VTB-1...built-in compression?

B

Bodhisan

Hillbilly
I've been recording, mostly mic'd acoustic instruments, with the VTB-1 for over two years. I recently acquired a lefty jazz box and tracked with it today. I wanted a dirty sound, so I dialed in the tube at about 4 p.m., getting a pretty nice sound with a touch of crunch. The sound wave was without any dynamic peaks. Just like a bumpy worm (picture the steady wave of a keyboard that you're just chording). I was mic'ing an old Gibson Falcon with an AEA R84. At first, I thought it was the result of my ribbon mic, but I decided to record a clean track. I turned the tube dial to the 7 p.m. position, which is all SS. Well, the peaks and dynamics returned, like the typical waves I get. Just to make sure I wasn't mistaken, I recorded another 4 p.m. tube track, and the compression returned.

You smart people out there probably already knew this or know why it happens, but I had no idea. It's quite the bonus. I'm no rich man (how do I explain the R84? Uh...I sold a few things), so I'm always happy about how great these little VTB-1's (I've got two) are.

Bodhisan
 
Some of the preamps with heavy transformers can start to slow down the signal enough as the output transformer is pushed that it acts as signal compression. Could be that when the starved plate tube drive is pushed on the VTB-1 that it also slows down the signal enough to cause some compression. That's my guess.
 
Bodhisan said:
I've been recording, mostly mic'd acoustic instruments, with the VTB-1 for over two years. I recently acquired a lefty jazz box and tracked with it today. I wanted a dirty sound, so I dialed in the tube at about 4 p.m., getting a pretty nice sound with a touch of crunch. The sound wave was without any dynamic peaks. Just like a bumpy worm (picture the steady wave of a keyboard that you're just chording). I was mic'ing an old Gibson Falcon with an AEA R84. At first, I thought it was the result of my ribbon mic, but I decided to record a clean track. I turned the tube dial to the 7 p.m. position, which is all SS. Well, the peaks and dynamics returned, like the typical waves I get. Just to make sure I wasn't mistaken, I recorded another 4 p.m. tube track, and the compression returned.

You smart people out there probably already knew this or know why it happens, but I had no idea. It's quite the bonus. I'm no rich man (how do I explain the R84? Uh...I sold a few things), so I'm always happy about how great these little VTB-1's (I've got two) are.

Bodhisan
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I can't say for sure what's happening here, but if you are getting "crunch," it's probably due to clipping (later in your signal chain) rather than the tube drive itself. I have never been able to get a good distortion sound out of my VTB-1, which I presume is due to the starved-plate design. You just don't get enough flow through the tube to cause any major breakup. So, I would guess that you are just creating too much gain with the VTB-1 and it is causing clipping in another component, which would result in distortion without much in the way of dynamics. Just a thought.
 
He's Right!

No No No! You're absolutely right dude and I gave you a rep point for it.

I've been messing around with my new (used) VTB-1 and the all-out-tube setting gets a noticable amount of distortion going. on tracks that have been recorded at full tube, it almost sounds like i was running the channel through my marshall! as you say, you can see the distortion in the wave form. this distortion is not present when the preamp is set to SS, so it is not merely a result of it clipping, or of clipping further down the signal chain.

on another note- i like this feature of the VTB-1. the distortion has lent my digital recordings a more tape-like feel. i keep it at full tube.

what do other people set their VTB-1's at?
 
mcolling said:
No No No! You're absolutely right dude and I gave you a rep point for it.

I've been messing around with my new (used) VTB-1 and the all-out-tube setting gets a noticable amount of distortion going. on tracks that have been recorded at full tube, it almost sounds like i was running the channel through my marshall! as you say, you can see the distortion in the wave form. this distortion is not present when the preamp is set to SS, so it is not merely a result of it clipping, or of clipping further down the signal chain.

on another note- i like this feature of the VTB-1. the distortion has lent my digital recordings a more tape-like feel. i keep it at full tube.

what do other people set their VTB-1's at?
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i dunno... i don't think going past straight up 12o'clock on my vtb1's impart anything useable. the starved plate thang can add a bit of "fatness" to a vocal track when used sparingly, but to say diming the thing sounds like a marshall... well, i would have to hear that to believe it.:rolleyes:
don't get me wrong, i like the vtb-1 enough to own two of'em, but this sounds farfetched to me, at least in my experience. mine are definitely more subtle than that. i think you must be clipping something else to get that kind of distortion, but i don't want to rain on your parade... knock yourself out :D
- jv
 
johneeeveee said:
i dunno... i don't think going past straight up 12o'clock on my vtb1's impart anything useable. the starved plate thang can add a bit of "fatness" to a vocal track when used sparingly
Click to expand...

So.... you agree that there is distortion

johneeeveee said:
don't get me wrong, i like the vtb-1 enough to own two of'em, but this sounds farfetched to me, at least in my experience. mine are definitely more subtle than that. i think you must be clipping something else to get that kind of distortion.
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But you don't at the same time?? Please clarify.

Now clearly I was exaggerating when I said it sounds like a Marshall. Point being is that the tube distortion is there when you put it at the tube setting. I happen to like that sound, but I can understand why many would not.
 
Certainly the tube drive adds harmonic distortion. That's its purpose. The question is whether it can create that overdriven kind of sound. Frankly, without hearing what this poster is accomplishing, we are all just speculating. All I can say, based on my experience, is that I have never gotten an overdriven sound from cranking my VTB-1 all the way up. I have, however, gotten a nasty distortion from clipping either my compressor and/or soundcard. If the poster is happy with the sound he is getting, it really doesn't matter how he is accomplishing it.
 
scrubs said:
Certainly the tube drive adds harmonic distortion. That's its purpose. The question is whether it can create that overdriven kind of sound. Frankly, without hearing what this poster is accomplishing, we are all just speculating. All I can say, based on my experience, is that I have never gotten an overdriven sound from cranking my VTB-1 all the way up. I have, however, gotten a nasty distortion from clipping either my compressor and/or soundcard. If the poster is happy with the sound he is getting, it really doesn't matter how he is accomplishing it.
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scrubs said it better than me... and as i said before, mcolling, i didn't mean to rain on your parade, and if it sounds good to you, knock yourself out... it is however my feeling from my experience that the type of distortion that you are describing probably isn't coming from the starved plate tube in the vtb-1. if you are getting sounds that work for you it really doesn't matter how you're getting them, as long as you aren't damaging your gear. i just wanted to put my 2 cents in there so folks might not be mislead into thinking that the vtb-1 is a good choice for distorted direct guitar tracks. i personally don't find it to be a very good direct box at all, but think it's a good affordable mic pre. i didn't mean to ruffle your feathers, but simply wanted to give another first hand viewpoint.
peace - jv
 
Thanks for the rep nom and support, mcolling! I wasn't expecting a debate on the "distortion" quality of the VTB-1, but rather the compression that occurs when the tube's dialed up (that's what I find interesting). There is, however, definite breaking up when the dial's turned up -- at least with my VTB-1's. In the past, I've had occasion where I forgot to turn the tube dial off after doing a vocal with it (where I do not get a breaking up, interestingly), and would get a little distortion on my pedal steel with no clipping in my meters -- turn off the tube and the distortion disappears. If the distortion was occurring elsewhere in the chain, then when the tube was turned down, the distortion would still be there (wouldn't it?), and it's not -- it goes away as it's dialed back more toward the solid state side of the dial. Maybe my use of the word "crunch" was wrong. Just adds a little sizzle and brightness, and most definitely a little breaking up in a bluesy way.

However, as a caveat, so as not to mislead anyone, I would not recommend buying the VTB-1 as your source of distorted effects for guitar, as Johneeeveee stated.
 
Mmm...interesting. I recently went to part exchange my VTB-1 and the guy put it through its paces to make sure it was working to spec, which I presumed it was. He started looking suspicious and pulled out a new one to compare mine to. He ended up refusing to take it, saying that the tube must be bad, compressing the signal after about 1 or 2 o'clock. I said "Nonsense, it's done that since new - it's tube compression kicking in, right?" But the guy demonstrated that the store one wasn't exhibiting anything like the amount of compression mine was, instead thickening the sound without any noticeable leveling of signal, unlike mine.

Sounds like VTB-1s might have a consistency issue, at least in the tube.
 
robin watson said:
Sounds like VTB-1s might have a consistency issue, at least in the tube.
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yeah- that could easily be the case. mine levels out the signal noticably when the tube is up all the way, which is apparent looking at the wave form on cool edit pro. i guess the question with regards to the consistency issue is:

do other people experience this?

as far as my "marshall" comparison, i was only pointing out that a drum track i did with it had a noticable distortion to it, not unlike that of a tube guitar amp (although much less pronounced). of course you can't use it for distorted DI tracks! but don't worry, you're definitely not raining on my parade. :)
 
I like mine, but only dial in a small amount of tube (maybe 9 o-clock at most) and it sounds great. Anything past that, and it sounds like a cheap Chinese tewb-pre. IMO.
 
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Robin -- thanks for the tip. I'm sure I would have noticed this before, but haven't, so maybe it is a tube issue, and it's recently gone wacky on me. I'll check my other VTB-1 and see if it also compresses...
 
Okay. I tracked with my other VTB-1, and no compression like the other. Must be a tube problem. I'll get in touch with SP just to verify before I get in there and stick in another tube.
 
How much compression are we talking? Do you think you could describe the difference so that I can verify if mine is faulty, please?

.... oh wait, I like the sound.
 
mcolling: It's a drastic compression. If I've got the faulty pre set with the meter in my pro tools hitting the yellow and an occasional red, turning the dial up to 3 p.m. stops the reading a lttle past midway up the meter poll -- cutting it almost in half. Using my "good" pre, turning the dial to 3 p.m. or even all the way does nothing to the signal -- it still reads identical as to the signal with no tube (reaching yellow and an occasional red).

I heard from PMI, and they're going to "check with their designer." They claim they've never heard of this problem before.

I thought I liked the sound, too, but as someone mentioned, when I compare to the good pre, it does turn the sound thinner -- which could be good if it's what you're looking for.

Bodhisan
 
Appreciate that. :)

Thankfully, my pre isn't like that. When I turn the tube up, the strenght of the signal isn't affected. What I do notice is flattening of the wave form in cool edit, as though it were clipping (well, i guess it is clipping, sort of). But the signal strength does not really change much. Dynamically, the peaks seem to reduced a bit, and the quiter parts are boosted, much as though the signal was being compressed.
 
The problem with the DI I beleive is that different opamps work better with different impedences, and the opamp in the VTB-1 is tailored for lo-Z, and not for the hi-Z of a guitar. If you need a DI, get a DI. Try swapping out your tube and see if it still compresses.
 
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