TOPIC: Help with active monitor speaker design please.

I have built a pair of studio monitors using twin full range drivers, wired in series with a 70uf cap over the lower driver to counter comb filtering/phase issues. The box is a twin enclosure bass reflex.

The sound, on the whole, is awesome, but the LF needs a small boost for audio nirvana. With the NanoDigi I have put a low shelf filter +3db rolling off at 200hz.

The big question - I want to produce a few pairs for sale but I don't know the best way to engineer them using the dsp kit/kits. A dsp plate amp is appealing but apparently I need to buy two plate amps, even though I'm only using two drivers with no crossovers. That gets a bit expensive.

Is there a more cost effective route using mini digi or combinations of kit? It may be obvious to some of you, but I'm a tech newbie and need some help please.

Many thanks in advance.

Hi there, you've posted in the PWR-ICE forum and so the default implementation would be one PWR-ICE125 per speaker, I assume?

Since you're implementing a 1.5 way speaker, another approach would be to use a single amp in one box, and run a speaker wire to the other box. Lots of inexpensive "active" speakers do this. In that case you would still need the passive crossover component in each speaker (for the"0.5")

Speaking of the passive component/s, I'm a little unsure about your 0.5. I would have thought that an inductor (not a capacitor) in series with one of the drivers would provide the desired high pass filter. Perhaps you could post a schematic of your current speaker, as I may have misunderstood something

Those are the speakers, the caps across the terminals of the lower driver sending the HF back, so more of a low pass filter.

I'm not after any crossovers, the two drivers are wired in series, so run as on driver really. What I need is a left and a right channel and the ability to apply some shelf filters.

I don't know much about the curryman DAC and it's quality, but the amps seem to be of good standard. Or I could employ some third party Tclass amps.

Would a mini digi and a curryman DAC in each speaker be a feasible solution?

Hi again, OK my bad, I can't read You have the two drivers in series and the lower one is bypassed by a cap. Are those Mark Audio drivers? (Look familiar...)

One way as I mentioned would be to simply use one PWR-ICE125 and put it on one box, with a speaker wire run to the second box.

Another would be to put a miniDSP and miniAMP in each box.

Another would be to take what it looks like you already have there and put it into a standalone box e.g. .nanodigi, DACs, amps.

Mark Audio 7.3's, finest 4" full range in the known universe

I ran the idea of one plate amp, with dsp, for this set up. The boys from Mini Dsp said I would need two plate amps! It may well be that they misunderstood. After all it's not a usual set up.

The somewhat frustrating thing is, all they need is a little muscle upto 200hz, and only 3db at that. Without it the balance is just a little to bright, but with it the box design works wonders and gives a bass and sense of sub bass that's simply amazing.

What's the consensus on the quality of the mini amps? And the curryman DACs? I'm aiming high end, because the A7's can image like nothing else I've heard, and I want to avoid too much loss in SQ on the quest for a little more LF gain.

Thanks for your help and time, much appreciated.

You could always build the plate amp into another box or into one of the speakers and simply run a single speaker cable to the other speaker.

Though, to be honest, although some "full range" speakers don't sound bad, with DSP, it's so easy to integrate a proper tweeter and get authentic high frequencies and better dispersion that you're kind of marrying two not quite so compatible concepts.

But if you just want EQ, why not just add an Open DRC and get plenty of FR control?

Lorienblack wrote:
Aha I have yet to put mine in a box... (hides)

Well, one plate amp per box would be the normal way you'd do it. That way you could lose that capacitor and just be fully active. The one amp in one box and a speaker wire between them with passive components is a bit clunky but it's more cost effective no doubt.

Interesting to hear.

I don't think too many people have used them. I don't think you'd expect the same of them as the ICEPower module. But at any rate, they would only deliver a few (6-7?) watts into each driver.

The Curryman DACs are I2s input, AFAIK most are using them with the miniSHARC board. But by the time you go down that route (per speaker, and add amps) the cost will exceed two ICE-PWR amps.

Tweeters? Not with the A7's, they cover it beautifully, I have never heard of anyone popping a tweeter on top. Often something beefy to cover the LF.

Open drc - I would do that for my own set up perhaps, but I have the NanoDigi for that.

If it were up to you guys what route would you take?
1 add some DSP, crossovers interesting but not essential.
2 digital to analouge conversion
3 amplification

Any stage can be third party, the amps for example can be Tclass (personal preference/bang for buck) SQ is important.

Budget all in? Under $400 per pair.

Many thanks agin for your time and thoughts

A single plate amp for both channels seems to meet your criiteria. Otherwise (given item 2 in your list) a nanoDIGI, a DAC board, and your choice of power amp in a separate box.

I guess your right. It's hard to get any feedback as to the quality of the components in question.

Cheers guys, looks like an evening with the calculator and then I'll have to take a punt one way or the other.

Going with one plate amp wont work at the moment since the actual PwrICE plugin is configured as 1x2 (one input, two outputs). Have a look at the user manual, page 18. As input for both! output channels you can choose the right or left channel or a mix of both. You can not route the left input to output channel 1 and the right input to output channel two. So DevTeam is correct, you'd need two plate amps

Thanks for that, makes me wonder how people do it and charge less than 2k a pair

People use "full range" drivers to avoid the awful damage by passive crossovers. But that really isn't an issue when you switch to active systems. Damage and inefficiencies from the DSP crossover drop to almost nothing, but the gains in dispersion, dynamics, resolution, integration etc, is awesome. No 4" driver can properly do treble. The best ones do a decent imitation, but, basically, DSP makes things like horns and full range drivers and other things DIY guys like to do a little on the obsolete side. Which isn't going to stop anyone, but it's something to keep in mind.

All "solutions" are compromises of a sort and the decisions get harder when attempting to put together an active speaker. The dsp is fine until people want to feed in a line level analouge, then the signal is digitized and rap up through a DAC again. For people with high end components, that's like doing your washing in dirty water.

At home I use a little DSP, feed that to a DAC (£900) feed that to a SS amp (2K) and the results are as rewarding as you might expect. The twin FR have sat in front of people who have used high end monitors in London studios for many years, and they have repeatedly said the imaging, clarity and musicality of these speakers is truly exceptional. The MA7's lack nothing in the HF, sit down in front of a pair one day, maybe you'll be the next old fart banging on about the magic of FR

But I also accept that I'm a FR fan and generally find the compromises painless. The modern sound of most high end gear sounds painfully artificial to my ear, despite the XO, I would be happier sat in front of some 40yo celestion ditton 44's.

Sorry about the ramble

curryman wrote:
Yikes!! You're absolutely riight, what was I thinking I'd had in mind a setup with two subs driven by one plate amp, but that of course is mono (left+right). Two plate amps it is!!