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MiniDSP - Page 2

post #31 of 1592
10/7/10 at 3:55pm
Cool. One thing that would be super cool to see is a loop-back measurement. That way we can see if this little guy is accurate to the numbers in the software.
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post #32 of 1592
10/7/10 at 3:57pm
Thread Starter 
Do you think I can do that with something like REW?
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post #33 of 1592
10/7/10 at 3:59pm
Seems to me A9X-308 is right. The mini dsp and the DCX require different gain structures. But other than that they should have about the same s/n ratio (assuming the s/n specs are the same).

I have: dbx drive rack PA -> crown d-45 amp -> 115db/w/m horns. No hiss due to correct gain structure.
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post #34 of 1592
10/7/10 at 4:09pm
Quote:
Originally Posted by penngray View Post

Do you think I can do that with something like REW?

Most definitely.

Quote:
Originally Posted by steve71 View Post

Seems to me A9X-308 is right. The mini dsp and the DCX require different gain structures. But other than that they should have about the same s/n ratio (assuming the s/n specs are the same).

I have: dbx drive rack PA -> crown d-45 amp -> 115db/w/m horns. No hiss due to correct gain structure.

I sure hope so. The amps for the HF section on my active build is still up in the air. My first choice would be the d-45's but I need three of them. No way am I going to spend that much on those.
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post #35 of 1592
10/7/10 at 4:39pm
Quote:
Originally Posted by Scott Simonian View Post

I sure hope so. The amps for the HF section on my active build is still up in the air. My first choice would be the d-45's but I need three of them. No way am I going to spend that much on those.

Yeah it's hard to get into the idea of spending that kind of money for a 25w/ch amp.

What about used? I got lucky and found a local guy who sold me two d-45's and a d-150a sII for $600. You should be able to buy d-45's for around $200 on ebay or craig's list IIRC.

A t-amp can work for you too. I had one before the d-45's and was pretty happy with it. More hiss than the crowns, but you can buy modules pretty cheap.
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post #36 of 1592
10/7/10 at 4:43pm
Quote:
Originally Posted by steve71 View Post

Yeah it's hard to get into the idea of spending that kind of money for a 25w/ch amp.

What about used? I got lucky and found a local guy who sold me two d-45's and a d-150a sII for $600. You should be able to buy d-45's for around $200 on ebay or craig's list IIRC.

A t-amp can work for you too. I had one before the d-45's and was pretty happy with it. More hiss than the crowns, but you can buy modules pretty cheap.

Preferably, I'd like all three to be identical so it might be difficult to source three used ones but I'll keep my eyes open for em'. T-amps would be an inexpensive temporary solution too. I might try those.
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post #37 of 1592
10/7/10 at 4:57pm
Quote:
Originally Posted by Scott Simonian View Post

Preferably, I'd like all three to be identical so it might be difficult to source three used ones but I'll keep my eyes open for em'. T-amps would be an inexpensive temporary solution too. I might try those.

I went with a bigger amp (75w/ch) on the bass horn since the driver is rated for that power. Plus, have you seen the chassis-less design of the D-150's? They look cool...
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post #38 of 1592
10/7/10 at 10:12pm
Quote:
Originally Posted by steve71 View Post

Seems to me A9X-308 is right. The mini dsp and the DCX require different gain structures. But other than that they should have about the same s/n ratio (assuming the s/n specs are the same).

I have: dbx drive rack PA -> crown d-45 amp -> 115db/w/m horns. No hiss due to correct gain structure.

Sort of makes my case.

dbx PA specs



From DCX specs



Dynamic range: 109 vs 110dB: you've managed to do it Steve with a unit with the same basic specs, so it must be possible, something I've been saying, and doing, for ages.

And just to top it off here's someone else's set of measurements on a stock DCX, abeit using the SPDIF in (44.1k digital silence), so it shows the base noise of the processing and DAC and O/P stage.

[yellow curves]



and with a 1kHz -3dBFS 1kHz signal.



Note the vertical scale differences between the two images.

Analogue in won't be quite as good but the AD is a good unit (AK5393VS) and it's still a massive leap to go from this basic performance to a measured level of 60dB SPL.

From AK5393 datasheet.




My tests will be similar, but using the analogue in. Nothing else to get involved. I can get a stock DCX to loan, but maybe not till late in the week or next w/e. Going away this w/e.

When people continue to post technical rubbish, I will call them on it, no matter how much they scream and try to get me not too. Perhaps if said people did not post this, I wouldn't need to reply, no matter the title of the thread.
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post #39 of 1592
10/8/10 at 1:13am
Quote:
Originally Posted by steve71 View Post

Seems to me A9X-308 is right. The mini dsp and the DCX require different gain structures. But other than that they should have about the same s/n ratio (assuming the s/n specs are the same).

I have: dbx drive rack PA -> crown d-45 amp -> 115db/w/m horns. No hiss due to correct gain structure.

I'm curious: no hiss at what listening distance?
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post #40 of 1592
10/8/10 at 6:14am
Thread Starter 
Quote:
Originally Posted by steve71 View Post

Seems to me A9X-308 is right. The mini dsp and the DCX require different gain structures. But other than that they should have about the same s/n ratio (assuming the s/n specs are the same).

I have: dbx drive rack PA -> crown d-45 amp -> 115db/w/m horns. No hiss due to correct gain structure.


Never once argued about S/N ratio. Never posted it!

I said the DCX increases the noise in the speaker because it runs HOT. I NEVER posted that it creates NOISE. It just "amplifies" the noise the already exists. The problem here is the engineer in some people can not get past semantics. Word whores is what we call them in my company...its why I win contracts and some engineers can not get past the initial discussions.

I asked for this to be the miniDSP discussion so please respect that and drop the DCX stuff. There are enough threads for that and A9X can create his own thread to post stuff already known.

The last part here is about the stupid gain structure discussion. You guys have get off the pro audio mentality. Not all setups have pro gear and amp gains. Some of us live in a world where looks matter as much as functionality and in those cases Im not going to put an ugly pro amp/pro gear in the situation. Im not going to try and hide it either to statisfy some unknown pro guys online. You do not know my world so please stop assuming we do gain structure wrong unknowningly in all situations.

Even with proper gain structure (in my HT room) HISS exists. The problem here is that some do not know what "HISS" means.

Now that is the final word on this topic in this thread. Create another thread if you want to discuss those topis.

Please only discussion MiniDSP and not the DCX.


Any more post on the DCX will be removed because I will request them to be removed.
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post #41 of 1592
10/8/10 at 6:15am
Thread Starter 
Quote:
Originally Posted by findbuddha View Post

I'm curious: no hiss at what listening distance?

Please ask this in another thread.
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post #42 of 1592
10/8/10 at 7:10am
Quote:
Originally Posted by penngray View Post


The last part here is about the stupid gain structure discussion. You guys have get off the pro audio mentality. Not all setups have pro gear and amp gains. Some of us live in a world where looks matter as much as functionality and in those cases Im not going to put an ugly pro amp/pro gear in the situation. Im not going to try and hide it either to statisfy some unknown pro guys online. You do not know my world so please stop assuming we do gain structure wrong unknowningly in all situations.

Even with proper gain structure (in my HT room) HISS exists. The problem here is that some do not know what "HISS" means.



Speaking of gain structure, which version of the mini DSP did you buy? The 0.9 V rms / 2.5 V p-p max version or the 2.0 V rms / 5.6 V p-p max version?
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post #43 of 1592
10/8/10 at 7:12am
Thread Starter 
Its the RevA version with 0.9Vrms/2.6Vpp
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post #44 of 1592
10/8/10 at 8:15am
Bad form Penn.
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post #45 of 1592
10/8/10 at 8:19am
Thread Starter 
I actually agree with you! Im far from perfect in dealing with it.

I just want the thread to be on MiniDSP, not outstanding issues that are just rehashed from thread to thread.
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post #46 of 1592
10/8/10 at 10:24am
Hi Penn,

I know you have a lot of balls in the air, but have you considered using the miniDSP with your QSC 152i clones? I would love to hear your comments on active vs passive comparisons with this particular speaker.

Thanks,
Darrell
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post #47 of 1592
10/9/10 at 11:36am
Thread Starter 
I do not have my Passive XO done on the HPR152i designs. Im still active with those but I definitely want a comparison.
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post #48 of 1592
10/9/10 at 2:28pm
hey penn, the way that you will know when you have your passive voiced in right will be when you can't tell the difference between the passive and the active. that could take a lot of expensive components landing as "clippings on the floor" though.
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post #49 of 1592
10/21/10 at 11:37am
Thread Starter 
I didnt do a loopback test on the MiniDSP but I have tried it with my speakers and I like it.

What I like even more is that I took some small bookshelf speakers like the RB kit and I added bass bins too them to make a 3 way. Used the MiniDSP to XO around 150Hz with the RB Kit to my SC-8s and I like my new found bass. Simple and nice product, I have been looking for a DSP with RCA connections for years and finally I have it.

Its a pretty powerful little device!
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post #50 of 1592
10/21/10 at 11:42am
I'm glad it is working out. Wish it was around a few years ago.

Which software packages do you have on it?
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post #51 of 1592
10/21/10 at 11:59am
Thread Starter 
I purchased the 2-way Crossover Advance Version 2 with it.

I need to buy atleast 1 more now for my bedroom so I can finish my speaker project for that room.
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post #52 of 1592
10/21/10 at 6:13pm
I've lately been thinking of using a MiniDSP for crossover and PEQ with our Danley DST-10 Sub. With the Danleys quite eratic FR it unfortunatley need a LOT of EQ. I believe they also have a EQ software pack that I would also use with their crossover pack. Does this sound like a doable?

If I could use the MiniDSP it would free up the DCX2496 that I'm presently using. I want to use the DCX for 2 way active X'over for our L,C,Rs.

Thanks for starting the thread Penn.

Rod
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post #53 of 1592
10/22/10 at 4:49am
Thread Starter 
I think they have created a balanced version not sure if its in a box (kit) yet.

Also I have asked for measurements on the product to make sure it does not do anything screwy below 20Hz. I know i should do them myself and its probably 20 minutes but I still not sure just doing a loopback test using just HOLM is good enough.

MiniDSP has its own forum too. There seems to be some good activity and right now Im reading all about the "bi-quad" stuff and all pass filters which seem correct phase issues. Lots of math in that though and my head hurts but the bi-quad stuff makes the MiniDSP more powerful in some aspects then our DCX and my consumer setup likes the MiniDSP better then the pro DCX, no silly level/gain issues that come with the DCX.
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post #54 of 1592
10/22/10 at 6:44am
Thread Starter 
Here is a link to a LT circuit with the biquad filter

http://www.minidsp.com/support/forum...mit=6&start=24


One of the past posts as a zip file for download with many calcs. Pretty cool if you understand it (I do not really understand it but I can fumble around). It creates the values to be entered from just inputing some data. Like in the HPF table, I put 12Hz and it gave me the biquad values...that is impressive stuff. Now I need to know if it works.
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post #55 of 1592
10/22/10 at 7:28am
Thread Starter 
The miniDSP link on advanced filters.


http://www.minidsp.com/applications/...ad-programming

Quote:


Advanced Biquad programming trully opens the door to a new range of filtering applications such as:

Linkwitz transform
All pass filters
Cascaded filters (e.g. two low pass filters in series)
Filters of up to 16th order (96dB/oct) when cascading 8 biquads.. Still not enough? How about adding the remaining 6 biquad filters from the PEQ outputs and building a ( 8 + 6) * 2nd order = 28th order filter with 168dB/oct attenuation.. :-)
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post #56 of 1592
10/22/10 at 9:58am
Quote:
Originally Posted by penngray View Post

I think they have created a balanced version not sure if its in a box (kit) yet.

Also I have asked for measurements on the product to make sure it does not do anything screwy below 20Hz. I know i should do them myself and its probably 20 minutes but I still not sure just doing a loopback test using just HOLM is good enough.

MiniDSP has its own forum too. There seems to be some good activity and right now Im reading all about the "bi-quad" stuff and all pass filters which seem correct phase issues. Lots of math in that though and my head hurts but the bi-quad stuff makes the MiniDSP more powerful in some aspects then our DCX and my consumer setup likes the MiniDSP better then the pro DCX, no silly level/gain issues that come with the DCX.

Shouldn't take much more than hooking it up to your pc/laptop, booting up REW and disabling any mic calibration files. That will tell you right there whats going on <20hz.

Keep us updated on the custom bi-quads. Definitely interested in working that stuff out.
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post #57 of 1592
10/22/10 at 10:07am
Thread Starter 
The spreadsheet I downloaded is awesome. Its easy to use and it creates all the values to plug in. LT circuits and HPF even at 12Hz can be created.
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post #58 of 1592
10/22/10 at 10:11am
Thread Starter 
Some updates on questions since I have more info now...

Quote:
Originally Posted by Scott Simonian View Post

Sweet! Good to hear.

Penn, real quick one for you... how low (or high, even) in frequency can you modify with this dsp? Could you do any filters below 20hz?


Quote:
Originally Posted by Antripodean View Post

It doesn't operate below 20Hz but I have made this request to MiniDSP. I think if enough people ask it will become a part of the firmware.

MiniDSP does not have "basic" EQing for under 20Hz but in the advanced mode people can create whatever they want if they understand bi-quad or download a spreadsheet with all the formulas from the miniDSP forum.

The answer here is that in theory we can create a HPF at any frequency below 20Hz.
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post #59 of 1592
10/22/10 at 10:12am
Thread Starter 
Quote:
Originally Posted by noah katz View Post

Won't it take two to do what a DCX does?

Costs the same w/o a lot of the DCX's features, no, in particular the display?

After more time with it and if I understand the advanced features I would say that in some aspect it has more features then the DCX.

Especially in a 4 way design where cascading filters are really needed, not that Im doing a 4 way design but the DCX can not do cascading filters.
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post #60 of 1592
10/22/10 at 10:20am
Thread Starter 
Quote:
Originally Posted by Scott Simonian View Post

Shouldn't take much more than hooking it up to your pc/laptop, booting up REW and disabling any mic calibration files. That will tell you right there whats going on <20hz.

Keep us updated on the custom bi-quads. Definitely interested in working that stuff out.

Someone else did some awesome measurements...

http://www.diyaudio.com/forums/minid...ml#post2340627

Pretty well a flat response, if you can actually see the dB axis you will see its less then .4dB drop down to DC.

The noise measurements are very interesting compared to the DCX. I said subjectively the noise floor is lower on it but these measurements confirm my opinion.
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