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Thoughts on BBE DS 48


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Looks like a pretty useful piece for monitors, 4 mixes with a preset EQ curve and if I wanted to bi-amp later on could do that too. (I'm reading the manual now as I type) The intended function would be DBX231-BBE-amps. This is not a replacement for a graphic eq but rather something a preset EQ could be loaded into it and the graph then becomes flat to start and cut to taste. The BBE sonic-crap would NOT be used.

 

Any thoughts on this? Is it intuative? easy to get around?

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Looking at it the block diagram it's like this (4x4 mode)

 

INPUT - GAIN - HPF - LPF - PEQ (5band) - DELAY (0 to7ms in .1ms steps) - GAIN - MUTE - OUPUT

 

In 4x8 mode the input is copied to a 2nd output channel after the GAIN stage and both signals get from the HPF-LPF stage on out. INPUT 1 goes to (LF) OUPUT 1 and (HF) OUTPUT 2. INPUT 2 then uses OUTPUT 3 & 4 etc.

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7ms of delay doesn't bother me, for biamp wedges I don't see a big issue. But the lack of graphic eq sucks, more because used full range that's only 5 bands, off the top of my head I could fill that easy. But used biamp it's 5 bands per bandpass (5 for LF, 5 for HF) and that's reasonable.

 

I'll have to see what delay setting's I'm using in the driverack for the JBL tops I have.

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5 bands would prolly work fine. A graphic is needed though for room stuff. There doesn't seem to be a BBE process function at all which is kinda weird given that it's a BBE product. Also in the manual there are no specs to the peak input voltage at all, it is set up that 0dB is peak on the meters (Limit is 0dB and +8dB is Clip). It would be nice to know...

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http://acapella.harmony-central.com/showthread.php?t=2482645

 

I put one on my home listening system (DS24)and it works very well. I have not had any problems with it.

 

Note that the meters on Front are in DFS or Digital Full Scale. I will have to check but I believe that 0dfs on the meters is +12dbu or 4 vpp. Clip being +20dbu or 7 volts or so.

A normal +4dbu input to the bbe would be around -18dfs or between -24dfs and -12dfs on the bbe meters.

 

The Limiters are set up in DBV.

It is easy to set the limiters up if you know what DBV input is required for your amps to reach full power. If you only know the dbu at rated input imp. you can use this calculator to find what DBV setting is needed for your amps.

 

http://www.sengpielaudio.com/calculator-db-volt.htm

 

Like any new unit its important to note what is being used for measurement scale. As soon as you know how the unit is scaled it is easy to setup and use.

 

I see the ds48 from the same company I purchased mine from going for $260 plus free shipping. This is a very good price for what you get.

 

http://srforums.prosoundweb.com/index.php/m/488969/51/?srch=ds48#msg_488969

 

http://srforums.prosoundweb.com/index.php/m/320781/51/?srch=ds48#msg_320781

 

The crossovers do not have any of the bbe "sonic max" stuff in them!

 

Any other questions be sure to ask.

 

Dookietwo

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Is the max. output level 7 volts peak, or peak to peak, or is it RMS?

 

I would recommend verifying everything once programmed to be sure that it does exactly what you think regarding headroom and limiting. It's not uncommon vor there to be differences (significant) due to units used and perhaps RMS versus peak values.

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The max output on the BBE is 7.6v peak to peak. The max input voltage on the yamaha P5000 amps are "+6dBu Sensitivity (max) Rated Power 8 Ohm", P7000's are +8dBu.

 

Anyone care to help with this? My math isn't so good here, I know there are differences between dBv dBu and dvda (south park reference).

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The max output on the BBE is 7.6v peak to peak. The max input voltage on the yamaha P5000 amps are "+6dBu Sensitivity (max) Rated Power 8 Ohm", P7000's are +8dBu.


Anyone care to help with this? My math isn't so good here, I know there are differences between dBv dBu and dvda (south park reference).

 

 

Now here's the rub, if it's really peak to peak, that's only 2.69V RMS, or roughly +10.5dBu, so you have only 2.5dB between clip and the limit point of your amp (assuming of course it has a limiter).

 

Just a hunch (though it MUST be measured) is that it's peak voltage and not peak to peak, which would add 6dB and end up at 16.5dBu. Not positive, but makes more sense.

 

You can see that there are some very significant issues regarding gain structure.

 

Also, it must be reconciled exactly what is being measured, is this differentai peak to peak (ie. the swing of the positive and negative peaks) or exactly what is ment. There is a lot of potential confusion depending on exactly what is ment be peak to peak.

 

Knowing the analog power supply rails and output stage configuration (is it really differential balanced out or impedance compensated?) would tell the entire picture.

 

My opinion is that a group of designers who did not understand the pro audio indutry did this and I would really be suspect of the meter calibration, what does 0dB really mean. This disgusts me.

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It's becoming more clear that BBE is buying this unit from some other manufacturer to fill a price point/product gap. Creating a digital crossover from scratch can be very expensive and may not pay off at all. I would expect to see more companies coming out with similar 2x4, 2x6 processors priced slightly above an analog crossover, maybe they make them, maybe someone OEM's them, we'll see.

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The max output on the BBE is 7.6v peak to peak. The max input voltage on the yamaha P5000 amps are "+6dBu Sensitivity (max) Rated Power 8 Ohm", P7000's are +8dBu.


Anyone care to help with this? My math isn't so good here, I know there are differences between dBv dBu and dvda (south park reference).

 

 

+6dbu is 1.54 "volts" or 3.78 "DBV" and 4.37 volts peak to peak

+8dbu is 1.94 "volts" or 5.78 "DBV" and 5.5 volts Peak to peak.

 

This weekend I will connect my board to the BBE I have here and see at what input it takes to get the clip lights to come on. The unit shouldn't have any problems driving any professional amp to full power. With headroom to spare.

 

 

 

Dookietwo

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Now here's the rub, if it's really peak to peak, that's only 2.69V RMS, or roughly +10.5dBu, so you have only 2.5dB between clip and the limit point of your amp (assuming of course it has a limiter).


Just a hunch (though it MUST be measured) is that it's peak voltage and not peak to peak, which would add 6dB and end up at 16.5dBu. Not positive, but makes more sense.


You can see that there are some very significant issues regarding gain structure.


Also, it must be reconciled exactly what is being measured, is this differentai peak to peak (ie. the swing of the positive and negative peaks) or exactly what is ment. There is a lot of potential confusion depending on exactly what is ment be peak to peak.


Knowing the analog power supply rails and output stage configuration (is it really differential balanced out or impedance compensated?) would tell the entire picture.


My opinion is that a group of designers who did not understand the pro audio indutry did this and I would really be suspect of the meter calibration, what does 0dB really mean. This disgusts me.

 

 

So it's junk. Figures.

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+6dbu is 1.54 "volts" or 3.78 "DBV" and 4.37 volts peak to peak

+8dbu is 1.94 "volts" or 5.78 "DBV" and 5.5 volts Peak to peak.


This weekend I will connect my board to the BBE I have here and see at what input it takes to get the clip lights to come on. The unit shouldn't have any problems driving any professional amp to full power. With headroom to spare.




Dookietwo

 

 

You fail to see the jist of my comments.

 

There is less than a dB or two of headroom between the ability to drive the amp into limiting (or clip point) and the input or output of the device clipping or limiting, meaning that there is no room for limiter compliance. The limiters will be functionally ineffective.

 

This is the soft white underbelly of these "your name here" devices.

 

Use a scope and take real measurements, look at the actual clipping points and look at both the inputs and outputs. This is how real pitfalls are uncovered, plus measuring the analog rail voltages tell all.

 

The only possible thing that might work is for the analog input stages to operate at real rail voltages (+/-15 volts) and be padded down before going into the A/D or there being an input pad righ on the input doing exactly the same thing. So to the outside world it looks like it's handling +20dBu on the input where it's really padding it down 12dB to +8dBu internal operating levels, but on the way out, it's internally limited at +8dBu. This means that Don's recommendations (and mine to some extent) that it's ok to drop the amp sensitivity controls down by maybe 6dB will not hold true, as the output provides an atypical (for the industry) operating level.

 

Also, padding down the input will cause an operating level shift that will be inconvenient at best and useless at worst.

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This means that Don's recommendations (and mine to some extent) that it's ok to drop the amp sensitivity controls down by maybe 6dB will not hold true, as the output provides an atypical (for the industry) operating level.


 

It's fine, just make sure everything is on "unity" :lol:

 

Sorry ... should have posted this in the other thread.

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I did a quick check and looked at the in/out. This was an informal test using the units clip lights. Both were the same with no gain changed +/- from 0 with no crossover filters engaged and eqing bypassed.

With pink noise with a 6 db crest factor it took -6 DBFS (Digital full scale)for the clip lights to come on. This would be a VERY compressed loud mix.

As Aged horse had guessed. This would be Aprox +19 dbu. Athough not quite up to most units running in the +24 dbu and above range not as low as I had thought.

 

+ 19 dbu comes in as.

 

16.78 DBV

 

6.90 volts. (Very close to the stated 7 volts)

My test was just when the clip light starting to flicker on the unit. It very well may have been 7 volts had the clip light been on more than off.

 

19.5 volts Peak to Peak

 

I picked the DS24 for my home stereo but I wouldn't have any problems using it for live sound. It is what it is. A low cost, yet good sounding entry level DSP.

 

Dookietwo

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So, the term they use describing peak to peak is incorrect. It's the peak voltage, not peak to peak, which corresponds to the 6dB difference that I calculated as the low possible value.

 

This is why it's important for manufacturers to be accurate as well as users to understand all of the details if they are going to stray outside the generally accepted industry practice, otherwise they can end up with an unexpected result.

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