Doshi Audio EVO Series Tape Head Preamplifier | REVIEW

Words and Photos by Dave McNair

I had a fantastic time putting the most excellent Doshi Audio Tape Head Preamplifier through its paces. This latest version, labeled the EVO series, has some improvements over the previous Tape Head Preamplifier 3.0 series, but permit me to reminisce a bit first…

A Long Time Ago In A Recording Studio Far, Far Away

Sitting behind an enormous API console as I peered through the glass to watch the musicians in the tracking room, I heard the last bit of decay from the final chord and cymbal crash fade to silence. I hit stop, then the rewind button on the MCI JH-110 2” 24 track machine. I mashed the talkback button and asked the band to come in and hear the take. When all were gathered in the control room, I hit play.

It was a big sonic letdown.

In different situations, the disappointment was sometimes extreme, sometimes minimal and on a few very special occasions, I felt the playback actually had an enhanced quality. But it was NEVER the same as the input. Sure, the music and performances were many times excellent and captivating, but why wouldn’t the tape deck serve up all that goodness that I heard going to the input?

I used to explain to the musicians how much better everything had sounded when I was listening on input as opposed to playing back off the tape – was this the first sign of early-onset audiophilia? But I’d notice the following:

• A BIG loss in transient impact occasionally accompanied by a sense of smear 
• A very different contour to the low end 
• A darker less present top end 
• A blanket of hiss most audible of course on quiet passages

Those were the things I heard in varying degrees depending on the model of machine, type of tape, speed, and chosen record level calibration. And that was just the first generation. What happened when you made a copy? More of the same. No wonder some people went to the trouble of recording direct to a stereo tape deck or even direct to a cutting lathe! So it was no accident that when the first digital recording systems appeared on the scene, us engineers were by and large ecstatic over the initial sense of playback sounding exactly like input. the keyword being initial. 

This is important to realize: in a recording studio scenario, it’s not common or sometimes even possible to hear the feed to the recording machine prior to looping through the input of said machine, so in a digital setup, you are always listening through the analog to digital conversion and then back to analog. The pre-playback analog reference of looping through just the analog tape deck’s input is no longer there, so it took a minute for some of us to realize something was rotten in digital Denmark.

I should also remark that the earliest digital systems using tape, although not as good as current computer-based DAW systems, sounded FAR better than the first 10 years of Avid (initially DigiDesign) ProTools which very rapidly became the overwhelming industry-standard, shitty sounding or not. Even as the seduction of noiseless and shockingly linear recording quality remained, a lot of us started to hear something subtle yet quite off putting about this new digital world.

The rest is history. 

Digital got better (in no small part due to the protests and urging of many in the audiophile community), analog tape virtually disappeared and here we are. 

For the record, although lacking a certain je ne sais quoi of analog tape, I feel that the current version of ProTools has evolved to be as sonically transparent as it ever needs to be. Especially when using top-shelf converters. But that’s a different discussion/argument.

Then a funny thing happened. 

Vinyl records came back, followed by an interest in analog tape by some isolated corners of the recording community AND amongst audiophiles. Whadda ya know. Sometimes you don’t truly appreciate the thing you had until you’ve had to live with the newer better thing that may not actually be better…

Enter the Doshi Audio EVO Tape Head Preamplifier

I had a blast attending the 2020 Florida Audio Expo in Tampa. One of the highlights for me was hearing the sound in the Joseph Audio and Doshi Audio room. With a full set of Nick Doshi’s gorgeous looking and sounding electronics powering a set of Joseph Audio Perspective 2 Graphenes, the sound was sublime. I could have sat on that couch and listened for days. 

Some of that demo time was devoted to playing music off a Studer 810 R2R (reel to reel) tape deck. After meeting Mr. Doshi and inquiring about the system, he explained that the ¼” playback heads on the Studer were going directly to his own electronics (Doshi Audio Tape Head Preamplifier), then feeding his Doshi Audio Line Preamplifier and a Doshi Audio Stereo Amplifier. I immediately LUSTED after the notion of hearing these tape playback electronics in my mastering studio back home. 

I then came to find out that this version of Nick’s tape preamp is the newest EVO version incorporating several major improvements on the prior V 3.0. Woah. Dude.

The Doshi Audio amplifier has been redesigned to use dual mono ultra low noise regulation, and low-frequency EQ adjustment has been moved from the rear to the front panel and changed from standard shelving style to a Baxandall curve which sounds punchier and is easier to fine-tune. Voltage regulators are now discrete Schottky in the high voltage and head amplifier sections. All capacitors have been upgraded to the ClarityCap CMR series. The top plate has been redesigned as an aluminum constrained layer damped chassis component for the ultimate in damping and stability with the rest of the box, which looks like something custom made for the NSA. Two outputs include a Jensen transformer output plus a purist single-ended output straight off the toobs. Dayum. Oh, and the output is now fixed at Class A.

Whew. Bro, that’s enough tech to make my big toes curl, but I’m weird like that. 

Meanwhile, Back At The Ranch

Nick was kind enough to send me the Doshi Audio tape playback setup which is a two-box affair including a large and heavy power supply. The supply hooks to the main unit via a very thick cable with mil-spec locking twist collars to grab onto the multi-pin connectors for the high voltage supply and a second, thinner cable for the lower voltages. Impressive. NASA would be envious.

After carefully fitting the complement of eight vacuum tubes (3 ECC81/12AT7 and 1 ECC99 per side) to the appropriate sockets, I was almost ready to rock. The next bit of business was unplugging the stock channel electronics cards in my Ampex ATR-102 so that I could plug in some dummy cards. These cards were very kindly made up and loaned to me by Dan Labrie and the fine folks at ATR Services Inc, the world’s foremost specialist for all things involving Ampex tape decks. They also are one of the few places remaining to manufacture magnetic recording tape. They are also very cool people.

Mmmmm, I loves me the smell of analog tape in the morning.

The dummy cards take the edge connector traces coming from the repro (playback) head output and wire those to a short length of cable with male XLR at the ends. After rearranging some stuff around the Ampex, I was able to find spots to locate the Doshi Audio power supply and main unit to have everything playing together.

Okay, hang in there for more tech speak, but it’s important to understand how I did my evaluation.

Next, more rewiring. I wanted a purist path for the test I had in mind so I did some quick rewiring and had the output of the Doshi Tape Head Preamplifier going directly into a Prism Sound AD-2. The Prism analog to digital converter is normally fed by my Dangerous Music Master, which is a mastering “console.” The Master is normally fed by a Prism Sound DA-2, the companion digital to analog converter (DAC), being that most sources to be mastered are digital. If I’m mastering something mixed on tape, the Master is fed by the Ampex. For my tests as I said, I bypassed the whole shootin’ match and went right into the computer via the AD-2.

Have your eyes glazed over yet?

Gentleman, Start Your Tape Decks

Despite my protests, I still feel like analog tape has a certain thang about the sound that is very pleasing and almost impossible to completely replicate with digital. It’s very similar to vinyl in that unless the cutting and pressing (and mastering) were very well done AND the record is played back on a very high caliber cartridge/tonearm/turntable/phono preamp system, you’re just not going to hear all the glory of those polyvinyl chloride discs. At least not the full glory. But when it’s right, it’s an experience that is impossible to forget.

Analog tape is similar. Unless the tape machine electronics are very good sounding (my absolute favorites being the Ampex ATR-100 series or the decks made by Stephens Electronics) AND great care has been taken with alignment, recording level, and all the other variables, your tape recording can easily SUCK. 

Blank tape and maintenance is expensive and time-consuming, while fast computers are cheap and storage is basically free. Add in all the seductive editing and manipulation abilities of a DAW and it’s hard to even imagine why anyone would use multitrack analog tape in 2020. Except for the lunatic fringe who are committed to tape.

Remind anyone of vinyl enthusiasts?

But a stereo mixdown deck is a different story. There has been a bit of a resurgence in mixing to tape, even if the recording was done in a DAW. I still get a fair amount of ½” and ¼” two-track tapes in for mastering, hence my need to have a proper professional R2R. But what about playing back music at home using analog tape? 

Assuming the tape was well recorded, I can easily understand the mini-craze in some corners of the audiophile world for R2R playback. When the planets align, the sound is liquid and cohesive with a density that is different from even the best digital. And similar to high-end vinyl playback, the top end of tape has a certain smoothness and freedom from listening fatigue while at the same time being detailed and clear. Also the transient compression is unique and, I feel, part of the listenability. That’s why to this day, some people still like to mix to analog tape. Plus it’s just plain badass. 

C’mon, how cool is it to thread those reels with the real McCoy and hear that little chirpy sound as the tape flies past the head during a fast rewind, then hit play and hear all that analog goodness leaping out of your speakers? In the audiophile world, that’s about as cool as it gets.

In Use

You might have wondered WTF is he doing plugging the Doshi Tape Head Preamplifier into a computer? That’s downright sacrilegious, right?

Sure, I could have simply wired the thing up and played some tapes. But what is THAT gonna tell me? Squat. OBVIOUSLY that will sound great, but I’m ALL about the comparison. And what better thing to compare to than the electronics in the ATR-102? So, my test consisted of using several well-mixed master tapes played back by BOTH the Doshi Audio and the Ampex electronics and directly wired to my Prism Sound AD-2. Each pass was recorded to my mastering app of choice Magix Sequoia at 24bit 96K, enabling me to make listening comparisons at the touch of a button.

I used both the balanced XLR outputs AND the Jensen transformer coupled RCA outputs. Tapes used were an excellent sounding ¼” 30 IPS (inches per second) recording by Michael Zapruder and a ½” 30 IPS master by Luke Temple. After fine tuning azimuth of the playback head, the Doshi Audio preamp makes calibrating the level and EQ for the flattest response a breeze. The smooth feeling and clearly labeled knobs on the front panel are so much easier to tweak than the mini flathead trimpots on the Ampex cards. Record to Sequoia, then repeat the audio alignment process and record again using the Ampex cards.

The Big Reveal

Alright. If you’ve gotten THIS far you are (A) a hardcore R2R audiophile fanatic, (B) an audiophile with a rabid interest in anything High End or, (C) an interested audio reader who has now spent so much time on the toilet seat your legs are asleep. Get up and walk around so the blood comes back. I’ll wait. 

So what the effin’ VU meter does this thing sound like?

In my acoustically treated mastering studio control room using B&W Nautilus 801’s powered by a pair of Classe CT M600’s, I lined up each take side by side (Doshi Audio and Ampex cards) so I could push button switch on my Dangerous Monitor console as each version of the same song played. Using the single ended output without the Jensen transformer in line, the sound was transformed:

• Clearer top end. Not more quantity or brighter, yet more detailed. 
• A significant increase in the spaces between sounds, small or large. 
• A slight layer of grunge was removed in the upper bass/low mid area. Everything from about 400hz on down was subjectively tighter and harder hitting with the Doshi Audio preamp but with the same overall quantity of lows as the stock Ampex.
• Something very cool happened with my perception of the stereo field. There was an increase in depth and the clarity of things in the phantom center. More apparent layers of depth for everything panned inside the 10 o’clock to 2 o’clock area.
• A general sense of more harmonic complexity and refinement while still being very clean sounding.

Using the transformer coupled RCA connections on the Doshi Audio, very surprisingly, I heard all the above in even GREATER quantity. No idea why, I just call em as I hear em.

Final Thoughts

The Ampex ATR series decks and electronics are HELLA good, and while there may be less than a handful of esoteric pro decks out there like a Stephens or a Telefunken or maybe a Nagra that are also uber hifi in their stock state, the Doshi Audio electronics offer a way to have King Of The Hill sonics from a more easily available 2R2.

If you already own a professional R2R by Studer, or MCI, I can pretty much guarantee you that the Doshi Audio will SMOKE those stock electronics in every way possible, given that the Doshi Audio Tape Head Preamplifier edges out my reference ATR-102 electronics. For those that are contemplating diving into the 2R2 waters, you could find a Pioneer, Technics, Akai, Teac, etc., then have some basic servicing done like switch cleaning, pinch rollers replacement and get a simple mod to get direct access to the repro head output, then get yourself a Doshi Tape Head Preamplifier and have world class sonics.

So what are you waiting for? 

At an MSRP of $18,995, it’s not pocket change.  

However, I consider the EVO Series Doshi Tape Head Preamplifier to be a very fair price for such a high level of sonic performance, usability, and heirloom level construction. Plus it’s downright gorgeous looking.

You know you want one. 

I know I do.