dbx "Mini-Pre" versus ART Tube MP
David Satz
Due to a surplus of obstinate curiosity, I've just made a direct
comparison between the ART Tube MP (basic version) and the dbx
"Mini-Pre." I had suspected that they might be the same item
under different brand names, but they aren't--not quite, anyway.
The dbx preamp, unlike the ART, uses surface-mount technology except
for the tube and the rather numerous electrolytic capacitors. The
dbx preamp comes with a heftier 9 VAC wall wart (1300 mA vs. 900 mA);
the ART has a "+20 dB" gain switch while the dbx reverses the sense
of the switch and labels it as a 20 dB pad. But its effect seems
identical once you take the inverted sense into account.
Both units have slightly (~0.5 dB) elevated response at the bottom of
the audio range and slightly (~0.8 dB) reduced response at the top.
The input/output polarity of both units was correct.
The open-circuit phantom powering voltage of the ART was +44.2 VDC
while that of the dbx was +46.8 VDC. The dbx preamp passed my tests
for adequate phantom powering; the ART did, too, but just barely.
(I'm mainly interested in powering Schoeps Colette microphones, which
require 4 to 4.5 mA apiece depending on the accessories one uses.)
Neither preamp has a usable overload indicator. I easily got the ART
to put out 12.2% THD with no change whatsoever in its LED's color and
the dbx was at 3.3% THD before its red LED came on at all. But that
was with steady tones--with transients you could probably be 10+ dB
into clipping before any overload indication would be visible. (Those
two distortion figures were obtained under differing circumstances, so
please don't extrapolate anything from the difference between them.)
The ART preamp's input overload limit was about -4 dBu for a THD of
0.5%, while with the dbx this limit only about -15 dBu. The ART's
distortion decreased to about 0.25% with a -10 dBu input level, and
decreased to as low as about 0.13% at lower levels. In contrast,
the dbx's THD+N never got much below 0.25% at any combination of
input and output levels that I could find.
So the two preamps do have their differences. But I'd say that their
high distortion levels and lack of usable overload indicators make both
of them useless for most live recording with professional condenser
microphones. The dbx seems like a particularly poor choice given its
rather low input overload threshold and high residual distortion.
John Cafarella
"David Satz" <DS...@msn.com> wrote in message
news:e6a68193.02100...@posting.google.com...
> Dear all,
>
> Due to a surplus of obstinate curiosity, I've just made a direct
> comparison between the ART Tube MP (basic version) and the dbx
> "Mini-Pre." I had suspected that they might be the same item
> under different brand names, but they aren't--not quite, anyway.
What about the overall sound of the two? Significant difference?
I recently picked up an ART unit dirt cheap, based on comments here that it
was a good D.I. I replaced the tube with an old miniwatt that I had
kicking around, and found that if it's not driven hard, it's quite usable.
(context: bottom feeder, 1-4 projects/month). As a D.I. you can get some
pretty usable tones when driving it hard.
--
John Cafarella
End Of the Road Studio
Melbourne, Australia
John Halliburton
with good sucess. The distortion(isn't that supposed to be "crunch",
"overdrive" or some other guitar amp word?)does color the instrument sound
in a way that I see as good for the live sound of the instrument. I have
Countryman DI boxes as well, which produce an acceptable sound too, but
different-dare I say cleaner.
I would never considered the ART as a preamp for live recording with
Schoepps mics of any model.
Best regards,
John Halliburton
Servodrive/Sound Physics Labs, Inc.
Mike Rivers
> So the two preamps do have their differences. But I'd say that their
> high distortion levels and lack of usable overload indicators make both
> of them useless for most live recording with professional condenser
> microphones.
I'd agree with that assessment, but I thought these tooooob preamps
were used for their distortion. To people who can only spend $100 on a
preamp, it wouldn't sound like a tube without distortion.
--
I'm really Mike Rivers (mri...@d-and-d.com)
David Satz
> What about the overall sound of the two? Significant difference?
I didn't bother to listen to either preamp. The recording that I do
is nearly all live and nearly all classical. When equipment measures
this poorly, there's no reason to even consider using it, especially
since the overload indicators don't work.
At least on the "Studio" version of the ART there's a meter that can
be used during setup, though if I recall correctly each of its "dB"
units corresponds more like to 2 dB in the real world.
> I recently picked up an ART unit dirt cheap, based on comments
> here that it was a good D.I. I replaced the tube with an old
> miniwatt that I had kicking around, and found that if it's not
> driven hard, it's quite usable. (context: bottom feeder, 1-4
> projects/month). As a D.I. you can get some pretty usable tones
> when driving it hard.
That is the unit's reputation, especially for bass. But I'm unclear
which you're saying: it's OK to drive it hard, or it's not?
Anyway, I'm glad that you've found a good use for it.
Mark Richardson
David Satz wrote:
> As a D.I. you can get some pretty usable tones
> > when driving it hard.
>
> That is the unit's reputation, especially for bass. But I'm unclear
> which you're saying: it's OK to drive it hard, or it's not?
>
Somebody on this NG turned me onto using one as a bass DI, and I quite
like it. I've found that even keeping it well under clipping makes stuff
"rounder and fatter", not "clean" at all, which is a good thing for bass.
I'd never heard a DI bass tone I liked until I heard this (I'm not a fan
of clean, sterile bass). It's kinda noisy though, which makes it a good
idea to run as hot as possible without distorting. Driving it into
flat-out distortion makes it sound like a cheap stompbox.
I'm actually thinking about buying one just for use as a bass DI (the
ones I've used before were all borrowed)- it's a one-trick pony, but to
me, that one trick is worth the $80-$100 those things cost. It's unlikely
I'd ever run a mic through it though.
-Mark
Raymond
>I thought these tooooob preamps were used for their distortion.
So this may be an OK (but not best) pre for say... a rock/pop guitar?
When I got my DBX Mini (haven't used it yet) I didn't think it would be
anything close to high end. But will give a diffrent sound than I have in my
mixer (also cheap), I only payed $600.00 for the mixer and it has 12 pres in
it.
Raymond Ward
A.S. Recording Arts
J Pekka Makela
> That is the unit's reputation, especially for bass. But I'm unclear
> which you're saying: it's OK to drive it hard, or it's not?
According to my experience, depends on the tube you have in it.
I've tried only the stock Chinese 12AX7 and a NOS Philips
ECC83. The Philips gave much smoother and creamier (slight)
distortion when driven, but it did loose some definition.
THe stock Chinese tube sounds much edgier. If I'd use the
ART only as a bass/guitar preamp, I'd use the Phillips.
But for a mic preamp the Philips tube didn't fare as well.
(Yes, I do use the ART as a mic preamp. Sometimes the apparent
coloring works pretty well. And it just occured my mind that
the Philips' tube softer high end might work nicely with, say,
Rode NT1's edgy sound.)
--
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-"Yksikielinen ja yksitapainen maa on heikko ja sortuu helposti. Tämän -------
--vuoksi käsken sinua, poikani, auttamaan tulokkaita ja kunnioittamaan heitä.-
------------------------------ (Tapani Pyhä, Unkarin valtakunnan perustaja)---
John Cafarella
> > I recently picked up an ART unit dirt cheap, based on comments
> > here that it was a good D.I. I replaced the tube with an old
> > miniwatt that I had kicking around, and found that if it's not
> > driven hard, it's quite usable. (context: bottom feeder, 1-4
> > projects/month). As a D.I. you can get some pretty usable tones
> > when driving it hard.
>
> That is the unit's reputation, especially for bass. But I'm unclear
> which you're saying: it's OK to drive it hard, or it's not?
Both. As a pre, if you don't drive it too hard you can get some useful
tones out of it. This was however, after changing the tube. As a google
search shows, the sound of it is very dependant on the particular tube
that's in there. I tried 3 different tubes, and it had 3 quite different
sounds. The original was definitely the had the muddiest loose sound in the
low mids.
As a D.I., driven a bit harder it sounds good too. Kinda like gentle
compression, taking a few db off the top. Sorry about the clumsy wording in
the previous post.
cram
> comparison between the ART Tube MP (basic version) and the dbx
> "Mini-Pre." I had suspected that they might be the same item
> under different brand names, but they aren't--not quite, anyway.<
I applaud your comparison between these two pres, mostly because
nobody ever believes me when I say they are different.:) However,
these pre's were obviously not designed for highly critical recording
situations like live orchestral performances. The starved plate
design creates too much distortion for this application. Changing the
tube in a starved plate design really changes the way it sounds, as
others have suggested. I settled on an old GE 12au7 I had lying
around. With this tube, it does make a great D.I. box for bass, also
as others have already suggested. I've used it with great success
with keys as well, like Wurli, and Clav. Personally I would never use
it for vocals or drum overheads, but some folks I've talked to love to
use it on vocals for a special effect.
I find running your high-end Schoeps mics through a $100 pre-amp to be
deliciously perverse.:D :P
Tom Cram
dbx Senior Technical Support
(801) 568-7530
tc...@dbxpro.com
"I would rather be exposed to the inconveniences attending too much
liberty than to those attending too small a degree of it."
-Thomas Jefferson-
Mike Rivers
> Mike wrote
> >I thought these tooooob preamps were used for their distortion.
>
> So this may be an OK (but not best) pre for say... a rock/pop guitar?
Sure - consider it as a signal processor with gain. But if you want to
capture exactly what you hear coming out of the guitar amplifier, no
less and no more, then you're going to get more (and less) with this
preamp.
Raymond
>Sure - consider it as a signal processor with gain.
Thanks for the input Mike, I was thinking about an mid/late 70's sound for an
already distorted guitar. I think that a guitar that is overdriven to start
with may sound a bit warmer with some extra tube pre distortion (set to taste).
I'll try some tests next week as I have some time coming up to brake out the
DAW.
Raymond Ward
AS Recording Arts
David Satz
> I applaud your comparison between these two pres, mostly because
> nobody ever believes me when I say they are different.:)
Thanks for posting here. Glad to back you up ... I saw far more
difference inside the two boxes than on the outsides. However, I'd
really like to look at a circuit diagram for the dbx since I suspect
that its arrangement of stages, etc. is quite similar to the ART's.
> However, these pre's were obviously not designed for highly
> critical recording situations like live orchestral performances.
That's not obvious at all from the way these products are marketed.
This type of equipment is aiming at a kind of sound that isn't the
sound of "vintage" audio tube equipment. But in the sales pitch,
that distinction is getting lost, I suspect on purpose. (I'm not
blaming you for that--just bringing it up for possible discussion.)
> The starved plate design creates too much distortion for this
> application. Changing the tube in a starved plate design really
> changes the way it sounds, as others have suggested. I settled
> on an old GE 12au7 I had lying around. With this tube, it does
> make a great D.I. box for bass, also as others have already
> suggested. I've used it with great success with keys as well,
> like Wurli, and Clav.
Again, thanks for participating here and for posting your advice
and experience. It always helps when someone who knows what he's
talking about is posting here; I wish that happened more often.
> Personally I would never use it for vocals or drum overheads,
> but some folks I've talked to love to use it on vocals for a
> special effect.
Anyone certainly has a right to use any (legal) device to get any
desired effect. I would just suggest that the designers try to record
anything remotely rock and rollish through a TLM 103 with this preamp
some time; the output levels of modern condenser microphones are higher
than the designers seem to have realized. The inputs of a mike preamp
these days should be able to take at least half a Volt without clipping.
> I find running your high-end Schoeps mics through a $100 pre-amp to be
> deliciously perverse.:D :P
It was an interesting sound--not a true sound, but very "listenable."
I do all kinds of crazy things just for the learning experience, and
that one was well worth trying.