1U Rack space

8 individual channels of
TRS or XLR in
TRS out
Passive (or active if necessary) control of volume/output

I've posted before with regard to why i need this. Outputs from mic pre
(even with input gain ALL the way down) are too hot for RME Multiface
inputs.

Why not just put the offending outputs through a compressor ? Don't
have 8 channels of compressors, and i'm trying to keep the rack small
and mobile.

The SMPro Audio DI-8 is close, but why am i suspicious of a $90 price
tag for 8 channels ? Plus the config is not optimal - inputs are in
back and outputs are in front. if it's not going to degrade signal,
then i'll use it if it's the only thing out there.

accepting all recommendations.

for those who wish to continue educating me as to why this is
happening, or if there are other affordable options for avoiding it,
i'm all ears for that too. one signal chain example - km184 drum
overhead mic to sytek mpx-4a to RME input. the input is clipping at the
RME input. RME input is configured via internal jumper to "Low Gain"
setting, which if i understand it correctly is supposed to be the max
setting for hot input.

thanks in advance
-dan

follow up to original post -

anyone recommend an in-line transformer/pad like Audio Technica's
AT8202 ?? likely i'll only need attenuation for the condensor mics.. so
i might survive only needing 4 to 6 of them.

does anyone rack these buggers ??

"bantamdl" wrote ...
1U Rack space

8 individual channels of
TRS or XLR in
TRS out
Passive (or active if necessary) control of volume/output

The SMPro Audio DI-8 is close, but why am i suspicious of a $90 price
tag for 8 channels ?

A line-level mixer is one of the simplest kinds of audio circuits.

"bantamdl" wrote ...
follow up to original post -

anyone recommend an in-line transformer/pad like Audio Technica's
AT8202 ?? likely i'll only need attenuation for the condensor mics..
so
i might survive only needing 4 to 6 of them.

If you need only attenuation, spending money on transformers
seems wasteful of both money and quality.

"bantamdl" wrote in message
ups.com
1U Rack space

8 individual channels of
TRS or XLR in
TRS out

Passive (or active if necessary) control of
volume/output

I've posted before with regard to why i need this.

Under a different alias, if google searching is any guide.

Outputs from mic pre (even with input gain ALL the way
down) are too hot for RME Multiface inputs.

Ever hear of passive attenuators?

They are cheap, they are simple, and they work.

Here's an example of some simple ones:

http://www.fullcompass.com/Products/...142/index.html

Here are a more flexible one:

http://www.bhphotovideo.com/bnh/cont...list&sku=68600

bantamdl wrote:
1U Rack space

8 individual channels of
TRS or XLR in
TRS out
Passive (or active if necessary) control of volume/output

I've posted before with regard to why i need this. Outputs from mic pre
(even with input gain ALL the way down) are too hot for RME Multiface
inputs.

My gawd! What are you doing? Are you connecting the mic preamp's line
outputs to the Multiface's mic level inputs because they both have XLR
connectors? Hook your stuff up right and you'll be fine.

Line OUTPUTS go to LINE INPUTS. Connectors can be adapted.

one signal chain example - km184 drum
overhead mic to sytek mpx-4a to RME input. the input is clipping at the
RME input. RME input is configured via internal jumper to "Low Gain"
setting, which if i understand it correctly is supposed to be the max
setting for hot input.

Did you try setting the jumper to the "High Gain" setting? I read
through the manual when this came up a while back and it seemed like
maybe the interpretation was backwards of what it seems. As long as you
have the gain on the Sytek preamp set low enough so that you're not
clipping, its output level will be within the range that the RME LINE
input can accommodate.

bantamdl wrote:

anyone recommend an in-line transformer/pad like Audio Technica's
AT8202 ?? likely i'll only need attenuation for the condensor mics.. so
i might survive only needing 4 to 6 of them.

Sure, everybody should have a drawer full of the things around. Although
I recommend the Shure ones because they are switchable between three
attenuation levels.

does anyone rack these buggers ??

You could make your own with a rack panel and a bag of resistors.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

My gawd! What are you doing? Are you connecting the mic preamp's line
outputs to the Multiface's mic level inputs because they both have XLR
connectors? Hook your stuff up right and you'll be fine.

Line OUTPUTS go to LINE INPUTS. Connectors can be adapted.


RME Multiface doesn't have mic inputs... well mine doesn't... just line
level.

David Grant wrote:

RME Multiface doesn't have mic inputs... well mine doesn't... just line
level.

There are so many RME interfaces with similar names I can't be sure
which is which. Looking at the web site, there's a Multiface 2 that
specifies:

Analog level @ 0 dBFS (set by front panel switch): +2 dBV, +13 dBu, +19
dBu

Assuming that this is what he has, let's do the numbers.

According to the specs on Sytek's web site, nominal input level is -60
to -10 dBm, with up to 65 dB gain. It doesn't say what the minimum gain
is. It's reasonable to conclude that with an input level of -10 dBu,
somewhere in the range of adjustable gain, you should get output at the
nominal level of +4 dBu. But it might also mean that with -10 dBu in
and the gain set to minimum, you get +24 dBu out.

I suppose that a KM184 close to a loud drum might put out something on
this order of -10 dBu. The maximum output level of the Sytek is
specified as +24 dBu loaded with 600 ohms so going into the Multiface's
medium-impedance input, it's probably capable of something higher than
that. So it sure seems to me that if he has the Multiface set for +19
dBu for 0 dBFS, he should be at least in the ballpark but could go over
the fence some times. If the planets are sufficiently misaligned, It
may indeed be possible to bang on the drum and get more than +19 dBu
out of the preamp cleanly.

The Fireface setting of +19 dBu = 0 dBFS is the equivalent to "+4 dBu
nominal input level = -15 dBFS." This is fine for mixdown where you
have control over the dynamic range, but a bit on the hot side for live
recording, particularly for a source with as large dynamic range as
drums.

This is what system engineering is all about - making inputs and
outputs play nicely together. It would be nice if the RME had a more
conservative input sensitivity setting. +24 dBu = 0 dBFS would be the
ideal match for this preamp. However, it looks like a 6 dB pad between
the preamp out and the Multiface in is in order.

Spec sheets are useful some time (kudos to RME for publishing the
relationship between analog and digital levels - most don't do that so
clearly if at all) but you don't always know the whole story until you
measure, or at least understand what your meters are telling you.

funny - while i'm not as clear on how all the numbers result in the
final level that hits the Multiface, everything you've said here is
exactly what's happening.i have it set to that +19 setting, and it's
still clipping ... yes... not all the time, but some of the time ..
mainly with snare hits.

anywhoo.. it seems, while not as scientifically as others, i've arrived
at the right conclusion. i'll go out and get me-self some attenuators.
that should do the trick.

thanks guys.
dan

wrote in message
oups.com
funny - while i'm not as clear on how all the numbers
result in the final level that hits the Multiface,
everything you've said here is exactly what's happening.i
have it set to that +19 setting, and it's still clipping
... yes... not all the time, but some of the time ..
mainly with snare hits.

anywhoo.. it seems, while not as scientifically as
others, i've arrived at the right conclusion. i'll go out
and get me-self some attenuators. that should do the
trick.

At this point there's still one way that attenuators can't help you when
inserted between the preamp and the interface, and that's if the clipping is
in the mic pre. Of course then you can just move the attenuators downstream
from the mic preamp outputs to the mic preamp inputs. Win-win, right? ;-)

"David Grant" wrote in message
...


My gawd! What are you doing? Are you connecting the mic preamp's line
outputs to the Multiface's mic level inputs because they both have XLR
connectors? Hook your stuff up right and you'll be fine.

Line OUTPUTS go to LINE INPUTS. Connectors can be adapted.


RME Multiface doesn't have mic inputs... well mine doesn't... just line
level.

The O.P. isn't the only person who's had problems with the Sytek preamp not
going low enough in gain. Used with hot condenser microphones on loudish
sources (read: drums), they clipped the bejasus out of a ProTools rig I was
working with, set to nominal +4dBu input sensitivity.

Basically, he needs an attenuator, either at the mic input or between the
preamp and the Multiface. I'd suggest the former.

Peace,
Paul

Arny Krueger wrote:

At this point there's still one way that attenuators can't help you when
inserted between the preamp and the interface, and that's if the clipping is
in the mic pre. Of course then you can just move the attenuators downstream
from the mic preamp outputs to the mic preamp inputs. Win-win, right? ;-)

More like win-draw. If the preamp was actually clipping, it would be
trying to put out more than +24 dBu, which is 5 dB more than it takes
to clip the RME.

With a 6 dB pad at the output, the preamp and the Multiface will clip
at the same point, and that's the best you can do. By padding down the
mic, you could keep the preamp output down, but you'd be compromising
(admittedly by a trivial amount) the S/N ratio right at the front end.

"Paul Stamler" wrote in message
...
"David Grant" wrote in message
...


My gawd! What are you doing? Are you connecting the mic preamp's line
outputs to the Multiface's mic level inputs because they both have XLR
connectors? Hook your stuff up right and you'll be fine.

Line OUTPUTS go to LINE INPUTS. Connectors can be adapted.


RME Multiface doesn't have mic inputs... well mine doesn't... just line
level.

The O.P. isn't the only person who's had problems with the Sytek preamp
not
going low enough in gain. Used with hot condenser microphones on loudish
sources (read: drums), they clipped the bejasus out of a ProTools rig I
was
working with, set to nominal +4dBu input sensitivity.

Basically, he needs an attenuator, either at the mic input or between the
preamp and the Multiface. I'd suggest the former.

Peace,
Paul


Agreed. I used to have a Sytek & ran into the same problem. IIRC, the Sytek
has no padding. I once bypassed the preamp completely & sent the mic (451
w/ck3 close in on HH) directly to the input & it worked.

Preamps? We don't need no stinkin' preamps!

Mikey
Nova Music Productions

Michael Wozniak wrote:

I used to have a Sytek & ran into the same problem. IIRC, the Sytek
has no padding.

This may be a different problem, but it's not the problem under
discussion. The problem is that the RME interface has insufficient
padding to accept the maximum output level of the preamp.

Well, maybe it IS the same problem, just further downstream.

I once bypassed the preamp completely & sent the mic (451
w/ck3 close in on HH) directly to the input & it worked.

Probably not very well, however, without phantom power, assuming that
"451" is an AKG C-451, a fairly common hi-hat mic for thems as use 'em.

"Mike Rivers" wrote in message
oups.com...

Michael Wozniak wrote:

I used to have a Sytek & ran into the same problem. IIRC, the Sytek
has no padding.

This may be a different problem, but it's not the problem under
discussion. The problem is that the RME interface has insufficient
padding to accept the maximum output level of the preamp.

Well, maybe it IS the same problem, just further downstream.

I once bypassed the preamp completely & sent the mic (451
w/ck3 close in on HH) directly to the input & it worked.

Probably not very well, however, without phantom power, assuming that
"451" is an AKG C-451, a fairly common hi-hat mic for thems as use 'em.

Good catch. At the time I had an outboard phantom power box -can't remember
what brand or model. AT? Stewart?

Mikey
Nova Music Productions

yeah.. after thinking about this for a bit... am i correct in thinking
it would NOT be a good idea to put the XLR attenuator in between the
preamp and the RME... right ?? After all, those attenuators aren't
expecting line level signals right ??

Assuming it's more appropriate to put the pad in between the MIC and
the PREAMP input, and then turn the input level on the preamp up....
with KM184's it's not likely to multiply too much noise (mike rivers
alluded to this before).... but what if it's a 57 ?

i'm not looking at some ugly noise situation in that case, am i ?

it shouldn't be, right?...i mean, a lot of mics come with these things
as part of the microphone... and these attenuators are typically made
by the likes of shure and audio-technica... who should know something
about mic signals.. so im assuming that this should be of no
consequence

my guess is it's not going to be anything that would compromise the
audio, i'd just like to throw it out there for discussion.

bantamdl wrote:
yeah.. after thinking about this for a bit... am i correct in thinking
it would NOT be a good idea to put the XLR attenuator in between the
preamp and the RME... right ?? After all, those attenuators aren't
expecting line level signals right ??

If that's where the level needs to be attenuated, sure. Put it there.
It's a couple resistors in a barrel... it doesn't care what signal levels
across it are like. You could put 120V across it and it would attenuate
it just fine, probably. More than that and you might have heating issues.

Assuming it's more appropriate to put the pad in between the MIC and
the PREAMP input, and then turn the input level on the preamp up....
with KM184's it's not likely to multiply too much noise (mike rivers
alluded to this before).... but what if it's a 57 ?

If the preamp is clipping, put it in front of the preamp. If the RME
is clipping and the preamp is not, put it between the preamp and the
RME.

If you can just turn the preamp down a couple notches so the RME doesn't
clip, that would be preferable to adding attenuation. But sometimes
you can't.

The issue is to find out what's clipping and put the attenuator in front
of it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

well... i've just done a little testing with all of this... and it
actually looks as if my original suspicion is on the right track.

this is using the shure attenuator, always at the -15db setting.

((1)) mic-sytek-attenuator-rme
------------------------------------------
a) with sytek input gain at 0, yields, as expected, a *really* small
final level into the rme, and the final resulting recorded waveform
seems normal.

b) as you raise input gain on the sytek, it (obviously) raises the
level hitting the attenuator, but the attenuator can't handle it and
what results is a flat, distorted wave that maxes out somewhere in the
middle of the available db scale. so it seems that there isn't an
unlimited bit of "headroom" on that attenuator. (for the record... the
final distorted sound was kinda BITCHIN'. could this be usable
distortion???...hmmmmm.....but i digress..)

((2)) mic-attenuator-sytek-rme
------------------------------------------
a) with sytek input gain at 0, same as 1) a) above.
b) as you might expect, all is well, and you're amplifying that smaller
signal as you wish and can take it up as far as you need. there does
not seem to be any painfully obvious loss of signal quality. of course,
my ears ain't golden.

either way... seems like option 2 is the best way to go, raising the
mic pre gain as needed.

"bantamdl" wrote in message
ups.com...
well... i've just done a little testing with all of this... and it
actually looks as if my original suspicion is on the right track.

this is using the shure attenuator, always at the -15db setting.

((1)) mic-sytek-attenuator-rme
------------------------------------------
a) with sytek input gain at 0, yields, as expected, a *really* small
final level into the rme, and the final resulting recorded waveform
seems normal.

b) as you raise input gain on the sytek, it (obviously) raises the
level hitting the attenuator, but the attenuator can't handle it and
what results is a flat, distorted wave that maxes out somewhere in the
middle of the available db scale. so it seems that there isn't an
unlimited bit of "headroom" on that attenuator. (for the record... the
final distorted sound was kinda BITCHIN'. could this be usable
distortion???...hmmmmm.....but i digress..)

The attenuator can handle it fine. You're watching the Sytek clip.

Peace,
Paul

bantamdl wrote:
yeah.. after thinking about this for a bit... am i correct in thinking
it would NOT be a good idea to put the XLR attenuator in between the
preamp and the RME... right ??

Wrong. A passive attenuator will have no problem with a line level.

After all, those attenuators aren't expecting line level signals right ??

It's hard to make one that won't take line level. Transformers are a
different story. A transformer that's too small physically can cause
distortion with high level signals, so there are transformers designed
for line level and ones designed for not much higher than mic level.
But what you need is a simple passive attenuator. Nothing in there but
resistors.

i'm not looking at some ugly noise situation in that case, am i ?

By attenuating the signal ahead of the mic preamp, you will be
compromising the signal-to-noise ratio by not using all the gain you
have available (without clipping of course). But it's not a huge
difference. If it makes you feel better to put the attenuator at the
input of the preamp rather than at the output, do it. But be aware that
this will change the electrical load on the mic, so the mic may sound
different (again, not radically different) with the attenuator in line
than without. At line levels and impedances, however, this effect is
negligable.

ok. i'm slow, for sure, but eventually i'll understand this. What
you're saying (and what i've just seen in my own experiment) seems to
imply that there are 2 stages of gain in the sytek :

1) an input gain that is *changeable* (via the knob on the front), and
whose resulting signal hits :

2) the final amplification stage that is constant and unchangeable.

is that right ?

thanks for your patience so far, guys.

bantamdl wrote:
ok. i'm slow, for sure, but eventually i'll understand this. What
you're saying (and what i've just seen in my own experiment) seems to
imply that there are 2 stages of gain in the sytek :

1) an input gain that is *changeable* (via the knob on the front), and
whose resulting signal hits :

2) the final amplification stage that is constant and unchangeable.

is that right ?

There are probably a couple dozen different gain stages in a typical
IC-based preamp, actually.

There is stuff in front of the gain control, and stuff after it. You
can clip the front end, in which case the gain control will be down near
the bottom of its range and you will still have a hot output.

You can also clip the output stage, in which case the gain control will
be up near the top and the input stage will still be okay.

When in doubt, try and select input and output levels so the gain control
is about in the middle.

Better designed equipment will have more headroom in the electronics and
therefore a wider range of usable gains, because it will be harder to
clip an individual stage.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

well, then.. i'm really going to have to decide if i hear a difference
with the attenuator before the mic pre - because using the attenuator
in between the sytek and the rme, while keeping input gain low enough
to prevent clipping the sytek yields a really small signal into the
rme. and i'm always under the impression that keeping the signal as hot
as possible into the converters is desirable.

or maybe i need another solution.

thanks for everyone's help and tutelage

bantamdl wrote:
well, then.. i'm really going to have to decide if i hear a difference
with the attenuator before the mic pre - because using the attenuator
in between the sytek and the rme, while keeping input gain low enough
to prevent clipping the sytek yields a really small signal into the
rme. and i'm always under the impression that keeping the signal as hot
as possible into the converters is desirable.

In that case, you are almost certainly clipping the Sytek and you want
to use the attenuator on the input. As I have said three times so far,
you need to find out what is clipping and put the attenuator in front of it.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

scott, i'm with ya man. all i've stated here (in so many words) is
that, my most appropriate option with a 15db pad *is* to put it before
the sytek (which, yes, you've mentioned 3 times).

... and given that mike has suggested (in another branch of this thread)
that it might be compromising the sound - im simply adding that i'm
going to have to determine if it's a compromise i can live with. if
not, i'll have to look for another solution.

this was a rhetorical post, mainly, sorry if it seemed i wasn't
listening.

thanks again.

"bantamdl" wrote in message
ups.com

well, then.. i'm really going to have to decide if i hear
a difference with the attenuator before the mic pre -
because using the attenuator in between the sytek and the
rme, while keeping input gain low enough to prevent
clipping the sytek yields a really small signal into the
rme.

What do you mean by "really small".

Do you mean that its a small squiggle on the screen? Probably not a problem.

and i'm always under the impression that keeping the
signal as hot as possible into the converters is
desirable.

That would be misinformation. As long as the signal going into the
converters peaks within 10 dB or so of full-scale, you're OK. I'd get
worried if the largest peaks were much lower than 15 dB below FS.

bantamdl wrote:

you're saying (and what i've just seen in my own experiment) seems to
imply that there are 2 stages of gain in the sytek :

1) an input gain that is *changeable* (via the knob on the front), and
whose resulting signal hits :

2) the final amplification stage that is constant and unchangeable.

is that right ?

There may be more than two gain stages (and probably are) but
essentially, yes. You can control the gain of the first stage, and
what's beyond that is fixed. Of course dropping the gain of the first
stage will drop the level at the output, and this will accomplish what
you're after.

In this case, you're not going to boost the output back up to some
higher level so as far as noise performance goes, it probably will do
no harm just to back down on the input gain until you don't clip the
A/D converter input. But it would be a more engineer-like approach to
put an attenuator between the preamp output and A/D input so that as
long as the preamp isn't clipping, the A/D can't clip.

It would be bad practice to run the input stage too low and then add
gain at a later stage because that later stage would be amplifying the
preamp noise. Not to say that this isn't done in some preamp designs,
but it's (usually) done with care and concern for noise levels, not
haphazardly.