How do these APT Holman preamp tests look?

[SPOautos]

I noticed some years back Ken Rockwell tested a APT Holman preamp. He did several tests of the phono stage and RIAA curve. Anyone up for looking through his tests and giving insight regarding how the APT phono stage compares to the Cambridge Audio Duo that is tested here?

These tests are all new to me so I dont really understand all of them. Would love some educated thoughts.
https://www.kenrockwell.com/audio/apt/holman-preamplifier.htm#rex

Here is the Duo https://www.audiosciencereview.com/...nts-of-cambridge-audio-duo-phono-preamp.6901/

 

[kevinh]

That preamp is almost 40 years old the measurements look outstanding for the time. The biggest downside I can see is that the caps likely need replacing, and there are no balanced inputs or outputs. It appears to be a well engineered unit.

 

[SPOautos]

That preamp is almost 40 years old the measurements look outstanding for the time. The biggest downside I can see is that the caps likely need replacing, and there are no balanced inputs or outputs. It appears to be a well engineered unit.

Yeah the age of internals would be my concern as well. However, as far as the unit Ken used goes, he said he picked it up on Ebay sold 'untested and as is' so it seems to be all original....that was in 2015. Pretty amazing to get such good results from such a old piece that seems it has not been worked on.

I suppose with new caps it would probably test even better.

 

[JeffS7444]

Kind of disturbing, because back when that was still a current item, I saw the set on display at my local dealer, had read really good reviews and thought it was just what I wanted. "You don't want that, it's nothing special" is what I was told and ended up going through a series of trendy audiophile-approved products. I could have bypassed all of that nonsense! Versus the mid-1980s Douglas Self preamp that I just built for myself, I see less aggressive high pass filtering for phono (I've discovered I really like that filtering) but otherwise, what's not to like? I wonder if tone controls on the old Advent 300 receiver had a similar action: That Advent's treble control was super useful for taking the edge off shrill recordings.

 

[SPOautos]

Kind of disturbing, because back when that was still a current item, I saw the set on display at my local dealer, had read really good reviews and thought it was just what I wanted. "You don't want that, it's nothing special" is what I was told and ended up going through a series of trendy audiophile-approved products. I could have bypassed all of that nonsense! Versus the mid-1980s Douglas Self preamp that I just built for myself, I see less aggressive high pass filtering for phono (I've discovered I really like that filtering) but otherwise, what's not to like? I wonder if tone controls on the old Advent 300 receiver had a similar action: That Advent's treble control was super useful for taking the edge off shrill recordings.

Yeah I've come to the conclusion I never take a sales person's word on anything, gotta research and know for yourself. This is a wonderful forum for that....so much to learn that I dont understand! But until the 2000's that was hard to do.

Salesman probably made more money off some products than others....or maybe he was just ignorant of the facts. There was prob a preamp that fattened up the lower frequencies and that sounded better to him and made the APT sound 'weak'....when really the APT was more accurate. Who knows how much good equipment is looked over because of things like that.

 

[kevinh]

Kind of disturbing, because back when that was still a current item, I saw the set on display at my local dealer, had read really good reviews and thought it was just what I wanted. "You don't want that, it's nothing special" is what I was told and ended up going through a series of trendy audiophile-approved products. I could have bypassed all of that nonsense! Versus the mid-1980s Douglas Self preamp that I just built for myself, I see less aggressive high pass filtering for phono (I've discovered I really like that filtering) but otherwise, what's not to like? I wonder if tone controls on the old Advent 300 receiver had a similar action: That Advent's treble control was super useful for taking the edge off shrill recordings.

IIRC Tomlinson Holman designed the Advent PreAmp as well as the Apt Holman unit.

 

[JeffS7444]

I partly blame the high-end audio press of the era: Those guys may not have been very technically-minded, but the best of them sure could write persuasively!

 

[SPOautos]

I partly blame the high-end audio press of the era: Those guys may not have been very technically-minded, but the best of them sure could write persuasively!

I think they are still persuasive. Honestly it's taking a lot for me to change my thinking away from subjective reviews and over to charts and graphs. I still feel like phono pre tests show 'these two' as having the same freq response and distortion but so and so person says one of them has better bass response or more detail or whatever. It's hard to get past that ear comparison way of thinking.

I still am not sure if I understand how the tests relate to hearing the music. If two phono pre's test the same does that mean they sound exactly the same? One cant be more detailed or clear?

 

[kevinh]

I partly blame the high-end audio press of the era: Those guys may not have been very technically-minded, but the best of them sure could write persuasively!

Good point, I used to visit Roger West at his facility when he first started Sound Lab ( very nice Gentleman BTW) we talked about reviewers, he felt that they were pretty bad because they always needed new equipment to rave about which wasn't good for a manufacturer who improved a product over time as opposed to bring out a new product.

Then ther is the bias towards expensive equipment, after all how could a cheap component like this POSSIBLY have the Magic of the $2,000 Pre Amp (of the time). The situation is worse now when a $1,000 diy amp outperforms/is indistinguishable from a $20,000 gold plated beauty.

 

[JeffS7444]

I think they are still persuasive. Honestly it's taking a lot for me to change my thinking away from subjective reviews and over to charts and graphs. I still feel like phono pre tests show 'these two' as having the same freq response and distortion but so and so person says one of them has better bass response or more detail or whatever. It's hard to get past that ear comparison way of thinking.

I still am not sure if I understand how the tests relate to hearing the music. If two phono pre's test the same does that mean they sound exactly the same? One cant be more detailed or clear?

Most of those reviewers probably really do "hear" those things, because until you very carefully match levels between components being compared, almost everything will seem to make a difference, sometimes a big one. The gold standard is to level-match within 0.1 dB, and you can do this by ear by adjusting until differences go away (per Larry Klein, Stereo Review). Ideally you want to do this double-blind, but even if done sighted, you may be astonished at how little sonic difference there is between competently designed amplifiers and DACs.

Phono is one of the last great areas of tweaking of course, and considering all of the allegedly perfectionist products out there, it's kind of maddening to see a lack of info on cartridge loading and correct alignment. But ironically, I got what seems to be some decent info on setting Stylus Rake Angle from someone known for subjective reviews of very costly equipment:

 

[JeffS7444]

Then ther is the bias towards expensive equipment, after all how could a cheap component like this POSSIBLY have the Magic of the $2,000 Pre Amp (of the time). The situation is worse now when a $1,000 diy amp outperforms/is indistinguishable from a $20,000 gold plated beauty.

True, and how can they hope to maintain a sense of perspective when they don't pay the same retail prices as you or I, and they are dependent on maintaining their insider status?

 

[SPOautos]

Most of those reviewers probably really do "hear" those things, because until you very carefully match levels between components being compared, almost everything will seem to make a difference, sometimes a big one. The gold standard is to level-match within 0.1 dB, and you can do this by ear by adjusting until differences go away (per Larry Klein, Stereo Review). Ideally you want to do this double-blind, but even if done sighted, you may be astonished at how little sonic difference there is between competently designed amplifiers and DACs.

Phono is one of the last great areas of tweaking of course, and considering all of the allegedly perfectionist products out there, it's kind of maddening to see a lack of info on cartridge loading and correct alignment. But ironically, I got what seems to be some decent info on setting Stylus Rake Angle from someone known for subjective reviews of very costly equipment:

Wow.....I love at 5:33 he says "it doesnt have to be exact". I started laughing....hes setting up his stylus with a microscope and computer, he isn't fooling nobody..... it has to be exact.

He probably couldnt stand to look at mine lol. Mine is like eyeballing it compared to what he is doing.

 

[gene_stl]

It was said that THX stood for Tom Holman Experiment

 

[Wes]

I had both units and enjoyed them. The pre-amp had outstanding control functionality. Finally sold to get a unit with a remote...

Krockwell is a very poor photographer IMO (and that of many others). He claims he is a "photographic artist" apparently in response to others calling him a blogger. I would trust his ability to use audio measurement gear even less.

 

[JeffS7444]

Wow.....I love at 5:33 he says "it doesnt have to be exact". I started laughing....hes setting up his stylus with a microscope and computer, he isn't fooling nobody..... it has to be exact.

He's right about that you know: Best you can hope for with SRA is to get it pretty close, because even if you're willing to adjust for each and every record thickness, when was the last time you had one which was completely flat? Just realigned my own setup via that technique, and it told me I had the arm height too high.

 

[SPOautos]

I had both units and enjoyed them. The pre-amp had outstanding control functionality. Finally sold to get a unit with a remote...

Krockwell is a very poor photographer IMO (and that of many others). He claims he is a "photographic artist" apparently in response to others calling him a blogger. I would trust his ability to use audio measurement gear even less.

I believe photography was just his hobbie, I believe his career was electronic design. He mentiond this on his website in the article about how people like the euphoric distortion of tubes......

"As an engineer with a BSEE, patents, and an Audio Engineering Society (AES) member for about 40 years...."

 

[Dialectic]

It was said that THX stood for Tom Holman Experiment

It stood for Tomlinson Holman's Crossover (Xover), the famous 80 Hz crossover from LCRs and Holman's preferred dipole surrounds, handling everything above 80 Hz, to subwoofers, handling everything below.

 

[Omar Cumming]

I purchased an APT Holman preamp in the 80's used it for a few years, then put it away for 30+ years. When I needed a preamp for my office to drive powered speakers I remembered it, hooked it up and crossed my fingers. Suprise, it worked perfectly! no problems. Hook up computer usb port>>> Topping D10>>> APT Holman preamp>>> powered speakers. It is a beautiful piece of kit with interesting features.

Glad I kept it
Cheers

 

[sejarzo]

I owned both the Apt Holman preamp, purchased as a demo in 1977, and the Apt One power amp, purchased new in 1980. The store I bought them from was just across the street from the Purdue campus. That store sold more Apt gear than any in the country, so Tom Holman came to visit for a whole day in 1977 to answer questions about the design and what to expect from Apt in the future.

Everyone seemed to agree the tone control profile was far more useful than those on other units. When asked about the continuously variable mono/stereo control, Holman said it was because he was an opera fan, and it was a simple way to adjust the volume of vocals versus instruments. He also played "Dreams" from Fleetwood Mac's Rumours with the control in full L-R to demonstrate how one could find odd audio engineering errors, like out of phase drum beats. Yes, that was rather geeky, but he was speaking to a room full of Purdue engineers, so he had that going for him, right?

The only widespread problem I know of was that the muting relays had a bad tendency to get stuck in both the preamp and power amp. When that got to the point of being more than an infrequent nuisance with the preamp, I shipped it back to Apt and it was returned with new relays plus a new face plate with nicer paint and sharper screen printing at no cost to me other than one way shipping.

A few years later, I was ready to order a different power amp from the same store when the Apt One wouldn't produce sound after 15 years. The LEDs showed it would not come out of the power on protection mode. My friend at the store called me back after thinking about what I had told him and told me to pick it up and drop it 3-4 inches. That freed up the stuck relays and I used it another 8 years or so before selling both units for a surprisingly good price to someone who was going to have both of them recapped.

 

[mhardy6647]

IIRC Tomlinson Holman designed the Advent PreAmp as well as the Apt Holman unit.

He did indeed do the phono preamp (at least) in the Advent 300 receiver -- and the APT Holman preamp (and power amp, I presume) as well.
The phono preamps were widely (albeit not universally) regarded as the top of the heap in their class(es) when new.