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Preamps overload very easily on 1818 ------->>> SOLVED! via Audiobox VSL 1.2 Driver
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Jason.Harris
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Joined: 01/10/2010 16:19:09
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andrewmcdan87 wrote:Guys, we have to keep in mind that any changes the Presonus engineers make to the firmware have to be thoroughly beta tested before they will even let us know if they're working on it. That's like a 4-6 week process. I'm waiting three more weeks before I get too concerned about Presonus's lack of response. But at that point, I'm going to be questioning whether or not Presonus is worth buying from.


^^

This is true. We are working on it (which I said two weeks ago). There are people above my pay grade spearheading this issue. I will not be giving daily/weekly updates to this because I'm not getting any further info either. When we have a solution/statement/etc., i will post here to update you.

Cheers,

Jason

andrewmcdan87
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Joined: 15/09/2011 22:33:36
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I think I've found a problem with the "simple" fix I've suggested. I bought an oscilloscope and I'll be performing some tests later today. I'll report back when I have results, although I fear I won't like it...
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beachside
Presonic
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Joined: 29/07/2010 00:29:21
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Hardware issue?
Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
PvG
Presonic
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Joined: 15/03/2011 22:36:23
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Andrew, I hope you found that missing piece of the puzzle (the link between the digital(?) issue you found and the (proven ) analog issue Mike found). Since the symptoms are very much alike (inverted/flipped signal at peak level), I still suspect they are related.
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andrewmcdan87
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I haven't had a chance to do the tests I wanted but I did get to hook up the o-scope to the main outs of the 1818. I measured the peak-to-peak voltage and confirmed that the main outs are producing a +10dBu signal like the documentation states. This means that if my digital-nonsense-theory is correct, then the output gain is set to produce a +10dBu signal when the DAC's are being fed a (digital) -6dB signal. If the Presonus engineers were to implement my "simple" solution of reconfiguring the A/D/A converters on power-up, then the output gain stages would be receiving a signal from the DAC's that is potentially twice the level that is expected. In this scenario, if you turn up the volume on the outputs, it would almost certainly be distorted (and quite loud).

I plan on hooking up my o-scope to the analog inputs and outputs of the A/D/A converters in order to see exactly what level the incoming and outgoing signals are at, and I'm going to connect my logic analyzer to the digital input side to see what sort of signal the DAC's are receiving.

In a way, this would (potentially) explain why we haven't heard any news from Jason.Harris. I think there are three potential scenarios that are happening now (in reference to the 1818 issue):

1. (Best case scenario) The digital signal from the XMOS chip to the A/D/A converters is in the format that the converters expect and we are not losing digital resolution on the output side. The digital signal from the A/D/A converters is not in the format that the XMOS chip is expecting and we are losing headroom and digital resolution on the input side. The Presonus engineers are implementing the change-the-converter-signal-format fix and are having to rework how the XMOS chip outputs the digital signal. In this case, we (the consumers) are waiting for the beta testing to be complete and will likely see some sort of results in the coming weeks.

2. The digital signal from the XMOS chip is NOT in the format the converters expect along with the signal from the converter to the XMOS chip. We are losing digital resolution on the output side and this cannot be fixed as doing so would increase the output level from the converters and would overdrive the output gain stages. The Presonus engineers are reworking the software so that the output signal from the XMOS to the converters is never more than what the output gain stages can handle but the input side will have all the digital resoltuion and analog headroom that the hardware supports. We will either see a new firmware in the coming weeks that fixes one issue (the input problem) but potentially causes another, or we'll see a recall (or nothing at all will happen).

3. (Worst case) Presonus has identified either the issue I've attempted to detail in this thread or another issue that hasn't been discussed here, and the engineers are unable to come up with a viable (and financially sound) solution. They (the engineers, not Jason.Harris or any of the others that try to help us as much as possible) could also be ignoring us because they still hold that there is nothing wrong with the device and that we should just turn down the volume. This would be bad for us for obvious reasons and bad for Presonus because I've heard of tons of people returning these interfaces because of issues that have been discussed here.

Until I complete my tests, most of this is speculation although it's based on some real facts (input digital signal craziness, output at +10dBu). I likely won't be able to hook up and test this week but as soon as I do, I'll be back here with results and data. And to anyone that is holding their breath on this issue (if anyone even is, I hope not though) please just relax and wait. Even in the best scenario, we are weeks away from a firmware update and unless your are a superhero or a robot, you can't hold your breath that long.
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beachside
Presonic
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Joined: 29/07/2010 00:29:21
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I have tested the output level. 0dB 1K tone from PC. Plus 10dBu output at Main out 1 with Main out pot at max. Meter on unit shows 0dBFS and is unaffected by main pot. To spec.


From mic pre's-:

-40dBu into mic input 1 - input pot set to before clip led (just below 0dBu) - Soundforge input shows 0dB - unit meter show -4dBFS - Main pot at max. Output at Main 1 - Plus 10dBu. Looks clean.

This message was edited 5 times. Last update was at 16/03/2012 23:07:18

Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
beachside
Presonic
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Is it not possible the XMOS is outputting Left Justified, so the output path is OK? The difference in the units meter seems to suggest this. But I'm not sure where that is tapped off.

Perhaps the XMOS is configured to receive I2S but output left justified. That could explain the difference in paths to the convertors. Changing the input format wouldn't change the output of the convertors (?) and not overload or change the output stages. Just thinking aloud....

This message was edited 1 time. Last update was at 17/03/2012 02:35:32

Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
PW
Prenoob

Joined: 26/08/2010 01:13:13
Messages: 17
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Anyone hear anything new? I still like this unit if it did not overload. Nothing else I owned from Presonus did that.
Peter
beachside
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Joined: 29/07/2010 00:29:21
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Nope.
Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
bluesriff
Presonic

Joined: 26/01/2012 22:41:56
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Location: Los Angeles
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andrewmcdan87 wrote:I haven't had a chance to do the tests I wanted but I did get to hook up the o-scope to the main outs of the 1818.....Until I complete my tests, most of this is speculation although it's based on some real facts (input digital signal craziness, output at +10dBu). I likely won't be able to hook up and test this week but as soon as I do, I'll be back here with results and data....


...bump


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beachside
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About a week ago I submitted a support request for this issue. To date I've had no response at all and the ticket has not passed the first step of being assigned to anyone from Presonus. Not a good look. This is not the way to handle it. I'm not blaming Tech Support staff as I guess there has been a directive from management to not comment or respond.

This message was edited 1 time. Last update was at 29/03/2012 01:51:58

Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
Jason.Harris
Presonoid

Joined: 01/10/2010 16:19:09
Messages: 1649
Location: Baton Rouge, LA
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Hi Beachside,

We are working on this and as there is not an official statement or solution, there will be no statement from individual Tech Support agents. Look to this thread for updates as they are made available.

thanks,

Jason

themuzic
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Joined: 17/04/2010 05:42:47
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As it is I've gotten pretty used to carefully dialing in settings that work. I use the 1818 in all my Livestream broadcasts and the unit is still totally usable.

Just thought I'd throw that out there.

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PW
Prenoob

Joined: 26/08/2010 01:13:13
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Could they just add a pad on the inputs? I recorded a DI bass with the volume set at 0 and it overloaded . I sold the unit because of this. I may be needing another interface soon and would consider this if it is fixed.
Peter
beachside
Presonic
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Joined: 29/07/2010 00:29:21
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This thread started November 2011. Another month goes by..........

This message was edited 1 time. Last update was at 14/05/2012 03:08:47

Focusrite 18i20. An '1818' that actually works as advertised and has great support!! But Presonus will continue the story it was all my systems and there is no hardware issue with the 1818 and the drivers are great.

Almost two years on and Presonus continues to say it's a 'top priority' but have no driver updates, make excuses and blame others (Intel, USB3 Microsoft, Apple and now the company that writes their drivers!) when other companies have it all working on the same systems!! And it so refreshing to get regular software updates and responsive and effective support!

And the 1818 does not have 'on-board DSP' as continues to be claimed.
 
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