Time delay is just a suggestion. It's one of the things we really wish we had in the passive world. There is an all-pass circuit, but they are complicated and limited. Being able to dial in delay in micro-second resolution per driver is sweeeeet.
Update:
I've got some amplification on these for now. While researching my more-tailored and possibly integrated Class D options, I managed to procure a Theta Digital Intrepid (5x100w AB) for a song. Will resell it if/when I decide to move on, but now that the Paradigms have enough dedicated channels of amplification to their name, I'll do some more serious tuning this weekend.
When these speakers were passive, they were powered by nCore 400 monoblocks, and I was very happy with those amps, so I may go back to Hypex, though I can't say the Theta is a step down!
I've got some amplification on these for now. While researching my more-tailored and possibly integrated Class D options, I managed to procure a Theta Digital Intrepid (5x100w AB) for a song. Will resell it if/when I decide to move on, but now that the Paradigms have enough dedicated channels of amplification to their name, I'll do some more serious tuning this weekend.
When these speakers were passive, they were powered by nCore 400 monoblocks, and I was very happy with those amps, so I may go back to Hypex, though I can't say the Theta is a step down!
Also update re: the matter of DAC posed earlier, I have removed the DC-1 from the chain and will be using the MiniDSP DAC as primary. Should be interesting. I see no detriment in this system, since the MiniDSP is necessarily in-chain, but will report with outcomes when I have a chance to be empirical.
What made the decision for me was the discovery that the MiniDSP 2x4 HD supports USB HID volume control, which allows me to use Roon to control system volume.
What made the decision for me was the discovery that the MiniDSP 2x4 HD supports USB HID volume control, which allows me to use Roon to control system volume.
They are, and if it ever breaks, I'll have one of the sweetest chassis ever for a 5x Class D build. That said, Theta gear isn't exactly flimsy, so I'll probably be bored before this thing really needs replacing.
Ah, and public note, for the legion future googlers of this matter when more people realize the raging bargain that is Theta gear on the used market: Intrepid needs a good ground like you would not believe. It is so susceptible to ground loop interference that I had to isolate it from basically everything else. Much less so using the balanced inputs, but still... do yourself a favor and find it a good ground, or buy a power isolator.
Most power isolator's don't work, including balanced. Here's a blog with some links to even better reading at the top and bottom:
Random Acts of Upgrades: Fix Ground Loops Quickly, Safely and Easily
I think the latest gen of Theta multi-channel amps are all Hypex nCore, so hopefully their ground issues are gone.
Random Acts of Upgrades: Fix Ground Loops Quickly, Safely and Easily
I think the latest gen of Theta multi-channel amps are all Hypex nCore, so hopefully their ground issues are gone.
Nice link, thanks. My isolation right now is a Tripp Lite unit I had around from some datacenter work I did years ago, a 1000w 4-outlet unit. It's been effective, but good to see simpler and less cluttered solutions (and to know which are potentially hazardous snake oil).
Ok, I spent some more time working on this today. Thanks eriksquires for the recommendation on time / phase. I did correct (between drivers, not between speakers yet, as that'll come later). Things are sounding excellent right now.
Decisions from earlier in the thread, and what I ended up doing:
To anybody with an old pair of speakers around that aren't all that bad, I would highly recommend doing a project like this as an intro to loudspeakers. There's very little cost involved, very little downside, and, in this case, significant potential for improvement.
Now I can move on to making much more expensive and esoteric mistakes with my ignorance!! Thanks diyaudio forum!
Decisions from earlier in the thread, and what I ended up doing:
- I deferred the Class D decision. Went with a dirt-cheap used Theta Intrepid 5x100w amp for the four channels I require. It's... large. And it also works beautifully.
- Per the advice of eriksquires, I time-aligned the drivers on each speaker individually before PEQ.
- MiniDSP is doing time alignment, crossover (1776Hz LR 24dB slope) and PEQ. That's all. If I want to do room correction, I'll add another device.
- On the matter of whether to use my "higher quality" DAC, I chose simplicity. MiniDSP is doing my only DAC now, and just before the amp.
- It's something the internet doesn't seem to know (nor the documents at MiniDSP), but MiniDSP does indeed do USB HID Volume control. Roon can use it for lossless volume control just fine, and that's how I'm doing volume.
To anybody with an old pair of speakers around that aren't all that bad, I would highly recommend doing a project like this as an intro to loudspeakers. There's very little cost involved, very little downside, and, in this case, significant potential for improvement.
Now I can move on to making much more expensive and esoteric mistakes with my ignorance!! Thanks diyaudio forum!
Attachments
You can use the silk dome voice coil replacement in that Vifa D25 tweeter:
https://www.madisoundspeakerstore.c...eak-voice-coil-600058-for-d27tg35-or-d27tg45/
Postscript on the Paradigm Saga
So this is quite an old thread but I thought I’d post an update. Syzygetic sold me the Paradigm Export Monitors sans the active crossovers a couple of years ago. At that time, I was rebuilding an ancient pair of AR4x speakers using the “Speaker Dave” crossover mods from the Classic Speaker Pages forum. The Acoustic Research speakers sounded great paired with my other restoration project at the time, a circa 1965 Dynaco SCA-35 tube amp so I had the brainstorm of employing the same 3rd Order crossover design as the AR and swapping out the Peerless Ring Radiator tweeters with some extra CTS Phenolic Ring tweeters I had laying around. What I was aiming for was an improved AR4x, combining the Paradigm woofer and enclosure with the modified AR crossover and tweeter. One bonus was that the mounting dimensions of the CTS tweeter were exactly the same as the Paradigm so no additional surgery was required.
The result, however, was underwhelming. Whatever synergies and magic that characterized the classic AR4x sound were entirely absent. So the Paradigms were relegated to the role of serving as a speaker stand for a rotating roster of bookshelf speakers including a pair of KEF Q-150s, Q Acoustics 3020s, Paradigm Atoms, and a few others. Syzygetic had told me they’d be perfect in that role given that the robust internal damping that he applied had made them quite inert acoustically speaking.
The story could have ended there but for the forced Coronavirus homestay which had me looking around for things to do. I was unhappy with the weak bass of my Q-150s and thought there must be some way to employ those magnificent 8 inchers on the Paradigms. I decided to re-install the Peerless ring radiators and combine them with the high pass section of my modified AR4x crossover. Given the impedance mismatch (the ring radiators are 4 ohms, the crossovers were intended for an 8 ohm tweeter) I suspect that the tweeters were crossing over at around 3200hz instead of the intended 1600hz.
I didn’t have the parts on hand to create a low pass crossover at 3200hz so I let the woofer run without a crossover while keeping my fingers crossed that there were no odd peaks or resonances as the woofer reached the limits of its upper frequency range.
The result was surprisingly good. So good in fact that the current setup had been my go-to main system speakers for the past couple of months. The ring radiators don’t have the widest dispersion, but in the sweet spot they image very well, plus they seem much happier crossing over at a relatively high frequency. I’ll eventually get around to wiring up an appropriate low-pass section for the crossover but I am enjoying the speakers very much as they are. Huge thanks to Syzygetic for selling me the Paradigms, they’ve found a good home for now!
So this is quite an old thread but I thought I’d post an update. Syzygetic sold me the Paradigm Export Monitors sans the active crossovers a couple of years ago. At that time, I was rebuilding an ancient pair of AR4x speakers using the “Speaker Dave” crossover mods from the Classic Speaker Pages forum. The Acoustic Research speakers sounded great paired with my other restoration project at the time, a circa 1965 Dynaco SCA-35 tube amp so I had the brainstorm of employing the same 3rd Order crossover design as the AR and swapping out the Peerless Ring Radiator tweeters with some extra CTS Phenolic Ring tweeters I had laying around. What I was aiming for was an improved AR4x, combining the Paradigm woofer and enclosure with the modified AR crossover and tweeter. One bonus was that the mounting dimensions of the CTS tweeter were exactly the same as the Paradigm so no additional surgery was required.
The result, however, was underwhelming. Whatever synergies and magic that characterized the classic AR4x sound were entirely absent. So the Paradigms were relegated to the role of serving as a speaker stand for a rotating roster of bookshelf speakers including a pair of KEF Q-150s, Q Acoustics 3020s, Paradigm Atoms, and a few others. Syzygetic had told me they’d be perfect in that role given that the robust internal damping that he applied had made them quite inert acoustically speaking.
The story could have ended there but for the forced Coronavirus homestay which had me looking around for things to do. I was unhappy with the weak bass of my Q-150s and thought there must be some way to employ those magnificent 8 inchers on the Paradigms. I decided to re-install the Peerless ring radiators and combine them with the high pass section of my modified AR4x crossover. Given the impedance mismatch (the ring radiators are 4 ohms, the crossovers were intended for an 8 ohm tweeter) I suspect that the tweeters were crossing over at around 3200hz instead of the intended 1600hz.
I didn’t have the parts on hand to create a low pass crossover at 3200hz so I let the woofer run without a crossover while keeping my fingers crossed that there were no odd peaks or resonances as the woofer reached the limits of its upper frequency range.
The result was surprisingly good. So good in fact that the current setup had been my go-to main system speakers for the past couple of months. The ring radiators don’t have the widest dispersion, but in the sweet spot they image very well, plus they seem much happier crossing over at a relatively high frequency. I’ll eventually get around to wiring up an appropriate low-pass section for the crossover but I am enjoying the speakers very much as they are. Huge thanks to Syzygetic for selling me the Paradigms, they’ve found a good home for now!
Dude, this is so cool that they're still ticking!! I'm happy to see this post, and glad you got them sounding good.