AudioCircle

Industry Circles => Audio by Van Alstine => Topic started by: iclark on 27 Jun 2009, 11:44 pm

Title: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: iclark on 27 Jun 2009, 11:44 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
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Tone Depth 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.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: dB Cooper 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.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: avahifi 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. 
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold 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
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 13 Jul 2009, 02:56 pm
(https://www.audiocircle.com/image.php?id=186088)

Model One brochure and Owner's Guide


(https://www.audiocircle.com/image.php?id=186089)

(https://www.audiocircle.com/image.php?id=186090)

Model One Motherboard Schematic and Power Supply Assembly



(https://www.audiocircle.com/image.php?id=186091)

Model Two brochure and Operation Instructions


(https://www.audiocircle.com/image.php?id=186092)

(https://www.audiocircle.com/image.php?id=186093)

Model Two Service Manual(25 pages) / Power Amp Channel


... still playing after 30 years ...  :thumb: ... - Best Regards - Toni
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Musicoal 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
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 25 Feb 2012, 01:12 pm
PM sent.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: dB Cooper 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.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: avahifi 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
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: rcag_ils 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.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: danvillesignal 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
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: tompro on 12 Apr 2015, 01:33 pm
toni could you send the schematics of model one ?
br tom
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: alfagil on 21 Apr 2015, 03:13 pm
Toni, I have a model two power amp.  Could you please send me a copy of the manual and schematic if you have them?  Thanks.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: avahifi on 21 Apr 2015, 06:39 pm
Toni, I certainly would like any service and or technical information you can provide me on the VA Systems Models 1, 2 and 3.

Your help would be appreciated.

Frank Van Alstine
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: dB Cooper on 22 Apr 2015, 02:48 am
It's probably a testament to how these things were designed and built (especially for a very small company, there most likely weren't that many to begin with) that these things rear their heads every so often, kind of like a Vulcan mating ritual.
Title: Bias adjustment
Post by: depaj on 4 Sep 2018, 12:57 pm
Hello,

I recently found a model 2 by with some issues. I repaired what had to be repaired (driver failed on one channel and 2 diodes were open on the other). It's now up and running again but I can't find any info on how to set bias current (what value). I see Toni Rambold seems to have a service manual, I would love it if you could sent it or even just copy the instructions on how to set bias.

Thanks
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: depaj on 13 Sep 2018, 01:32 pm
little update, I know have the info that I need but I'm a little worried about the huge filter caps.
My model seems to be adjusted for the European 230V line voltage but with a dimm bulb in series I already measure 76V across the caps that are rated at 75V. All 4 of them look like they're ready to blow (the grey rubber seals are pushed out.  Can someone confirm my configuration is correct (transformer has 10 primary wires going from 1 to 10 from left to right.
(https://www.audiocircle.com/image.php?id=184386)


 
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 13 Sep 2018, 09:09 pm
… for the Multi-Tap-International Transformer referred to as the 250 V setting:

(https://share-your-photo.com/img/86f6fa3537.jpg)

Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: depaj on 13 Sep 2018, 09:21 pm
Thank you very much, this is very helpful !!
Weren't they cutting it very close with those 75v caps as there should actually be 75v (+/-5v) across them) ? I'm just asking because one of them on my amp just blew the safety valve and spewed its guts out after only 1 minute (volt meter showed 74v just before that). It worked perfectly with a 100w dim bulb that dropped the voltage down to 72V so I don't think there is anything else wrong with it.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 14 Sep 2018, 12:05 pm
… These are the Biasing Instructions:

(https://share-your-photo.com/img/8629eb3e63.jpg)

(https://share-your-photo.com/img/08f2107cdc.jpg)


the bias adjust potis on the boards are the outer ones. the inner ones
are called offset trim - you have to ask my old master of electrical engineering
what that means.


hope i could help - Regards Toni
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: avahifi on 14 Sep 2018, 03:52 pm
When you replace those old power supply electrolytic capacitors, you are going to have to be creative.

The problem is that new electrolyics have gained vastly in volumetric efficiency over the years.  A capacitor of the same capacitance and voltage rating is now MUCH smaller physically than the ones made 30+ years ago.  This is a good thing, except in your case.

The Model 2 was designed for specific physical size capacitors to provide support for the audio circuit boards.  These capacitors are now long gone.  You will find the right value and voltage ratings at DigiKey or Mouser, but you will need to add connection wires to get their terminals to the audio boards as they will be much smaller.

Frank
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: dB Cooper on 15 Sep 2018, 03:20 am
Wow, this thread was started almost ten years ago....
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 15 Sep 2018, 11:45 am
 :lol: ... no, it started almost 40 years ago, when a magazine in his January 1979 issue

introduced the three van alstine components:

(https://www.audiocircle.com/image.php?id=223587)

... sorry for the cutout !

Remember the good old days:

A pair of Magnepan Tympani 1D for $1395, a Model Two for $800 and a Model One for $600 -

and you could live happily ever after !

Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: depaj on 25 Sep 2018, 08:17 am
Hi guys,

Sorry for the delay, I didn't get a notification for your replies (strange because I got them for the first ones).

Thank you Toni for the info on the biasing procedure  :D

Anyway, I bought the new caps, 100v 22000µF Nippon Chemi-con with exactly the same dimensions except for a little less high. I will place something underneath them to get them to the right height.

Is there something I should absolutely check before turning on the amp with the new caps, waht they call the "monistor" for example, or the triac ? Are those prone to failure ? I ask this because when I first turned on the amp without the dim bulb the circuit breaker was "cracking like hell before stabilizing after a few seconds and well next of course the cap blew so... (again voltage across the cap was 76V.

Also I noticed the thermal sensor that is in parallel with one of the resistors in the fan circuit is reading open circuit, which means I guess that the fan is always going to be in the high position right ?

Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: depaj on 25 Sep 2018, 08:40 am
Well, I answered my own question partially, the triac is dead, any advice on what part to replace it with ?
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: depaj on 25 Sep 2018, 03:19 pm
I was wrong about the thermal sensor for the fan speed control. Its open below 63°C and when heating it above that point (with a hair-dryer) it closes, makes perfect sense now that I look at the circuit again.

So only thing to replace would be the triac, I saw a previous post mentioning the Q6015L5 as a replacement that has now been replaced by the Q6015L5TP from littlefuse.
I will order one and keep you posted.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Toni Rambold on 25 Sep 2018, 04:20 pm
Triac and Movistor work as a switch-on current limiter.

(https://www.audiocircle.com/image.php?id=186195)


(https://www.audiocircle.com/image.php?id=186196)

part no. triac: Q6015L5

part no. movistor: 2502 GEKB



There are thermal sensors on both boards, e.g.:

(https://www.audiocircle.com/image.php?id=186197)


so the fan operates in two speeds:

under 63°C low speed - over 63°C high speed

thermal cutoff is at 85°C:

(https://www.audiocircle.com/image.php?id=186198)


Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: charmerci on 25 Sep 2018, 04:24 pm
Remember the good old days:

A pair of Magnepan Tympani 1D for $1395, a Model Two for $800 and a Model One for $600 -

and you could live happily ever after !


There are inflation calculators - they really aren't such bargains when you add that.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Pineappledave on 6 Jul 2021, 01:23 am
Hello Toni,

Can I get a copy of the service manual please?
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Tone Depth on 15 Jul 2021, 01:12 am
I have a Model 2 Amp that I would sell at a fair price to a good home, I am the original owner of it. One channel cut out some years ago, and a local high end repair shop was able diagnose and fully repair it. Anyone message me if you're interested in it.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: danielgk on 15 Jul 2021, 12:25 pm
75v capacitors on 75v lines was probably not the best choice to make way back when these guys were designed and built.  Capacitor technology has come a long way since then, the next step up in voltage back then probably made the capacitors too big to fit in the box.  All is not lost though:  a reasonable over voltage on a capacitor will not blow it immediately, it will merely reduce its expected life.  So the 2000 hour capacitor will become a 1900 hour capacitor, no big deal.

There are also some interesting theories about how it is NOT good design practice to use capacitors that are too high in voltage, like putting a 200v capacitor on a 75v line.

Dan
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: opnly bafld on 15 Jul 2021, 01:08 pm

There are also some interesting theories about how it is NOT good design practice to use capacitors that are too high in voltage, like putting a 200v capacitor on a 75v line.

Dan

Good post dank.

I recently replaced some caps in an older 6973 tube amp to reduce some noise and also because the previous owner went a little crazy on the voltage ratings.
Title: Re: Heads Up! Van Alstine Model One preamp and Model 2 poweramp
Post by: Pineappledave on 21 Jul 2022, 12:22 pm
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.

Hello Toni,
Is it possible to get a copy of the service manual please.
my email is discodabs@hotmail.com