Finally put up a system... mostly so that people can see what my recommendations/opinions are based upon.  Feel like I'm getting closer all the time, but it's very much still a work in progress.  Fairly happy with the current sound, but am very interested in trying out different (digital) sources and working with the gear to make the sound as warm and inviting as possible.  

A LITTLE HISTORY:  I bought my first stereo equipment from Wal-Mart when I was 13 and have been into music and music reproduction ever since.  Got some big MTX speakers for my 16th birthday, and got into hi-fi when I was in graduate school at Ohio State University.  Lived in shared houses for many years and have been a bad neighbor on many weekend nights... I'm sorry folks, thanks for your tolerance. 

PAST SYSTEMS:  Built around 2005 when I first joined the site, my first real system was a pair of Thiel 1.6s driven by a Classe CAP-151 and an Exemplar modified Denon 2910.  The Classe won out over a Bel Canto eVo2i I also auditioned.  Five years later I upgraded to Thiel 2.4s, driven by a Pass Labs INT-30A and PS Audio Perfectwave DAC.  The INT-30A won out over a Pass Labs X250.5 and a McIntosh MC402.

After blowing yet another set of Thiel drivers and seeing the company be on the ropes after Jim's death, I did a lot of reading to figure out what to do next. Based on the recommendations of member Charles1dad, I ended up moving to the high efficiency Coincident Super Eclipse IIIs (92db sensitivity, 14ohm impedance).  One draw of these speakers was that they would allow me to try different amplifier topologies.  After purchase, I put my Pass Labs INT-30A up against a First Watt SIT-2 and a pair of 8W Coincident Frankenstein 300b monoblocks.  Loved, loved, the all Coincident combination and the experience piqued my interest in trying the company's top of the line speakers, the Pure Reference Extremes. Although challenging, they are the cornerstone of my current system.


SPEAKERS:  The 94db, 8 ohm Coincident PREs have only a single capacitor and single inductor in their crossover.  The mid-range driver goes straight to the amplifier.  The capacitor provides high pass filtering for the accuton ceramic tweeter.  It responds very strongly to capacitor changes and (as promised by others) I've found the Duelund tinned copper CAST to be the best.  Despite being advertised as having Mundorfs, my PREs came with the run of the mill Solens pictured above.  I replaced those with ClarityCaps bypassed by Duelund .01uF sliver foils, replaced those with Jupiter Copper Foils, and then replaced those with the Duelunds.  The ClarityCaps were "ruler flat", the stock Solens were a bit noisy, but with some nice color/richness, and the Jupiters combined the best attributes of the two.  The Duelunds are better in every way.  Natural, rich in color, and somehow also the most accurate/detailed of the bunch.  Highly recommended.  I found I didn't like the sound of adding bypass capacitors to the speaker crossover, as it seemed to produce some smearing or phasiness that made me uncomfortable.  

As recommended by member Grannyring, I run the speakers with unterminated Duelund tinned copper in oiled cotton cables -- 16ga on the top and 12ga on the bass.   These are way better than the anti-cables I had from the previous system.  Curious to try more cables, but also hesitant to go down the rabbit hole.  I also saw that Jim Smith uses these cables on his current (2019) system... seems like another solid recommendation.

AMPLIFICATION:  Despite the advertised specs, the Coincident PREs are less efficient than the Super Eclipses IIIs and I was forced to search out new amplifiers to replace my beloved Coincident Frankenstein 300bs (run with Mullard CV378 rectifiers and EML XLS 300bs). The Franks simply couldn't drive the PREs in the low frequencies and would start to distort on loud music.

I tried a Lyngdorf 3400, Atma-Sphere M60s, and a Pass Labs XA25, but in each case settled on the Franks despite their poor bass performance.  Eventually I decided to built a DIY First Watt F4.  It only provides current gain and my plan was to use it as a booster amp to power the PREs' bass units while being driven directly by the speaker outputs of the Franks.  Unfortunately, bi-amping killed the speakers' coherency.  That was also true when I tried pairing the Franks & Lyngdorf using the latter's active crossover.

To my surprise, when I tried the F4 as the sole amplifier of the PREs it beat out the Franks.  It retained a great deal of the sweetness of the Franks, improved the bass, improved clarity, and reduced distortion.  Soundstaging is also amazing.  Perhaps there's been a small reduction in tonal color.  After having it in the system for a month, I put the Franks back in and it was clear that there was no going back.  The F4 is based on a simple, no feedback Class A circuit and the PREs really sing with them.  These speakers really do seem to prefer simplicity.  

Although a single F4 is plenty of power for the speakers, I built a pair of monoblocks to keep speaker wire runs short.  This also allows me to do a vertical biamp solution, with each of the PRE's four cabinet boxes getting its own 25w amplification channel.  Plus no R/L channel crosstalk.  Thank you to Nelson Pass and the community for providing the resources and technical support that allowed me to build such wonderful amplifiers.

The F4s use custom 12ga Furutech FP-S032N based power cords from member Grannyring's Acoustic BBQ line.

PREAMPLIFIER:  Adding the Don Sachs 6SN7-based preamp has greatly improved the sound of my system and I simply can not go back to using my DAC direct.  This was true both with my PS Audio Perfectwave DAC that has a less than ideal volume control (i.e., it throws away bits below a certain level) and with the PS Audio Directstream DAC's improved volume control (full resolution at all levels).  This pre seems to just make the music better in every way.  It is not at all syrupy or tubey, just passes on the sound of the source and makes it better.  

Having gotten into modding my gear, I also like that the preamplifier is based on a kit (the VTA SP-14) that I can read about so I can learn the circuit.  That fact and the unit's two separate outputs lines encouraged me to try different capacitors.  Don recommends Miflex copper foils, but I found them a bit two-dimensional and veiled in my system.  I installed Mundorf Supremes and found that the system was capable of a lot more front to back layering than revealed by the Miflexs.  I then put in Mundorf Supreme Silver/Gold/Oils.  They added in a nice touch of richness over the plain Supremes while retaining all the wonderful soundstage depth.  Very happy with the current sound, but will continue to try out various competitors.  TFTF V-Caps just got installed.

As recommended by Don, I run the preamp with a pair of Shuguang Black Treasure CV181zs as the main tubes.  They're complimented with a wonderful pair of RCA grey glass VT231s as the buffer tubes.  Compared to CV181zs in all positions, adding in the RCAs reduces the pre's punch/impact a bit, but adds in some smoothness and layering.  I use the standard 6X5GT rectifier Don provides.

The preamplifier connects to my F4s via Ocellia Silver Reference RCA interconnects and is powered by a DIY DH Labs Red Wave AC cord with Furutech copper screw on connectors. I tried building my own DIY interconnects using the Duelund 16ga wires and KLEI absolute harmony plugs, but the Ocellia cables were significantly better.  

SOURCE:  Despite its age, the PS Audio Perfectwave DAC MKII is really a great sounding piece of equipment.  I'm sure there are better units out there, but it is a very functional piece that allows me to switch between my three digital sources (network audio, TV for Ohio State football & video streaming, and a PS4).  Critically, it's also a highly musical, natural sounding piece.  I've tried to move on twice (2015 & 2019) and have gone back both times.  Adding in the Bridge II network card made the DAC much, much, better and allows me to stream CD-quality music directly from Tidal (served by BubbleUPNP running on an Android tablet) without having a computer in the rig.  Again, highly recommended.  I miss buying music, but am never going back to spinning disks.  Tidal often sounds better than my ripped music collection as well.

I run the PWD with a SR Blue fuse in the digital slot and a Furutech fuse in the analog slot.  It's connected to my router with a Supra ethernet cable, and is powered by a DIY DH Labs Power Plus AC cord with Chinese copy Furutech Rhodium screw on connectors.  It connects to my preamplifier using balanced MIT cables (a lost model number from many years ago).

ROOM:  Some compromises have been made in order to blend the stereo with a video system and drop it into the primary living space.  I'd love a dedicated room, but would also suffer greatly removing the system from living room where it is the daily driver for music, a show or two, and some PS4 play.  The room is 19' across, 16' deep, with 23' peaked ceilings.  It opens up to the rest of the house in two places.  Half of the "back wall" is open to the dining room, which drops back another 9'.  The 23' vaulted ceiling also opens up to a second story master bedroom/loft space.  This all makes it so that the stereo is basically in charge of pressurizing the entire house except for a spare bedroom and small basement.  Fortunately I am able to set it up in such a way that the speakers are not parallel or perpendicular to any walls.  It's on the room diagonal, a placement forced by the location of the front door and attached dining room.  

This has a couple benefits, one being that the equipment cabinet and TV can be pushed further back away from the speakers.  The second is that the traditional side wall first reflection points aren't a problem.  Aside from a rug over the hardwood floor, there are no room treatments... don't really know where to put them.

POWER, CABLES, ETC:  As much as I'm loath to admit it, I have found that all of these tiny variables matter.  This wasn't really true (or the impact was too small to care) with my other systems, but the Coincident PREs reveal the impact of every small change.  This has made it clear that cables, power cords, and fuses can have a very substantial impact.  I find it incredibly frustrating that I don't understand how or why the fuses or power cords could possibly matter, but in this system they do.  Again, curious to try more than my current DIY solutions, but also scared to go down the path...

Based on recommendations from Ralph Karsten @ Atma-Sphere, I purchased an Elgar 6006B to condition the power to my system.  I run everything except my amplifiers off of its perfect sine wave.  Given its age, it is recommended to replace all capacitors in the unit, which is on my to do list.  Unfortunately I can't get myself to listen to the stereo without it in the chain, so I haven't gotten around to "fixing" my unit yet.  The PREs' accuton tweeters can get aggressive and removing distortion from the incoming power is essential to keeping them warm and inviting.  Note that this unit must be installed in a separate room, as its (industrial) fan and transformer are both too loud for a listening room.  Also, it's heavy AF.  I purchased the Elgar because despite the dedicated lines, I still got some electrical feedback from various objects at the stereo (e.g., a slight pop noise when an LED bulb was turned on).  The Elgar has completely eliminated that issue.

The stereo is on its own dedicated circuit with two 10ga romex lines both run off the same leg of the incoming power.  The Elgar runs one line, and my amps reside on the other.  


Happy to field comments.  Hopefully some folks find the information useful.  Thanks to all the people who have written about their experiences and thereby helped me build the system... almost all of it was purchased blind without prior exposure, so finding some trustworthy voices out there in the digital forest has been incredibly useful. Thanks folks.

Room Details

Dimensions: 16’ × 19’  Medium
Ceiling: 23’

Components Toggle details

    • Coincident Speaker Technology Pure Reference Extreme with Modified Duelund Crossovers
    Very revealing.  94db efficient, with a flat 8 ohm impedance.  Accuton ceramic drivers on the head units.  12" aluminum bass drivers on the subs.  

    A single inductor provides low-pass for the subwoofers and a single 4.7uF capacitor provides high pass for the tweeters.  The midrange is connected directly to the amp.

    I have upgraded the capacitor to a Duelund Tinned-Copper CAST and it was a wonderful change.  More clarity, better imaging, and more natural tonality over the stock Solen capacitors.
    • First Watt F4 Monoblocks
    A DIY build with help from the community.
    • Don Sachs Audio DS-2 6SN7 Preamplifier
    Don's modification of the SP-14 6SN7 circuit.
    • PS Audio PerfectWave DAC MK II with Bridge II
    Have tried to move on to a more modern DAC a couple times, but keep coming back.  Just a nice, natural sound.  

    Adding an ethernet input with the Bridge II was an essential upgrade.  Much, much better than the USB connection, and it removes all the variables that come with having an attached computer.
    • Duelund Coherent Audio Tinned Copper Speaker Wire
    16ga to the PRE head units, 12ga to the PRE subwoofers.
    • Ocellia Silver Reference RCA interconnects
    2m connections to the monoblocks.
    • Duelund Coherent Audio 4.7uF Tinned Copper CAST Capacitors
    The only component in the Coincident PRE high pass crossover...
    • Elgar 6006B Power Conditioner
    Industrial power conditioner... a great improvement to the digital system, but must be installed in a separate room.

Comments 25

@r_f_sayles Indeed.  Brutally revealing is certainly a proper descriptor.  They let you know about every mm of the chain.  I'd love to hear more about what you've built around yours if you've got the time to post details (here or on your own page).  

And certainly the Duelund caps are a great step in the direction you want to go, really highly recommended.  Do be careful attempting to remove the midrange.  When I bought my pair they were damaged in shipping and I had to replace a midrange driver.  I simply could not get the thing to budge and just ended up cutting out the ceramic layer so I could get my hands directly on the metal supports to pull it out.  It was still incredibly difficult.  

The tweeters are much easier to move around, but unfortunately that opening won't be big enough to get many high end capacitors inside the cabinet.  I think the Duelund's will fit in the bottom of the cabinet because they're flat (Jupiters and other large cylinder styled caps will not) but I have not tried because I had so much trouble removing the one midrange.  

On the plus side, getting the cap into a quieter external environment is supposed to be a plus...

Anyway, please do post more details about your PRE journey if you've got the time.  


@billheiser Those are the Coincident Super Eclipse IIIs.


Nice to hear you have tamed the CPREt's Cal. They can be brutal revealers! I know because I live with a pair. Great kit you have there. 

I would love to hear more about your journey with evolving the crossovers. Not much of a DIY guy myself, but a lot of positive buzz is in the air about the virtues of the Duelund caps and wire and your system posting has lit a bit of a flame under me in regards to sweetening the Israel's attempt at a reference.

Anyway, happy listening and congrat's on the progress toward musical bliss!


What are the speakers shown in the view from over the railing?


And sorry, power cords are 12ga Furutech FP-S032N based power cords from member Grannyring's Acoustic BBQ line. They've got Chinese copies of the furutech carbon/rhodium connectors. He sells for cost plus a small labor fee (and commented below if you want to contact him for a cord).  Makes highly regarded Duelund-based interconnects too...


@scott_wolff Thanks, wish I'd tried them, but I didn't do anything besides the duelund vs stock comparison.  I've actually pm'd a couple other owners of the PRE's, and it's a pretty strong consensus that the Frank's don't provide enough power. Both of the other two had purchased and sold Frankenstein's as well. Both recommended amps with at least 30 watts...


@4581 You're not into cheap knockoff rugs??



Cal –


Many compliments on the system, especially the speaker crossover. With the bass-shy-ness with the Frankenstein’s – ever consider VH Audio’s Teflon’s? These were introduced into one of many mods for my stereo Frankenamp’s coupling caps. The result was a tremendous (in a good way) bass improvement in clarity and pitch with equally beneficial ‘cleaning up’ of the remaining audioband. Coincidently, my speaker designer also used an all Dueland crossover complement (VSF Stacked Copper caps, CAST Inductors & sandbar resistors). Love ‘em.

Btw, what kind/brand of power cord is that pictured in the system?




Your system/components look great and probably sound great, but I'm wondering about that rug?


@islandmandan The m2 will actually have 15 db more gain than the F4. The transformer in the m2 provides more gain, but increases noise and distortion.


Cal, as I recall, the M2 just didn't have enough gain. I was using a Sonic Euphoria passive pre at the time. I sold the SE and built the Transcendent Sounds Grounded Grid (with certain parts and tube upgrades, and Bent Audio remote volume control).

It sounds like the F4 might be a better match.



@islandmandan Looks like I'm on the right track, just read this from zen mod at diyaudio in discussion the m2 (he designs his own pass inspired amps and gets rare parts directly from Nelson):. "if you have F4 handy - just insert appropriate xformer"


And here's the link:


@islandmandan Honestly, if my speakers were run properly with a 300b I'd still be using the Frankenstein's. Unfortunately they suffered at the frequency extremes (lack of bass and distortion up top) due to the mismatch. The F4s fixed those issues and the system improved as a result. 

Not sure you'd find much difference in result of F4 vs M2. I haven't read a ton about the M2, but it appears to be similar to the F4 (i.e., uses the same mosfets, but only 2 instead of 6 per channel). That must mean it has a lower current capacity despite identical power ratings? It also provides 15 db gain with a transformer on the input, vs the lack of a gain stage for the F4. Should mean that the F4 is more transparent, but also a more specialized amp. Unfortunately I'm not a circuit expert, but that all suggests to me that unless either current or transparency were your problems with the M2, then you'd probably still prefer your 300b. 

Of course if you'd just like an additional amp around for flavor (and comparison), then $800 gets you a great one. 


Thanks Cal, for the info. I had looked at First Watt & DIY Audio and I couldn't find where to order them. I'll know more when I check out your links. Thanks for that. At one time, I bought an M2, and decided not to keep it after listening to my SET 300B, especially now that it's had some new caps and had the voltages optimized for the EML XLS SET 300B tubes. I wonder how much difference there is between the M2 and F4? Maybe I'll find out.



@grannyring Thanks for all your input!  You saved me so much money and improved my sound by pushing that beautiful Duelund wire.  And I love the Duelund tinned copper cast capacitors.  I didn't get to hear them fully when I was using them as coupling caps in my Frankensteins... they sounded nice, but also sucked out some of my bass, which made me a little gun shy about buying more.  

As you noted, I did try the Duelund bypass caps on the output capacitors of my preamp, but actually couldn't hear any impact and sold them to Dave @ ZenWave Audio.  Tried them on two sets of caps and wasn't able to hear any difference at all.  Very different from when I added them over the Solen coupling caps in the Franks.  They went in and never came out until I had to sell. Had to pull them and the upgraded tube set to make the price low enough for someone to bite...

Thanks again for all your help.  Also, your power cables are great.  I hope people are keeping you busy purchasing your wonderful creations...


Great system and pics.  Love those Duelund caps on the tweeters as well as the Jupiters! Also noticed the wonderful tinned copper CAST bypass caps in your preamp in key locations.  Great! 

That Duelund wire is so darn musical. Well done.....


@thosb Thanks for the compliments... wish I could say it was a purposeful journey, but it certainly feels very unplanned.  I guess that's why I ended up with the strange, non-traditional equipment combination.


Thanks a bunch for posting your system and all the gory details - you've heard and learned a bunch in 15+ years, thanks for sharing!  Oh, and way cool btw, fun seeing a digital front end into "new vintage" pre followed by DIY amp and unique speakers.


@islandmandan Also, when I sold off my Frankensteins and associated tubes, I got around $4500 back in the account.  The pair of F4s cost $1600 and are essentially the same quality as the actual First Watt units (assuming sufficient building skill).  $1600 for a pair when a single cost $2400 new?  Just a crazy good deal...  

I'm going to build some DIY SIT-3s this fall, mostly because it was fun to build the F4s and will be entertaining to try another amp.  Once you build one First Watt clone, you can reuse everything (case, power supply, etc.) and just replace the old amplifier circuit boards with the new ones.  That's what Nelson Pass does at the company itself.


Hi Dan.  You can order the circuit boards, power supply boards, & chassis directly from the store.  Unfortunately there's no standard kit, but the parts list isn't too crazy.  I can e-mail you a spreadsheet with all parts sources listed.  It's also posted here:

If you go to the first page of that thread, you'll see the full build guide.  It's so well done, that you're basically building adult legos.  

Also, I'd be happy to help with ordering or parts questions if you decide to take the plunge.  I'd never built any electronics before making an F4, and it was very doable for me.  With all parts, it costs around $800 to make one.  Such a steal for a wonderful amp.  


Cal, I'm wondering where you ordered your F4 amp kit from. That looks like something I'd really like to do. I know how much more enjoyable your system can be when you actually built a large part of it yourself.

I forgot to mention I built my own plinth for my Garrard 401, and mounted a Dynavector 501 arm. It is a joy to live with.



@islandmandan & @jond.  Thanks for the comments.  Prior to this year I didn't really trust myself to open up any equipment, but thanks to a UPS/Fedex drop of my speakers, I was forced to learn.  I'm so glad I did.  That set me down a path that resulted in my amplifier build and my modification of every other piece of gear I own.  It's so much harder to hurt a component than I ever imagined, and learning about what's inside and how it impacts the sound has been incredibly rewarding.  I can't recommend it enough.


As a sometimes DIY'er, I admire your efforts. I've built some kit amps and preamps, and mostly built my speakers (finished them anyway, wiring them, building my crossovers, and polishing the high gloss finish to a higher degree than when they arrived from the shop where they were actually built).

I also had the foam surrounds replaced with cones that were modified with "Hard Edge" surrounds. Drivers are 1975 Tannoy HPD 315's (12" Dual Concentric).

They seem to work well with pretty much any amp I've tried, SET 300B, SET 845, and even Class D. Fun stuff, especially when you can't really afford High-End gear, but want the sound.

Regards, and enjoy,


Cal thanks for posting gorgeous room and a very interesting system. Great write-up too now I totally understand your thinking and direction with your system. I am not a DIY guy myself and I envy you guys who are comparing caps sounds fun. Keep us posted on any new updates and happy listening!


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