Apt Holman Preamplifier Review (vintage Audio)

[david moran]

Yes, the DB Systems gear is still available, at least some of it. It is fine and well-engineered, and David H (and I, and others) are still active in the somewhat aging-out BAS, yes. When the dbx CX1 phono section was being designed I suggested acquiring the DBS one, but the Apt and sundry NADs had already been investigated to death, plus Mark Davis could weigh in about his Davis-Brinton phono preamp work as well.

I have little comment to make to anyone who thinks or thought AR made substandard speakers at any point. Most were smooth and downward-sloped above the bass a little bit, the earlier models, and a lot compared w rocker hard treble from JLB and such, sure.

I have and use the very Allison AL125s Aczel and Rich panned, an insane outcome, which they sent me in lieu of payment for editorial work for them. But they did not measure speakers correctly (anechoic radiation pattern plus some room responses is the way to go, as most here have come to realize). See fig15 here, http://ethanwiner.com/aes/david_moran.pdf, though this is an unusually good room response.

I measured and otherwise assessed those Yamahas for some magazine or other, maybe CD Review, Speaker Builder or $ensible Sound, something like that, I forget. They were okay, and powerful and on the hot side. Stax products are not what I was referring to when generalizing nationalistically for the WSJ.

ty both for the warm / nostalgic / geezerly welcome

 

[Dan Clark]

You might find this Vandersteen 2c measurements interesting..just to push you a little bit more on nostalgia ( ..or not? ):

Vandersteen Model 2c Review

Vandersteen Model 2c Review

erinsaudiocorner.com

Interesting to see, thanks for sharing! I wouldn't put too much stock into the measurements though, after 31 years the spiders and surrounds on the driver are going to be have aged and won't perform the same... That said the bass response looks about right, it had a bit of elevation in the upper bass region.

 

[JeffS7444]

Pounds, and unpopulated, that''s not a cheap preamp.

That's for sure! All told, price was roughly comparable to the Akitika PR102 nicely optioned with headphone amp, phono and remote.

 

[david moran]

I've always wanted to try this model. I love older preamplifiers because modern ones normally don't have all the features of the past (tape loops, external processor loops, tone controls, switched outlets, etc.). For someone like me, who still listens to a multitude of formats, including compact cassette, records, CDs, radio, and minidisc, there's a real joy having all the buttons and bells and whistles in these older preamps that serve as the "command center". I have a small collection of various preamps and like them all for different reasons. I feel like manufacturers have really cheaped out on features, not to blame them entirely because I suppose it's a response to the audiophile trend that seems to shun any alteration of sound. I can appreciate that some people are the opposite, and just want their preamp to attenuate the signal, but rooms and ears are all vastly different so I like having the ability to use a preamp that has more than a simple volume and balance knob. Some of my faves include my Pioneer C91, Mcintosh C712, and my DBX CX1. I got a NAD 1300 that was fully restored last year, and I love it. The tone controls are well thought out and are incredibly useful. By now, most of these vintage units require some restoration, but I think the $$ is well spent to bring them back to life if you appreciate any of those older features. There's also a tactile joy that comes from using them, often lost on more modern gear.

Do you use your CX1? Its tone controls are the most useful I know. And its ambience spreader does leave LF alone.

 

[anmpr1]

Mark Davis could weigh in about his Davis-Brinton phono preamp work as well.

To keep this in some historical perspective, Mark Davis (whom David Moran mentions in his post) was a more or less 'lone' instance of reason back in the day-- the days when everyone heard everything and anything from preamps and amps, except what they were actually hearing. The Stereo Review gang (Julian Hirsch, Larry Klein, et al) always argued that any two pieces of properly working electonics would 'sound' the same over loudspeakers, as long as levels were matched. Others, including some at the competing Audio magazine, and especially the 'undergrounds' (Gordon Holt, Peter Aczel, Harry Pearson, Peter Moncrieff et al) were able to hear all the subjective stuff-- to be fair, the same stuff we've all heard, in our own undisciplined comparisons.

From the manufacturer point of view, David Hafler was probably the most realistic, once admonishing Gordon Holt, telling him that his subjective electronic reports were essentially worthless (Dave didn't say it like that, but that was what he meant). Others, boutique designers (too many to name) realized that as long as they could keep Harry and Gordon in business, they'd likely stay in business, too. So they went along with all the magical nonsense. Did they really believe it? Who can say?

Anyhow, in 1977 or thereabouts, Mark Davis demonstrated that level matching took all the differences away. The general underground response? Everyone laughed at him. They criticized his gear (AR speakers, his homemade 'Davis Brinton' preamp, and a Shure M91 cartridge), saying that these were deficient in the 'resolution' department. Aczel was probably the loudest critic (I think others simply ignored him, hoping he'd go away).

Later, Peter realized that Davis was essentially correct, and he was wrong. I once told Peter that perhaps he was mistaken (I began audio life as a true believer, as most of us did). After all, I pointed out to him that he was using exotic Japanese moving coils, expensive class A amps and preamps, unobtainable MC transformers, and highly touted electrostatic loudspeakers. Peter was not impressed with my argument.

FWIW, and in the context of this ASR review, Tom Holman was also skeptical of Davis' results. He'd worked up a lot of 'esoteric' tests in order to objectively distinguish everything that everyone was 'hearing' in phono preamplification, some published in the AES journal. But in the end it all came to nothing. At the time, Davis reported that Holman's listening methodology was pretty sloppy, but gave him a pass by saying that Tom wasn't a psychoacoustician (Mark had a psychoacoustic lab at MIT, if I am not mistaken).

None of this takes away from Holman's excellent preamplifier. At the time it was an excellent value, and, evidently, once refurbed, it remains so. In fact, it's really a shame you can't buy anything like it for the price, anymore.

 

[EJ3]

Does it take unleaded? Have seatbelts? Here I am with Amir.

As a mater of fact yes the (Built NOT bought [yes, I don't trust authority & certainly not the minimum government safety standards]) Factory Five Racing 35 is a computer controlled, fuel injected modern engine that does run on 93 octane unleaded:

LT4​

Bring the heart of the Corvette Z06 – the most powerful production vehicle in Chevrolet history – to your project with the 650-horsepower 6.2L V8 LT4. Then conveniently harness that power with the production-based 8L90-E 8-speed automatic perfectly matched to it.

Chassis construction (likely way safer in an accident than anything bought from a car factory):

Seatbelts? Yes, (for each passenger) a shoulder harness for each shoulder with lap belt & anti submarine crotch belt (you are not going to the floorboard with this on).

Certain prominent parts of ones anatomy may feel "temporarily squishy" if ones body were to attempt submarining to the floorboard during a collision with some unmovable object.

 

[EJ3]

One superb design from a decade later which some here might want to keep an eye out for is a preamp explicitly modeled on (and featuring several small improvements over) the Apt: the dbx CX1. (For current users or anyone else interested, I have schematics and OM, which I wrote.)

I am interested. Please PM me.
EJ3

 

[anmpr1]

I have and use the very Allison AL125s Aczel and Rich panned, an insane outcome, which they sent me in lieu of payment for editorial work for them.

I would like to say that that is a pretty funny story, but don't want to minimize not getting paid for work. You always want to get paid. Maybe the passage of time mitigates some of the disappointment. Maybe the loudspeaker is still working and you get some enjoyment out of it? As much as I learned from Peter, he wasn't the best of businessmen, for sure.

I'm reminded of a story Jim Bongiorno told about his work for Rectilinear, a now defunct NY based speaker company of some technical note, from back in the day. James accused the owner of being a criminal because, after designing a speaker, he got nothing at all. Nada. Zip. No money, and not even a loudspeaker to take home! At least that is how he told it.

For my part I wouldn't want a Rectilinear, but wouldn't mind a NOS Ampzilla kit. Especially if it had the meters.

 

[david moran]

Aha. Here are comments by a person knowledgeable with Apt's thinking:

As for RIAA, it is wrong. Most preamps get it wrong because they look like this. RIAA is a pole at 3180 µs, a zero at 318 µs, and a pole at 75 µs. This is roughly speaking starting to slope down at 6 dB/oct at 50 Hz, stop the slope at 500 Hz, and start again at 2122 Hz, forever.

Most designers use two parallel RCs in series with two more parallel RCs in the feedback loop. The gain is Av = Zf/Zi +1.

Zf is the feedback term. Zi is the resistor to ground.

What they forget is the +1. That makes the system shelve and thus tip up from the desired curve at hf.

This unit may have been modified wrong.

Lipshitz wrote a long analysis of various schemes and measured many. Only the Quad, the Advent, and the Apt/Holman were right out of many, many.

As for parts, all designers are limited to the parts available at the time of design and Apt pioneered the use of the TL072 in its earliest years, using >100,000 of them within a few years of launch. Of course it became a favorite in analog console design somewhat later which used a much larger number of them per unit, yet with many fewer units than the Apt. But then using them at another company for years thereafter, they suddenly got noisier, and TI wouldn't fess up to it, but they had moved factories and lost the formula. Wouldn't use them now and there's probably reason to change.

The problem is stability. You've got to be very sure the layout works. It may or it may not. We built a complex board with dozens of NE5532s on it. It did not reach its SPICE predicted noise floor. We looked for oscillation with a 350 MHz scope and didn't see any. We then took it to corporate where they had a 1 GHz scope and found that the whole board was oscillating at 850 MHz! This is so far out of band for the pro audio 5532 we thought it impossible. This was in the days that the 072 was still good, so we replaced the "pro" 5532s (a lot of them) with "consumer" TL072s and it got quieter. Weird, huh? So that's the reason not to recommend any old replacement that's quieter and with more bandwidth and slew rate. If you've got a 1 GHz scope, have at it.

We caused three or four major changes to ICs -- they aren't just fixed things but amenable to change when you are right and the design is wrong. Two cases: Lockup of OP27/37 through unintended SCR action on the die when using a head demagnetizer in a tape preamp. Input stage blowup caused by taking ICs in circuit inside a product as through airport security x-ray just after 9/11 when the machines were set to "stun": the input stage protection diodes all blew up (more than a dozen in the product).

As speculated at the start, RIAA is wrong because that's a modified unit with a part cut out apparently because the guy who worked on it liked a zippy high end. Lipshitz in AES Journal said only three commercial designs were right that he could find, and there were some amateur designs that were. The three commercial ones were the Quad 33, the Advent 300, and the Apt/Holman. Holman did the latter two.

Emitter followers work fine with pulldown current-source transistors instead of resistors. See Fig. 7-7 of manual. This is the driver for the volume control stage and is very low-distortion. There is one in the tone control bootstrap but perhaps there it's less critical. Surely Holman knew about this.

As for "not state of the art in the late 1970s," are we talking about human-observable differences? The distortion is so far below that of phono records or speakers as to be a silly argument, much like some manufacturers made. 0.0005% instead of 0.03%--is there any difference audible? [Moran notes --- someone was praising the insanely low-distortion high-neg-feedback Jpn amps of yore, and someone else was talking about charges of transistory sound back when at the same time ... come on.]

Lot of coupling capacitors to prevent clicks and to make the pots long lasting as if you draw ANY current through the wiper of a pot it will get noisy. Proof is in 40 years in practice.

"low end response is as poor as it is." Yeah, and 18 dB/octave below 15.5 Hz too! Take that, warp wow, speaker FM distortion [therefrom], source dc thumps, etc.

Phono overload is covered in the Audio magazine article. Apt cut lacquer masters at Sterling Sound in New York with Bob Ludwig and did extensive testing with various cartridges, revealing peak levels, and, among other things, ultrasonic ringing of the stylus tip mass and the groove wall compliance around 50 kHz. That all got included in the overload design. ... warped records were played on turntables and arms with infrasonic peaking of warp wow to examine infrasonic overload. Nobody ever did anything so extensive in overload, and the observed distortion is orders of magnitude below that of the phono system itself.

The Apt beat the pants off the Yamaha. In sales! They couldn't understand it and wondered why. How about UTILITY?

"Too many components" Too many notes, Mozart? Nothing in the box and a very high price: best for audiophiles and profits. Bipolar coupling caps with <1 Hz highpass gives best of both worlds. You can't even draw FET input currents through a pot wiper without it deteriorating over time and getting scratchy. Note they gotta be bipolar as you don't know the bias on them. An engineer at another audio company tried many combinations for coupling caps (hundreds are in every console, dozens in every path therein), and the bipolar was best compared with biased series double ones, etc.

The buffer amps are far quieter than any tape machine. Moot. Yet adding a bad input stage of a tape machine in a tape loop won't screw up the main signal as in most preamps.

Using a 100k pot for volume and balance is just dumb. That was learned on the Advent 300. They are bloody noisy just because of the Johnson noise of the resistance in the tone control pots. You can tell this most easily on a Crown DC300. Turn it all the way down and source it with a short. It's quiet. Turn it all the way up and again it's quiet. Turn it halfway in between and it's noisy -- Johnson noise of pot with top and bottom halves in parallel like 25 k-ohms instead of zero.

 

[david moran]

I would like to say that that is a pretty funny story, but don't want to minimize not getting paid for work. You always want to get paid. Maybe the passage of time mitigates some of the disappointment. Maybe the loudspeaker is still working and you get some enjoyment out of it? As much as I learned from Peter, he wasn't the best of businessmen, for sure.

I'm reminded of a story Jim Bongiorno told about his work for Rectilinear, a now defunct NY based speaker company of some technical note, from back in the day. James accused the owner of being a criminal because, after designing a speaker, he got nothing at all. Nada. Zip. No money, and not even a loudspeaker to take home! At least that is how he told it.

For my part I wouldn't want a Rectilinear, but wouldn't mind a NOS Ampzilla kit. Especially if it had the meters.

It was no problem, really. I had spent a long weekend w PA to discuss my managing / editing / running his mag (early 1990s this was) and it was an exceedingly pleasant sojourn. We disagreed about how to look at speakers. I then edited a David Rich piece on power amps, using my recent knowledge (plus the long manual) of the dbx BX1 design process. Neither publisher nor author liked what I did, or liked it okay but did not think it worth much, and by then PA had decided to unretire, or something, or talk to other empirically oriented audio journalists. This was long past his making-up w MDavis and maybe Carver and other genuine and self-styled scientists. (It was also around the time, alas, when Peter Mitchell somehow went over to the dark , Stereophile side of audio journalism.) Anyway, I did not get the TAC job offer, and part of the Allison thing iirc was that Allison liked or at least still would use first-order filtration, when and as appropriate, which both of those guys thought was worse than quaint.

Yes, I do most of my serious upstairs listening over those smooth AL125s w a Hsu sub (my smaller desktop multichannel system is all Allison, whereas the big iron in the basement batcave is all dbx Soundfield + Hsu).

I did not know of any Davis-Holman difference of opinion about anything, and will have to run it down a little w each of them, lighthandedly.

Mark was really something to work with and watch his products come to life in dbx engineering, where I worked through the 1980s. Holman I knew chiefly from the decade prior, and he did some writing for me at the Boston Phoenix. There is nothing like real, actual audio EEs (MD has his doctorate) to do really good work and also tutor and otherwise help out a lay tech writer. It was crushing when he went off to Dolby, though not for him.

 

[david moran]

>> Mark Davis ... was a more or less 'lone' instance of reason back in the day

not really, not in the BAS, which was full of such, from Roy Allison to Peter Mitchell and many many more. (Kotsatos, Riggs, Ranada, Meyer, me, many many others)

>> Others, including some at the competing Audio magazine, and especially the 'undergrounds' (Gordon Holt, Peter Aczel, Harry Pearson, Peter Moncrieff et al) were able to hear all the subjective stuff

this dig at Audio is completely warranted; Pitts did not do a good job with that book, and Heyser was laughable ('everything he ever wrote was either incomprehensible or wrong', as Allison used to say)

>> Hafler was probably the most realistic, once admonishing Gordon Holt, telling him that his subjective electronic reports were essentially worthless (Dave didn't say it like that, but that was what he meant).

But Holt was not the worst of these, and everyone know his famous quote toward the end of his days, yes? (he had been a colleague of Allison, who also started in audio journalism)

Audio as a hobby is dying, largely by its own hand. As far as the real world is concerned, high-end audio lost its credibility during the 1980s, when it flatly refused to submit to the kind of basic honesty controls (double-blind testing, for example) that had legitimized every other serious scientific endeavor since Pascal. [This refusal] is a source of endless derisive amusement among rational people and of perpetual embarrassment for me, because I am associated by so many people with the mess my disciples made of spreading my gospel. For the record: I never, ever claimed that measurements don't matter. ...

>> Others, boutique designers (too many to name) realized that as long as they could keep Harry and Gordon in business, they'd likely stay in business, too. So they went along with all the magical nonsense. Did they really believe it? Who can say?

Brad Meyer once pondered in the BAS Speaker whether JAtkinson was actually like Dr Zaius.

>> Anyhow, in 1977 or thereabouts, Mark Davis demonstrated that level matching took all the differences away. The general underground response? Everyone laughed at him. They criticized his gear (AR speakers, his homemade 'Davis Brinton' preamp, and a Shure M91 cartridge), saying that these were deficient in the 'resolution' department. Aczel was probably the loudest critic (I think others simply ignored him, hoping he'd go away).
>> Later, Peter realized that Davis was essentially correct, and he was wrong. I once told Peter that perhaps he was mistaken (I began audio life as a true believer, as most of us did).

wow

>> FWIW, and in the context of this ASR review, Tom Holman was also skeptical of Davis' results. He'd worked up a lot of 'esoteric' tests in order to objectively distinguish everything that everyone was 'hearing' in phono preamplification, some published in the AES journal. But in the end it all came to nothing. At the time, Davis reported that Holman's listening methodology was pretty sloppy, but gave him a pass by saying that Tom wasn't a psychoacoustician (Mark had a psychoacoustic lab at MIT, if I am not mistaken).

yes, he has his PhD in EE/psychoacoustics from there

(I was a pubs director in the public sector in the early 1980s, having left journalism, and a friend told me dbx was looking for a tech writer. I had little interest in anything dbx had done. But it was high tech and more money, and so I called old pals Henry Kloss and Roy. Both said, first thing, 'Well, you do know that Mark Davis just took a job there.' omg omg omg. I knew him from a stray article or two he had done for the Phoenix and also from BAS meetings and demos, but not well.)

Some here might recall or, if not, enjoy these by him:

p53

https://worldradiohistory.com/Archive-All-Audio/Archive-High-Fidelity/70s/High-Fidelity-1978-06.pdf

(letter)

https://worldradiohistory.com/Archive-All-Audio/Archive-High-Fidelity/70s/High-Fidelity-1978-09.pdf

He has said since that if rewriting now he might modulate some of his views on vertical radpat and human audition vertical acuity.

p48

https://worldradiohistory.com/Archive-All-Audio/Archive-HiFI-Stereo/80s/HiFi-Stereo-Review-1982-05.pdf

A cool interview w him by Ranada in TAC about speakers and his Soundfield work, indirect lighting vs treble highbeams:

https://www.biline.ca/audio_critic/mags/The_Audio_Critic_19_r.pdf

I go on at length about this because he was about the first in the early 1970s to assert (and it was not a new thought at the time, really; see my windy history article referred to earlier and the nod to Jensen in the 1940s and Olson in the 1960s) that what we hear from a speaker in an enclosed space IS its radiation pattern. This was dawning on Toole then as well, I believe. Not that many Brit designers got it.

 

[rdenney]

One superb design from a decade later which some here might want to keep an eye out for is a preamp explicitly modeled on (and featuring several small improvements over) the Apt: the dbx CX1. (For current users or anyone else interested, I have schematics and OM, which I wrote.)

Dam...it! As soon as I buy a vintage preamp, all of a sudden we have a whole freaking conversation on preamps that fulfill my requirements that I didn't even know about, making me question my choice. Grrrrr!

But though I see CX2's and CX3's, the CX1 isn't thick on the ground. But, dagnabbit!, it has a two processor loops and THREE tape loops. ARGH!

Rick "using a dbx 400x to extend the gozintas and gozouttas from the B&K preamp; wouldn't be needed with the CX1" Denney

 

[anmpr1]

I really wish someone in the US close to Amir could send him the old Japanese classics of the same era, such as the Yamaha C-2/2a/2x, Denon PRA-1000/2000/3000, Kenwood LO-7c/7cii, Sony TAE-86/86B, Technics SU-9070/9200/9600 etc. Surely some of you guys have some in your collections?

In the US, the items you mention were not very common. In stores, one could usually find the higher end Yamaha gear. The others? Probably in this class/range, Technics was most known, via advertisements, but seldom seen in the field. The 'problem' was that they were expensive, and at that time folks interested in spending more money than on a 'Pioneer receiver' gravitated to boutique gear from smaller American manufacturers. Why? I think it was mainly because the 'high end' press pushed that angle (Japanese gear was supposed to have 'sounded' bad), and dealers could make more money selling local product.

Plus, people in general want to buy locally. I think that's a fair statement. Folks want to support their national economy, if that is an option. Which, today, it is usually not.

Next, it was often difficult for local 'mom and pop' dealers to sell Japanese product at a competitive price point. Pioneer, Kenwood, Sony were heavily discounted by mail order outfits (Warehouse Sound Company and a handful of others). They didn't have storefronts, but just shipped out mass quantities of boxes. One dealer told me he refused to sell Pioneer/Kenwood/Marantz/Sony because of that. People would walk in to his store, play with the knobs, ask a bunch of questions, take home a stack of brochures, and then order from the discounters.

He sold Denon, but only the lower range--cassette decks, entry turntables, some receivers. And the cartridges, which sold well for him. His higher range 'receiver' line was Tandberg, which was not discounted, and was visually unique (it has a 'Euro' mystique about it). Then it was all boutique American stuff--Conrad Johnson, Counterpoint, Acoustat and so forth.

Another dealer sold 'lower end' Luxman gear (from Lux's Alpine days), but not the expensive Lux product. For that, he'd push customers into his McIntosh room. His big Japanese seller was Nakamichi cassette decks. He didn't bother stocking their other gear.

If a customer wanted it, 'high end' Japanese stuff was typically special order, for the dealer. It wasn't as if you could go to your local Sony or Kenwood franchisee and pick up a TAE or LO7 amp. Those were really outliers. For reasons I still don't quite understand, I wanted a Sony TAN-77 ES. It was special order, and I paid list for it. Another time I wanted to try out a QLY-66F turntable. Don't ask me why. The local JVC dealer thought I was certifiable, but took the check and ordered it. About three weeks later it arrived. I think I was the only person in the state, maybe the region, with a QLY-66F. LOL

Finally, anyone with money and who 'had to have' expensive Japanese product probably ran down an Accuphase. Not so much now, but Accuphase used to have a pretty good dealer presence in America. I believe Teac was the importer, for a while. If you lived in a big city, you might have been able to find a dealer that sold 'off the wall' Japanese gear, like Stax class-A amplifiers.

 

[david moran]

Dam...it! As soon as I buy a vintage preamp, all of a sudden we have a whole freaking conversation on preamps that fulfill my requirements that I didn't even know about, making me question my choice. Grrrrr!

But though I see CX2's and CX3's, the CX1 isn't thick on the ground. But, dagnabbit!, it has a two processor loops and THREE tape loops. ARGH!

Rick "using a dbx 400x to extend the gozintas and gozouttas from the B&K preamp; wouldn't be needed with the CX1" Denney

yeah, the Jpn OEM CX units are okay but nothing like the CX1 so far as anyone knows. Technically noisier, I am told, not sure that matters, since the CX1 is so silent. (Gordon Holt said it passed, rarely, his bypass test.)

I hope you like your 400 and my manual for that too.

You should be able to get a CX1 at some point. Or an Apt with all of these parts replacements (uh ...).

The explosion of dbx early 1990s, shortly after I got laid off, was a real tragedy, not that it coulda been prevented. Davis's codec work changed the course of the industry (not only stereo TV but the AC3 stuff at Dolby), as did Bob Adams's low-bit DAC designs. Tyler and Hebert went to THAT, which is still in business. Aylward (HT cleverness) and Lemanski (NC headphones) did very cool work at Bose. The pro RTA1 never fully caught on, but it remains the handiest quick speaker assessment / xover design iterations device available and set the standard for temporal averaging (nobody had it before, everyone has it now: essential for good measurement). The speaker name was sold to DAK, alas, no longer called Soundfield and not performing like anything along those lines. The ADC consumer brand waned eventually, as did that laser turntable.

Speaking of CX1, I must put into service my remoteless Lexicon DC1 and see what's up with that. ...

 

[restorer-john]

For reasons I still don't quite understand, I wanted a Sony TAN-77 ES. It was special order, and I paid list for it.

Really? It was special order over there? Any Sony ES dealer here could get it, or had one on the floor. (for the few years it was in production before the TAN-80es came along) Here it cost AU$2399 RRP.

 

[rdenney]

The dbx 400x manual is excellent--one of the few for the stuff I have that actually told me more than I could figure out just by looking. And the 400x is complicated--I use it as a spousal don't-mess-with-me force field (not the only one, but fully effective by itself). I just have to make sure to use it with only one source. It's possible to use the processor loops as additional source inputs, but there is crosstalk between them. It isn't an issue with a bit of discipline.

I also use the processor loops as additional line-level outputs, particularly to an external headphone amp that is puts a headphone volume control at my listening chair. I don't need no steeenking remote.

With your work with Kloss and your Boston presence, you and I may share a mutual acquaintance, but that should be taken offline.

I was mostly ignorant of the history of dbx. In my earlier years, when I was a sometimes assistant to a sound/studio/broadcast engineer and a sometimes roadie, dbx was top-tier. Not so much now, but even their current Drive-Rack PA processors are the standard of wonderful for me, for live-sound applications.

Rick "who'll keep an eye out for a CX-1 unique buying opportunity" Denney

 

[EJ3]

They never would unfortunately. The feature set is pretty much normal to us older guys, but it would be a tough sell to people these days.

I really wish someone in the US close to Amir could send him the old Japanese classics of the same era, such as the Yamaha C-2/2a/2x, Denon PRA-1000/2000/3000, Kenwood LO-7c/7cii, Sony TAE-86/86B, Technics SU-9070/9200/9600 etc. Surely some of you guys have some in your collections?

Anyone who is looking for equipment or parts, home or pro, vintage or not (but not "throw away" audio gear, [including things I have, things restorer-john mentions]) should check out: https://www.audioproz.com/AP.php?About_Us
From them:
Audioproz.com tries to pick equipment based on longevity and serviceability, as well as equipment which is supported by its manufacturer.
We are a very different kind of shop. For a smoother experience read our letter about our current shop policies.
Enjoy! (the music0 EJ3

 

[JRS]

I have little comment to make to anyone who thinks or thought AR made substandard speakers at any point. Most were smooth and downward-sloped above the bass a little bit, the earlier models, and a lot compared w rocker hard treble from JLB and such, sure.

<snip>....

Thanks. I owned Ar 5's and later AR-LSTs and while one might characterize them as "polite", I thought of them as polished, and perhaps anticipated the famous Harmon preference curve by decades. My friends all had JBL's and thought I was deaf.

 

[david moran]

The dbx 400x manual is excellent--one of the few for the stuff I have that actually told me more than I could figure out just by looking. And the 400x is complicated--I use it as a spousal don't-mess-with-me force field (not the only one, but fully effective by itself). I just have to make sure to use it with only one source. It's possible to use the processor loops as additional source inputs, but there is crosstalk between them. It isn't an issue with a bit of discipline.

I also use the processor loops as additional line-level outputs, particularly to an external headphone amp that is puts a headphone volume control at my listening chair. I don't need no steeenking remote.

With your work with Kloss and your Boston presence, you and I may share a mutual acquaintance, but that should be taken offline.

I was mostly ignorant of the history of dbx. In my earlier years, when I was a sometimes assistant to a sound/studio/broadcast engineer and a sometimes roadie, dbx was top-tier. Not so much now, but even their current Drive-Rack PA processors are the standard of wonderful for me, for live-sound applications.

Rick "who'll keep an eye out for a CX-1 unique buying opportunity" Denney

Yeah, we probably have more than one mutual acq

hmm, there should be no crosstalk or leakage in a 400; I wonder what is going on

yes, all loops can be used as separate ins / outs. It might help, if only intellectually, to jumper the enc/dec ins-outs in the middle of the design, just to reduce the variables

I too cared nothing for the history of dbx, as I said, the work of Blackmer and Rene J, during the 1970s; but then as employee I got to know DB pretty well and it was he technically who hired me, or gave the final approval. But BSR and eng VP Tyler were trying to buffer him away from engineering dept to an extent, as we were really rocking along in the early and mid-1980s. And beyond, for a while.

I did come to appreciate their aggressive NR schemes for everything but solo piano (or bongos) where lack of overtones means no masking of noisefloor modulation; I also made all of the manuals advise hitting the tape nice and hard to help overcome that problem, whereas before the corporate policy was recording at low levels, which is simply asking for that breathing to be more audible.

I came to appreciate even more the utility of euphonious easy-onset compression, and all the things you could do w rms-level detectors and good VCAs.

I would think the Harman dbx stuff would be fine, but don't know anything about it. I wonder if the auto-EQ drive-rack stuff uses any of the 20/20 / 601, 10/20 / 14/10, or RTA1 technology. You would suppose it would have to, but I dunno.

I did no work particularly w Henry, but covered him as a journalist before dbx and then some freelance manual writing for videobeam afterward, and he too stiffed me to the tune of $4k, and in that regard was indeed kind of like Aczel. I must sound like a dope as a freelancer .

 

[rdenney]

I did no work particularly w Henry, but covered him as a journalist before dbx and then some freelance manual writing for videobeam afterward, and he too stiffed me to the tune of $4k, and in that regard was indeed kind of like Aczel. I must sound like a dope as a freelancer .

Well, we all have skeletons in the closet. I foolishly started a modest music publishing company many decades ago, ran into trouble with it almost immediately, and shut it down before the bleeding became arterial. The journal I advertised in got a bit stiffed on that one, I have to admit. Groceries were on the line, but by the time they weren't, the ship had sailed.

Hmmm. Jumpering ins and outs for the noise reduction unit loops. I thought also of shorting plugs on unused tape-loop inputs--I'm using the Tape 1 output to go through an ADC to the computer, but not the input. The other two tape loops are populated (I take the computer into the preamp directly--no use case for recording from the computer onto tape, but certainly use cases for sending tape 2 and 3 outputs to tape 1, which is easy on this unit). I'm using the processor 1 output to a headphone amp, but not the other two loops, or the input to that one. "Pre" sends line in or tape monitors to the headphone amp, and "post" ignores it.

I can't quite recall the sequence of events that led me to hear increasing (but low) line-in signal as I switched in EQ loops closer to the line-in plugs, but it suggested to me that the inputs from the EQ loops (left side of the design) might be heard in the line out even when not directly routed to it.

I've only been using it for a week or two though, so I'm still experimenting.

(I loved the line in the manual about using the record selector in lieu of the source selector on the preamp. "We emphasize this because the impulse of most people is the opposite." With my setup, I don't have to do that--when I want to listen to the source directly, I just don't press the tape monitor switch on the preamp--the advantage of a processor loop on the preamp where I put room-correction EQ. The preamp's Record selector feeds the 400x independently from the source selector, making it possible to feed an amp in a different room with a different source.)

It's a powerful piece of equipment! All power tools need care and practice.

Rick "it would take a lot of Advent loudspeakers to pay off a $4000 debt" Denney