Mods and restorations

Audio upgrades

In a capitalist society 99.999% of audio equipment is built with cost related compromises. Contrary to what you may read on the forums or hear from marketing departments, circuit design has NOT universally improved in the last 40 years. In fact most of the greatest discoveries in audio equipment were made over 50 years ago by large companies like Bell labs, GE, and individuals like Walt Jung, John Curl, and many unnamed engineers in Japan. Now what has improved is the PARTS QUALITY and CONSISTENCY. The combination of great circuit designs in vintage audio equipment and todays best components decimates most of the affordable current new products in both reliability and sound quality. With the rising cost of manufacturing and more so the ever increasing greed of corporations the current new equipment which an average person can afford is FULL of sound degrading compromises. So don’t think your old silver faced amplifier is obsolete like an old computer or car! Think of the work we do as like a speed shop for cars but instead of horsepower we are going for improving the sound and reliability.​

electrolytic capacitors

The number one reason a good quality vintage amp, receiver, or speakers may sound bad, lacking detail, lacking bass, lacking air, poor soundstage, etc…is because ELECTROLYTIC CAPACITORS. I have measured hundreds of old electrolytic caps and most over 20 years old NEED to be replaced in order to insure proper performance. Now, I have heard of quite a few service techs electing to not change them out in their restorations and this is a big red flag! They may claim that they “measured the caps” and they were “in spec”. Most are either full of shit or ONLY measured capacitance which tells very little. Capacitors have MANY different measurements that most people have no idea about. High “ESR” is the most common tale of an out of spec electrolytic capacitor and a high ESR can wreak havoc on the sound.Now, in addition to their limited life-span, many companies compromise on their Electrolytic caps and use the cheapest they can find, even in multi-thousand dollar equipment. When you are a manufacturer ordering one million capacitors at a time and have bean counters in corporate deciding things, audio grade caps take a backseat to stuff like faceplate design and other aesthetics. This is where we can make big gains in improving the sound of equipment!

I have done extensive testing of every name brand electrolytic capacitor series I could find. Elna Silmic II caps are my go to for signal path duties. I first heard about these caps as a recommendation from one of the audio legends, Nelson Pass. When I cannot get the proper value in Silmic II, I use Nichicon Fine Gold or KZ (Muse). For power supply duties I use Nichicon Gold Tune level 1,2, or 3 depending on customer preference and size constraints. Also, if customer prefers a specific cap like Mundorf M-Lytic, Jensen 4 pole, etc…I can usually accommodate.


Film caps

Film caps are far better than electrolytic caps in sound and measurements as well as life-span. So why don’t manufactures use film caps instead of Electrolytics? The main reason is SIZE and COST. See Below:

Polyster Capacitors: These are the most compact type of film cap and measure better and sound better than any Electrolytic cap. These caps are more expensive than electrolytics but the gains in sound quality make them worth the extra cost. These are the most common film cap that manufacturers use if any at all. ALL ELECTROLYTICS under 4.7uF are replaced with at least Polyester film caps. The addition of these film caps offers a more transparent sound, imaging and soundstage depth are improved.

Like the Electrolytic caps, I have done extensive listening testing with many different Polyester film caps. Most commonly you will see Red Wima caps. I feel that the Wima’s are not the best sounding and can be improved upon with the Kemet R82. The R82’s are in my experience the best sounding metallized polyester caps.

Polypropolene Capacitors: These are the caps you see used by high end companies like Conrad Johnson, Audio Research, Lampizator, Audio Note, and many other very high end designers. Polypropolene caps offer a very big step up in measurements and sound compared to Electrolytics and Polyesters. The problem with these caps is SIZE and COST, much more so than with Polyester film caps. These caps are only practical in low values as their physical size is very large relative to their capacitance and voltage compared to Electrolytics and Polyesters. They are mainly used in signal path in critical areas where they have a DIRECT impact on the final sound of the unit. Their are many different companies making these caps and a wide range of subtle sound differences are obtainable.

I have tested everything from Solen MKP-FC’s to Clarity Cap MR’s all the way up to Dueland CAST. My favorites that do not cost more than the unit their going in are the Mundorf EVO Oil series. These offer a SIGNIFICANT improvement over polyesters and Electrolytics and also  lower cost Polypropolene’s like the Solen MKP series. I use these when size and price permits. It will be discussed with the customer and depends on specific units. For the people that want no compromises, I am happy to work with them to squeeze out everything possible from a particular design! An amp full of Clarity Cap MR’s will sound more transparent and realistic than one filled with Mundorf EVO in Oil but the difference between those is much smaller than say Solen MKP-FC to the Mundorf’s or Polyesters to the EVO in Oils.

Below are some good reputable links to more information on capacitors. LEARN.

http://www.reliablecapacitors.com/pickcap.htm  This is the famous Walt Jung and Richard Marsh article on Capacitors.

https://www.youtube.com/watch?v=xlvqUts9H9c&t=320s      Here is a quick video on the common types of caps. Not audio specific but a good quick summary.


specs game

Have you ever wondered how two different amps with the same “specs” can sound different? Well, in the slimy world of audio equipment “specs” are more often than not manipulated or certain important specs are left out altogether. Ever heard of 7th order distortion? I didn’t think so. “7th is what I consider to be one of the hardest distortion patterns to get rid of. 2nd and 3rd harmonic are like music compared to 7th! The Radiotron Designers Handbook of 1940 stated that ANY 7th order distortion is TOO MUCH”, John Curl. This spec is nowhere to be found! This is just one example, their are many more.

Below is a link to a good presentation on “specs” in the audio industry. Watch it, you will be informed and more protected from their tricks!


tda1541a based cd player mods:

One of the most musical DAC chips of all time, the TDA1541A. The problem with the TDA1541A is that it is very sensitive to complimentary circuit and parts, this is also a plus as the chip’s potential is VERY high. The TDA1541A is seen in many vintage CD Players and below I will provide a link to the TDA1541A based player list.  Just about every TDA1541A based player is a candidate for modifications and the sound can be improve significantly.

Some of the best players to look for are below:

Nakamichi CDP-2A
Nakamichi CDC-3A, 4A
Sony CDP-227ESD, 337ESD, 557ESD: Any of these three can be a world class reference player with a few hundred dollars of improvements! Good luck in finding one!
Arcam Alpha 5
Cambridge CD-3
Naim CD-3, CDS-1
Any Philips or Marantz TDA.
And many more….

Here is the TDA1541 list


Other vintage dacs and cd players

Their are quite a few vintage DAC’s with very high sound quality potential with modifications and or current audio grade components from audio grade caps to better OP AMPS all the way to discrete output stage or a tube output stage similar to what Mr. Lampizator did while on his CD player journey. Here are just a few of the best candidates for mods. Feel free to send me an email if you have a specific unit that you are interested in finding out its potential, I live for this stuff!

Adcom GDA-600: This DAC responds VERY well to better parts and goes for very little money on the used market. The dual  Burr-Brown PCM-63 J grade DAC chips are some of the best ever made. This particular DAC is one of the best bargains I have come across and with some key changes the sound improves significantly.

Audio Research DAC 1-20: This DAC already comes with a design which uses very few electrolytic caps and mostly Wima Polyesters. These Wima’s are the weak link and this DAC has world class potential with better Polypropolene caps, better tubes, and a few other key components. The chip used is a very special DAC, the Ultra-Analog D20400A!

Sonic Frontiers SFD-1, SFD-2: Another DAC that with some love and care sounds close to as good as digital gets and MUCH BETTER than most of the ESS Delta Sigma designs that are all the rave today. Tube output stage comes standard as does the D20400A DAC. If you have one of these, hold onto it! Years from now these D20400A tube output stage based DAC’s will be worth big $$ IMHO.

Pass Labs D1 DAC: The D1 features a true discrete output stage and a damn good one. No OP AMPS! 4 PCM63 K grade DAC chips are used, one of the best chips ever made and Burr Brown’s best ever. The electrolytic caps are now getting up there in age and can be improved greatly with Mundorf Mlytic’s in the power supply and Elna Silmic II’s in signal path and also polyester caps replaced with polypropylene in key places.

Average cost of the full treatment varies between $200-$1200 depending on a number of different things which will be discussed prior to sending the unit.


amps and preamps

I have extensive experience with the following:
Accuphase E, P, C

Arcam Delta & Alpha

Adcom GFP & GFA

DBX-BX3 & CX3

Kenwood KA & KR, Supreme, L-monos.

Krell KSA, KAV

Luxman R, M, L

Marantz many different series

Mark Levinson ML

McCormack DNA

Musical Fidelity A

Onkyo M

NAD PE, C, more

​Nakamichi PA, RE, TA, CA

NEC AUA

Parasound JC, HCA

Pass Labs F5, Aleph J, 1, 5,

Sansui AU, G, GX, B.

Sony TA

Threshold Stasis SA, S/

Yamaha R, CR, A, AX, MX, B

And many more!

Full treatment can vary from $250-$2000+ depending on which model and work done. General price for most amps is around $400-$600 which includes very high quality parts. No shortcuts or cheap components go into my work at any price! Every unit I restore/upgrade receives extensive cleaning, all switches and pots cleaned/lubed, solder joints carefully examined and reflowed if needed.

Preamps are generally between $150-$600 depending on specifics.

I will not work on home theater receivers! Only 2 channel. 

Speaker crossovers

An often overlooked but very critical component in the audio chain is the loudspeaker crossover. Many crossovers are built with clarity killing low quality electrolytic capacitors. This is likely done because most people never even see the crossovers in their speakers so it is easy to slide on and save money for that CEO’s seven figure salary. Well with electrolytic caps they wander out of spec over time which has direct effects on the critical crossover frequencies the speakers were designed to be played at. We can seriously improve the sound by replacing the poor quality electrolytics for Polypropolene film caps. The difference in clarity is noticed even by the most skeptical listeners like the cult-esk group of ABX or nothing people! That is the minimum, Polypropolene caps run between $50-$300 per set in most cases. Better resistors, better wiring, and copper foil inductors are also available but caps are what I recommend first and offer the biggest increase in resolution. The price depends on complexity of crossover, size, and quality of caps. I use Solen MKP-FC as my standard poly crossover caps for the tighter budget people and Mundorf Evo in Oil for the best sound for their price. If you want something better, their are more expensive caps that do sound better like Mundorf supreme, Audyn True Coppers, Jupiter Beeswax, I could go on. Each offer a slightly different sound.

Vintage speakers in particular are the most effected by old electrolytic caps and any good classic speaker should be recapped to hear what they should sound like. I am happy to help if you want to do this yourself so shoot me an email! But, if you want to send me your old crossovers I am happy to do it for you at a reasonable cost.


Summing it up

I do not offer partial restorations or repairs only. I want your unit to last another 30 years+ and not a few years until the next thing breaks. Do it right the first time and do not worry about it again.

Feel free to message me at for any inquiries or general questions. I do plan to add an in-depth how to series to this website for DIY oriented people that would like to do their own restoration on some of the more popular units. I will also be creating Youtube videos of some of my restorations and what goes into them so check back once in a while.

Thanks for checking out my site!

Nick.