Heads Up! Van Alstine Model One preamp and Model 2 poweramp

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iclark

Saw this to day on Canuck Audio Mart.

http://www.canuckaudiomart.com/details/132941-rare_van_alstine_model_one_prea_mp_and_model_two_power_amp/

Preamp looks Hafler based.
The price is in Canadian dollars. Less thab $1000 US.
I don't think there is any upgrade path on these units.

Ian

Tone Depth

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Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #1 on: 28 Jun 2009, 05:17 am »
I've got a Model 2, quite an awesome amp for late 1970's technology, but is transcended by AVA Insight 440H.

dB Cooper

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #2 on: 28 Jun 2009, 12:35 pm »
Saw this to day on Canuck Audio Mart.

http://www.canuckaudiomart.com/details/132941-rare_van_alstine_model_one_prea_mp_and_model_two_power_amp/

Preamp looks Hafler based.
The price is in Canadian dollars. Less thab $1000 US.
I don't think there is any upgrade path on these units.

Ian

I bet Frank will breathe a big sigh of relief when the last of these finally goes away and he no longer has to explain why he cannot fix them.

These units were built several years before Hafler launched his operation in the late 70s. Never upward facing input jacks on any of the Haflers I saw (owned a DH-101). Front panel has a vague resemblance to early Hafler styling I guess. I thought these things had potted circuits though and I don't see any; maybe that came later.

I wouldn't sink a grand into anything this old although they do look relatively clean.

avahifi

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #3 on: 28 Jun 2009, 02:45 pm »
This Model One preamp is very interesting as it DOES NOT have the standard potted modules.  It appears from the photo that these are the original active circuit boards, but without the final potting process.

I was not at VA Systems when this change was made, evidently late in the production of this unit.  But it is a good thing as the potted modules were impossible to service.

The trimpot on the bigger (phono) boards is to set DC offset to as close to zero as possible.  With the potted modules, this was impossible to do as the unit aged.  This one still has some hope.

This looks like an original Model Two power amp too.  Unfortunately we have no service information or repair parts available for these units.

Regards,

Frank Van Alstine

P.S.  These units are certainly NOT Hafler based. 

Toni Rambold

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #4 on: 10 Jul 2009, 01:23 am »
Quote from: avahifi
This looks like an original Model Two power amp too.

... the amplifier card of the right channel has double pairs of Motorola output transistors
either 2N3773/2N6609(old) or 2N5632/2N6229(new) - the output transistors of the left channel I have never seen.

On first view it is hard to believe that the Model Two is a "rearranged" Double Dyna 400 but
if one compares the schematics of both amps they look alike except of the 2N3440 current mirror
of the Model Two.

The Model Two is a very reliable amp.
The only failure I had decades ago was the switch-on current limiter.
So I had to replace the triac(Q6015L5) and the movistor(2502 GEKB) as described on
page 2.3-4-1 in the service manual.

The Model One (potted modules) is flawless ever since.
I think, I will reread the review of the Model One in "the absolute sound", number 11, winter 1978
by J. Tamblyn Henderson and the "Manufacturer's Comment" on page 359:

"We agree with your observations that optimum sonic results are achieved using the Model One preamp
with our new Model Two power amplifier,..."


Thank You, Mr. President

Toni Rambold

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #5 on: 13 Jul 2009, 02:56 pm »
Quote from: avahifi
Unfortunately we have no service information or repair parts available for these units.

... maybe I can help:

   

Model One Motherboard Schematic and Power Supply Assembly




Model Two Service Manual (too many pages) - e.g.:


      

2.5-6 Bias Adjust, Offset Trim




Model Two Power Amp Channel


... still playing after 30 years ...  :thumb: ... - Best Regards - Toni

Musicoal

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Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #6 on: 22 Feb 2012, 05:04 pm »
Toni,

Came across a very old post where you put up a few pages of old Van Alstine gear. I have the preamp and both amps and would love to get full copy of the manuals and schematics if possible. I hope this message finds you well and enjoying the sounds.

Ken
musicoal@gmail.com

Toni Rambold

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #7 on: 25 Feb 2012, 01:12 pm »
PM sent.

dB Cooper

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #8 on: 27 Feb 2012, 03:40 am »
A scan would be a lot more readable but I still doubt AVA would touch them. And understandably so. Where would you get the potted active parts for instance.

avahifi

Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #9 on: 27 Feb 2012, 02:45 pm »
One big problem is that we have no service data on the Model One or Model Two at all.  I was supposed to get documentation when I left VA Systems, but that never happened.  I have never even seen the Model Three amp.

Regards,

Frank Van Alstine

rcag_ils

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Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #10 on: 27 Feb 2012, 05:11 pm »
Solid State devices become obsolete very fast, especially from that era, so I think these potted modules are almost in non-existent. Unless maybe the person who made these still have some left in his personal stock. The guy who made these is in Canon Falls now and he's making tone gear for the telecomm market, I've seen some of the rack mount notch filters for VHF/UHF communication that he makes.

danvillesignal

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Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
« Reply #11 on: 22 May 2012, 05:21 am »
I was one of the designers of the Model One. I don't remember non potted modules. The phono preamp was quite novel at the time. It used a split passive topology and a servo loop. My name is on the patent.

We designed an improved version in 1979 that was going to the basis of the Model 7. We were fans of old Marantz gear. Only two prototypes were ever made. I also built an improved perf board module for a Model One that was stolen in the late 1990s.

I designed "on paper" a modern version a few years ago just for fun, but I never actually built it. I also derived DSP transfer functions for a DSP phono preamp on DIYaudio a few years ago. Today, my company makes high performance audio products targeted at OEMs using DSP.

The Model Two was basically a repackaged Double 400 with improved current mirrors. Our best amplifier was the Model Three which was an original design. It used a current feedback topology.

Model Ones with a bad module would be difficult to repair. The Model Two would be fairly easy. I would expect that Frank Van Alstine could fix this amplifier if he chose to. He was part of the company when these products were created. The Model Three came after Frank's departure, and he never knew the details of this design.

Al Clark