Thoughts on creating DIY powered DSP speakers

[ck42]

So I'm currently looking to replace the regular passive speakers I have in my office (14'x12' - do a lot of listening in there - work from home). Bear with me a second while I explain why I've created the thread in the first place. Sorry for the lengthy post...I tried to keep to just the bare facts though.

The room with these speakers is not very acoustically friendly and has sub-optimal placement of the speakers. But short of completely redesigning the whole room - which really, I don't think can be improved as it is anyway, I'm instead now considering DSP-based room correction (speaker DSP-EQ'ing). I definitely lean to the purist side of things (which is why I'm here at ASR) so I've not ever seriously considered using DSPs anywhere in my audio chain before. But I think that w/o it in this room, playback is always going to suck. (Also, I sit roughly 5-6ft away from the speakers...so I guess a nearfield situation too)

So....I began investigating powered/DSP speakers....for many, many....MANY hours. Here's my summarization:
Have to spend at least $1000 on a pair or else I'd be making compromises I likely wouldn't be happy with.

[EDIT]: Forgot to mention - A very common theme to nearly all of these speakers is tweeter hiss. With my setup being so close to me, this would be a complete show stopper if it was loud enough to actually hear - which I've found MANY comments saying is the case. What is up with this????

It seems like pretty much anything short of something like a Genelec is deficient in some way that would make my arse itch.
My biggest hope was for the Yamaha HSx monitors. @amirm review of the HS5 left me very disappointed with its performance though. No idea if the HS7/8 have the same issues and can't find anything online to validate hint, hint @amirm.
In case you're curious, models from the other vendors I looked and considered (in no particular order): Vanatoo, Kali, Mackie, Adam Audio, M-Audio, Neumann, Audio Engine, Fluid, JBL, IK Multimedia, and Presonus.
(Then there's the whole decision of...do I want a large/capable enough monitor to give me decent low-end? Or should I go with a 2.1 setup (more $$)

So finally....back to my original thread intent.
With all these $400-700/pair powered DSP speakers (which seems to be the price range that they're all shooting for), I just can't see how they can produce decent speaker (parts/drivers) and shove an amp and DSP in there for these prices. Just a decent passive monitor is going to be at least $400-500 pair by themselves!
My conclusion is that the speakers themselves are lower'ish end....and the amps are on the lower'ish end....and then they try to clean up the results of all that lower'ish end 'stuff' as best they can by using a lower'ish end DSP. That's the only way I can see them keeping the prices of these poweredDSP speakers down as low as they are. (But then you have the reliability concerns that go along with lower'ish end amps and DSPs)

What I'm wondering is...what would it take to replicate what these powered/DSP speakers are doing?
Can we do all of this by grabbing some decent speakers to begin with, throwing in a miniDSP(HD?) and a lower cost (but decent) Class D amp? Can we create a setup like this that would do everything that something like a Yamaha HSx does?
Sure...we're likely back up to near lower end Genelec prices by then, but would that be worth it?

Something else that most of these systems do that I really like the idea of is that they're bi-amped 2-way's. This would certainly seem to allow a lot of flexibility in how the DSP's can manipulate things. But to replicate this, it would take additional amp channels and more miniDSP's, right? Would that even be worth it?

Or, if I'm going to go the powered/DSP route, should I just stick a crowbar in the wallet and buy some Genelecs and be done with it?

 

[andreasmaaan]

Something else that most of these systems do that I really like the idea of is that they're bi-amped 2-way's. This would certainly seem to allow a lot of flexibility in how the DSP's can manipulate things. But to replicate this, it would take additional amp channels and more miniDSP's, right?

MiniDSP is 4-channel. So for a pair of two-way speakers, you'd need one MiniDSP (or MiniDSP HD) and 4 amp channels.

 

[andreasmaaan]

Or, if I'm going to go the powered/DSP route, should I just stick a crowbar in the wallet and buy some Genelecs and be done with it?

It would take a lot of work and a fair bit of learning to better a high quality monitor like a Genelec for less money, but it's possible. The most difficult part to DIY would be the waveguide or some other means of controlling horizontal durectivity. I'd give it a go if I were you but expect to have a lot of work on your hands.

 

[NTK]

For the DIY route I think the Hypex FusionAmp plate amps should be pretty easy to implement. For example, you can get a FA122 (2 x 125W @4 Ω) from Madisound for $384 per channel. It includes DSP and takes digital and analog inputs. 3-way and higher power versions are also available.

 

[ck42]

MiniDSP is 4-channel. So for a pair of two-way speakers, you'd need one MiniDSP (or MiniDSP HD) and 4 amp channels.

Thanks for that correction. So just a single miniDSP would then help bring down the DIY route price.
Big question though is: Will going with an 'outboard' amp/dsp setup be able to do what these powered/dsp speakers are doing? seems like it should, but I feel like maybe there's something I'm not taking into account.

 

[andreasmaaan]

Thanks for that correction. So just a single miniDSP would then help bring down the DIY route price.
Big question though is: Will going with an 'outboard' amp/dsp setup be able to do what these powered/dsp speakers are doing? seems like it should, but I feel like maybe there's something I'm not taking into account.

The short answer is yes. These commercial active monitors use basically exactly the same kinds of devices internally.

 

[tomtoo]

What ever you do. Dont think is realy cheaper. You can learn. It's fun. But cheaper as two 305's is hard to get for two acceptable speakers.

 

[dwkdnvr]

IMHO the sweet spot for DIY efforts tends to be neither the entry level where economies of scale dominate, nor at the very high end where cabinet construction is a big differentiator, but instead in the midrange . I think this applies here due to the way DSP cost scales - going from a 2-way to a 3-way might not add too much cost/complexity to a DIY effort, but offers an opportunity for a much better DIY design.
e.g. Hypex FA123 runs about $1k/pair, and would power a good high-end 3-way vs the FA122 @800/pr. Similarly, using a minidsp nano digi, using something cheap like a Tone Board and TPA3255 amps going from a 2-way to a 3-way probably only adds $200-$250.

So, it's seems feasible to create a true higher-end 3-way for under $2k/pr which I don't think you can get in an active DSP monitor from the better brands. Of course, it's still on you to design something that actually performs well, which is not a trivial task. e.g. I actually just purchased drivers for an experiment. Dayton RS225, SB15NBAC, Peerless DA25TX - all high quality value-priced drivers coming in under $400 for a pair of 3-way speakers. Add the Hypex FA123, or say a nano-digi +3x Khadas Tone Boards + TPA3255 amps and you're comfortably under $2k, maybe closer to $1500 even accounting for cabinets.

 

[Cahudson42]

My conclusion is that the speakers themselves are lower'ish end....and the amps are on the lower'ish end....and then they try to clean up the results of all that lower'ish end 'stuff' as best they can by using a lower'ish end DSP.

I have had many exactly the same thoughts. Here is what I am thinking of for a passive/DSP 'office' system for our Adirondack camp when I get back in May:

I looked hard at the 2x4 HD. What I definitely don't like - and it's a showstopper for me - it appears (I may be wrong) that there is no way to program the XOs and PEQs w/o a PC. No Android app. Unbelievable, IMHO. So - the Dayton DSP-408 at $149 is my current choice. But no ASR review yet - so not yet bought.

Amps/speakers - I actually have - which is what will be replaced with the new setup - a Lepai 2020 and pair of Dayton B652 AIRs. After reading @amirm Yamaha RX-596 review, I managed to pick up 2 of them the last couple months. Less than $100 total including shipping..This gives me 4 pretty decent amps.

Speakers - before selecting new passive 2-way speakers, I plan to rip out the 'crossovers' in my pair of 652 AIRs, and drive each AMT' and 6.5" woofer directly with each of the 4 596 channels. I will then 'play with' the 408 to see how 'pleasant' I can get the system to sound (source - for the 408 is an LG V20 3.5mm and Amazon Music HD). I may buy the miniDSP Mike and use REW as part of this. (I do own a bunch of PCs. Just really object to the idea of needing to use it every time I want to 'adjust' the DSP box)..

Anyway, that's the 'plan'.. Please keep us informed as you go forward ..I think a number of us might think just as you do about the cost and compromised performance of Actives, and would prefer to use replaceable separate DSP and AMPs, and Passives..

 

[ck42]

@Cahudson42
This is essentially what I am considering as an alternative DIY solution to all of these active/DSP systems.

It seems to me that if we can START with a speaker that measures & sounds already halfway decent...and then 'fix' it the rest of the way using something like a miniDSP, then it should work/sound/measure at LEAST as good as one of the active/DSP systems.

The advantages I see to going the DIY route are that you now upgrade individually, as needed/desired, your DSP, your AMP, and your speakers. You also don't run into a situation where you have a completely non-functional system if either the amp or DSP craps out in your active/DSP speaker.
With the DIY solution, if the amp or DSP has an issue, you can bypass it temporarily....and you can replace just that 1 part individually...w/o having to RMA an entire speaker(s). I would also think that the overall reliability of individual amp and DSP would be better than whatever versions are being used in most of these active/DSP speakers.

The advantage to the active/DSP solutions though are convenience...and they're a clean setup...and just easy to implement.

Where things start to maybe getting a little hairy is if the DIY solution starts approaching $1000...because at that price, you can get something like a Genelec or Neumann (albeit those will typically be 4" drivers at that price range)...but still, it would make me stop and question if I should just get a pair of KH 80's at that price point instead of going DIY.

 

[ck42]

Nearly forgot!! Instead of the miniDSP HD, you could also go with the DDRC24....and now you have Dirac Live...and then you can have auto room EQ! Like the IK iLoud MTM's...but better! (Also adds another $200 to the cost of the DIY solution).

So then let's say you spend $300 on some decent small 5"/6.5" speakers to get things started. Then another $400 for the DDRC24. We're now at $700! And we haven't even added any amps yet.

Or $300 for the speakers and just the miniDSP HD for $200. We're at $500....and need two stereo amps. That's do'able. (Can add Dirac Live option later to the miniDSP HD if desired, which is cool). Or could we maybe get away with starting with some speakers that are less than $300 that could be DSP corrected well enough?

So for a LOT of these size powered speakers that I've been looking at, it seems pretty common to run the main driver off of something like a 50-75W amp and drive the tweeter off of something like a 20-50W amp. So the question then is....how good of amps can we get to fit this power range for say....another $250? (Giving us a grand total of $750 for the complete system)

 

[Ilkless]

https://heissmann-acoustics.de/en/produkt/baumappe-dxt-wave-fusion/

This is a 3-way Hypex-based active design using the SEAS DXT waveguide. Off-axis:

 

[ck42]

Well just ran across this. Had no idea miniDSP had so many products!
https://www.minidsp.com/products/plate-amplifiers/pwr-ice125

So it sounds like each of these is basically a miniDSP HD combined with 2 channel 125W ICE amp.
So pick out a passive speaker....cut giant hole in the back and install these. ($650 + speakers...so not an inexpensive option, but I like it!)
[EDIT] Looks like this thing has been around since 2013. Haven't these class-D amps improved quite a bit in 7 years?

 

[andreasmaaan]

Well just ran across this. Had no idea miniDSP had so many products!
https://www.minidsp.com/products/plate-amplifiers/pwr-ice125

So it sounds like each of these is basically a miniDSP HD combined with 2 channel 125W ICE amp.
So pick out a passive speaker....cut giant hole in the back and install these. ($650 + speakers...so not an inexpensive option, but I like it!)
[EDIT] Looks like this thing has been around since 2013. Haven't these class-D amps improved quite a bit in 7 years?

This is an older class-D amp, but a good one. It was measured by Amir here actually. It's very good value for money.

And yes, things have improved in the past decade or so, with arguably the best-performing amps on the market now being class D.

 

[somebodyelse]

At the lower end of the spectrum there's the Sure/Wandom ADAU1701 DSP board for 20 euros. They mostly talk about the 2 in 4 out analog part with its internal ADC/DACs but the board does expose the TDM capable I2S ports as well. You'd probably end up doing the filter design in SigmaStudio, but the DB-DP11224 programming board will let you do it over bluetooth from an android/iOS app. They put the same DSP on some of their JAB3 amp boards which are around the 30 euro mark, but that only has one of the I2S ports accessible. I think Dayton are reselling the same boards.

 

[andreasmaaan]

At the lower end of the spectrum there's the Sure/Wandom ADAU1701 DSP board for 20 euros. They mostly talk about the 2 in 4 out analog part with its internal ADC/DACs but the board does expose the TDM capable I2S ports as well. You'd probably end up doing the filter design in SigmaStudio, but the DB-DP11224 programming board will let you do it over bluetooth from an android/iOS app. They put the same DSP on some of their JAB3 amp boards which are around the 30 euro mark, but that only has one of the I2S ports accessible. I think Dayton are reselling the same boards.

This is actually precisely the same AD/DSP/DA chip used in the MiniDSP 2x4. Since the ADAU1701 chip has inbuilt ADCs and DACs, the audio performance of this and the miniDSP unit are close to identical. In fact, arguably the cheaper Wondom unit is actually superior in some ways, since Sigma Studio is a more robust piece of software than MiniDSP's 2x4 plugin.

 

[wwenze]

Well learnt something useful today.

MiniDSP needs Chinese competition.

 

[andreasmaaan]

Well learnt something useful today.

MiniDSP needs Chinese competition.

MiniDSP is based in Hong Kong, so the competition is pretty close to home

Analog Devices is the company that makes the chip, however, and it's American (but little doubt the bulk of the manufacturing and possibly even the development takes place in Asia).

 

[somebodyelse]

This is actually precisely the same AD/DSP/DA chip used in the MiniDSP 2x4. Since the ADAU1701 chip has inbuilt ADCs and DACs, the audio performance of this and the miniDSP unit are close to identical. In fact, arguably the cheaper Wondom unit is actually superior in some ways, since Sigma Studio is a more robust piece of software than MiniDSP's 2x4 plugin.

I hadn't realised that was the one MiniDSP were using. It's the one used in the original FreeDSP designs too. There's a lot more info about the Sure in this diyaudio thread, including some important points about the analog pinouts and the need for a reconstruction filter.

 

[andreasmaaan]

I hadn't realised that was the one MiniDSP were using. It's the one used in the original FreeDSP designs too. There's a lot more info about the Sure in this diyaudio thread, including some important points about the analog pinouts and the need for a reconstruction filter.

It's likely that MiniDSP adds reconstruction filters in their implementation - I'm actually not sure. The Wondom ADAU1701's reconstruction filters are on the RCA add-on board, which costs an additional $10 and which IIUC also corrects the output polarity (ADAU1701 is phase-inverting).