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Old 25th June 2012, 09:08 PM   #31
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DevTeam? I would really appreciate a solution to this problem....
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Old 26th June 2012, 03:02 AM   #32
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Understanding gain staging really is the key to your problem. If you have invested a bomb in commercial gear then pay one of your dealers to come out and set it up for you. They (or you) could use something like this

Amazon.com: Dayton Audio XATT20 In-Line XLR Attenuator Pad 15dB: Musical Instruments

as a fixed attenuator between the MiniDSP and your power amps. The MiniDSP should easily be able to meet your requirements and will sound much better, as well as quieter, when it is driven, and driving, at the correct levels.

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Old 26th June 2012, 07:22 AM   #33
minidsp is offline minidsp  Hong Kong
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Quote:
Originally Posted by Leeuwarden View Post
DevTeam? I would really appreciate a solution to this problem....
Over the week end we typically try to relax.. :-) However we do our best to answer all inquiries within 3-4working days as you've seen before though so thanks for your patience. :-)

Ok, so I've read these comments and before going further, I'd like to ask something to make sure we are talking of the same issue we're trying to solve here. Could you please point me to the online articles you read about gain structure? It would be a great start to be able to point out the elements few of us are trying to explain here. Most of the content we read were from books, but a simple google search pointed some very good reference. Let's see which one you read and how you understood/how they explained the issue of optimizing SNR.

On a DSP (or actually any piece of an audio chain with a DAC/DAC), optimizing the gain structure between the different elements is very important (but I've said that many times already..:-) Saying that the miniDSP can't work with a preamp isn't accurate I believe since there are a lot of us doing it already. I think that we need to acknowledge that each of you have a different setup (amps with a different input sensitivity, gain control before, after, various filtering in the DSP), quite a few are DIY setup, and while some time is spent doing some measurement, little time is spent looking at the gain structure from what we see typically. Adapting your gain structure to the DSP isn't some one button fix all. :-)

I'm reading some of these between the lines on few things here... (i.e. Is the gent from Triple Audio the one with your board?). But basically, our general understanding from what you are describing is as follow:
1) You have a preamp at the input side, that's fine. Many of us have this and no issue.

2) You used to have a miniDSP unbalanced, so I'm guessing that level wize, your amp was fine with the output. Going to the balanced you're talking of a 4x gain. Has any change been done to the system? (e.g. padding as suggested by blacksheep). Or you're just attenuating all these in the digital domain (i.e. DAC/ADC running at their worst SNR)

These are just few of the questions you need to figure out basically when you put pieces together.. Now, as i"ve mentioned before (but not sure if it got lost in between), and as Blacksheep is mentioning, gain structure is to be done in any audio system. Just few people pay attention to it because in most cases, you don't have a chain (i.e. Preamp going to amp). Is it possible that the gain that you have out from a miniDSP balanced is just too high for your amp (i.e. you'd need to attenuate for an appropriate level)

3) With regard to the pop noise, it's the caps discharging and this issue has actually been solved on the latest batch as we've indeed listened to the request of the community. Both unbalanced and balanced shouldn't have the issue. There are few using some delay relay which might be an alternative.

Hoping this info helps

DevTeam
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Old 26th June 2012, 10:05 AM   #34
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@ Devteam:
regarding your point 3): interesting info about pop noise problem being solved in the latest batch. May I ask how this has been solved
Maybe it's possible to fix (DIY) also for the older batches

@Leeuwarden:
I can only repeat what has been said many times before (also by me ): have a look at your gain structure! If you can give us some more information about your preamp and poweramps, we will try to help you optimizing your gain structure. It's really the best to stop trying (try AND error ) but to systematically analyze the levels in your chain and optimize all this.
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Old 26th June 2012, 11:26 AM   #35
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What is Gain Structure?
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Old 3rd July 2012, 08:13 PM   #36
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I have 2x8 and when used with unbalanced outputs and 3xSure amps had noise.
Changed to balanced outputs and 6 channel amp-dead silent.
Both with 100 to 109dB drivers.
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Old 12th July 2012, 01:43 AM   #37
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Originally Posted by coit View Post
I have 2x8 and when used with unbalanced outputs and 3xSure amps had noise.
Changed to balanced outputs and 6 channel amp-dead silent.
Hmm. Which amp did you end up pairing with the miniDSP?
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Old 12th July 2012, 08:17 PM   #38
coit is offline coit  Australia
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Australian Monitor KMA750,but I thought it was the balanced outputs.
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Old 12th July 2012, 08:58 PM   #39
Pallas is offline Pallas  Pakistan
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Originally Posted by coit View Post
Australian Monitor KMA750,but I thought it was the balanced outputs.
Darn. I was hoping you were going to say it was a class D board like to Sures you mentioned in your previous post. I am unaware of a multichannel board that takes balanced inputs, hence the curiosity.
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Old 13th July 2012, 03:32 AM   #40
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In my previous life as an AV consultant (or "insultant" as we joke about it), I have seen plenty of very nice (and very expensive) systems that got out of whack. Most of the time, a messed up gain structure was to blame.

I wish I had a dollar for every system we inspected, supposedly "malfunctioning" and in need of replacement according to the local contractor, that ended up being "cured" by a simple gain structure alignment procedure.

I feel for those having to endure the noise challenge at hand, but having gone through similar issues myself, I strongly second the manufacturer's recommendations so far. I am not saying that this is the answer, but a pretty good starting point.

My first miniDSP was ordered today, so I can play along with other DIY fellows.
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Last edited by dudaindc; 13th July 2012 at 03:34 AM.
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