Art PRO VLA – U.S. Version Differences
Old 24th January 2012
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Art PRO VLA – U.S. Version Differences

Recently I was looking at getting an older/original US-made Art Pro VLA. In my research and searching I noticed a few variations or differences in the US versions and thought I would share. Form what I’ve read; all Chinese versions have Phillips screws on the faceplate and this seemed to be true with all the VLA’s I looked at. I also noticed that most Chinese versions have a small “Made In China” sticker on the back next to the “CE” mark. I also saw several Chinese versions with a round green RoHS sticker on the back as well.

In short, I originally intended to buy one VLA but another came along at too good of deal to pass up. So I now have two US-made VLA’s and after some use I noticed a few physical differences between them.

Differences

NOTE: Older/lower serial # unit on bottom (2-2-98), newer/higher serial # unit on top (1-27-99)

Knobs:
Older unit has smaller white dials/marks and don’t run down the side/shaft of the knob. The older units “white” marks are not painted such as the newer units and appear to be bare alloy and reflective. Older units knobs have flat type screws that hold them on where are new unit has hex type.

Power Button:
Though similar, they both operate in opposite positions. I have seen a power button with “O” and “|” symbols on a US version.

Finish / Faceplate:
Also similar but older unit seems to have a deeper brushed finish (hard to tell from pic). Newer unit seems to have a more precise cut (edges) and just slightly thicker than old unit.



Backside:
TRS nuts are different between the two. Sticker placement and sticker size differences. Newer unit has AC/Mains ~ symbol.



Chinese Backside: (notice sticker)



Chinese Front: (notice Phillips screws)



Tubes / Inside: (No idea if original or changed / upgraded)
Older unit has 12AXNA China tubes. New unit has Philips JAN 12AT7WC USA tubes installed. Couple ribbon cables are different but all PCB’s seem to be the same. Threshold pots are different.

Sonically:
I haven’t used the units enough to provide sonic feedback.

Please let me know if you find this post useless or unimportant. Thought it may help those looking for either US or Chinese versions and their physical differences.
Old 3rd March 2012
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How funny, this is EXACTLY what I was looking for....

I know this was discussed on HomeRecording forums, but the visuals really help!
Old 4th March 2012
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Quote:
Originally Posted by FilmNMusicman View Post
How funny, this is EXACTLY what I was looking for....

I know this was discussed on HomeRecording forums, but the visuals really help!
Thanks for the reply, I'm glad you were able to find the post helpful!
Old 4th March 2012
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So, how do you like those things. I have a Pro VLA II that I really like on certain things. I like running acoustic guitar thru it on the way in, as well as certain dynamic vocals. Did a fiddle session that I used it on too and it was really good. Mine is completely stock, as I bought it new and have never opened it up. I really like the tone/color of the makeup gain.

Just wondering how useful you find the "fixed" attack/release settings.
Old 5th March 2012
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I actually just purchased an original Chinese Pro VLA...

I owned the VLA II but would prefer the auto attack release times.

My version has Chinese 12ax7's

I'll probably put in some 12AT7's (maybe)
Old 5th March 2012
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Why do you prefer the auto attack/release over the manual control?
Old 5th March 2012
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Quote:
Originally Posted by NYCruiser View Post
Why do you prefer the auto attack/release over the manual control?
Basically just set it and forget it controls...I already notice that this VLA I doesn't roll off as much top end which I like...More of a crisp sound in comparison to my VLA II

I'm using the AX7's stock from 1998 I think, at least that's what they look like.

The big advantage of the VLA II is the stereo handling, having to set each channels output on this VLA I is annoying.
Old 5th March 2012
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Oh, I didn't realize the originals didn't have the stereo link. That would be huge to me. TBH, I usually leave the attack/release straight up in the middle and only adjust them when I hear something I want to try and grab, or not grab. Usually the straight up position is fine. Its not a very fast comp anyway.
Old 5th March 2012
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Quote:
Originally Posted by NYCruiser View Post
Oh, I didn't realize the originals didn't have the stereo link. That would be huge to me. TBH, I usually leave the attack/release straight up in the middle and only adjust them when I hear something I want to try and grab, or not grab. Usually the straight up position is fine. Its not a very fast comp anyway.
Yeah I'd actually prefer to have my attack time have a way to be slower than it is...The release is fine on the original...Funny thing is I prefer the sound of this original to the VLA II...A lot more gain reduction almost no top end roll off...very transparent, I'm very very happy I switched!
Old 5th March 2012
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Yeah, I notice the high end roll-off. Easy enough to put back with a touch of eq....kind of like a ribbon mic. Sometimes it really works during tracking certain things though. Can be interesting on acoustic guitar, and was really cool when I was tracking a fiddle player.

You're saying the VLA I isn't affecting the high end at all? Or just less.
Old 6th March 2012
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Quote:
Originally Posted by NYCruiser View Post
You're saying the VLA I isn't affecting the high end at all? Or just less.
Definitely if you get up more than 10db with an agressive ratio it still will hit it...But I noticed that with the VLA II it was almost automatic that it would taper the high end a bit, no matter what you fed into it.

I'm thinking I'll go and pic up the JJ AT7's, I'm running it with the 12AX7's, Bowie PM'd me and said I might get better results from a lower gain tube.
Old 6th March 2012
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Interesting. I'm running stock tubes in mine. I wonder if a different tube would help the high end at all.
Old 6th March 2012
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Quote:
Originally Posted by NYCruiser View Post
Interesting. I'm running stock tubes in mine. I wonder if a different tube would help the high end at all.
It's funny you say that..I actually switched out the tubes in my PRO VLA II with the 12AT7 JJ's...The stock were Ruby tubes if I remember correctly...Truthfully they were very close, I may have actually preferred the stock tubes at the end of the day.

I have to say after using the VLA I for a day now I miss that manual release time a lot :(
Old 6th March 2012
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My understanding is that the tube is only in use on the gain stage, and not the compression stage. Other than the losing a little highs, I haven't been motivated to open the thing up and mess with it.

LOL….that's why I was interested to hear why you preferred the fixed attack/release. I figure the manual controls can be set to match the fixed settings on the VLA I, but not the other way around.

Difference is if the units actually "sound" different. Which I'm getting that they do. I have my eye out for an EQ to put in line with the VLA II to solve the high roll off.
Old 8th March 2012
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Quote:
Originally Posted by NYCruiser View Post
My understanding is that the tube is only in use on the gain stage, and not the compression stage. Other than the losing a little highs, I haven't been motivated to open the thing up and mess with it.

Correct. The compression stage is an optocompressor. The tube circuit is on the gain stage. I have a matched set of Mullards in my modded VLA II, and haven't noticed any high-end rolloff. But I can't hear anything over 13K anyway...
Old 8th March 2012
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Quote:
Originally Posted by Old Goat View Post
Correct. The compression stage is an optocompressor. The tube circuit is on the gain stage. I have a matched set of Mullards in my modded VLA II, and haven't noticed any high-end rolloff. But I can't hear anything over 13K anyway...
Ha ha ha ha……I'm probably only a few years away from having all the highs roll off myself…..I guess I'll just wait and pretend the highs are really all there!!
Old 8th March 2012
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Quote:
Originally Posted by Old Goat View Post
Correct. The compression stage is an optocompressor. The tube circuit is on the gain stage. I have a matched set of Mullards in my modded VLA II, and haven't noticed any high-end rolloff. But I can't hear anything over 13K anyway...
I'm wondering, the tube gain stage is on the input right??
Old 8th March 2012
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Nevermind, from looking at the schematic it appears to be on the output.
Old 8th March 2012
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Yeah, most compressors will have gain on the output…"make-up gain" to counter the level loss from the limiting stage. Its the part of the process that makes the low parts louder. No sense in gaining up the signal first because then the peaks would be clipping.
Old 8th March 2012
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Though I'm not sure that the output knob is affecting the tube gain. It looks like the tube has a fixed gain, and then the output knob is solid state. 45v going to the tube so it's starved plate (but I don't care.) Sounds good to me, just interested to know.
Old 8th March 2012
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Check it out
Attached Files
File Type: pdf art pro vla schem.pdf (144.3 KB, 53 views)
Old 8th March 2012
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Cool. I never looked at the schematic before. This schematic is for the original VLA I. It is showing the fast/slow attack/release switch.

Interesting design. The output of the tube is run thru a varistor "VR3" on the Pots PCB…I guess that is the gain knob. The output of that center tap then feeds the input of the opamp "A2A". So the output knob is determining how much tube signal is sent to the input of the output op amp A2A. That avoids the tube having to be biased to provide all the gain, but still provide the "sound".

Thanks for sharing that.
Old 8th March 2012
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Quote:
Originally Posted by NYCruiser View Post
Cool. That avoids the tube having to be biased to provide all the gain, but still provide the "sound".

Thanks for sharing that.
Definitely, does provide the sound...When checking a 1K tone through it on an analyzer it definitely does something harmonically with the sound adding even order harmonics pretty nicely.
Old 8th March 2012
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Yeah, I like mine too. After seeing the schematic, I know why the tube sound is so prominent. The entire tube ouput is sent thru an opamp. The harmonics get amplified with the signal at that stage I would think.
Old 9th March 2012
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Quote:
Originally Posted by FilmNMusicman View Post
Though I'm not sure that the output knob is affecting the tube gain. It looks like the tube has a fixed gain, and then the output knob is solid state. 45v going to the tube so it's starved plate (but I don't care.) Sounds good to me, just interested to know.
I had mine modded, and one of the mods was upgrading the tube circuit to full plate voltage. Now, take this with a grain of something, but I've read that starved plate harmonics are odd, and full plate harmonics are even, which gives a more pleasing sound.

All I know is that I really like the sound, especially on vocals.
Old 9th March 2012
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I don't know if I buy into the even/odd harmonics, but a full plate voltage tube will give a "truer" tube sound as long as it is modified so the tube amp is actually made to be the functional output amp.

According to the schematic, the stock arrangement uses an op-amp for output gain and the tube just to color the sound before it is input to that stage.

Not a really hard mod to do really if someone is motivated to do it. The biggest part of it would have to be modifying the power supply to supply the plate voltage without making the unit noisy.

I kinda like the stock sound of mine so far, so I'm not motivated. That could change at a moment's notice though! LOL!!

Edit: If I was going to mod this device, I think I would replace the op-amp with a transformer coupling on the output before I messed with the tube plate voltage. I wouldn't need to mess with the power supply to do that.
Old 9th March 2012
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I guess someone beat me to the punch on the transformers….LOL!

If I was going to mod my VLA, it would be something like this:

Scroll down to post #9 in this thread;

JJ Audio Pro Vla Mod tests....
Old 10th March 2012
  #28
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Hey there. Great to see so much useful information in one thread. I'm new to Gearslutz, and I had a question that was similar to what you are all discussing in this thread... but I posted in in Low End Theory, not knowing there was a more tech-based forum. Oops.

Anyway, I don't want to cause too much trouble, but perhaps some of you may be able to take a look and chime in so I'm not reposting?

ART VLA & MPA IIs Tube Install... Matched Pairs?

Thank you very much!

C
Old 10th March 2012
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"matching" the tubes on a tester would ensure similar performance between the two, which of course would be desirable for stereo operation. But, not having them matched doesn't automatically mean that they won't match - or be close enough for your usage. You'll just have to pop 'em in and see if you see any noticeable difference in performance.
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