Upgrade for Art Pro VLA?

[spratz]

I am looking for upgrade ideas on this compressor. Specifically more than just swapping tubes. Has anyone done any mods that have improved the sound/quality of this unit?

Thanks,

jason

mudstonemusic@yahoo.com

[sapplegate]

I haven't modded one, in fact I got rid of one of these and a Pro MP for some real gear ;) , but to try and be helpful, here's a link to a site that performs mods to these units.

http://nanaimo.ark.com/~pat/record.htm

You are probably already aware of this site if you've done any web searches for schematics. I don't know if the person will give any more info about the mods than what is supplied on the site, but you might try shooting an email that way.

Good luck and keep us informed!

[spratz]

Correct. I have searched and seen the site. I have tried selling the unit but not to many people are interested in one. So, my latest thought was to look at upgrade options.

Thanks,

jason

[Kev]

What is this unit ?

A circuit, as usual, would be helpful.

Just to give us a head start .. what is the main components in this circuit and how many. What would you like this units to do for you ?

If this unit is built on a PCB it may be difficult to make wholesale changes but if there is some point to point there may be the scope to make some changes and improvements to components etc.

[spratz]

Here is a basic web link for the device.

ART Pro VLA Comp

It is built on a PCB. I don't have the unit with me to reference. It is in the used gear rack at a shop in Rochester. I guess I was looking for thoughts/advise from someone who might have looked into this before me.

A Google group search brought up this information.

Google Search link

I don't have a copy of the schematic. So I am not sure how much this info will help my cause.

Thanks.

jason

PS: I hope the links work. I have not tried linking them like this before. If it does not work I will post again.

[Kev]

The first link gave me a little to work on.

... hybrid design utilizing the latest and most advanced analog and tube technology.

Chips and Tubes, This does spell PCB.

... 12AX7 vacuum tube gain stage

I think this could be the 'make up gain' section
I wonder if the tube has lots of volts or if it is starved in a side chain. Then it might not be for gain ???

... Vactrol-based Leveling Amplifier

See our T4B clone/substitute at Group DIY. I also use one of these as an option for my Opto Comp.


Before you even start we do need a circuit and we need to estabish why a mod might be necessary. What, if anything, is wrong with it now ?

[ciminosound]

As I understand it the Pro VLA is basically two Levelars in a rack with VU metering. I have a Levelar but no schematics. Double sided PCB in the thing. I forgot which Vactrol they use. (5C4 I think?)

I'm trying to remember all the details about the inside. The tube was starved plate. I forget but it was at least a voltage tripler off the wall wart. The manual said 12AX7 but mine had a JAN-12AT7 from the factory.

jenricks "favorite" schematics site had some mod ideas for a while before taking them down. I printed the page.

Bypass all eight electrolytic signal path caps. Change the 5532 vactrol driver to a high current chip. R32 (100K) to 50K, this opens up the air, speeds up the fast setting, and changes the 6:1 limiter to 4:1.

No specific high current chip recommended maybe an AD844 of "video" chip. These types tend to be high current, super high slew rates too. Never wound up doing that to mine. Did the other things though and I really liked it better after I did.

Also recommends changing the tube type. Specificly recommends a black plate 5751. I had a black plate RCA Command series 5751. It made a HUGE difference in the sound. Tried a bunch of tube types and plate structures and you could hear a real difference.

Don't forget the Neumann U-47 is starved plate circuit!

Another unstarted project of mine is a 12AX7 page with photos of all the different plate structure types I have. Some real nerdy sh*t......

[cjenrick]

Turns out my favorite schematic guy is also an actor...

http://movies.yahoo.com/shop?d=hv&id...f=info&intl=us

[ciminosound]

HA!!!
:D :D :D