solder short lengths of no more than 22 ga wire to the remaining loop. Solder these six in the same order/position as the Alps and replace everything. Huge upgrade. Or follow the Alps removal with a 50K resistor and run the output to your transformer.

WAJ  -  PC, I did a few quick checks on TKD pots - used by Audio-Note, Lamm, etc., huge upgrade over Alps in DIY projects too - you may have a point, there. Thanks for the heads-up. Thanks a million! 

Poster D says...... Yes, and you can read similar praise for the PEC mentioned above. Do a Search on Tube/DIY. 

WAJ  -  Thanks!

Poster E says.....  If posters say the Alps Blue is so bad -How come Shindo use them?

Poster C says.... If true...kinda makes you wonder about paying $12,000 for a simple design?  ( $12k for a design with a $20 volume-pot? Is that so? - WAJ)

Interesting?

The last point is poignant, and indicative of the existing state of affairs. My investigations have so far revealed that the Alps pot (potentiometer) as used in ARC pre-amps such as my own, and alleged to be used by the
manufacturer of that $12,000 unit, is among the cheapest (and most sonically-compromised) volume-controls (V-Cs) available for 'high-end' use. Yet, it's also perhaps the most widely used, by very many high-end manufacturers. Good, though it may be, there are better pots available.

Get the point?

Further up the thread, you'll have seen where Audio-Note and Lamm use the better, and somewhat more expensive, top-of-the-line TKD stepped-attenuators  for volume-control - allegedly the best commercially-available stepped-attenuators. But this is, also, nothing to get too excited about. Arguably, there are better means of volume-control that they could have used, more in keeping with the high cost of these units - TVCs similar to those used by Coincident, for argument's sake, or LDRs like those of the above-mentioned darTZeel pre - arguably any of these could elicit better performance from these units, or any unit so modified. Nevertheless, the use of the  top TKD attenuator in these units is still commendable. The reality is that most use cheaper and less accomplished means of v-c, especially in models that are not at the very top of their lines.

As you'd expect, each pot manufacturer (is that illegal?) carries several models in their lines, with different prices. However, I'll relate the approximate prices of the pots/attenuators/V-C devices suitable for my own pre-amp, as these prices reflect the general difference in price (and consequent sound-quality, generally speaking) between the different brands (or types of volume-controls, in some cases). The list is not comprehensive, but representative of the better examples:

Blue ALPS - $20, PEC - $38, TKD - $70, DACT - $200, TVCs (and I include AVCs - Auto-former V-Cs - here) run any where from below $400 to over a thousand, for silver-wired units, I believe. And LDRs (Light Dependent Resistors) seem, generally, to cost less than the latter. A complete Lightspeed LDR passive pre-amp can be had for around $450, for instance, Eva is another complete passive pre at $330. A Warpspeed LDR volume-control kit is at about $155, and a similar LDR v-c kit; the SKA OptiVol, would cost about $45, to name a few.

Regarding the pots and stepped-attenuators, so far as I've gleaned, each price-level is also reflective of the increase in quality over the previous, generally speaking. The better atts run, in price, from $150 to $250, with the top TKD att, in conjunction with its recommended 4 Vishay S102 bypass resistors, costing significantly more - but worth every penny, allegedly.

Here are the views of another poster, at another forum (Pink-Fish Media, here) on the matter of ranking some of the available volume-controls. Others have indicated similar sentiments:

Original Poster  says.....  He's been following the preamplifier threads with some interest, he doesn't fit in the camp of believing an active preamp will always improve any system, as some people at least appear to believe, but neither does he reject them out of hand, having owned plenty in the past. In his valve integrated amp he's changed volume control from Alps Blue > TKD > DACT Stepped Attenuator > Passive TVC, and at each stage there has been an improvement.  [Note; the first three are pots he's changed in his integrated-amp. The latter is a separate (TVC) passive pre-amp he now uses - WAJ.]  If he owned an active preamp, right now, and it was supplied with something like an Alps Blue pot, he would immediately swap it out for the DACT for an overall system improvement. ......

Respondent  says .......... He's tried all the permutations you (the original poster) mentioned. DACT stepped attenuator is the daddy. Passive preamps sound dynamically flat unless the runs of cable connecting them to the power amp are very short which is why they work best in integrated amps.

Original Poster  says....... He has a DACT stepped attenuator sitting in a box having replaced it with a Django TVC (passive pre-amp). The improvement wasn't as big, from DACT > TVC, as the other improvements through volume pots, but the TVC is superior in his system.

Note; if , as these posters and others have indicated, the upgrade to a DACT attenuator in the active pre-amp stage (of an integrated amp, in one instance, in this case) brings its high-frequency performance, among other things, so very close to that of a highly-regarded purely passive pre-amp (the Django TVC) then this is extremely remarkable, significant, and outstanding. Many of the world's most expensive active pre-amps struggle to achieve this level of H-F performance. This achievement is, as the audiophile with the ARC pre in our first example declares; "stunning", and/or "absolutely astounding".

However, nothing in audio is ever clear-cut. Despite high praise regarding the transparency of the better stepped-attenuators such as DACT, some also criticize them for thinness, or a lack of body, to the sound reproduced thru these devices.

Here's an example of such concerns, from a poster at diyaudio.com:

He relates that; in the past he's tried stepped attenuators, ladder type, with metal film resistor. Compared to common cheap carbon pot (like ALPS and some TKD) the sound of stepped was somewhat clearer, better soundstage, but overall the carbon pot sounds better, more musical, more natural. How does the lightspeed (LDR) compare to carbon pots? Is there really so big a difference, does it sound musical?

Respondent #1 had this reply; .... The material the LDR is made out of just sounds wonderful. Its so far better than a carbon pot that you really should try it....

In a nutshell, at the top of the pile, there seems to be strong arguments for stepped-attenuators, TVCs, and LDRs. (We've already established the approximate pecking-order amongst carbon pots below this level).

[For me though, since I'm averse to components which display a lack of natural body (no matter how transparent the sound may otherwise be) I'd eschew stepped-attenuators, if further research confirms that there are no examples bereft of this trait. If such is the case, I'd prefer to consider an upgrade from my ALPS to one of the better carbon or plastic pots, such as the TKD. But I'd, more likely seek the ultimate from a TVC or LDR. And since the TVC may be too cumbersome for my purpose, that leaves my choice between the top TKD pot, or the much better sound-quality of an LDR (ie; transparency with body -  when incorporated into an active pre, as my research has so far indicated). Dependent upon whether the installation of an LDR is simple enough for a non-techie like me to perform, or whether I find a techie in my region who can carry-out this mod, my choice would be the LDR.]    

Nevertheless, just as with almost everything else, there are concerns about LDRs. Allegedly, measurements have shown them to have tube-like non-'linearties' and harmonic distortions which, however pleasant, are inaccurate. In response to the summary of a thread I started at diyaudio.com (provided below) one respondent voiced his disapproval of LDR in this manner; "I disagree completely and absolutely. CDS cells are both non linear in terms of their resistance change with light, but also WRT signal power passing through the element(s). Rather non-linear in all regards. One can speculate that if one wants to add some extra 2nd harmonic, etc. to the signal, then they will sound very nice..."    
 

My response to that was; 'You may disagree, X, and I can see your reasons why. But the reality is what it is - and that's what I've reported. Look at the meteoric rise of the Lightspeed, and the gathering momentum of others that are similar; Eva, Warpspeed etc. The cold hard fact is that many are captivated by the transparency, and general sonic characteristics of LDRs, regardless of arguments regarding harmonic distortions - shades of the tube/transistor debates, all over again. Do you use tubes, btw? If you do, then it'd be interesting to hear your sentiments on these similar issues with tubes, as you so rightly point out about LDR. Just a thought.' The gentleman who, as it turns out, specializes in the use of tubes (which, arguably, feature the very same musically-relevant  traits) opted not to counter. 

Summarizing the options:  OK, perhaps it'd be a good idea to summarize my findings for the benefit of those who're, like me, new to the in-depth subject of volume-control. (Understandably, technically-oriented and long-standing fans of passive 'pre-amps' are the undisputed experts on this topic. And my own comments should, ideally, be viewed in the context of the recent discoveries of a long-standing audiophile who may be reasonably learned in most areas of high-end audio, but relatively new to this one - a novice in this particular field).
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Stepped-attenuators are, in my view the standard-bearers in the field of volume-control. For those of us seeking the very best in transparency, and overall sound-quality, all other means of volume-control must be measured against the best of this standard. However, there's a caveat in the fact that some seem to believe that atts tend to thin-out the sound, as compared to other means of V-C, which do not display this trait. The results of my investigation, in this regard, are inconclusive. The fact is that most of those, who aired such a concern, were using DACT attenuators, though other brands were also implicated. On the basis of my findings, I'd be inclined to believe that there is a legitimate concern, regarding a thinner midrange conveyed by DACT atts. Fuller mids seem to be a feature of both the Goldpoint, and TKD atts. As to whether these eradicate the problem completely, I'm not sure. Nevertheless, according to a comprehensive study done by Bob Crump ('sourcer' and partner to John Curl, designer of the Blow-Torch pre-amp) the very best stepped-attenuator of all is the top TKD. (A reference to his findings is linked here).
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Potentiometers (carbon-based, or plastic) generally speaking are less transparent than atts. However, the very expensive ALPS RK50 is THE EXCEPTION, with reputed transparency comparable to the best atts, but at much higher cost - $1k. At a lower level, the best TKD pot is alleged to be close (but not quite there) to the quality of the better atts. Citing a few of the popular examples, the consensus seems to be that the sound-quality of pots, in ascending order of ranking, would be; Blue-ALPS, PEC, and the afore-mentioned TKD - this much was firmly established. (Based on what I've gleaned, I'd guess that the Black-ALPS and Panasonic would be nearly equal to the PEC, and the Nobel would be closer to the TKD - pure speculation, on my part, though).
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Transformer-based volume-controls (TVC and AVC) are generally much more expensive than atts. The sound-quality is usually comparable - with the best of these alleged to be slightly better than stepped-attenuators - a claim hotly debated by att-advocates.
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Light-Dependent Resistors (LDR) volume-control, by all consensus, seems to be the very best means of V-C, with singular regard to sound-quality. Many, who had previously used atts, now attest to slightly more transparency and resolution of low-level detail, with their current use of LDR V-Cs. The same applies to those who'd previously used TVCs. There are several LDR passive 'pre-amps' available in the form of the likes of LightSpeed, WarpSpeed, Eva, etc. However, though perhaps all can be used in the context of a replacement volume-control for an active pre, perhaps the most attractive, in terms of physical-fit and cost (comparable to an att in both regards) is the OptiVol LDR volume-control by Ska. With regard to its sound-quality (in the context of passive and active applications, respectively) here are two example of the prevailing sentiments - from a thread at that site:
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Example A: This audiophile belives that; the SK OptiVol is actually better (and cost less) than the passive Ladder Volume switch that he was using. Using a 27K series resistor, the minimum volume is -54.5db.  His speakers are 92db and -54.5db is sufficient for them. Here's what he wrote a few months ago about the SK Pre c/w SK OptiVol ... Quote: Hi All I have just completed an SKPre c/w SKOpticalAttenuator and thought that I would give a short report on it. This is a very transparent and neutral preamp. The stage is very open, deep and wide. It is very musical and detailed. The highs and mid-range are very detailed and have no edge to them. The bass is very detailed and full, also. Everything has a very "there" feel to it. Nothing seems to stand out or be out of place ... very nice Also, the SKOpical-Attenuator is also very good sounding ... Actually, I would say that Greg's SKOptiVol is fantastic and will be my choice of volume pot in the future - :thumbsup.
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Example B: Title: Re: Simple LDR volume control!   - I shoehorned my Optivol into a Bottlehead Foreplay Tube linestage pre-amp, powered via a wallwart dc supply. It's the best attenuator I've had in it, including a stepped switch!.
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All other options we've discussed do offer incremental improvements over the original volume-controls of many pre-amps - opt for the one that best suits you. The best potentiometers and stepped-attenuators could bring the performance of a good active pre to within touching-distance of the best active pre-amps. With the top TKD att, it might even be possible to be just as good as some of the best - depending on the quality of your original pre-amp. The same could be said of a very good TVC volume-control, if it will fit, or it could actually take the performance further - all else being equal, of course. But, from all indications, the LDR does seem to offer the ultimate increase in sound-quality - the ideal route to achieving, or surpassing, the performance of that $20k pre - at potentially the least cost to boot.

For another example, consider the Transcendent-Sound Grounded-Grid active pre-amp which sold for less than $1.2k, complete, and even less as a kit. Audiophiles at that forum have experimented with upgrading the volume-control to LDRs, with phenomenal results. Suggestions that this mod takes the performance of a $1k pre to 'cost-no-object' territory, should not be taken lightly - these guys know what they're talking about.

These are some of their paraphrased comments:

Poster A tells us that; his GG pre (Grounded-Grid pre-amp) has been modded with (LDR) optocoupler volume/balance control. The increased resolution over the "stock' carbon pot isn't small. It's made a great pre-amp better.

Poster B says,  he built his GG kit about three years ago and has enjoyed the clean, clear, fast sound very much.  He made many of the mods talked about here and elsewhere, (alps blackBeauty pot, better output caps, metal film resistors in signal path, bypassed electrolytics, etc). Sounds good to him and all that have heard it. On a lark he bought the Warpspeed LDR.  By itself, just as an attenuator it blew away the GG. Not enough gain, but it certainly sounded wonderful. he has not put it in the GG yet.   Right now he's listening with the LDR in the Dodd buffer.  This sounds great up to a point.  It starts distorting when he turns the volume up to max.  Must be an impedance mismatch, so he's going to try a different tube. He has not decided if he's going to try the LDR in the GG yet

Poster C related that; his Grounded Grid was optocoupled (LDR) modded, along with balance control, and parts upgraded.  The mods were performed by his buddy Erick (Buzz) of Greenvalve Audio.  The Grid by itself is a wonderful product. Erick's mods take it into 'price no object' sound quality

If the foregoing doesn't convince you, then nothing more I'd say ever could. For the believers, though; order that pot and light-up that solder-bolt. (No, no, not the matches! What earthly-manner of pot were you thinking of, really?) And, after you're done assessing the sonic-results, do suppress that snicker when others mention their 40-grand Lamms, for instance. (Not to be forgotten, though, and as mentioned before, combining this with a coupling-capacitor upgrade should be awesome).

Price-no-object sound-quality - indeed!

"Let the music play!"

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