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No pictures yet, but thought there might be a bit of interest in something slightly different. My projects tend to move at the pace of glacial creep albeit without the sense of inevitable certainty, so when I hit a milestone it merits a bit of celebration.
My particular DIY 'itch'/interest has been the use DSP crossovers, particularly FIR filters. Maybe because I pretty much suck at soldering :-) I had a pretty good system set up with the Yorkville U15 cabs, but then almost simultaneously
a) my PC died taking my xover/correction filters with it
b) a household re-org dumped a ton of storage requirements into my 'music room', and I lost my dedicated space.
After a few false starts, I stumbled across the fact that NHT still had a few of the Xds monitors they were closing out. This was long after the initial $100 each deal from Jack Hidley - I had to pay $250 each. Given that there is ~$200 in drivers per speaker, I was quite happy particularly since I got the 'special dark' black/brown version.
So, given my interest in FIR filters it was clearly time to recreate the full Xd system in quasi-DIY mode. Given my lack of dedicated listening space though, I settled on a desktop/nearfield application. Fortunately I have a nice large corner/wraparound desk that can absorb a good system.
For bass modules I went with a pair of Dayton RSS-210, each sealed in a PE 1.0 ft^3 MTM enclosure. This is a tight fit - the driver flange just barely creeps over the start of the baffle roundover when surface mounted. Some might not like the surface mount look, but IMHO it's not bad - definitely 'beefy'. Between the Xds itself and the cherry pre-fab PE cabinets, fit and finish is laughably better than anything I could aspire to at the moment.
Now, a pair of 1 ft^3 cabinets might not fit with 'desktop' in most cases, but it works pretty well. They flank the monitor to create something of a 'wall', and the Xds are on a shelf that spans the woofer cabs above the monitor. this allows getting wider-than-usual separation of the Xds which seems to work quite well. The Xds are tilted downwards to get the listening position back closer to on-axis.
Signal path is decidedly less purist than most here go for, but it was an interesting process putting it together.
The PC interface is a Steinberg MR816X. This is a pro interface that hits something of a sweet spot in price/performance. Not up the very top-tier gear, but only ~1/3 the price of a Lynx Aurora and a clear step up from the entry-level stuff. One nice feature is a front-panel knob than can be linked to the master fader for the analog outs, effectively working as a volume control. It also includes a pair of spdif outputs, so adding external DACs is a potential upgrade path (although it might complicate volume control since analog outs and digital outs are controlled separately).
The MR816 directly feeds the amps. Mid and tweet are Class-D-Audio SDS-224 kits, powered by a connecelectronic smps module. Bass is handled by an Alesis RA-150 that I had lying around. I chose the SDS modules for 2 reasons:
a) variable gain. it was possible to lower their gain dramatically compared to normal amps, allowing the use of DSP volume without requiring excessive attenuation
b) balanced input. they use a THAT input stage; my experience is that pro audio interfaces tend to work better balanced and I wanted to run balanced if possible.
Sources are a Squeezebox (SB3 for now - I'll upgrade to a Touch) and an Oppo DVD981 fed through an Atlona de-embedder to send SACD converted to 88.2k PCM over spdif . In order to allow the PC to run at a fixed sample rate, I use a Behringer SRC2496 which is slaved to the word clock output of the MR816. Slaving the SRC allows the MR816 to serve as the master clock rather than having to use a PLL recovered spdif clock.
Software is Reaper serving as a VST host. At the moment, I'm just using IIR filters (I modeled them based on the transfer function of Zaphs passive xover for the Xds). I'll eventually use Pristine Space to apply FIR filters that will reproduce the original DEQX versions - steep filters @2.3k or so.
Even with the IIR filter transfer functions, things are sounding pretty darn good. I'm applying about 20dB of DSP attenutation for volume control which is more than I'd like, but I'll need to get some fixed resistors installed to lower the amp gain even more. Still, for an unoptimized system it's still a major step up from anything I've had running recently.
This definitely ended up being more complex and expensive than I original envisioned. I think I'm somewhere around $2500 not counting some things that I got but am not using. I think my setup should basically match the original Xd system in terms of quality, so if you look at it as spending $2.5k to reproduce something that was considered a bargain at $6k it doesn't seem so bad. On the other hand, since complete used Xd systems hit a'gon for ~$2k-2.5k, it may not have been the best use of time
Oh, well, at the moment the important thing is that it works and sounds pretty darn good :T
My particular DIY 'itch'/interest has been the use DSP crossovers, particularly FIR filters. Maybe because I pretty much suck at soldering :-) I had a pretty good system set up with the Yorkville U15 cabs, but then almost simultaneously
a) my PC died taking my xover/correction filters with it
b) a household re-org dumped a ton of storage requirements into my 'music room', and I lost my dedicated space.
After a few false starts, I stumbled across the fact that NHT still had a few of the Xds monitors they were closing out. This was long after the initial $100 each deal from Jack Hidley - I had to pay $250 each. Given that there is ~$200 in drivers per speaker, I was quite happy particularly since I got the 'special dark' black/brown version.
So, given my interest in FIR filters it was clearly time to recreate the full Xd system in quasi-DIY mode. Given my lack of dedicated listening space though, I settled on a desktop/nearfield application. Fortunately I have a nice large corner/wraparound desk that can absorb a good system.
For bass modules I went with a pair of Dayton RSS-210, each sealed in a PE 1.0 ft^3 MTM enclosure. This is a tight fit - the driver flange just barely creeps over the start of the baffle roundover when surface mounted. Some might not like the surface mount look, but IMHO it's not bad - definitely 'beefy'. Between the Xds itself and the cherry pre-fab PE cabinets, fit and finish is laughably better than anything I could aspire to at the moment.
Now, a pair of 1 ft^3 cabinets might not fit with 'desktop' in most cases, but it works pretty well. They flank the monitor to create something of a 'wall', and the Xds are on a shelf that spans the woofer cabs above the monitor. this allows getting wider-than-usual separation of the Xds which seems to work quite well. The Xds are tilted downwards to get the listening position back closer to on-axis.
Signal path is decidedly less purist than most here go for, but it was an interesting process putting it together.
The PC interface is a Steinberg MR816X. This is a pro interface that hits something of a sweet spot in price/performance. Not up the very top-tier gear, but only ~1/3 the price of a Lynx Aurora and a clear step up from the entry-level stuff. One nice feature is a front-panel knob than can be linked to the master fader for the analog outs, effectively working as a volume control. It also includes a pair of spdif outputs, so adding external DACs is a potential upgrade path (although it might complicate volume control since analog outs and digital outs are controlled separately).
The MR816 directly feeds the amps. Mid and tweet are Class-D-Audio SDS-224 kits, powered by a connecelectronic smps module. Bass is handled by an Alesis RA-150 that I had lying around. I chose the SDS modules for 2 reasons:
a) variable gain. it was possible to lower their gain dramatically compared to normal amps, allowing the use of DSP volume without requiring excessive attenuation
b) balanced input. they use a THAT input stage; my experience is that pro audio interfaces tend to work better balanced and I wanted to run balanced if possible.
Sources are a Squeezebox (SB3 for now - I'll upgrade to a Touch) and an Oppo DVD981 fed through an Atlona de-embedder to send SACD converted to 88.2k PCM over spdif . In order to allow the PC to run at a fixed sample rate, I use a Behringer SRC2496 which is slaved to the word clock output of the MR816. Slaving the SRC allows the MR816 to serve as the master clock rather than having to use a PLL recovered spdif clock.
Software is Reaper serving as a VST host. At the moment, I'm just using IIR filters (I modeled them based on the transfer function of Zaphs passive xover for the Xds). I'll eventually use Pristine Space to apply FIR filters that will reproduce the original DEQX versions - steep filters @2.3k or so.
Even with the IIR filter transfer functions, things are sounding pretty darn good. I'm applying about 20dB of DSP attenutation for volume control which is more than I'd like, but I'll need to get some fixed resistors installed to lower the amp gain even more. Still, for an unoptimized system it's still a major step up from anything I've had running recently.
This definitely ended up being more complex and expensive than I original envisioned. I think I'm somewhere around $2500 not counting some things that I got but am not using. I think my setup should basically match the original Xd system in terms of quality, so if you look at it as spending $2.5k to reproduce something that was considered a bargain at $6k it doesn't seem so bad. On the other hand, since complete used Xd systems hit a'gon for ~$2k-2.5k, it may not have been the best use of time
Oh, well, at the moment the important thing is that it works and sounds pretty darn good :T
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