Behringer ADA8000 pre bypass questions

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This is just being used to add more outs in our writing room. That being said, there is no more manufacturing cost involved in making this unit deliver a standard output level, there are already balanced output drivers, it is only the choice of circuit employed.
I was hoping tho find that in a column where DIY improvements to this device are being discussed, this obvious fault had been deal with (and save me the trouble of searching 100+ pages!....I am so grateful for this forum, but the search engine leaves a little to be desired /I only wish that I was capable of helping to improve it)!
 
... there is no more manufacturing cost involved in making this unit deliver a standard output level, ...
Click to expand...
yes there is
and
what is standard these days ?

there is a world of manufacturing out there that wants an unterminated world
and
an unterminated world that works with +/-15volts rails
and
then there is a world of manufacturer that doesn't want analog at all except for the final stage and speaker drive

IF
you had a standard 28dBm on ALL 8 outputs, the power supply reqiuirement would be far greater then the ADA80000 or Ai3 has right now
and
Can those balanced output chips handle the current requirements for those levels and 600 ohm termination

The THAT balanced line driver is one of the newest devices to hit the market and I don't think it has that much grunt
nor the Texas instruments ones
and I have been using the SSM2142 for years ... and I restrict it to +/-15 volts and have no output resistors

and who would you be satisfying ?
the bulk of owners probably have a crappy Behringer desk top mixer that doesn't have the headroom anyway.

Manufacturers do what manufacturers do
if they all made great gear for a bargin
we wouldn't DIY
:roll:
... well ... not as much as we do

Yes
the search engine is a little ordinary when trying to search for deatailed info as above

Some around here have chosen to use a line driver on the outputs to acheive the BIG BALANCED and TERMINATED levels mentioned above

Try a Hybrid from JLM
Try the NEW I/O PCB from JLM
Try an API line driver


:shock:
oh and as for 12dBFS or 14 dBFS not being enough
again manufacturers and software writers do what they do

when the Tascam DA30 DAT machine arriver ... ALL those years ago
it was -14dBFS = +4dBu
Protools out of the box is -14dB
but yes
Sony DVW500 ihas two choices -18dB and -20dBFS

none of the above means that anything is faulty
 
I measured the output of the ADA8K today, it is -4Db (on a VU meter) or 0.6 volts AC unterminated with a -18 digital 1k signal.....-4? what is that? 8Db different than +4 4 shure!
 
it is very hard to understand what you have said

-4Db (on a VU meter) or 0.6 volts AC unterminated
Click to expand...
:?

I refer to Analog Devices dB calculator
http://www.analog.com/Analog_Root/static/techSupport/designTools/interactiveTools/dbconvert/dbconvert.html

-4dbV = 0.631 V rms
or
-4dBu = 0.6911791407907192 V peak = ( 0.4887 V rms )

some digital volt meters are not accurate at 1kHz so try at 100Hz

-18 digital 1k signal.....-4
Click to expand...
if your meter is dbV then you may have -18 FS = -1.782dBu and that would put -14dBFS at around +2dBu which in the sceme of things isn't that far from typical and your VU meter may be incorrectly calibrated if you have used a DVM at 1kHz

I can't see your test or test equipment so it is difficult to comment



As Jakob asked on the previous page
" so what is the level then, at 0dBfs (digital fullscale)? "
try again at both 1kHz and 100Hz
at 0dBFS and -14dBFS
with the DVM and the VU meter
(if possible with the VU as it may not have an attenuator for the 0dBFS)
 
It is exactly as in your post ...-18 digital full scale = -4 DbVU (as referenced to 0DbVU = +4 Db /1.23 Volts A. C. RMS) 0.6 volts (lob off all the extra digits!) AC RMS. I am using a Fluke 89 Mk IV meter, it has been extremely accurate so far
 
OK
:?
I'm still worried about the 0.6 V rms and how it fits in

try -14dBFS
and you should get

0dBVU = +4dBu = 1.23 V rms
(+4dBm if the output amp is good)
 
Actually I feel like doing this on my MX-2424. I hate the damn tubby sound it has as well as the rolloff of the high end. Everything sounds like you are hearing it though a blanket going through that damn thing. the I/O opamps are opa2604, not an IC i like anyway. I've pulled the output caps on the DAC boards as well as changed some of the opamps to Signetics 5532 but the input board is all SMD and I didn't have any SMD 5532.. but now I do..

I also plan to crack open a Motu 24 i/o if I get one to replace the MX-2424. We'll see how that goes too.
 
The ada8000 claims +16dbu = 0dbfs... are you guys saying it's not?

In practice it seems to mate well with modern as well as vintage gear... I tried to calibrate the 1/4" inputs for +18dbu = 0dbfs, but this can be a bit difficult as you need to use their stepped pots to adjust the gain (stock the input is +26Dbu = 0dbfs b/c of the -10db pad) which means you end up setting the pots somewhere on the hump of the stepped rotation...

I manged to get all of my inputs within +/- 0.2db of one another...

On a side-note. My modded ada8000 died!

I left it on overnight and in the morning it was dead. I have no idea what went wrong... no burned components... no strange smells. I don't quite have the trouble-shooting skills to track down what went wrong.

At $200 a pop, I just bought another one.

In fact. If anyone wants to pay the shipping costs, I'll give away my dead ada8000 !!

Although, getting a dead ada8000 might be like getting a lump of coal for x-mas. :green:

Happy Holidays! ~
 
[quote author="norman_nomad"]The ada8000 claims +16dbu = 0dbfs... are you guys saying it's not?

In practice it seems to mate well with modern as well as vintage gear... I tried to calibrate the 1/4" inputs for +18dbu = 0dbfs ... [/quote]I haven't claimed anything ... because I can't find my manual and I can't fire one of to test it right now.

someone else above, said they were having trouble.

IF the manual claims +16dBu = 0dBFS ... that is for the A to D and it could be true. You have said it involve the input circuitry and the stepper pots and the PAD.

this input attempt to be Microphone and Line levels is as far as calibration goes it is going top be a little flakey.

BUT
I'm sure I remember a spec of
MAX input level = +26dBu

as for the D to A
Max output level is what we were looking at.
As it is a +/- supply at typical voltages it is likely to be just like most of the other units out there.

0dBFS leading to +16dBu is very probable

so -12dBFS should lead to +4dBu
and so
0dBVU for a meter set for +4dB
and
-18dBFS should = -2dBu

nielsk
has " measured the output of the ADA8K today, it is -4Db (on a VU meter) or 0.6 volts AC unterminated with a -18 digital 1k signal.....-4? "

refering to the Analog Devices db calculator
0.6 rms = -2.218 dBu
(0.6 was been rounded off - see above)
0.6153 rms = -2dBu
.... your VU-meter seems to be dBV or it's just wrong ?

:green:
everything seems correct

for times when you need to interface to equipment that can run higher levels a patchable DA (distribution amp) with adjustable gain/level could be useful,
likewise a passive patchable Adjustable Input Level and Termination Unit can be useful.
 
:shock:

is this what the manual says ?
or
is it what you have measured ?

dBu means unterminated so I don't think the manual will say 500 ohms for a dBu spec
and 500 is very unusual for an audio spec anyway

and
if it is an actual measurement
then you will probably find that it also will do +16dB in to 600 ohms
 
That dead ADA8000, check the voltage regulators, IC27 goes bad. The transformer also goes bad. I have a pile of ADA8000s that need the power supply reworked.
 
[quote author="walter"]That dead ADA8000, check the voltage regulators, IC27 goes bad. The transformer also goes bad. I have a pile of ADA8000s that need the power supply reworked.[/quote]

I appreciate it Walter. Svart snatched up my dead one already... so maybe he'll have luck replacing the VR's or transformer...
 
Here is a quote from the datasheet of the A/D converter:

"The digital section of the AL1101 compensates for the passband amplitude deviation of an external single-pole 80kHz anti-alias filter (@ Fs=48k, scaling with Fs). To remove highfrequency noise at the differential inputs, the capacitor between the differential inputs should be located as close as possible to the input pins."

In the ADA8000, those capacitors are not mounted as close as possible to the input pins. Channel 1 & 2, C108 is mounted by pins 15,16 but it goes to pins 1,2. C109 is mounted by pins 1,2. this layout could be improved. I'm curious about how the grounds are configured as well.


I tried to copy the specs here, but It doesn't make it. The manual states: Line Outputs
Type XLR, electronically ballanced
Impedance approx. 500 ohm balanced,
approx. 250 ohm unbalanced
Max. output level +16 dBu @ 0 DBFS
Click to expand...
 
good page
I agree with most of it and you can probably fine some of the same info here in the pages of the LAB

The noise floor figures seem unforgiving ... but they do also add
Do not be misled by this!
Click to expand...

We have experience using this product regularly in a live sound application and have encountered no problems in either reliability or sonic fidelity.
Click to expand...
agreed
I use them live and for location recordings
I do use it in the studio for extra inputs and on synth and hardware reverb returns
... ouputs as effect send and extra Headphone cues etc ... non critical

The observation of the regulators is interesting
... The regulators are all very hot to the touch, too hot to hold your finger on, which is a concern that they do not have a lot of margin in their power supply. The transformer is completely cool to the touch.
Click to expand...

the price still remains the big drawcard for this unit
 
Did you see the pcb layout of the DIY 8 channel AD/DA Converter? Very interesting!! For me as a musician and electronic newbe this looks like a map of the London Underground. The main IC must be Paddington Station :? :green:
Regards
Bernd
 
here's the link.

http://audiorail.home.comcast.net/#E2.

you can also find Partlist, PCB Layout, schematics and artwork.
Amazing!! I wish I could ever do that :sad:
Bernd
 
Thanks for the great clips. The result from (aligned) polarity(/phase) inversion is quite interesting. There is a lot more of a difference than I expected, however the difference sounds pretty decent.

Listening normal, the converted track has a sligthly brighter top end, and a lot more distortion on snare hits than the original. Makes me guess (wildly?) that the colouration comes from the analouge output section. Was it at 0dBFS?

[quote author="norman_nomad"]Here are a couple more listening samples if anyone is interested.

The first one is the source file, and the second one has been passed through one of the stock channels set on its internal clock.

http://www.musicians-samples.com/Original - Palo Alto.wav
http://www.musicians-samples.com/Stock x 1 internal clock.wav

So after MANY different listening test, I've decided that these converters sound just fine without any mods...

The ONE things, however, that really bugs me about the stock channels is the apparent high-end boost I hear after running something through them... it's subtle... but its there and I find it a bit abrasive. (Flip the phase on the source file and line it up the stock x 1 file to hear the extra high frequencies).

Question:

1. How could I smooth the high end on these converters? Does the small 3n3 cap (actually a 1n8 cap on mine) right before the a/d inputs have anything to do with this?

Any comments would be greatly appreciated![/quote]
 

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