Adcom GFP-565 is a winner

Rdenney

Well-Known Member
I recently built a system using an SAE P102 preamplifier. I think it’s cool and unusual, and extremely flexible. But the noise level is a touch above inaudible, and there was no way my wife could figure it out.

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Sound-wise, it’s a good early 80’s preamp with some interesting features. But it is an early op-amp design, and there is room for extending the frequency response as we learned to do later.

(I also thought I had a problem with the processor loop, but that turned out to be relays in the E101 equalizer, and replacing those solved the problem. But I had already started researching newer designs.)

I spent time in the Audio magazine archives. The target year for my system is 1990, just to have some sort of theme, and to find the sweet spot between old enough to be cheap but not old enough to be collectible. SAE was done by 1990–Morris Kessler had sold out to a record producer in 1988 who sold out 8 months later to DAK who blew out the inventory and shut it down.

I compiled a list of requirements:
-two tape loops. I keep a cassette deck available for vintage private location recordings available no other way, and I wire my computer interface into Tape 2.
-a defeatable processor loop.
-sensible tone controls that are defeatable.
-phono input. I’m not prepared to buy a separate phono preamp. Moving magnet is fine, but I wanted a first-class phono preamp.
-independent listening and recording selectors, which are Understandable By Wife.
-S/N over 100 dB in the line stage. The SAE was 90.
-uncoupled outputs and a minimalist signal path, but I still want an active preamp and lots of control options.
-independent reviews validating quality in the context of the time. This wasn’t easy—archives from 1990 are spotty. I have my own ears, but I also respect experience, especially from those who have experience listening to high-end stuff.
-under half a kilobuck. I paid $110 for the SAE.

There were only a handful of preamps that met those requirements in the 1990 Audio Magazine Equipment List. Carver, Soundcraftsman, etc. A Bryston caught my interest, but by the time I adddd a decent phono amp it was going to cost too much. And too few of the excellent B&K preamps have phono stages.

I narrowed it down to two: the Kenwood Basic C2 and the Adcom GFP-565. (The later vaunted Adcom GFP-750 didn’t meet all the requirements, and it was too pricey). I have a C1 and a GFP-555, so I like both brands.

I went with the TOTL Adcom on the force of two factors: The C2 is just too complicated on the front panel while being rather limited on the back panel. And the Adcom was very favorably reviewed by several reviewers, including several at Stereophile, whose opinions I listen to even when I’m skeptical.

It took me a couple of tries to get one in perfect condition.

What a great preamp! Sound clarity is superb, with no grittiness or switchiness. The tone controls are subtle enough to be useful, centering as they do the bands at the limits of hearing rather than making humps or holes in the audible band. And the tone amps are constrained. With music, turning the tone controls has only a subtle effect. The preamp has a bypass output, but these tone controls are useful, so I used the lab outputs. .

The electrolytic caps are high-precision Panasonics and as long as the faulty batch (the ones that tended to explode) is avoided there is no need to change them yet. All the caps in the signal path are high-spec film caps, just as are the resistors. After a DeOxit treatment, there was nothing else to do under the cover.

The preamp’s gain takes it to a maximum of 2 volts RMS, against the 1-volt RMS input sensitivity of my B&K amp. There’s no chance of clipping the preamp, but the amp is only leaving 6 dB (out of well over 100) on the table, and it has good headroom. I can’t make it noticeably clip before reaching levels intolerably loud. And I think it will go into protection before clipping. Just testing it required the wife to be out of town.

The phono preamp is simply superb. At full output, I can just hear slight cartridge hiss—every cartridge is at least a little microphonic—but with shorting plugs the phono input is a black hole. The turntable is a Thorens TD166II with a Grado Green2 cartridge.

I played a very old and rather scratchy bargain-bin pressing of E. Power Biggs playing the Sion organ in Switzerland—the oldest playable organ in the world, made in 1390. I thought—ooh, strident—and then I realized that the organ stops he was using at first were strident. But when he played the flutes, I could hear every delicate detail of the complicated connection between fingers and pipes.

But the pops and clicks of the vinyl surface were rather subdued. This album had been marginal previously. I read a review which claimed the phono preamp was smooth in how it dealt with surface defects, and I was skeptical, but the difference is quite noticeable.

By the way, I only use the equalizer and tone controls for when the music is too bass-heavy, like some rock recordings (ELP—a reference for me) and electronica (Tubular Bells). For jazz and classical, a press of the tone and processor switches and they are gone.

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It’s been said that there are no bad preamps, because preamps are made for people already discerning enough to buy separates. I would agree. But some are better than others. The 565 is much better than the 555, and the SAE P102 probably sits between them. My Kenwood C1 probably sits between the SAE and the 565.

Another addition: Musical Fidelity V90 DAC. So, my CD signal path is now: Tascam CD-401 (vintage 1990), coax digital output to V90, to Tape 2 input to preamp, to GFP-565 line stage amp (tone and processor usually defeated), to B&K Reference 125.2 amp, to stacked Advent NLAs. Not a bad mostly vintage mid-fi quality chain.

Rick “notching things up a bit” Denney
 
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A GFP-565 was front and center in my primary system for a bunch of years. It never called attention to itself, and faithfully passed the signal from source to amp without adding any "character" (distortion?!) of it's own to the sound. It took a Forte Model 2, and later a McCormack TLC-1 and an Adcom GFP-750 to finally push it to the sidelines and eventually out the door.
 
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Congratulations! I bought my 565 a couple of months ago and have it paired with with a 545. I agree with your detailed description of it. I owned a C2 as part of a Kenwood Basic setup I had several years ago. I'm not a audio expert or critic but I found it a much more veiled sound compared to the Adcom 555 preamp that replaced it and the 565 is IMO a much better preamp than the 555 Rest assured that you made the right decision to get the Adcom. Enjoy!!

BTW - I think it sounds best using the Bypass input to connect to my Adcom amp.
 
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I liked mine. Had it for a couple of years. It only went away because it was replaced with a HT processor.

Triple output jacks--but none of them balanced. Alps volume and balance controls--nice.

Eventually, I bought another two-channel preamp, but I had to give up tone controls to better the Adcom '565. (Aragon 24K w/ Penny & Giles volume pot.)
 
i was complacently happy with my GFP565 until i came across an audio research SP3a1 tubed preamp for a song. i expected the stereotypical tube preamp sound (soft highs, squishy midrange, and full, billowy lows). BOY was i surprised and my jaw dropped in response.

fast, tight, dc to daylight response, excellent depth/soundstaging/imaging, and tonal coloration as vivid as a SONY Trinitron tv. the ADCOM preamp never came back into my system but instead, the ARC kept driving the GFA 555II amp which proved to still be up to the task. i recommend using a tube preamp like my ARC, VTL or conrad johnson or similar. i am not alone in this wonderful world where all the attributes of tubes are fed to a good ss amp like my ADCOM.

also, a friend used a Counterpoint SA3000 pre with the ADCOM 5400 driving his martin logan reQuests to excellent results. Rogue uses tube front ends with ss driving stages also to excellent results.

i am sorry to pop your balloon but that was my experience. i see the 565 as an almost high end preamp.
 
Well, I’m sure there are better preamps out there. But no tube amp, and certainly not any ARC I looked at, fulfills my other requirements. There was a McIntosh that I saw, but at $1200 was out of reach.

Almost high end is probably about right, and fits all my gear pretty well. My balloon is not popped. But almost high end can still sound really good.

The 565 was at Class C at Stereophile in 1990 (Class B for the bypass outputs and Class A for the phono preamp), and that also sounds about right. But, as they say, a well-selected Class C system can sound quite good.

Rick “there’s always a bigger fish” Denney
 
Congratulations and I’m sure you’ll enjoy the 565 as it’s a fine preamp. I owned one for a few years and liked it. If however you come across a 750 and think “well it doesn’t meet all of my needs...” I respectfully say you should reevaluate your needs, as it’s the best SS preamp I’ve ever had.
 
dc to daylight response

I don't mean to pop any balloons either, and I don't think anyone would be misled about the upper end of the response as specified here. But I wasn't 100% sure about whether the low end is a little bit of an exaggeration, so I was compelled to go check. Turns out that Audio Research, in their wisdom, did put DC blocking caps at both input and output of the control amp section. (That's according to the schematic I'm looking at. YMMV, I s'pose.)

There's no blocking cap at the phono preamp input, but I guess they weren't worried about phono cartridges producing DC...

Sorry. Back to you, Adcom fans.

chazix
 
No DC-blocking caps on the Lab or Bypass outputs of the Adcom.

But at the daylight end, the Adcom has better response than my amp, far better than my speakers, and even farther better than my ears. Sure, that high frequency response means crisper transients and square waves. But I think by the time the response is in the 50-60 KHz range, there is little more to be mined. And the GFP-565 goes to 90 KHz before dropping half a dB. The Kenwood has frequency response to like 350 KHz or something like that.

Whatever those better preamps bring, I’m not sure frequency response is the cause.

Rick “probably more an issue of phase distortion” Denney
 
part of the whole reason i posted about the ARC SP3a1 was that tubed preamps can deliver what seems like dc to daylight which wasn't expected by me. as for a ss unit that i had that impressed me for its transparency was a B&K pre/pro. when i passed the arc through it, there was almost no degradation. most ss electronics don't have that cleanliness, such as the GFP565. gary galo was quite wrong to compare it to audio research products in his stereophile review. it's one of the times i relied on a stereophile review and came up short.

the GFA555II STILL resides in my system and i will be surprised when i find a worthy replacement. i also respect the 5400, 5500, and the other nelson pass designs.
 
Perhaps the guy who said that there were no bad preamps had a hearing impairment ..
There are certainly better and worse preamps, and like the amps that they are, they all sound different..
And I'm reserving the word preamp for a device that amplifies ..
So called Passive preamps aren't preamps .. just switching junctions with volume pots ..
Passive amplification ?? Does that mean quiet, withdrawn, and wimpy amplification ??
 
Hi, I picked up a kenwood c1 for a very good price and upgraded it to LeeStereos specs that's can be found here on AK and also a gfp565. Has anyone else noticed the c1 to be slightly on the bright side?

Is the line stage of the c1 quieter than the 565?

I'm also using the lab outputs to use tone controls with Kef reference model 3 speakers.

If you were to pick between an upgraded and rebuilt c1 or stock very clean 565, which would you choose?

Thanks
 
having bought my 565 ON THE BASIS OF THE GARY GALO REVIEW and the 555II with it, i ias content for years UNTIL i i substituted an audio research sp3a1.

i ias embarassed to myself because the sp3a1 was ever SOOOOOO much more transparent. gary galo was wrong to rave anout the ADCOM. Now i i try to influance people to use a good tube preamp in front of a ss amp.

the 555II held its own because its its transparency was more than adequate. the 565 made the system seem clouded over in comarison. had it had the crystal clarity of my previous B &K pre/pro, i woudnt have noticed.

i had bought the pre/pro to tranition to A/V capability.

try for a used arc or c-j tubed pre.
 
Nice to be reminded about the 565. I bought one in 1988, used it for 12 years before going HK AV prepro, and have had it slumbering away in the audio closet ever since, back in its factory box.

The only thing I wish it had was remote control; otherwise it is a stellar piece. Glad you are enjoying yours.
 
It is a nice piece and I enjoy the tone controls and different output capabilities. Im just wondering, if I were to sell both units and buy something better used with the combined money, what would someone buy in the $6-800 used market to better either of these?
 
I had the GTP500 and wished I had purchased this instead. The electronic switching system in that was a mess. Blew up on me 3 times.
 
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