Why does the APT Holman preamp sound so good?

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"Is the Pass that bad?"

No

I have found 90% of people cannot hear in the audiophile sense, and of the 10% that can, 90% of those pick the worst unmusical sounding gear.

The 1% that could tell whether something was musical never seemed to have any money.

I would describe the APT as uncolored, but lacking in dynamics, lifeless.

"Any schematic ?"

Unfortunately, yes, but I am moving and not likely to find it anytime soon.
 
Yessssss!..why?....why?.... i am crazy to discover those things!

fourty years researching and having not too much idea that "what" makes a good sound!

I have a friend that said to me that the good sound is the one he has at home, the most pretty wife is the one he has at home.

Others said that must have mirrors, some say that must have CCS.... others said without differential sounds different, others that triple darlington is magnificient, others say that better is to use a single darlington...others say that....i could not "capture" what makes a good sound!

But i have one idea of it...beeing with your wife.... with deep passion..can you understand how deep is the love i am talking about?..... welll....the sound that is playing in that moment is the best amplifier on earth.because ...you will not perceive nothing more than hormons circulating, heart beating strong...you will hear a lot of things.... the only thing that you will not capture is the sound.

Some very inteligent guy or girl, once told that the best sound is the one you do not perceive it playing..... maybe, as not disturbing you anyway...if distorted you will perceive, if too high you will also perceive..... if disappear is a good amplifier..this makes some sense too.

regards,

Carlos

regards,

Carlos
 
AES Article

Tomlinson Holman wrote about preamplifier design in "New Factors in Phonograph Preamplifier Design" AES May 1976, Vol 24, Number 4.
From memory he suggested that many solid state preamps of the day had reactive components to the input impedance and that this was one of the major sonic differences as compared to the best tube designs of the day.
He also paid attention to rejecting low frequency warp and rumble at the input before any amplification.
I was told many years ago by a reliable source who was there, that much of this paper came from discussions at Advent and that Holman did more to raise awareness of the issues. I believe that the topology covered in the AES paper was first used in the phono section of the Advent Receiver. I do also believe, IIRC, that the Apt Holman phono section is very similar.
 
Holman Patent

See patents 4,032,855 and 4,117,412
http://patft.uspto.gov/netahtml/search-bool.html

From: http://www.tech-diy.com/patents_amplifiers.htm

Phonograph preamplifier network with infrasonic cutoff response
4,032,855
Holman, II June 28, 1977
A phonograph preamplifier network with infrasonic cutoff response. The preamplifier network is an active filter configuration with a high gain, high input impedance differential amplifier provided with an RIAA equalization feedback filter network coupled between the amplifier output and inverting input. An RC filter network is coupled between the inverting amplifier input and ground potential to provide a single, low frequency real axis pole. In addition, an input filter feedback network is coupled between the preamplifier input terminal and the non-inverting input of the amplifier, and further bootstrapped to the amplifier inverting input. The network provides a pair of low frequency off-axis complex poles. The RC filter and the input filter feedback networks are adapted to control the infrasonic frequency response of the active filter preamplifier network so that the preamplifier network is characterized by an 18 dB per octave roll-off response at frequencies below a predetermined infrasonic frequency, and a relatively flat response at frequencies in a range adjoining and above that infrasonic frequency.
 
"Not a very nice thing to say especially since you have no facts to back up your claims. Maybe you are in your self proclaimed majority."

The truth hurts, and is very depressing.

The people that were buying very expensive stereos from me in general preferred the sound of a boom-box.

I hand selected all the Decca cartridges. I played three samples for most people, a bad one, a good one, and another bad one.

If people could hear they always had me play the first bad one over again (number one), rejected the good one (number two), and settled between bad one (number one) or bad one (number three).

We were a couple of hundred yards from a piano store, they usually had a half dozen or so concert grands in a temperature and humidity controlled room. Taking a customer over there and letting him hear the real thing was always interesting. Bringing him back to the store and playing a solo piano piece then generally had the customer totally changng his mind as to what he wanted to own.

It breaks the preference cycle and brings it down to: what sounds the most like the music.
 
Very true. Lots of people like nice smooth sound from their systems. The total opposite of live acoustical music.

Regardless, I think it is one fine sounding preamp. Compared to my X2.5, it is a bit more detailed in the midband, and also a bit more forward. Both are differences I prefered, hey, I spent a load of cash on the Pass, so it must be better. :)
 
I listened to both of those preamps years ago, and the Audio Research SP-9, in a direct comparison, made them sound second-rate at that time, in the demos I heard at the old Havens and Hardesty store on Bolsa Chica in Huntington Beach (long gone....too bad).

The Audio Research SP-16 and LS-16 are 3 generations newer, with sound that makes the SP-9 sound broken, due to new coupling capacitor technology for low phase distortion, better power supply engineering for lower noise, and a few other major significant improvements in the volume control and switching.

If you think those two preamps you have sound good...you are a litttle out of touch with the improvements made in sound quality in preamps in the last 20 years. Try going to Optimal Enchantment in Santa Monica, Visualsound in La habra, or one of the other high-end dealers in s. cal. and arrange to borrow a superior preamp overnight and let your ears tell you how far your old preamps really are from the performance of a well-engineered new unit.

I would even bet you that the NAD integrated amp that sells for $399 (the one with the 'BEE' suffix to the number, which I forget) would blow away the sound you have now, if you want to keep it cheap. I don't know who the local NAD dealers are in southern cal. anymore, but their website will tell you.
 
I remebered the number of that NAD integrated amp ; it is the NAD C320BEE.

It received very favorable reviews in BOTH Stereophile and The Absolute Sound mgazines.

For either of these magazines to say anything good about an integrated amp costing under $1000 is rare as heck, and for BOTH of them to both give favorable reviews AND both of them to list it in their Recommended Components list (Stereophile) and Editor's Choice list (Absolute Sound) is very impressive.
 
At the time it was hard to beat

I purchased an Apt Holman preamp new in 1979. Up until then I had used tube separates, and I had not heard any transistor equipment that I could even stand to listen to for long, for a variety of reasons that could be summed up as listener fatigue.
During my college days studying acoustics I had a job as a listener for an electronic organ company – listening to their various circuits played through 120 Mac amps driving 240 12” speakers and comparing them to real organ pipes. I worked with the engineers to perfect their circuitry and became a critical listener.
Later, working in a high-end stereo store, I took dozens and dozens of preamps and amps home for several years, but I took them back, too.
The Apt Holman was the first piece of solid state gear I listened to that didn’t have 1. phase shift distortion, 2. crossover distortion, and 3. audibly high IM distortion.
Its sound was uncolored, it was quiet, had huge dynamic range, and wasn’t bothered by microphonics (loud sounds being transmitted mechanically to its outputs). And it didn’t have that “transistor sound” that tube folks dislike. And it had perhaps the best phono section I have heard to date.
Clean and simple, that’s how I describe the Apt. I think I'll update its innards and see how it compares today.
(I didn’t find a solid state amp I liked until the Edge M6 in 1998.)
Mike
 
I had a chance to recently meet and see Thelma Houston of the Shefileld Records "Thelma Houston & Pressure Cooker". This was one of my reference records that i used to buy gear with in the late 70's. I ended up with an Apt Holmon and Yamaha P2200 into Magnaplanar IIIc. Those were happy days.

Last year after pressure from my wife I turned the Apt, since it wasn't reliable anymore, into an electronics recycle event. Now that I met Thelma I wish I'd kept it and had it reconditioned. On the other hand I still have the Advent 300. Need to have it reconditioned.

The schematic was on the bottom of the preamp. It had a knob that you could separate the left and right field from the middle. Sort of a early Karaoke. Since at the time most vocals were center stage you could subtract the left and right channels from each other and the middle vocals would disappear.

At the time I was going to Purdue Univ as a EE on the GI bill. I spent way more on audio than I did on my education.

Norm
 
hi DJK, re: "The people that were buying very expensive stereos from me in general preferred the sound of a boom-box." - boomier than Khorns? (mine have never been in a solid wall enviroment) IIRC in a letter from Holman, he felt the tube preamps were adding a type of ambiance from noise. I had the little Advent receiver but not the APT and I generally used tube preamps in those days - one had 6SL7 front end (very microphonic) and have a 6SL7 phono preamp today (very microphonic)
 
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