# MiniDSP 2x8 bench test



## Ludemandan (Jul 13, 2005)

Having played around with the MiniDSP 2x4’s quite a bit, I’m already a fan of the concept, and familiar with their strengths and shortcomings. When the 2x8 came out, I had to try it out. Conveniently enough, I have a bench system with a 7-channel amp mounted on the wall in my garage, and some speakers I’ve been meaning to test, and all it needed was a big DSP to make it work. Justification for purchase, check!

miniDSP 2x8 kit | miniDSP

First and foremost: at 200mm x 300mm, there is nothing mini about this DSP. It probably has the largest footprint of any DSP available for 12V. It's almost the size of my laptop. Unlike the 2x4, much of the circuit board is wasted space. It looks like they took a large PCB template and rushed the product to market without much time spent on form factor (I hope this is the case, because that means they might be working on a more compact one). 











On the board on the wall in 3-channel initial hookup phase. You can get the scale of the thing by the objects next to it.











I'm just starting to play with it, and I'll post my impressions as they are created.


Dan


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## Ludemandan (Jul 13, 2005)

Here are some screen shots that should illustrate the functionality pretty well. Unlike the classic 2x4 unit, this doesn't have a selection of different plug-ins. It just has a single DSP software. 


Input stage, with PEQ, gain adjust, input level monitor and mute. Notice it has two analog and two digital inputs, which can be used at the same time. It also has four separately adjustable configurations.











You can see the flexibility in the channel routing. Any input channel (analog or digital) can be routed to any output channel (analog or digital), really making this a 4x10 unit if you have the hardware to take advantage of it. The routing pictured is how you make L/R pairs of channels 1 & 2, 3 & 4, etc.











Output home page. The delay adjustment is here, and has very high resolution. Unfortunately, it only goes up to 9ms. If you want left-minus-right delayed rear fill, you have to hook up a 2x4 downstream. 











One new feature of the 2x8 is an output level meter for each channel.











Another cool feature is real-time linking of any channel to any other channel. It is no longer necessary to take an extra step to transfer an EQ or Xover setting to the other side.











The crossover has nice resolution on the slopes. Notice 30 db, etc. Also in this shot, two channels are linked.











As before, you can track the EQ curve with the mouse.











And the same EQ curve, but with "high shelf" instead of "peak" selected as the filter type.


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## ErinH (Feb 14, 2007)

Thanks for doing this review. Looking forward to more info. 

Do you have a means to measure preout voltage so we know what it's capable of in stepped volume?


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## Ludemandan (Jul 13, 2005)

bikinpunk said:


> Thanks for doing this review. Looking forward to more info.
> 
> Do you have a means to measure preout voltage so we know what it's capable of in stepped volume?


I have a multimeter, and better yet I have a Velleman oscilloscope that I bought but haven't used yet. I'll put actual preout voltage on my to-do list.


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## nar93da (Dec 11, 2008)

Man, I've been waiting for someone to try one of these out! Thank you, thank you. 

That board is rather large, looks like they could've made it half that size. With all the inputs, RCA outputs, balanced outputs it would have been cramped if/when you make a case for it. 

I've already mentioned something to the fine Mr. Roberts about looking at one if problems do arise and it needs improvements and such!

I could've sworn I read something on the minidsp forum about a volume control for it? You know anything about that or am I imagining it?


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## bkjay (Jul 7, 2009)

Man I wish that thing had a sub input, it would be nice to control sub volume from head unit.


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## bkjay (Jul 7, 2009)

Thanks for taking the time to post this for us.


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## bkjay (Jul 7, 2009)

I just noticed no 31 band eq? or did I miss that?


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## Ludemandan (Jul 13, 2005)

That is true, the 6 band per channel PEQ is all you get.


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## 9mmmac (Dec 14, 2010)

I'm seriously considering this; but haven't been able to find a proper sized case for it. Has anybody else had luck?


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## Ludemandan (Jul 13, 2005)

Another cool feature I found, you can rename all the channels. Characters are limited though.


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## Alchemy12s (Jun 1, 2011)

sub'd. Thanks OP for the review thread. Very interested in where they take this technology. 

hopefully the mobile audio scene buys in enough that they see a dc-dc isolated 2x4 with 2-4v rms outputs has a good sized market(and i would imaged it does).


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## funkalicious (Oct 8, 2007)

Thanks for the review! Have you contacted miniDSP about possible future plug-in options?


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## chefhow (Apr 29, 2007)

Any more info on what you like/dislike about the unit? Ease of use? Noise issues?


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## Ludemandan (Jul 13, 2005)

My bench install has taken a back seat to my car install this week, but I'll try to finish this up soon.


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## funkalicious (Oct 8, 2007)

9mmmac: Found a DIY case here - Metal Project Boxes. Even has a 5V power supply and is cheap!


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## 9mmmac (Dec 14, 2010)

COOL! That's neat stuff there. Wild to think about the engineering that went into all those different items. Now it's kinda... derelict. Thanks for finding!


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## nar93da (Dec 11, 2008)

I'll be ordering one in the next couple of days. May give some thoughts as well if Ludemandan can get to it. I may opt for the digital input/output board since you get a deal if ordered at the same time. Even though I won't need it with the deck I'll be using, may be good for future use.

I mentioned something about volume control above. I looked through the manual and saw you can wire a 10K linear pot into the board. Damn good idea!

Those project boxes linked above seem to be either to large or to small. To save space in the box it would be a good idea to remove the RCA inputs and outputs and use chassis mount RCA terminal's and run wire to the board.


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## tyroneshoes (Mar 21, 2006)

When you get it set up in the car, please report on any noise issues.

For those worried about adjusting bass from the dash, get an amp with a sub level remote.


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## nar93da (Dec 11, 2008)

I won't be able to give you any impressions installed in a vehicle as I'm still far from an install. Just gathering some equipment at the moment.

As soon as a few cable's come in and I stop delaying and order the Minidsp I plan on getting some measurements using Right Mark. I can also try it out on my bench set-up and get pre-out voltage and what not.


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## BowDown (Sep 24, 2009)

Wow very cool. Almost kicking myself for the H700 purchase. :lol: Considering I have a carPC.


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## Ludemandan (Jul 13, 2005)

The 2x8 has a remote turn-on feature with a delayed output trigger. With the old one you had to power it with the remote lead. With this one you can power it with +12V and trigger it on like other equipment. The remote output has a 2 second delay to avoid pops, both on power-up and power-down.










Two seconds is pretty short, compared with Audison's 9 seconds, which is unnecessarily long. Sometimes I can hear the tail end of the Zapco i-force amp shutting down, though it's faint and the pop is gone. 

What the manual doesn't say is that the little black jumper above the green power terminals is a short from +12V to remote on, thus it turns on the DSP as soon as it is powered. I thought the feature didn't work properly for a while, until I removed that jumper, and now it behaves the way you would want for car audio.


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## bginvestor (Jan 13, 2008)

I was looking at the specs below for the minidsp 2X8 kit. The input voltage is max at 2v RMS. Does this bother any of the experts in noise floor quality. I hate a loud noise floor. thx.


Digital Signal Processor 172MHz, 28/56bit Digital Signal Processor
Control Driverless USB 2.0 control interface for Windows/Mac OS x environments
Audio inputs Balanced (Phoenix Terminal Block) OR Unbalanced (RCA) inputs
Audio outputs Balanced (Phoenix Terminal Block) AND Unbalanced (RCA) outputs
ADC/DAC Resolution - Sample rate 24bits bit depth - 96kHz sample rate
Dynamic range of ADC/DAC converters 114dB
Maximum Input signal RCA input: 2Vrms (8 dBu) in unbalanced mode
Phoenix terminal: 4Vrms (14 dBu) unbalanced OR 8Vrms (20dBu) balanced
Maximum Output signal RCA output: 2Vrms (8 dBu) in unbalanced mode
Phoenix terminal : 4Vrms (14 dBu) unbalanced OR 8Vrms (20dBu) balanced
Infrared Red (I.R) receiver (Future) Front panel I.R. receiver controls volume, mute and preset recall
Expansion Bus I2S in&out expansion connector compatible with miniDIGI I/O card
Power supply Single 12Vdc power supply, 18W power supply - Terminal block connector
Dimensions (H x W x D) mm 30 x 200 x 250 mm


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## Thumper26 (Sep 23, 2005)

Balanced input with unbalanced output gets you 4v. This can be done with a zapco balanced adapter. Or you can get a line driver.

Mine is waiting for me at work, will be installing tomorrow night.


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## takeabao (Jul 18, 2005)

They need to make a box for this thing ASAP.

It will sell like hotcakes.


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## roduk (Sep 19, 2008)

Hello Ludemandan,

Really interested in your review - any further thoughts? I'm running an Alto UCS Pro atm and need the minidsp for three reasons - 

8 channels over 6
Software Mac OSX compatible
More modern

But I need to know if it is silent in operation - the Alto has a very very slight hiss and I hate it, I will not be buying the Minidsp if it introduces any noise.. Can you confirm?


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## GLN305 (Nov 2, 2007)

I would like to know if you can adjust on the fly and hear your adjustments?


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## Ludemandan (Jul 13, 2005)

roduk said:


> Hello Ludemandan,
> 
> Really interested in your review - any further thoughts? I'm running an Alto UCS Pro atm and need the minidsp for three reasons -
> 
> ...


I haven't installed it in my car, but I'm pretty sure it would have the same noise issues as the original unit. MiniDSP came out with a DC power isolator that works with the 2x4 but does not have enough power for the 2x8. Hopefully that is in the pipeline.


GLN305 said:


> I would like to know if you can adjust on the fly and hear your adjustments?


You can hear your adjustments in real time. "On the fly" may not be a fair description though, since you have to plug into it with a laptop (I think of "on the fly" as reaching down to adjust the suspension settings on your fork while mountain biking).

Dan


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## Ludemandan (Jul 13, 2005)

Also, the board has been operating reliably since I first posted this thread, averaging several hours a week on 7 channels whenever people are spending time in the garage. I haven't played with the adjustments much since the initial setup or taken voltage measurements yet, but I'm about to install my BG planars in the wall, and then some tuning will commence!


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## M-Dub (Nov 29, 2006)

Ludemandan said:


> I haven't installed it in my car, but I'm pretty sure it would have the same noise issues as the original unit.


The 2x8 does not have the same noise issue the 2x4 did.

Not sure what kind of magic they put in it.

*Source* I have two 2x4 boards and one 2x8.


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## Ludemandan (Jul 13, 2005)

M-Dub said:


> The 2x8 does not have the same noise issue the 2x4 did.
> 
> Not sure what kind of magic they put in it.
> 
> *Source* I have two 2x4 boards and one 2x8.


Great to know! They must have included a noise isolator on the board.


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## bginvestor (Jan 13, 2008)

Ludemandan said:


> Great to know! They must have included a noise isolator on the board.


Can you please elaborate on the noise issue for the 2X4? All 2X4 or just some of the older ones..

Reason why I am asking is because I just bought one for a desktop PC setup at home.


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## M-Dub (Nov 29, 2006)

bginvestor said:


> Can you please elaborate on the noise issue for the 2X4? All 2X4 or just some of the older ones..
> 
> Reason why I am asking is because I just bought one for a desktop PC setup at home.


The noise is engine whine that fluctuates with RPM. It's unnoticeable on a test bench or desktop. You should be fine.


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## bginvestor (Jan 13, 2008)

M-Dub said:


> The noise is engine whine that fluctuates with RPM. It's unnoticeable on a test bench or desktop. You should be fine.


Thanks


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## bginvestor (Jan 13, 2008)

Ludemandan said:


> Great to know! They must have included a noise isolator on the board.


Hey Ludemandan,

Have you installed your 2X8 in the car yet? It would be great to see how it worked out for you. Very interested in sound quality.

I've decided to install my Ipad in the car and I believe the 2X8 can be a great processor.

I currently bought a 2X4 for a PC setup and its working very well. thx.


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## Ludemandan (Jul 13, 2005)

bginvestor said:


> Hey Ludemandan,
> 
> Have you installed your 2X8 in the car yet? It would be great to see how it worked out for you. Very interested in sound quality.


I'll try to make a point of it over the holiday break. I definitely need to set aside some quality garage time.


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## fcarpio (Apr 29, 2008)

Thanks for the review, but how does it sound?


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## X Ray (Oct 29, 2007)

I installed the 2x8 in my car a few days ago. There is a terribly loud noise floor when hooked straight to 12v. And I mean LOUD. 

When hooked up to a 12v wall-wart in the casa, it's super quiet. 

Not sure what the problem is. I'm assuming it needs some form of isolation from the cars electrical system. 

Did anyone else install this in a car yet? Issues?


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## fcarpio (Apr 29, 2008)

Mine is installed in my car and I don't have such issues, the thing is pretty quiet. Have you checked your ground?


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## X Ray (Oct 29, 2007)

fcarpio said:


> Mine is installed in my car and I don't have such issues, the thing is pretty quiet. Have you checked your ground?


I have it grounded to the same exact spot as my amp in the trunk. 

I guess I'll get out there and mess with it some more.


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## X Ray (Oct 29, 2007)

It was mounted to close to the amplifier. I moved it away and the noise is gone.


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## Ludemandan (Jul 13, 2005)

I just tore out my BitOne and plugged in the 2x8.

With my phone as the input source, there was no noise at all. With the HU as the input source, there was a huge din of noise (2x4 status).


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## lbp775 (Jul 7, 2011)

Ludemandan said:


> I just tore out my BitOne and plugged in the 2x8.
> 
> With my phone as the input source, there was no noise at all. With the HU as the input source, there was a huge din of noise (2x4 status).


Were you able to fix this? I'm having the same issues. Hooked up a 2x4 with DC isolator and get no noise. Replaced it with a 2x8 and I'm getting a ton of alternator noise.  I've checked my grounding and the 2x8 is nowhere near the amps. Any ideas? Can I build a DC isolator suitable for the 2x8?


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## Ludemandan (Jul 13, 2005)

I haven't had the necessity to solve this problem because I'm not running miniDSPs in my car. But the 2x8 datasheet says it has an 18W onboard power supply, which means at 12V you would need an isolator that provides 1.5A.


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## Thumper26 (Sep 23, 2005)

i believe the manual has a section on a jumper you move to change the ground on the power supply from isolated to non isolated.

didn't read the thread, so if this was already covered then sorry.


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## lbp775 (Jul 7, 2011)

Thumper26 said:


> i believe the manual has a section on a jumper you move to change the ground on the power supply from isolated to non isolated.
> 
> didn't read the thread, so if this was already covered then sorry.


Can you direct me to the page on the manual? I only see jumper settings for input voltage and the remote out function. I really hope this is it.


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## BowDown (Sep 24, 2009)

Hopefully in the next week or 2 I can continue this thread with more listening impressions and such. Hopefully not coming back here with noise issues. :laugh:


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## Ludemandan (Jul 13, 2005)

BowDown said:


> Hopefully in the next week or 2 I can continue this thread with more listening impressions and such. Hopefully not coming back here with noise issues. :laugh:


Please do. I think separate opinions by a few different people in a few different cars will help filter out any mistakes and individual circumstances.


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## BowDown (Sep 24, 2009)

This is true. I believe the design of the minidsp has changed greatly in favor of vehicle installation since it's original release. Can't wait to see how it compares to my proven h700 dsp. 



Posted from my Samsung Galaxy S III 32gb via tapatalk 2.


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## pionkej (Feb 29, 2008)

Looking forward to updates as well. I'm ordering one next week and I'm curious why there are mixed results for noise. I had read the dc isolator was already on the board with the 2x8 and 8x8.


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## BowDown (Sep 24, 2009)

True. There is an isolator built into the board and it's rated for 5v - 20v. If I was to take a wild guess I would imagine it's a ground loop issue with using analog inputs off a headunit. 

Mine is coming with a DC-DC 12v power supply, and I have a couple 1:1 isolation transformers I'm going to use prior to the DSP off the HU (FM Radio). Rest of the inputs I have are toslink.


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## Ludemandan (Jul 13, 2005)

Is it the miniDSP power supply? That's only supposed to work with the 2x4.

Here's one with plenty of ampacity for the 2x8. 
VCD30-D12-S12-T CUI Inc | 102-1608-ND | DigiKey


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## BowDown (Sep 24, 2009)

No it's some kind of eBay special external power supply.


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## BowDown (Sep 24, 2009)

SD-25A-12 Mean Well | Mouser this is my voltage regulator.


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## BowDown (Sep 24, 2009)

Well I got the miniDSP installed and working last night. 

First impressions: I love it. 

The software is very easy to use.. and not overly intimidating. The on the fly changes work very well. I keyed in the TA, Crossover, and GAIN settings from my H700 and it's pretty damn close. I will be tweaking the tune for sure though. 


Things I miss coming from the H700:
-Small footprint of the H700 was nice.
-Optical In (miniDSP 2x8 doesn't have one without adding the DIGI-FP card)
-Physical Volume Control 
-31-Band Graphic EQ

Overall I believe this miniDSP is a step in the right direction for me. It's just going to take a **** ton of tweaking to figure out how to tune with this 5-Band Parametric EQ. I'm going to break out the RTA this week and see what I'm looking at. Having control over each of the tweeter/midrange in the pillars is adding a new level of tuning. The H700 used to combine them when controlling EQ, now I can figure out which one is the problem around 4-5.6k.


BTW: No noise what so ever. I'm using that regulated power supply listed above, and a pair of 1:1 isolation transformers on the analog inputs. 


I did run into an issue using the delayed REM option on the board. It appears that (3) amps is too much for the board to handle. Specs say the board only outputs 10ma? Ouch. I'm going to wire up a relay on the delayed REM... but even with the amps coming on along side of the miniDSP I have no pops.


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## Ludemandan (Jul 13, 2005)

You're using isolation transformers inline with the RCAs? That kind of nullifies the noise test. Have you tried it without them?

It's true, the 5 bands are kind of limiting, but as a PEQ they're quite flexible. 31 bands would be nice but I'm not sure being stuck with a GEQ would be worth it.


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## thehatedguy (May 4, 2007)

Download the active crossover design spreadsheet from Charlie laub to see if you can do more with the eq and crossovers. You can program your own biquads with the minidsp, so you have more flexibility than you might think. And you can import room eq wizard settings straight to the minidsp for "auto " tuning too.


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## BowDown (Sep 24, 2009)

Ludemandan said:


> You're using isolation transformers inline with the RCAs? That kind of nullifies the noise test. Have you tried it without them?
> 
> It's true, the 5 bands are kind of limiting, but as a PEQ they're quite flexible. 31 bands would be nice but I'm not sure being stuck with a GEQ would be worth it.


Yes I used the isolators and the dc-dc converter off the bat. I can go back and test in a different configuration later. At the moment I just wanted to make sure the used piece functioned correctly and get some tunes back in my ride.

You are correct.. the PEQ is VERY flexible. Much more so than the 31-band for my needs. It's just going to take a learning curve to get everything dialed in. I've never had to think in terms of Q before.


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## BowDown (Sep 24, 2009)

thehatedguy said:


> Download the active crossover design spreadsheet from Charlie laub to see if you can do more with the eq and crossovers. You can program your own biquads with the minidsp, so you have more flexibility than you might think. And you can import room eq wizard settings straight to the minidsp for "auto " tuning too.


Cool. I was looking for a spreadsheet to help interpret my GEQ and maybe give me an idea what it would look like in PEQ. I will be tuning from scratch though. No point in repeating history when I have more tools at my disposal.


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