isa-one A/D - has anyone tried stereo through it?
Old 31st December 2011
  #1
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isa-one A/D - has anyone tried stereo through it?

Hi everyone, my first post here - I've searched all over, and read the manual through, but i'm still wondering: if those nice converters on the digital isa-one preamp come to live in my house will i be able to put stereo stuff through them from time to time? It looks to me as if using the 'extra' input and the main input set to 'line' and 0 gain should be similar.. but isn't one channel going through the transformer? Would this mess with a stereo recording?
and most importantly, has anyone actually tried this and is happy/unhappy with the results?

Cheers
Mark
Old 31st December 2011
  #2
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euphoria89's Avatar
 

Yes, i do believe the main line input will be ran through the transformer, so you will have tonal differences.

Can you not just run the process twice?
Old 1st January 2012
  #3
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thanks - I'm under the impression that running stereo material in off analogue media will have minor speed differences every pass - so one channel at a time isn't an ideal way of doing it?

Seems strange (to me) that they shoe-horn those nice converters in there and there's no way to get stereo (or an equal for each channel signal path) into them...

perhaps just clocking my audiophile 2496's analogue ins from the isa's clock would be an 'upgrade' anyway

or maybe the audient mico will be a better choice to give me a proper stereo option?

so i'm looking at audiophile 2496 vs audiophile 2496 clocked by isa-one vs isa-one with one channel through a transformer vs audient mico...



i don't suppose there are very cheap ways of splitting the stereo into m/s, so i could bung just the mid through the transformer....
Old 1st January 2012
  #4
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While the ISA ONE is a single channel unit, the A/D option (which is quite good by the way!!) is actually a 2-channel protocol. Notice I said 2-channel instead of stereo, because whether you want this to be stereo depends upon the software you are using---it is indeed (2) streams of digital input. The audio out of the ISA is hard-wired (internally) to one channel of the converter while the other channel, you would connect via the line input. If you were to connect a second ISA ONE into that A/D converter input, it would sound identical to the source unit. As to one channel going through the transformer---that is part of the mic-pre, NOT the converter.
Old 1st January 2012
  #5
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Thread Starter
cheers Brad, and happy new year.
I guess my question is:

as it seems the two-channel converter has one channel hard wired to a preamp with a transformer in it, is there no way to create an equal signal path for an analogue stereo signal to reach the converters? Are you suggesting that a second analogue-only isa-one on the other channel is the only way?
Old 1st January 2012
  #6
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Thread Starter
thinking... brain ticking slowly... would the insert return offer a simple line-in? after all the insert is after the mic pre, and just before the converter.. so i'd click 'insert' and i'd click 'post insert' for the meter... would it need a dummy plug in the insert send maybe?

if anyone knows the circuit, or has used one for this could confirm that would be great... suddenly I'm optimistic again, and maybe the world won't end in 2012
Old 1st January 2012
  #7
3 + infractions, forum membership suspended.
 

if your talking of recording two different sources instead of stereo, the DI and the MIC can be recoded at the same time and it should all go through your digital card at the same time and thats your stereo....so YES you can....but not in stereo because of the tonal differences...insert, try that....the transformer is on the input before your insert...
Quote:
Originally Posted by mutetourettes View Post
thinking... brain ticking slowly... would the insert return offer a simple line-in? after all the insert is after the mic pre, and just before the converter.. so i'd click 'insert' and i'd click 'post insert' for the meter... would it need a dummy plug in the insert send maybe?

if anyone knows the circuit, or has used one for this could confirm that would be great... suddenly I'm optimistic again, and maybe the world won't end in 2012
Old 1st January 2012
  #8
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Thread Starter
Thanks Jimsi - this is me trying to figure out if it's ok before i click buy...
Yeah I'm comfortable with its intended use as one mic, one DI.. I'm trying to establish if it can also, at a pinch, convert proper line-level stereo through signal paths that are pretty similar for left and right (ie a stereo synth, an old tape, nice fat reel-to-reel, an effects return etc etc)..

it looks as if the only difference (using the insert return for 'left') would be the left channel driving the needle vu meter, but that shouldn't affect the sound much should it? both channels would be driving the led peak meter anyway.

I hope to get some kind of confirmation from focusrite about whether the signal paths are equivalent, but if anyone here has the necessary machinery to check if the same signal split through both paths is still identical (will null) in digital land that would be great.

thanks
Old 1st January 2012
  #9
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I have an ISA One with the digital card....and what you want to do is possible.

Here is an excerpt from the manual regarding the Insert / return:

Insert
Activating the INSERT switch (illuminated when active) breaks the signal path of the channel, so that the signal sent to the first ADC Input and the analogue output on the rear panel is the signal received at the INSERT RETURN connector (on the rear panel) rather than the direct mic, line or instrument signal. This switch is designed to allow the input signal to be routed to other hardware for processing and then back into the ISA One for digital conversion. The POST INSERT switch on the front panel allows the ‘return’ signal level to be viewed on the left-hand LED peak meter before conversion (see the Metering section on the next page for details).


Soo.....from the paragraph above it indicates the signal sent to one ADC input is the signal received from the 'return' jack...logically this would be post-transformer since the signal would already be amplified in a normal send/return scenario.

This would suggest if you put one channel in the EXT I/P, and one channel in the 'return' jack with the signal set to 'line' and the 'insert' button pushed you would get two-channel conversion without the transformer in the path.

NOTE: I just tested this with program material I am familiar with and and the answer is "YES" it works as described above. In this mode...the gain settings on the front panel have no effect on the signal...nor does the filter or the phase switch.

EXT I/P is the left channel. SEND RETURN is the right.

This mode basically turns the ISA One into a straight two-channel converter.

BTW there is a video on YouTube of a guy in a studio using the ISA One as conversion...

Hope this helps.
Old 1st January 2012
  #10
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Thread Starter
Thanks Kamurah! That's the confirmation i wanted to hear, cheers for testing it, and happy new year
Old 1st January 2012
  #11
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euphoria89's Avatar
 

And I suppose with the fact that the send/return are separate would indicate that these are also balanced inputs, as opposed to regular unbalanced single connections?

If that's the case, then both channels should be converted identically, creating a standalone 2 channel converter.

Why Focusrite wouldn't promote this is beyond me!

I love my ISA One Digital
Old 1st January 2012
  #12
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Kamurah's Avatar
 

Quote:
Originally Posted by euphoria89 View Post
........

I love my ISA One Digital
Me too! I managed to pick mine up for a steal they were on closeout. Best deal I've ever gotten on this level of studio gear.

I wouldn't mind adding a 428 down the line.....with the A/D card of course.
Old 1st January 2012
  #13
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Quote:
Originally Posted by Kamurah View Post
Me too! I managed to pick mine up for a steal they were on closeout. Best deal I've ever gotten on this level of studio gear.

I wouldn't mind adding a 428 down the line.....with the A/D card of course.
Me too. In fact, I blagged myself another £25 off when said I was a music tech student. £375 all in all.
Old 1st January 2012
  #14
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BradLyons's Avatar
 

Quote:
Originally Posted by euphoria89 View Post
And I suppose with the fact that the send/return are separate would indicate that these are also balanced inputs, as opposed to regular unbalanced single connections?

If that's the case, then both channels should be converted identically, creating a standalone 2 channel converter.

Why Focusrite wouldn't promote this is beyond me!

I love my ISA One Digital
Well it's kind of assumed, because they want you to purchase a second unit----and then plug it in for a true stereo sound via the converter. I guess that was the point I was getting at is that the converter IS the same on both channels, from the internal connection to the external second unit connected.
Old 1st January 2012
  #15
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Earcatcher's Avatar
 

Quote:
Originally Posted by euphoria89 View Post
And I suppose with the fact that the send/return are separate would indicate that these are also balanced inputs, as opposed to regular unbalanced single connections?

If that's the case, then both channels should be converted identically, creating a standalone 2 channel converter.

Why Focusrite wouldn't promote this is beyond me!

I love my ISA One Digital
Yes, not only is the ISA One digital a very good and versatile preamp, it can also be used as just an A/D converter for any stereo signal at line level (balanced) that you throw at it. Through optical out you can directly run it into your Mac. And the conversion is really good too, while it can also be externally clocked by Wordclock. This way you can simply ad it to your interface to create two more digital inputs. ISA One digital is a rare bird with lots of unexpected tricks up its sleeve. An underrated piece of equipment.
Old 5th January 2012
  #16
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Thread Starter
Hi just for completeness, Focusrite support got back to me saying the paths are equivalent so stereo should be fine:

Quote:
There are no significant differences between the insert return and EXT I/P inputs as both are balanced inputs going directly to the converter. As such, using it to achieve stereo conversion, although not how it is designed, shouldn't cause any problems.
Old 5th January 2012
  #17
Quote:
Originally Posted by Kamurah View Post
I have an ISA One with the digital card....and what you want to do is possible.

Here is an excerpt from the manual regarding the Insert / return:

Insert
Activating the INSERT switch (illuminated when active) breaks the signal path of the channel, so that the signal sent to the first ADC Input and the analogue output on the rear panel is the signal received at the INSERT RETURN connector (on the rear panel) rather than the direct mic, line or instrument signal. This switch is designed to allow the input signal to be routed to other hardware for processing and then back into the ISA One for digital conversion. The POST INSERT switch on the front panel allows the ‘return’ signal level to be viewed on the left-hand LED peak meter before conversion (see the Metering section on the next page for details).


Soo.....from the paragraph above it indicates the signal sent to one ADC input is the signal received from the 'return' jack...logically this would be post-transformer since the signal would already be amplified in a normal send/return scenario.

This would suggest if you put one channel in the EXT I/P, and one channel in the 'return' jack with the signal set to 'line' and the 'insert' button pushed you would get two-channel conversion without the transformer in the path.

NOTE: I just tested this with program material I am familiar with and and the answer is "YES" it works as described above. In this mode...the gain settings on the front panel have no effect on the signal...nor does the filter or the phase switch.

EXT I/P is the left channel. SEND RETURN is the right.

This mode basically turns the ISA One into a straight two-channel converter.

BTW there is a video on YouTube of a guy in a studio using the ISA One as conversion...

Hope this helps.
Why didn`t someone mention this earlier. This is a big deal. If this was mentioned as a selling point, i`m sure more people would have bought the digital version. Now ,it`s discontinued. Oh dear.
Old 6th January 2012
  #18
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Quote:
Originally Posted by Caramel View Post
Why didn`t someone mention this earlier. This is a big deal. If this was mentioned as a selling point, i`m sure more people would have bought the digital version. Now ,it`s discontinued. Oh dear.
Well...technically, the ISA One digital with the card PRE-installed is discontinued...the digital card is still available and can be installed by literally anyone AND is compatible with the analog version of the ISA One.

I installed my card myself in about 5 minutes....you unscrew about 10 screws holding the top on...carefully remove the top (there is a grounding wire attached so don't rip the top off)....plug the card into the board....screw it down....and replace the top and fastening screws. Hold down any button on the front during first power up to initialize the board. All done.

If you are willing to search, you can find some good deals on the ISA digital card on ebay.
Old 8th January 2012
  #19
Gear interested
 

Hello all,
Ive been scratching my head as to what interface to buy to step up from my MOTU828mk1, and have decided that until I need more inputs, the ISA One would be great connected through the MOTU's ADAT (Only recording voice, guitar, and getting some samples from an 808, SH-101 and 707 before selling)....

Only problem is, the ISA One Digitals seem to have suddenly jumped up 100-200 quid (e.g. dv247) while Ive been making up my mind!

Any ideas where I can still get a good deal? Closer to the 399 they were going for until recently?

Many thanks!
Old 8th January 2012
  #20
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£499 absolutely music seems the cheapest place that has them in stock. £100 more than they were though, but they are soon to be EOL, so the prices will go up. Still a great bargain at that though. Quality is no different.!
Old 12th January 2015
  #21
Gear nut
 

All great to know. My only question about the above mentioned confirmations is this:

Does channel 1 (the pre) need to be set to "line?!?"

As I inderstand it, as long as the front panel insert is lit, then presumably Id be able to have full acces the the preamp section and take the pre line out via the insert send, the. Still use the ExtIp and ch1 return as my stereo ADC for ST prints, correct???
In the above explanation, the poster said the pre had to be set to "Line."

As understand it, that shouldn't affect the signal feeding the return, but rather the "pre/input" source, and my the send signal (which would be line either way regardless of input.

Am I correct here? I know this is an dee thread, but clarification on this specific detail with decide my workflow.

I have a patchbay that I'd like to have the ISA preamp "send" would act as a standalone pre and feed aine input on my DAW I/O. While at the same time feeding a summed ST print into the ISAOne ADC.

Anyone doing using both sides of the pre like this? Obviously, at this point the pre would be usable as pre/line/DI independently from the ADC.

Thanks,
Old 12th January 2015
  #22
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Thread Starter
i didn't get one in the end - but i think you're correct - it shouldn't matter what input (line/mic) once the insert switch is pressed to break the path. Early in the thread I hadn't figured out that 'insert' was the right tool for the job, and was wondering about using 'line' in - but clearly that's not an equal path... I think that was just a red-herring on the thread.

fwiw focusrite were quick to respond, so it might be worth asking them anyway before you buy...
Old 12th January 2015
  #23
Gear nut
 

Thanks! This makes this Unit a swiss army knife. I owned the ISA One for a long time before getting the AD card. My current setup is in transition so I haven't had a chance to try this. Cant wait. Thanks again!
Old 4 Weeks Ago
  #24
Gear nut
 

Ok, so I've tested the 2 channel (stereo) A/D setup, running the abolish side of things seperately.

I created an Stereo Aux with a signal generator feeding a sine wave out a stereo pair from my D/A.

This is going into a summing unit that I've tested and is working properly (equal balanced levels throughout).

When I take the ST summing out back into the ISA one, there is a difference in the D/A out by -3db once it gets back into protools.

It seems that the ext/input is the right channel on my unit (unlike the above mentioned). The left channel is actually the send return and it is 3db lower than the right channel!

Can anyone offer a suggestion as to why? How can I fix this? It certainly is the send return input and not signal or cabling being fed into it.

Last edited by Allaboutrhythm; 4 Weeks Ago at 06:27 PM..
Old 4 Weeks Ago
  #25
Gear nut
 

After bringing up the gain on the signal generator to 0db and back down, now the left channel is hotter by about 1-1.5db. This is so weird. Again, tried different cables and reset/power cycled everything.

Everything things seems matched for the most part on meters now, except for PT. It's now showing the left side as vein a bit hotter.

Oppostite of my experience 30minutes ago, where the left side was 3db lower.

The post insert L/R metering on ISA, as well as the Apollo metering are now even, but PT St print return channel is not even. Left channel is still slightly hotter. At this point, it's hard to tell wether it is an inconsistency in the ISAs Return input, ISA AES A/D, or PT mix window metering.

Any suggestions?
Old 4 Weeks Ago
  #26
Gear nut
 

What is strange is that now the mix window metering is slightly off, but the metering visible on the left in the edit window is even. Thinking my ISA mig actually be fine, but PT metering is playing games?!?
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