MiniDSP: An excellent alternative! 56k, beware!

[ErinH]

*Note: I wrote this for a car audio forum. The simple fact is, though, that this product is meant to be used anywhere that one would use a DSP. It is not a car audio product. In fact, you probably have seen threads on it on diyAudio.com forum. A lot of what I say below is directed at car audio guys. I will not be parsing it out because I honestly don't want to reformat just for a few paragraphs.

The meat of the review is about the product itself. It's applicable to anyone using it for any purpose. I hope you enjoy. If you have any questions, please visit their website, linked at the end of this review.

And, yes, the pictures of the board are large for a reason. I wanted the components used to be seen without a magnifying glass.

With that, let's get this show on the road.... *











What is it:
A digital signal processing board with 2 inputs and 4 outputs per board. Multiple boards can be connected to make as many output channels as you want.


They have an array of boards to choose from. The most basic is an all analog DSP board, called the miniDSP (which this review is based on).
http://www.minidsp.com/products/minidspkits
Note there are two versions of this board:
Rev A = 0.9V input
Rev B = 2.0V Input
For car application, you’ll want the Rev B version if you have a headunit with a high pre-out voltage. Otherwise you’ll clip the inputs. This may seem like a huge concern when looking at the numbers, but read the “Concerns” section of this review to see my findings on the matter.



The next step is a DSP board which uses optical inputs and outputs known as the miniDIGI:
http://www.minidsp.com/products/minidigi

The other option is the miniAMP which is about the same size as the DSP boards listed above, and serves as a class D amp pushing out 4x10w @ 4 ohm or bridged for 2x20w @ 8ohm.
http://www.minidsp.com/products/miniamp


Who makes it:
A company out of Hong Kong, called miniDSP.
Here’s t heir website:
http://www.minidsp.com/index.php

Don't be concerned about this. Shipping took less than a week to reach me from Hong Kong.


What does it do:
Well, I think the real question is what can’t it do.

This processor is a standalone board with the ability for multiple options of DSP. So, you can order the board and the software separately. The software is called a “plug-in”. They offer a wide range of various plug-ins varying form a simple 2.1 stereo w/sub setup to a 4-way P-EQ plugin which allows you to have 6 channels of parametric eq per input (2) and output (4).

The cool thing is that the company is always updating their plug-ins, and you get the upgrades for free. Once you pay for one version of the software, you’re future proofed.

For more information on their plug-ins, see this link:
http://www.minidsp.com/products/pluggins

You have many, many options with these guys. In fact, if one wanted, they could have 31 bands of graphic eq + 6 bands of parametric. This would be a great solution for those who want the ability to focus and fix particular problems with a parametric equalizer and then shape the overall output with a 31 band graphic equalizer.
The best part about the parametric is the ability to have a Q (bandwidth) as wide as 0.5 or as narrow as 50. That’s insane!

Beyond the EQ capabilities, here's a run-down of the other standard features:

• Time Alignment in 0.02ms increments
• Phase Flip (0/180)
• Channel muting
• Linkwitz-Riley with slopes of 12, 24, and 48dB/octave slopes
• Butterworth with 6, 12, 18, 24, 30, 36, 42, and 48dB/octave crossovers
• Bessel crossover (fixed slope)
• Individual channel input/output gains with attenuation of up to -70dB
• Bypass: You can bypass the crossovers, or EQ to compare the changes you've made to what it sounds like without those changes
• Levels of Equalizer is ±16dB
• Equalizer Types can be standard (Peak) or High or Low shelf.

Yea, yea, that's nice. But how much does it COST!?
Each board runs only $100 and each plug-in costs only $10. One could have an 8-way setup with both graphic eq and parametric eq for $220+shipping!



Product Pictures:
Here are some pictures of the product. What you get when you order one of these boards is a 4.5’ usb cable, a set of RCA cables, and standoff posts.
The following pictures are for you EE gurus out there. I won’t say anything about this stuff.

 

[ErinH]

Alright, alright, get on to the REVIEW:
As noted above, this review covers only the miniDSP board and P-EQ plug-ins. For the purpose of this review, I illustrate only the parametric EQ as we all know what a 31 band graphic equalizer looks like. Since the P-EQ is much more diverse than you’re probably accustomed to, I wanted to highlight its features.


System input screen allows you to choose subwoofer type (mono or stereo) if you have the 2.1 plug-in, load, and save settings, and do a few other things which I haven’t used:

Here’s the input gain screen of the 4-way PEQ plug-in. Note that you can see how the mapping structure links the crossovers. This is different from how the 2.1 screen maps the inputs to the outputs (pictured below 4-way screenshot).
This screen also allows you see how the input signal is affecting the input stage, in case you're worried about the preout voltage of your headunit being too high. More talk on this below...

Screenshot of the Input Parametric Equalizer settings. Note that you have 6 bands of P-EQ for each input and output.
More importantly, note how you can set the ‘Q’ bandwidth anywhere from 0.5 to 50 and you have a ±16dB swing to adjust the EQ levels. Quite awesome. I know of NOTHING else in the car audio world that gives you this kind of control. And, yes, you can overlap EQ bands.

Screenshot of the Crossover for the 4-way PEQ version. Note the various types of crossovers and slopes.
The coolest part? You can TYPE in ANY crossover point you want. Check the picture to see how arbitrary crossover points can be used. Note that you can bypass the crossover with the push of a button.

Here’s one of the output PEQs. Same as the input PEQ:

Output Levels screen, which also has the mute feature, time alignment and phase adjustment.

And here it is, sitting in my car:

Concerns that might plague others:

Pre-in Voltage:
The rated maximum input voltage for the miniDSP is 2v. As mentioned earlier, it seems like it could be a concern and I was worried about it, myself. So, this was something I really wanted to test.
I played pink noise FULL TILT on my headunit and watched the input meters. They never once came even close to clipping. This was out of the bitone’s output, with a 60hz tone on the subwoofer channel, and the bitone’s outputs are rated for 8v out. Regarding input voltage, I think we’ll all be just fine. And again, you have an input voltage meter you can watch if you’re really worried about it.

Pre-out voltage:
This one is a bit more tricky. Long story short is that I had to readjust my bitone’s software output level to about 4dB on the subwoofer channel after using this guy in my car. What does that mean? Simply that I would have had to jack the gains up quite a bit. I meant to take actual voltage measurements but honestly got so caught up in everything else that I forgot to take a final measurement.
Bottom line: The low preout voltage resulted in a sound that was noticeably weaker.
So, if you guys are worried about cranking the gains on your amps and inducing more noise floor, you might want to purchase a line driver.


Cons:
Below is a list of the cons I have. I’ve also included an e-mail reply directly from the miniDSP co-founder so you guys can see just what their response is and how willing they are to better the product. I could have re-worded some of these to more accurately fit just how they work, but I wanted you guys to see some of my trip ups and the response on how I was either misunderstanding the software or how it has been fixed. Please read the following carefully, because some of the items have been addressed since I initially typed this section up and put it in the other miniDSP thread and I want people to know that.

GUI delay:
Sometimes it takes a bit for the software to recognize my commands. I'm using the software on a very capable computer, too.
Fixed:
The newest version of the software has sped up the interaction time and I no longer have this complaint. Well done, guys @ DSP.


Also, I notice that when I save the settings the board, the 'refresh' symbol is deactivated, and the only way to active it is to 'x' out the air program notifier (which tells you the status of the board/comm). When I do this, it shuts off communication to the baord. It seems that whenever I save the settings, that's all I can do unless I close and reopen the software. This could be a glitch on my end, but I've noticed it happens with both the 2.1 and the 4-way PEQ versions.
Reply from Tony:

With regards to refresh symbol, it's not really a refresh symbol but more a "Connect to" symbol. When you click once, you gain access to the board AND synchronize your current plug-in settings to the board.
After that, you are live connected (live changes) and any changes you make are applied to both the memory of the miniDSP AND the setting file in your PC. There is no need at all to click save or refreshing anymore, because all your changes are applying real time to the board and will be recalled the same if you were to reboot the board right after that change. The save function is ONLY to save if you want to keep a backup on your PC, that's it. Hope this makes sense.

Syncing multiple boards’ plug-ins.
They said it can't be done, but if there's ANY way to be able to control both boards at the same time that would be fantastic. I can speak from experience that switching between GUI's is going to have some ill effects when setting up a system. If you have experience with the Zapco DC amp structure, think about this.
Though, I think at this price point, it's something that can be lived with.

Reply from Tony:

As for the multi-board, sorry no way as of now. Maybe in the future we can evaluate the idea, but at this point it's actually complex to make this happen both in the firmware AND software.

 

[ErinH]

Overall Impressions:

Recommended with 2 thumbs up from myself and 8 from my dogs. This little guy is practically a no-brainer. In my opinion, the ONLY thing that I can see being an issue is the fact that you can’t control two boards at once. But, man, for the price, I think I’d get over it quick. To put it in perspective (and nothing against Zapco), Zapco’s amps are structured the same; you can’t tune more than one without saving work and then going to the other amp. I had 2 DC ref amps, which ran me over $1k. I was willing to deal with the shortcomings of it for a few months even at the price. Scale it down to $200 and it’s nowhere near as severe.


It’s like this, guys… we spend $400-700 on processors that have 8 channels of processing.
The laptop based DSP tuning may scare some, but if you figure how cheap one of these guys is, you can buy one or two of the miniDSP+plugin AND still have enough money to purchase a laptop to control it with. Just something to consider.

The carPC guys have had it made for a long time, but there’s finally something out there for those of us who are scared to go full-bore. This is an excellent middle ground. And, quite frankly, if you are considering a carPC, this may be a great option to do your tuning with. Most of the 8+channel soundcards out there will run you at least the cost of one miniDSP, if not two. Not to get distracted… I just wanted to mention it.

Support from this company is like NOTHING I’ve ever seen before. They actually listen to their customers. People asked for the ability to have shelf EQ and they delivered. People asked for high order slopes and they delivered.
I must have e-mailed Tony a billion times and he’s always come back with a quick reply. And, furthermore, he’s no slouch. He’s just as technical as anyone I’ve come across and knows his stuff backwards. The best part is that he’s willing to learn and is curious on how he can improve the product.
Their website has a support section, and also a forum for recommending future upgrades. These guys listen. I can’t say that for Alpine or Audison. And, with their ‘buy it once’ policy, you’ll never have to pay to upgrade your software. $10 one time and you’re set.
http://www.minidsp.com/support


So, you want my honest opinion here?
If you’re looking for a processor, this should be at the top of your list. The sound quality is just as nice (ie: I couldn’t tell a difference) as anything else I’ve used. The control and abilities are further reaching than anything I’ve used or even seen in the car audio market. The price is dirt cheap. The support is there and will be.
I say buy a usb car adapter, a 15ft A-to-mini B usb cable to run the length of the car, a line driver if you want, and get to work.
For $100/board I can forgive my gripes listed above.
For the DIY’r on a budget this is a steal. And even if you’re not on a budget, you cannot beat the processing power available here. I mean, think about it, you get all the goodies of an h701 or bitone, with even more processing capability. Seems like a winner to me.


If you have any questions for me, ask. If you have any questions about the product check out their support forum.

- Erin

 

[pasoawe]

This is a good discussion.It is helpfull to me.

 

[yepimonfire]

wow this is really cool, must it be plugged into a computer all the time?

 

[ErinH]

no. I'm using my ipod wall charger to power it. I just plugged my usb cable into the wall charger and it's fine.

set it up using a computer.

power it with a computer or some other usb source.

there's also the option of powering it via another DC source (ie: a computer power supply).

 

[Mike007]

Awesome write up!

 

[GranteedEV]

nice one