TOPIC:

Hi folks, I'd like to gauge interest in a fully documented speaker design using the PWR-ICE125. I've got a couple of designs in mind, one of which I've written up here:

johnr.hifizine.com/2013/07/hifizine-acti...ay-speaker-proposal/

If it went ahead, it would be documented in HifiZine, with configuration files etc. I'd like to know what people here think. Does this design "grab" you? Or would you prefer to see something different (if so, what)?

This is one of two ideas I'm working on, the other is a hybrid active-passive 3-way.

I read your proposal, and as a beginner in DIY speaker building I think its a great idea. The thing lacking in most published designs is good documentation I've found. The better the documentation is for a DIY design, the more people seem to build them.

I would also much rather build active speakers than passive, this allows for EQ tweaking for room and taste very easily. A known amp source could easily be accounted for in the design, making it much more certain that a person building it would end up with a speaker working like the designer intended it to work.

I've also been on the hunt for a good DIY Studio monitor design (in my case farfield, but I've looked at all of the DIY i could find, which was about 3). Active speakers seems to be the norm for studio monitors these days, and a well documented, well researched build would get a ton of attention I feel. I can't tell you how many posts I found from people seeking a good design. Studio monitors as I'm sure you are aware would be popular with the HIFI crowd as well. Perhaps a design that was accurate enough to be a good studio monitor could be tweaked (probably toned down just a bit in critical listening areas) to pull double duty via a different dsp configuration.

DSP+amp configurations as kits, plates, or independent boxes including both seem like a great thing for the DIY community, allowing much more freedom in box(or boxless) and driver configuration. New designs simply require moving the DSP+amp for testing, and could be a "control" of sorts.

Exciting times in DIY I feel.

Best,
Andy

If only the plate was sealed it would be perfect for sealed and non sealed applications, but alas the plate leaks like a sieve - a lot of work required to seal it up it looks like too. I am having to do this for a sub plate project.

I really like the idea of being able to swap between ported and sealed. Thats a really cool feature. All in all the proposal looks very solid. You picked excellent drivers, and I would imagine the end result would be quite worthy of its price tag. Also, you hit the nail of the head for what I'm looking for in a design, "low risk".

wizardofoz wrote:

If only the plate was sealed it would be perfect for sealed and non sealed applications, but alas the plate leaks like a sieve - a lot of work required to seal it up it looks like too. I am having to do this for a sub plate project.

Hi, good point, the plan is to use a separate sub-enclosure for the amp. I'd be inclined to do so anyway, a lot of pressure inside a speaker box!

WhereitsAT wrote:

I really like the idea of being able to swap between ported and sealed. Thats a really cool feature. All in all the proposal looks very solid. You picked excellent drivers, and I would imagine the end result would be quite worthy of its price tag. Also, you hit the nail of the head for what I'm looking for in a design, "low risk".

Hi Andy, thanks for the feedback, that's very encouraging. Your point about a different DSP setting for studio monitors vs home hifi is a good one. The amp can have four different configurations loaded which can be switched between (requires using the plugin to switch).

I've been asked to consider a smaller speaker, which I'm working on now. I'll update when I have more info on that. The design concept has the same idea of being sealed or ported.

I've abandoned the three-way hybrid active/passive idea, for various reasons.

Hi folks, I've written up a proposal for a smaller speaker:

johnr.hifizine.com/2013/08/hifizine-mini...ve-speaker-proposal/

Key ingredients:

• miniDSP PWR-ICE125
• Seas U16RCY-P woofer
• Seas DXT tweeter

Let me know what you reckon

John,

It looks really neat with that removable base.. Quite a creative setup!
We certainly look forward to seeing more!

DevTeam

Hey John, I'm not sure what your experience level is, so I'm going to toss out a few basic ideas that you may find boring or helpful.

One of the advantages of steep crossover is that you can use extremely rigid drivers without audible consequence, unlike in a 1st, 2nd, 3rd order design. Paper, poly, carbon, all that stuff flexes, so it has a sonic signature within its intended bandwidth.

A problem with acoustics as well is that any time you try to limit a speaker's dispersion, you end up with consequence. But obviously, this has usefulness in PA applications, or rooms that are extremely live and can't be reasonably deadened.

If you have to choose a single driver size for voice, I recommend a 5" - typically more resolution with fewer upper range problems and better dispersion than a 6", better male vocal response and output than a 4". I consider 8" drivers to be simply too big for quality voice reproduction. The two best digital speakers on the market that' I've ever heard use the 5" SEAS Excel magnesium midrange. Then match with a couple of 8" drivers in a tower, or a 10" digital sub.

The 8" limited dispersion design you are doing will have applications for far field listening outside or for in an acoustically live room, but not sure if that's its purpose or not.

Hi John, thank you for your comments! I didn't model any of the magnesium-coned drivers, basically cost excluded them. I'm committed to the U16 in the 6" design for now but now that I look, the W16NX-001 uses the same frame and would be basically a drop-in replacement, requiring only port tuning (and different DSP settings) to swap in. An interesting thought for a future development...!

I'm not trying to limit dispersion as a goal in itself, but to get smooth off-axis / power response. Within the constraints of a two-way, I don't think there's much option other than limiting tweeter dispersion - ?

Hi John,
The other option is to keep the midrange dispersion high.

Dispersion is where crossover and driver size get important. A 1" tweeter will have broad dispersion under about 10kHz, and a 5" driver will have broad dispersion up until about 2kHz. So you can get very consistent and smooth off axis response if you use a steep 2kHz crossover or a bit lower. The steep crossover helps limit the dispersion problems from the mid, and helps the tweeter handle the lower crossover point. But the bigger the driver, the lower the crossover point must be. NHT's Xd and PSB's analog B5 (as I recall) have incredible midrange dispersion at all frequencies and a super smooth handoff to the tweeter. Both have steep 2kHz crossovers, the NHT has a 108dB/crossover, the PSB is 24dB/octave.

Another advantage of steep crossovers is that you get more of a point source behavior and you can get within inches of the speaker and it still sounds like a single driver. Can't do that in the analog domain easily, though I think Joseph Audio has very steep analog crossovers.

Hi folks, the first article on the HifiZine "Mini Convertible" loudspeaker is now online:

www.hifizine.com/2013/09/the-mini-conver...-loudspeaker-design/

Any comments (here or there) of course most welcome.

J

Sweet little design ... love it... interested to see how other bass drivers stack up like those used in the Linkwitz Pluto perhaps (also a seas unit)

very much looking forward to the plans and maybe a ball park cost at least for the drivers from Madisound or Falcon Acoustics UK (Jerry might like this in stable of kit options)

Hi wizardofoz, thanks for the comment, I'm not sure if I've modeled it but the Pluto woofer seems to be a physical drop-in replacement in the sealed enclosure with lower f3 and lower sensitivity. However it may not work so well in the ported alignment according to the Madisound page. The 4 ohm W16 Magnesium cone is another alternative option that does seem to model well albeit at significantly greater cost.

As I recall it's around USD320 for the four drivers from Madisound, plus shipping.

www.hifizine.com/2013/09/the-mini-conver...-loudspeaker-design/

The Mini Convertibles had their first showing last weekend:



More info: johnr.hifizine.com/2013/10/mini-converti...their-first-showing/