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Apt Holman Preamplifier Review (vintage Audio)

rdenney

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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
 

anmpr1

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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.
At their price point they were not common. I don't know the franchise deal. With some manufacturers, to get the license you had to buy a set amount of product, which could have included the higher priced spread, or could have been simply a dollar amount, made up from the lower ends. Much easier to sell five or six cassette decks or CD players than one two thousand dollar amp that few had read about.

I bought mine, as I recall, from an outfit called Sound Advice. It was a special order item. Later, during the twilight of two channel (everyone back then at that time was interested in home theater) I also special ordered a Yamaha AX-592 amplifier and TX-950 tuner. Because the dealer didn't stock them, there were no discounts. On the other hand, you could always get a 'home theater' receiver 'on sale' back then. and they had twenty in the box, in the storeroom, so you could take it with you.

On a related note, Sound Advice (no longer in business) made a push to get into the 'tweako high end' market. They started in South Florida, hiring marketeer Steve Zipser as a consultant for their high-end business. I remember them carrying Arnie Nudell's Infinity line--the tall speakers with the EMITs finished in rosewood, but don't recall the other stuff.

Zipser was a notorious/popular commenter on the old Usenet high-end board, rec-audio-high-end. Steve operated a business called Sunshine Stereo out of his house, and claimed the superiority of boutique brands. One day Tom Nousaine and his ABX partner (Steve Mackie?) flew down to Miami, hooked up the machine to Steve's home stereo (Nelson Pass mono class-A monsters), and then Zipser proceeded to become confused when asked to identify his special gear from a ten year old Yamaha integrated amplifier.
 

anmpr1

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Anyone interested in the historical background of the Tom Holman/Mark Davis controversy should review Audio Critic Vol 1 No 4 (1977). Two extended letters written by Mark, first to audio journalist Randy Tomlinson (who I believe was somehow associated with Harry Pearson's magazine), and second, to the Audio Critic. Aczel then provides his own commentary.

At the time, Holman might have still been with Advent. The Advent receiver's phono circuit was also designed by Apt's Holman (an example was reviewed on ASR), and was supposed to (Aczel) have 'sounded better' than the $1800.00 Yamaha C-1 preamp (although others claimed a different opinion).

Audio Critic 19 (1993) features an interview with Mark Davis conducted by David Ranada. This is more free ranging, but offers background on his history and research interests, findings and conclusions. Here, Aczel essentially apologizes to Davis, admitting that Davis was right all along.
 

sacguy231

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Do you use your CX1? Its tone controls are the most useful I know. And its ambience spreader does leave LF alone.
Yep! I have a full DBX stack in one setup. I love the tone controls on the CX1. They are extremely useful, and the owner's manual is the most well-written one I've ever seen. Brief breakdown in simple language of all the features, along with recommendations on how to use them, then pages and pages of design and implementation philosophy of the entire unit. I wish all hifi had manuals like this.

8P3vxtz.jpg


Also, not only is this a great preamp, it has a powerful and excellent headphone section! The stepped volume attenuator is quite nice, and provides superb channel matching even at the lowest setting.
 
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And it’s fully functional it has the expected features :) not like “audiophile” preamps that came later.

That said how is the performance with tone controls in circuit ?
Tone defeat switch is labeled on the bottom for two positions: "Defeat", and "Victory". Defeat for taking all tone controls and the ultrasonic filter out. Victory for putting the tone controls in and adding a 40 kHz Butterworth 2-pole 12 dB/oct low pass for slew rate protection of power amps, with inaudible consequence on the basic audio but preventing a distortion mechanism. In addition, when the tone controls were in, the 10kOhm control pots were paralleled inside with 100kOhm trim pots so the frequency response was adjusted in production to be perfectly flat (maybe ±0.1 dB at 100 Hz and 10 kHz, the test frequencies, as I recall).
 
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Started at $447 from dealers or the factory (there were so few at first that we did a 30-day in-home free trial). Went up in that period of high inflation. Don't remember the top price.
 
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Looks like the 1st of two graphs that show a channel is .25 Db. The second one is "God forbid!" a whole Db! There is actually an internal adjustment to fix that.

For further information see:

Apt Holman Preamplifier Service Manual.

Audio magazine, October 1978, pages 36 and 187 (ads).

Audio magazine, October 1979, page 42 (ad).

Audio magazine, February 1980 (review).

Audio magazine, October 1982, page 14, left side (ad).

Audio magazine, October 1983, page 217 (talks about Preamplifier 2 and the stereophony circuits).
 
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We noticed that phono cartridges exhibit imbalance so provided the phono balance control. A 45 rpm 7" record recorded at 0 level (5 cm/s) with a 1 kHz tone was shipped with the units (I don't know how long this was done) to be able to set the balance with the L–R mode control setting and nulling the outcome.
 
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Rick, tape loops routinely use resistors to loop out the signal, so as to not load the connected source. As such, there is a hit to S/N even if you looped straight back in with a cable and signal levels are different to the line inputs. And not all line inputs are created equal, some are padded down like CD and tuners.

View attachment 167460

The Holman buffers the rec-outs. That introduces noise when looped back in.

Tape loops can be anything from identical to a line input, to degrading the signal significantly.
 
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Of course your theory is that buffering adds noise, but note it is orders of magnitude below any tape machine, and the benefit of buffering is large. I've had systems where it made a huge difference because a tape machine would go non-linear on its input when turned off and bugger up the main signal path, even with built-out resistors. The thing about the Apt is that I designed it only after owning lots of preamps and seeking to fix their screw ups and copy their good features. I call is an anti-negative design. And that includes the buffering.
 
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David Moran, of the Boston Audio Society? Welcome. I've followed the BAS for years, often with a smile. As I recall, the typical BAS 'type' speaker was the 'polite' variety. The 'Boston' or 'New England' sound. More Henry James than Howard Lovecraft, for sure.

Allison? I recall Peter Aczel and David Rich, certainly not uncritical practitioners, panned them. In fact, I don't even think they ran the review, out of courtesy. Why kick 'em when they are down? Allison, a serious practitioner who got his start at AR, offered a variant of the AR formatted sound. AR was viewed (heard?) by many as a quite substandard loudspeaker. At least when compared to anything 'live'. That is, a live performance. It certainly had something new from a late 1950s perspective--low bass in a small cabinet; yet the rest was characterized by closed down and muffled sonics. Am I being harsh in my characterization? It's why Lansing sold so many L100s... that speaker, for all its faults, didn't sound like it was buried inside a large quilt blanket.

Japanese speakers were awful? I recall Harvey 'PT Barnum' Rosenberg building a cost no object variant of his Futterman OTL for a select few owners of Stax electrostatics--the floor standers, not the headphones. They probably didn't think they were unfortunate. But I know what you mean. No one really liked Japanese speakers, even the misguided folks who sprung for Yamaha's NS1000-- those who still think it feels (sounds?) good to them. What do they know, eh?

The 'Holman' gig was definitely a benefit to the audio scene, albeit because he and his company were based in practical engineering, and not due to any 'magic' the designer brought to the table. In the late '70s Holman came up with a lot of 'esoteric tests' that razzle-dazzled folks. For his part, Aczel was 'intrigued' by Holman's discussion of 'cartridge inductance interaction', and 'the spectral content of square waves passed through the preamp stage after suitable RIAA preemphasis' and so on and so forth. But eventually he (and Holman, if I understand it correctly) came to the conclusion that that was all a chimeric chase. What mattered was distortion, FR, getting the RIAA right, and build quality at a price point.

What makes this preamp 'special' is that it was designed and built by someone who was seeking the best engineering at a reasonable price. It's as simple as that. FWIW, I wonder how another 'Boston' area preamp, the DB Systems, might compare to Holman's? I think you can still buy a new DB preamp. Is Dave Hadaway still plugging along? Hopefully it is the case. We are all getting older. If I need a new preamp, I'd seriously consider the DB. Just because.
 
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You say:

The 'Holman' gig was definitely a benefit to the audio scene, albeit because he and his company were based in practical engineering, and not due to any 'magic' the designer brought to the table. In the late '70s Holman came up with a lot of 'esoteric tests' that razzle-dazzled folks. For his part, Aczel was 'intrigued' by Holman's discussion of 'cartridge inductance interaction', and 'the spectral content of square waves passed through the preamp stage after suitable RIAA preemphasis' and so on and so forth. But eventually he (and Holman, if I understand it correctly) came to the conclusion that that was all a chimeric chase. What mattered was distortion, FR, getting the RIAA right, and build quality at a price point.

Only one thing there is true. The impedance interaction at the input almost completely explained the listening results. Tube preamps were not subject to it because a tube grid as an input is inherently high Z. But transistors including in-loop gain input impedance improvement etc. made the first generation of transistor phono preamps mostly dull sounding. With the right careful switching you could a/b this and easily hear it. Our FET input was not subject to cartridge loading (and we provided the right load with termination capacitors and a booklet of all the tone arms capacitances we could find) so it did not suffer from this transistor fault.

What you say that is true is that the pre-emphasized square wave test was not a good predictor as we thought because it went much much faster than any diamond tracing a groove could do. The mistake was that we thought it was, when what was happening was the former. One effect which we thought had two causes but only had one. Still this one entered the legion of measurements made under IEC standards for phono preamps, because it was quite real.
 
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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.
Thanks. See my response to your earlier post. One of the tests I introduced proved the test of time and is in the IEC standard. The pre-emphasized square wave test made signals much faster than poor little stylii could go so was wrong. However we were trying to find out why things sounded different and came up with two tests for which one was and one wasn't true. Not too bad a track record working at the fringe, and "but in the end is all came to nothing" is clearly wrong.
 

david moran

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Yep! I have a full DBX stack in one setup. I love the tone controls on the CX1. They are extremely useful, and the owner's manual is the most well-written one I've ever seen. Brief breakdown in simple language of all the features, along with recommendations on how to use them, then pages and pages of design and implementation philosophy of the entire unit. I wish all hifi had manuals like this.

8P3vxtz.jpg


Also, not only is this a great preamp, it has a powerful and excellent headphone section! The stepped volume attenuator is quite nice, and provides superb channel matching even at the lowest setting.

wow, wow, tyvm !
 

restorer-john

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I've had systems where it made a huge difference because a tape machine would go non-linear on its input when turned off and bugger up the main signal path, even with built-out resistors. The thing about the Apt is that I designed it only after owning lots of preamps and seeking to fix their screw ups and copy their good features. I call is an anti-negative design. And that includes the buffering.

my post in March this year: https://www.audiosciencereview.com/...ones-when-speakers-are-off.21532/#post-715638

@david moran mentioned TI shifting production and the TL-0x ICs became noisy. I dug out some of old NOS opamps in my stash and I reckon it was when they moved fab to Malaysia in ~1977/8. There's an old original TI dated 23rd wk 1977 from the US. By 32nd wk of 1978 they were coming out of Malaysia. Was it a total shift or just an additional fab plant? All I know is pretty much all the TI opamps I saw in Australia had Malaysia stamped on them from '78 onwards and right through the 1980s.

Here's some pics, couldn't find any old TL-072s.

1977 (US)
IMG_0066 (Small).jpeg

1978 (Malaysia)
IMG_0065 (Small).jpeg


1983 Malaysia fab.
IMG_0055 (Small).jpeg


National Semiconductor oldie from 1982!
IMG_0064 (Small).jpeg


1976 Motorola:
IMG_0062 (Small).jpeg


Original Signetics 1974 uA741s.
IMG_0059 (Small).jpeg
 
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my post in March this year: https://www.audiosciencereview.com/...ones-when-speakers-are-off.21532/#post-715638

@david moran mentioned TI shifting production and the TL-0x ICs became noisy. I dug out some of old NOS opamps in my stash and I reckon it was when they moved fab to Malaysia in ~1977/8. There's an old original TI dated 23rd wk 1977 from the US. By 32nd wk of 1978 they were coming out of Malaysia. Was it a total shift or just an additional fab plant? All I know is pretty much all the TI opamps I saw in Australia had Malaysia stamped on them from '78 onwards and right through the 1980s.

Here's some pics, couldn't find any old TL-072s.

1977 (US)
View attachment 167889
1978 (Malaysia)
View attachment 167890

1983 Malaysia fab.
View attachment 167895

National Semiconductor oldie from 1982!
View attachment 167891

1976 Motorola:
View attachment 167892

Original Signetics 1974 uA741s.
View attachment 167893
 
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