Last Thursday (05/Feb/23), I received my DS-1 from Jeff & Son with a Vocm upgrade and the new PSA Beeswax Transformers installed. Unfortunately, it took a lot longer than I thought to give it a listen and report.
My DS had the SX4400 upgraded transformers plus the LPS with Jeff’s card for a year, with no other internal updates. This new transformer upgrade came at a great time as I haven’t changed my system in about a month. I sent my DS to Jeff because I don’t do internal projects (except fuses), so because the Vocm upgrade was essential to the APS upgrade I made Jeff do the work. I’m really thankful I did because Jeff and son found that I had a DC offset problem which they fixed for me.
So, I get my DS back, get it all set up in it’s spot on my shelve rack, power up my equipment, pressed PLAY, and, nothing. Turned out my primary McIntosh C-20 preamp decided this would be a good time to develop a problem. All lit up but no sound.
It took a while to figure out what was wrong and get the preamp out and deal with it. Luckily, I have a Quad system and I use two C-20s (one in front of the front channel amp and one in front of the rear channel amp). Normally I review new additions and upgrades just using stereo playback – not quad playback. So, I took the rear channel C-20 and moved it into the primary spot and slowly moved forward toward my listening. I mention all this because there is a reason the one C-20 is used as the primary. I’ve always felt my primary C-20 had a little edge in sound quality, although both preamps have been extensively upgraded and improved. Nevertheless, my primary C-20 might have performed a little better as I listened to Jeff’s work.
And, My-O-My what great work this is turning out to be.
Unfortunately since my DS didn’t have the Vocm upgrade this review will have to cover both upgrades at the same time. When I finally got everything all plugged in and ready to go, there was only about two hours burn in time on the new parts. Initially there was a bit of roughness to the overall sound but I had to do a lot of fine tuning to my adjusted equipment lineup before I could make any kind of judgment. I don’t know if the initial roughness was in part due to lack of burn in time, but if it happens to you don’t worry about it.
I came back two days later when my DS had about 50 hours burn in time and there was a sizable improvement in sound quality. I made a couple more adjustments to my equipment and all of a sudden my system just BLOOMED, (kinda like when the Wizard of Oz went from black and white to color). The major thing I noticed was that the instruments were now totally separated from each other almost like pinpoint stars in the sky. Because of this the background seemed blacker, but I think it was the fantastic separation that caused me to notice the background more. All of the instruments had definite positions on the soundstage and all were locked in. Up till now I always had a little bit of uncertainty in the soundstage spacing, but now any vagueness is totally removed.
Because the instruments are so distinctly located on the soundstage, more detail is available than I’ve ever had. There were some points in music I’m very familiar with, that I heard textures and tonalities I hadn’t heard before. I was listening to Annie Lennox sing and I heard her do a couple of subtle phrasings with her voice that I had never been able to notice before. The interesting thing here is while instruments seem to be locked into their own individual spaces, massed vocals still seem to be linked to each other. Background vocalists still sounded like a collective unit, rather than a number of individual voices. Personally, I like that
Likewise there were parts played by musical instruments that were clearer and more defined and yet the tonality improved and the warmth was maintained. Another song, this time by k d lang, called “Wash me clean”, presents a big challenge for musical systems due to an acoustic guitar playing arpeggiated chords while the bass pedals the dominant note of the guitar chords. Quite often when the bass and the guitar strike the first note the guitar notes simply wash out until about the third or fourth note. This time however both the base and the guitar were separate and you could follow the guitar all the way through while the bass held the note. Very impressive
A word on the bass response. The upgrade makes the bass much more noticeable than I previously had. Matter of fact, I had so much bass that I immediately turned down the bass on my system, so if any of you don’t have enough bass this may help you.
For me I’m calling this a big win, and this is just with 50 hours on the machine using a different preamp than I was used to. So, to sum it up I think the biggest gains here are:
• The definite locking down of the spatial positioning of different instruments.
• Added clarity of and the dark space around the individual notes and voicings.
• Better tonality and sound quality of instruments.
• The added detail actually helps reduce any harshness or raspy quality, especially in vocals.
• Better, more authentic, more distinct sounding bass – although at a louder volume.
Unfortunately I can’t tell you how much of the improvement that I heard is due to the Vocm upgrade or Jeff’s ASP transformer upgrade. I can tell you the upgrade seems to be well worth it. Right now, both my C-20s are in the shop so I won’t be able to really sit down with my new DS for about another week or so. The DS is idling and I might even run some music through it from time to time, so that when I get everything back in line it should have close to 200 hours on it.
I’m thinking that’s going to be a really good day.
Toolbox
Thanks for that well-written review!
It’s something we noticed here every time we test a DS with our new transformers. If you have subs you will appreciate this a lot as these transformers have little to no phase error. One of our goals when designing these.
Thanks for the very detailed review 
Nice write-up and has me excited! Like you, sent my DS to Jeff and he messaged a bit ago that the VCOM mod and Xformer upgrades are complete. He’d received it, yesterday, and done in less than 24 hours.
W/all tubed gear and more laid back speaker presentation I opted for the “natural” transformers. I prefer detail and rationalized that I can swap to more laid back tubes if my current selection is a bit too much w/respect to this.
Working out return shipping but I guess I’ll have the DS back in the next week. Looking forward to it and will post my impressions after a proper settling in.
Hi jkrichards, I have a couple of questions about 1:2 transformers. I’ve got a Topping Pre90 that I’ve been playing around with (Topping Pre90 line preamplifier Specifications | Stereophile.com). It’s a great little solid-state preamp, especially for the money. However, it has an unusually low input impedance of 2k ohm balanced and 10k ohms single-ended. The rule I’ve always followed is to maintain minimum of a 10:1 ratio (input Z to output Z). My first question is what effect does the XS4400 in 1:2 mode have on the Directstream output impedance? My second question is what effect does a low input Z like the Pre90’s have on the DS transformer distortion level?
BTW, I’ve got the VCOM mod and the external PS. Thanks!
2K is very low. The XS4400 in 1:2 mode has a high frequency roll off into a standard 20k load. I would not recommend this setup.
This is with a 50k load
Yes, but what is the outcome of lowering the impedance and increasing the voltage stability on the opamp’s VOCM pin? The output of the opamp goes to…
I was describing the mods in relation to each other and in terms of their individual effect on the audio.
But it doesn’t reduce noise/distortion.
Also it’s not simple designing a transformer with numbers we are getting with our nickel units.
Are you getting hung up on the terms? What else does a mod like the capacitor over R6 do in an audio system if not reduce the errors in the signal that leaves the opamp and goes to the transformer? Do you want to call those errors something other than noise/distortion?
And I have nothing but admiration for your transformer work. I very nearly placed an order for both MkI and MkII versions realising that these risk being limited-run pieces, but I’m needing to be more fiscally disciplined at this point in time. Hoping for the opportunity to get a MkII with your transformers sometime down the track.
No. Just want to provide accurate info.
No… We will continue to make these and many more.
Well how would you like to describe the difference in the opamp’s output as a result of stabilising the VOCM reference voltage?
Regardless of which words you want to use, the VOCM mod makes the signal that enters the transformer a more accurate representation of the digital input.
Agreed. That’s all that matters at the end. Our ears and what we hear.
Thanks for the response Jeff. I’ll just use my Dodd tube preamp when I either mod the XS4400 or purchase your transformers.
My son set up a few more units to test and measure transformers over the weekend. This makes it easier and faster to evaluate them. This same quick connect is in my DS. MKII next.
I miss my Dodd pre (still have the phono), what a great sounding piece.
I was fortunate enough to own Gary Dodd’s 6SN7 based reference preamp and the battery preamp. I recently sold his 120 mono-blocks. I’ve tried to replace the battery preamp but can’t find anything that out performs it for the money I’m willing to spend. I wasn’t willing to let go of the mono-blocks until I got the Pass X150.8.
Received a loaner MKII today. Will get started on the transformer R&D tomorrow. This one is burned in. Listening now. Should be a fun ride.
If this is not only a strange effect in your acoustic situation, ithere would be a quite limited compatibility to balanced or bass heavy setups. I suspect it rather has to do with individual room resonances and a just slightly different bass structure of the upgraded DAC which may escalate in some acoustic constellations… For me it would be a problem if the bass suddenly is so much stronger and not only better, more firm and deeper with maybe slightly different tonal focus.
Just for the records my individual rough path of changes (I will avoid the popular term “black background as this is nothing I perceive, although it may be one of the basic technical characteristics):
Original Mk I, critically seen only in retrospect:
Balanced, transparent, warm, but recessed on top end, a little undefined bass.
With added XS4400:
Mainly some more palpable imaging and air, little bit deeper bass, but not really better controlled, instead a bit fatter sounding. Top end even a bit more recessed. Was not my favorite status of the DAC in tonality.
With added Farad PSU for analog board:
More improved palpable 3D imaging and little better controlled bass, faster transients. Completed the XS4400 transformer upgrade positively, but still recessed top end.
With R5 and R6 upgrade and Lundahl transformer swap and 15nF C704:
Again but bigger 3D imaging/air upgrade, Some better defined and a bit deeper bass, more detail, little bit more open and little stronger highs but still recessed at the very top end.
With added cap over R6 (VOCM mod):
Hugely improved, better controlled, deeper and somehow differently aligned with some effects up into mids and much better bass/mid transparency. Needs a well balanced setup to not need some tonality adjustment. Big improvement, makes a new DAC.
With exchanged 15nF against 6800pF C704:
At long last very open top end. Hugely improved levitating, airy, transparent 3D character. Massive improvement of especially some analog sourced and all acoustic instrument recordings but also nearly all others. It makes a very new DAC.The upmost top end is a tiny bit too much and can be sounded out a bit by a slightly artificial character in case of not many but few very open recordings‘ „s“ and cymbal sounds, which is why I will change again (hopefully the last time) to 8200pF 
I think we are all aware that any of even those very noticeable tonal changes we experience measure absolutely flat as usual
OK, revisiting this thread. Been out of the loop on the mod thread for awhile.
I decided to cancel my order for the DS Mk2 at this time.
Here are my questions:
I have a Mk1 with the Edcor XS4400 Transformers mod and a fuse swap, and the power switch is bypassed. That is it.
What are next best options for upgrading the Mk1?
Who does these mods here? I see a few mods listed. Not clear what they all do.
What is ballpark investment for the mods?
Edit- OK, been pointed in right direction to find out more. Thanks.