ART Tube MP questions

**Matthew_84** · #1 10-26-2011, 09:20 AM

Hello TBers,

I use a ART Tube MP to regulate the signal going from a VT Bass Deluxe into a Crown XLS1000 power amp. But I have a couple of questions about it. The manual isn't very detailed, and a lot of the info I've read on the web is contradictory at best.

1) Is the tube necessary to producing an output signal? It is a "starved plate" design. I've read several different ideas that the signal will still come through without a tube, but other people say that it won't.

2) Because it is a starved plate design, is the tube suppossed to light up or no? I've never used tubes before but have heard that they light up. The only thing that lights up in my tube is two metal prongs at the top of the tube that glow orange from being really hot. I believe there are more than two prongs (or conductors) in that section and I'm not sure whether or not anything else should be "lit" up.

So I'm not sure whether the tube is functioning or not. I am still getting a strong output signal though, hence the first two questions.

3) Where should I have the input knob set to be just below clipping? In regards to the Power/Peak LED the manual says this, "If too much signal is present this LED lights red... The clip LED is positioned at the tube's output in the circuitry and lights when a level 6dB below hard clipping is reached." The signal is always green but as you push the signal it turns to yellow, to orange, and to red. I know red is hard clipping, but is it still clipping when it is yellow, or orange for that matter, or is just a warning that it's getting close to red? Really I'm not sure how clipping works, does the signal gradually clip the stronger it gets or is it an immediate progression from not clipping to hard clipping?

Thanks,

Matt

BassmanPaul · #2 10-26-2011, 11:54 AM

The starved plate indicates that the tube is being operated at a much lower voltage than normal. In the ART's case that's 48V DC. The two "prongs" that are lit are the heaters. That's all you see if the tube is in operation. I doesn't light up like a light bulb.

Because the tube has such a limited plate voltage it overdrives easily. If you set the output high and the input low the unit will operate cleanly. The reverse will give distortion. Using them both you can get any level of distortion you want.

bongomania · #3 10-26-2011, 12:23 PM

There's a lot of confusion and misleading statements out there about "starved plate" tube designs. Not you Paul--I mean in other threads.

Basically a tube can be implemented for "more" or "less" effect on the sound at any voltage, high or low. The flavor of the effect, the voicing or type of grit/warmth/other tone quality can be different at different voltages, but when people (again, in other threads) say things like starved-plate tubes are "just for show", they are missing the boat.

There are a lot of tube-containing devices out there where the tube IS "just for show", and often that show tube is run at low voltage, but it is wrong to lump all starved-plate designs into that just-for-show category. The amount the tube lights up can often be related to the amount of voltage feeding it, but has no relation to the tonal result.

End point: trust opinions from actual users, not from people ragging on starved-plate.

bongomania · #4 10-26-2011, 12:29 PM

Quote:

Originally Posted by Matthew_84

Where should I have the input knob set to be just below clipping?

Use your ears, exclusively. The LEDs are useful for a general representation of the signal level, but NOT actually useful for determining clipping. Forget what the manual says in that regard.

Quote:

Originally Posted by Matthew_84

Really I'm not sure how clipping works, does the signal gradually clip the stronger it gets or is it an immediate progression from not clipping to hard clipping?

It's gradual. Exactly HOW gradual depends on the specific device. With the ART pre, it's very gradual--lots of gray area.

**Matthew_84** · #5 10-26-2011, 02:20 PM

Thanks everyone for your input.

Yeah there are a lot of people who rag on these because of the "starved plate design". I watched a video by someone named ToneTaster (don't remember if it was on TB or not), but he put 5 different tubes in it and played the same tracks through the ART with the different tubes and there were noticable differences in tone. So when I read someone say that the tube is "just for show", I know with this unit, that isn't truly the case.

But I've also read that it works fine without a tube, so I'm a little confused as to how the tube really has much of an effect on the tone, unless the tube is placed in parallel of the circuit.

And thaanks Bongomania for your help about clipping. I have it set so when I really smack the strings it can get orange, but only when I really smack it at a point that I never would in a real playing situation. Even when I am playing hard I don't even see it reach yellow.

And I know you said to use my ears exclusively but I'm having a bit of a time with that. Unfortunately I've had to put this rig in a room with a lot of china (sounds stupid I know), but as I get louder I hear different antiques rattling on different notes. Sometimes it sounds so convincing as a bad speaker than I sit right in front of the cab and play the note until I can find out of sure that the noise is not coming from the speakers but from some china cabinet in the other corner. Actually I've found a lot of the rattling comes the body of the Crown XLS1000 placed on top of the cab. I put some felt pads under the amp to reduce this, but it doesn't seem to be helping much. If I put my hand on top of the amp then the rattling stops... Sorry got off topic there, so yeah, this rattling sound, to me, can sound a lot like clipping, but I only hear it when I start to turn the attenuator knob on the Crown up.

bongomania · #6 10-26-2011, 02:25 PM

Not doubting, just curious to read it myself--where did you see it said that the ART will pass signal without the tube?

will33 · #7 10-26-2011, 02:31 PM

Me thinks you're going to have to set the rig up in a room that doesn't contain china at least once to track down your rattles. You really should do this to tighten up the gear, vibrations, etc. aren't good for all the little parts in the amp. If any of that china is expensive or family heirloom type stuff you maybe don't want to be rattling it around all that much either.

steve_rolfeca · #8 10-26-2011, 02:34 PM

The MP sounds like heck when the tube eventually goes bad. I strongly suspect that anyone who thinks it will amplify a signal without the tube is mistaken.

will33 · #9 10-26-2011, 02:39 PM

Quote:

Originally Posted by bongomania

Not doubting, just curious to read it myself--where did you see it said that the ART will pass signal without the tube?

I'd be curious as well. I haven't tried mine without a tube but I assume it needs one. They're handy little units, good to have around. My only complaint is mine can get a little noisy if you have to get the levels up past 1:00-2:00. If need be, you can hit the +20db button and keep the knobs way low to run quiet but they get really touchy, to the point it's hard to get the right level without either clipping or being too quiet. The little bit of noise is a non-issue for live use but once in a great while for recording something that needs a bit of boosting, it'd be cool if that was a +10db button. Regardless, they're nice little units.

father of fires · #10 10-26-2011, 02:50 PM

Quote:

Originally Posted by bongomania

Not doubting, just curious to read it myself--where did you see it said that the ART will pass signal without the tube?

I heard it runs the tube in parallel with the signal.

**Matthew_84** · #11 10-26-2011, 03:22 PM

Quote:

Originally Posted by bongomania

Not doubting, just curious to read it myself--where did you see it said that the ART will pass signal without the tube?

Nowhere official Bongo.. It was just on other forums. One person was going on and on about how his friend insisted that the tube doesn't matter, he said that he tried different tubes and heard no difference, finally, he just tried it without one and the unit worked fine and he still didn't hear a difference. I called "bull****", because I know I've heard a difference, but it still made me curious about if it would really work without one.

I've just read that comment as well as a couple of other peoples, but it wasn't from ART or anything like that. If you're interested though, I'll try and find the links. I found all of them on other forums when I googled "ART Tube MP"

Quote:

Originally Posted by will33

Me thinks you're going to have to set the rig up in a room that doesn't contain china at least once to track down your rattles. You really should do this to tighten up the gear, vibrations, etc. aren't good for all the little parts in the amp. If any of that china is expensive or family heirloom type stuff you maybe don't want to be rattling it around all that much either.

Thanks Will, I should try that. My only concern is that the only good circuit in this house is in this room and there are antiques in every single room of the house so there's nowhere really to escape. Maybe I'll just have to wait until I take it out to a gig or practice or something. But I should figure out what's rattling, and if the rattling noise from the amp is simply the housing or if it's something else.

Thanks guys

will33 · #12 10-26-2011, 05:09 PM

Sell off a few antiques and spend the money on an electrician.

Set up outside, backyard or something. Nothing to rattle around out there and no walls to affect the sound. It's a good way to eliminate a lot of variables and find where the actual problems are. Share your talent with the neighbors. I suppose you would have to run an extension cord from your one good outlet in the china room.

will33 · #13 10-26-2011, 05:13 PM

You may want to get the wiring fixed before the house burns down and along with it your antiques, your gear and possibly even yourself....that stuff's no joke.

BulbousMoses · #14 10-26-2011, 05:24 PM

This is an interesting thread. I'm looking to buy an inexpensive, yet effective general purpose preamp to warm up and/or boost my signal. ART has been selling these Tube MP's for years so they must do something good to your sound...

**Matthew_84** · #15 10-26-2011, 05:30 PM

Yeah, the house is a rental though. I suppose the best money spent would be on a house, lol. The outside thing is a good idea though. Thanks Will. I'll set it up this weekend.

will33 · #16 10-26-2011, 05:35 PM

They're cheap and they don't do anything negative to your sound, maybe warm it up a little and they're handy. There are various models with more or less features. Mine is just simple input and output and has phantom power you can switch on and off. I've used it for a bunch of stuff. Boosting weak signals, splitting a vocal in two with one running to a board being recorded via hardwire to a computer and the other to a board for live sound, also works as a DI box should you have amp problems. It's also a preamp obviously, can run the output to a power amp. Probably find other uses for it too.

BassmanPaul · #17 10-27-2011, 09:59 AM

support@artproaudio.com An email will get you the schematic.

**Matthew_84** · #18 10-27-2011, 10:29 AM

Quote:

Originally Posted by BassmanPaul

support@artproaudio.com An email will get you the schematic.

Thanks Paul, e-mail sent.

bucephylus · #19 10-27-2011, 10:51 AM

My 2c experience is that the whole signal chain for an electric bass instrument operates with optimal tone when the instrument input is "saturating" (my term for providing an adequately hot signal) to the input stage of the actual preamp/amp. Bass instrument outputs are all over the place, and can commonly be not well matched to the input of the amp. The first bass I owned that really created some hot mustard tone-wise was an Alembic Series I. They have an exceptional preamp that really lights up most bass rigs. In contrast, a passive Jazz has an output that just starves the input on many bass amps. Of course, now there are a lot of outboard solutions out there, and many modern basses have active outputs that get in the same range as the Alembic (Sadowsky for example). However, many of the Bartolini circuits, like on the original Tobias, Zon etc instruments, have pretty weak outputs; and you need to use some kind of outboard device to get their true potential out of them. The passive inputs on the amps don't cut it. The ART remains a pretty decent very neutral solution. It works well with uprights and many electrics with low output. There are other solutions; but, for the money, its a pretty decent little box.

IME

PS: I will also add that this is really a missed opportunity, IMO, for the bass amp manufacturers. Some kind of similar circuit on the front end of the bass amps to actually support passive Fenders, for example, would be a real improvement. Kind of blows my mind that none of the Genz Benz's etc out there have picked up on this. I mean my '62 Jazz sounds fantastic; but, only if I put some kind of outboard between it and the amp. Same for a P. How can this still be the case with all the catering to customers and boutique work??? Oh well, I'll just keep dragging my outboard widgets around until someone makes an amp that actually supports passive basses. And, all for a $30 circuit. Go figure.

BassmanPaul · #20 10-27-2011, 11:48 AM

Quote:

Originally Posted by bucephylus

PS: I will also add that this is really a missed opportunity, IMO, for the bass amp manufacturers. Some kind of similar circuit on the front end of the bass amps to actually support passive Fenders, for example, would be a real improvement.

Every bass amp I've ever played through has supported my passive basses just fine. Sorry I am not getting your point.