TOPIC: NanoAVR Full-Gonzo Scenario Number 1:

Okay, so this little box looks very promising. For starters, it would plug & play right into my home system right now, so personally I'm kinda liking that idea a lot. The only change I'd have to make is to do all multichannel decoding upstream, instead of bitstreaming, but it looks like JRiver Media Center can handle that. It would then feed my 5.1 setup w/stereo subs with unprecedented control. (I could finally retire my trusty Outlaw Audio ICBM!)

BUT - If we REALLY wanted to go gonzo nutso, what would stop a guy from using an HDMI splitter into TWO of these little gizmos, then into 2 matching A/V receivers or preamps or whatever? With 16 channels, we could have up to 7 BI-AMPED 2-way speakers + stereo subs! Even if the receivers didn't match, any difference in propagation delay between units would be easy enough to measure & compensate for. And I'm assuming the new Ethernet hookups solve the old problem of multiple USB setup connections - just plug 'em both into the router! (Oooh - I hope someone's working on an Android app!!) And hey, why stop there! I know some of you guys are running 3- and 4-way speaker setups, hee!

Am I missing anything here, or does this look like it would work?

-- Jim

I can't wait to see "Full Gonzo Scenario Number 2"!

I would think it would work. Some of it might hinge on what exactly the splitter does, HDMI is not just an "output to input" type of deal, there is "negotiation" between devices. But it would certainly be interesting to find out...

I don't know what happens if you have two of them on the network at the same time.

john.reekie wrote: I was (am) hoping others will chime in with Scenarios 2, 3, 4, and so on...

john.reekie wrote:
Yeah, I was a bit premature with my ramblings. We don't have enough info yet. After a bit more thought, I can see a couple of potentially show-stopping problems with my gonzo scheme (master volume, for example). Besides, as for myself, my mains already have very nicely-done (i.e. not by me) passive 4-pole L-R crossovers - not sure how much I could improve on them (by going active) without a LOT of fussing about.

I guess I just got a bit excited the other night after reading the announcement about this newest little box of DSP LEGOs. I'll probably order one (just one for now), since it just looks like too much fun to pass up.

-- Jim

Jim,

That setup indeed ought to be tested! Interestingly enough, I'm sure that there are many similar ideas like that out there that we're not even considering...
We can purchase a couple of HDMI splitter (typical item here from Chinese Supplier) to run a couple of test to see how this could work...

It's a very neat idea... Good stuff and looking forward to Gonzo scenario#2..

DevTeam

devteam wrote:
That would be great! So far, the potential "gotchas" we've come up with are: Handshaking (HDCP?) issues, multiple-device programming hassles, master volume, and latency mismatches in the outboard gear. Definitely worth a try, though! Please keep us posted.

devteam wrote:
Thanks! For Gonzo #2, I'm wondering if FIR will be possible? (I notice there is a SHARC in the water here!) Perhaps with reduced channels for more horsepower / channel? Because, you know, maybe we could hook these little guys up in series as well as parallel...

-- Jim

FIR question: New product (with what we'd call already full featured!) and already asking for some new things... A bit premature is the right answer.
So It's quite unlikely at this time (8x8 + quite a lot of things actually already done on this IC). There is a lot to investigate in this HT world which we haven't even scratched the surface yet.. So plan is to let this implementation ride for a while before we think at future implementations. While software + firmware seems like everything is possible, we are just realistic with time/cost of implementation which are not always that obvious to outside world. We do want to keep the nanoAVR @ 299USD rather than a lot more. I'm sure quite a few will agree?

With this said, sure FIR is great idea..

DevTeam

devteam wrote:
OK, I will lift one Led Boot* from the Gonzo pedal and place the other on the clutch for now.

devteam wrote:
I definitely agree! I'll be ordering one as soon as my budget allows.

-- Jim
*Now playing: Jeff Beck: Wired

Jim the Oldbie wrote:
Incidentally, I just realized earlier tonight that I have enough junk lying around here to do a very preliminary test of this silly idea. I have 2 Yamaha AVRs that are very similar (basically 5.1 & 7.1 versions of the same model), so I connected them together tonight via an HDMI splitter using the feed from my PC as usual. It seems to work pretty well. I can control both volumes simultaneously with one remote, and they stay in sync as long as I keep my big feet off the coffee table (blocking line-of-sight to the receiver on the lower shelf! ). Also, the relative latency between the two units appears to be zero, but I'll have to bring the o-scope home from work tomorrow to verify this.

As a side note, I've connected one unit to mids & the other to tweeters (still using the LP & HP sections of the passive crossovers with bi-wiring links removed), and I'm somewhat surprised at how good the internal amps sound on these little Yamahas when they're only needed for half of the spectrum! Making a note of this for later...

Anyway - Of course there are no nanoAVRs in this picture yet, and I know that will be a whole 'nother gauntlet of HDMI handshaking (& other issues) to run, but for what it's worth, it sure looks to me like running 2 AVRs in "parallel" is doable!

-- Jim

Jim,

Cool! Thanks for the update. We have yet to get an HDMI splitter. Just out of interest, did you just pick up a random HDMI splitter? Wondering if there are any specs we should look for.

Devteam

devteam wrote:
It's from Monoprice.com, product #8204. I've had mine for awhile - it was in the closet, I forgot all about it! - but I just checked, and it's still a stocked item there. (I'd post a direct link to the product page, but I'm afraid of getting locked out of here again! ) I dunno about any specs in particular, I can't see any HDMI version compliance number anywhere in the description (1.3, 1.4 etc.). But it does mention things like 3D, 1080p/60, deep color etc., so it appears to be a reasonably up-to-date model. I do have a TV connected to the HDMI out of the receiver that's connected to HDMI Output 1 on the splitter, and the TV is working normally as well.

Update: Tonight I connected an oscilloscope in X-Y mode to the right channel outputs on both receivers. I then ran a sine wave sweep from 5 Hz to 22.05 KHz (44.1K CD audio) over HDMI thru the splitter to both units simultaneously The 2 outputs appear to be phase-coherent across the band. I noticed the tiniest phase shift (a very slight ellipse in the X-Y pattern) when I cranked up the scope gains to the point where the trace was widely overshooting the CRT. Since it varied somewhat randomly with frequency, I'm attributing it to the fact that one of my receivers is actually preamp-output connected to a completely different power amplifier (Outlaw Audio 7075). I'm confident that what I saw was just a minor difference in phase response between the Outlaw on one axis, and the Yamaha receiver power amp stage on the other.

Another positive test result: I checked the volume control tracking between the receivers by applying a contnuous 315 Hz sine wave to both (HDMI thru the splitter as before), then taking voltage measurements at the amplifier speaker terminals as I varied the volume control settings on both units (with one remote! ) from -20 dB to -70dB in 5 dB steps. There was a constant difference in output between the two of approx. 0.5 dB. I was surprised that this difference was so small - remember we're comparing two different power amp stages here - but the important result is that this difference varied by less than 0.1 dB across the board. (Actually, that 0.1 figure is the max deviation - the difference between the largest and smallest differences measured).

A few thoughts at this point:

I'll be the first to admit that this whole idea is a bit cheesy in several respects. Running two receivers with one remote, for example, is by no means an elegant approach. But hey, it works! I was sitting around listening to tunes on this rig for a couple of hours last night, running the volume up & down quite a bit, and after the initial foot-interference discovery, the volume settings stayed in sync the whole time. And it's certainly easy enough to fix if necessary - just place the remote directly in front of the single unit that needs realignment. And so far, I'm not seeing any technical problems with the idea. The one caveat that is revealing itself is that this scheme will likely only work smoothly with two receivers that are either identical or very close to it (like mine).

Anyway, so far so good. I'd like to stay up awhile again tonight & listen to some more music (that's what this is all about, after all) but it's waay past my bedtime!

--Jim

Another update:

At this stage I needed to take a step back and decide if bi-amping all my speakers would really be worth it. So tonight I tore down 2 of my 5 Sony SS-M3s (hey, don't laugh if you haven't heard them!), removed the passive crossover boards, connected the drivers (Peerless midbass & dome tweets) directly to the 4 binding posts (links removed of course), and hooked up my 4x10 HD through 4 channels of an Outlaw Audio 7075 power amp. I really wasn't expecting much to begin with; these Sonys have fairly nice passive crossovers (4-pole L-R), and I figured I'd be in for a lot of tweaking just to get back to a sound that was as good as I had before. I'd even planned to reconnect the passives externally at some point, just to plot the electrical transfer functions so I'd have a reference to work toward; but for now I just wanted to satisfy my curiosity.

Well, the results are pretty much the opposite of what I expected. After simply setting the crossovers to the original passive frequency (2 KHz) & alignment in the 2x8 plugin, then spending a few minutes getting the tweeter balance in the ballpark (by ear even!), these speakers are sounding better than I've ever heard them. Specifically, the top end has been transformed - the highs are smooth, clear, and just real. Everything else I'd planned to get done tonight has gone out the window because I can't stop listening to this.

Eventually I intend to take the Sonys to my workplace to do some actual measurements (much larger room there, better for gated impulse stuff), and see if there are any useful driver corrections to be made. But regardless, I think I'm seeing two nanoAVRs in my future. I sure hope they get along together!

-- Jim

P.S. I hope you guys don't mind my stream-of-consciousness rambling with this stuff. I know the "bi-amp epiphany" is probably old news for a lot of you; I just wanted to add a big +1 for the idea, heh.

Neat to read these updates Jim! We love to see people thinking outside the box so please keep it up.
With the Dirac box out, we haven't got any time to look into a complete test but hopefully we can have a try next week. We have few AVR here for our testing and we just purchased a splitter today. Should arrive by next week. We'll keep you updated.

Great to hear of your Sony SS-M3S investigation.. Neat to see that you can still get surprised by active. We know that we do too..

DevTeam

devteam wrote:
These little black boxes are such fun to think outside of !

devteam wrote:
I understand Dirac is taking a lot of your time - it seems to be generating a lot of interest. As far as testing, most of my HDMI questions are now answered except for a couple: First, it still remains to be seen if 2 parallel nanoAVRs will have any difficulties with HDCP negotiating-type stuff; also, does nanoAVR have a consistent, non-varying latency spec (not very important for a single unit, but critical for Full Gonzo). Anything you guys can do to test those two things would be mucho appreciated.

devteam wrote:
I should've tried it a long time ago! Nothing else has ever made such a dramatic difference, particularly in the clarity in the upper end as I mentioned. On that note, you may have noticed I ordered nanoAVR #1 (a.k.a. "Half-Gonzo") the other day (hope it ships soon... ). When it arrives, I first intend to do some testing to see if the internal power amp stages in my Yamaha AVRs will be sufficient for mids & highs. I have a feeling that some of these inexpensive lower-powered receivers might just do surprisingly well in an active setup, with the spectrum sliced up into smaller bites and without all those passive networks causing congestion. We'll see.

-- Jim

Another Update (read: more random ramblings):

OK, nanoAVR #1 arrived yesterday. So instead of doing my taxes like I was supposed to, I spent the day, and the evening, and all night, listening to music.

As I mentioned earlier, I was hopeful that the relatively modest power amp stages in my low-budget AVRs might be more useful in an active setup, each driving a smaller chunk of spectrum and with no passive filters to slog through (especially the tweet networks). This is indeed turning out to be the case.

I have nanoAVR connected to a single Yamaha RX-V573. The setup is 5.0; the center and surrounds are still running full-range, but I'm using the left & right main outs to drive the midbasses only (LP-filtered @ 2 KHz), and the rear surround outputs to drive the HP-filtered L & R tweets. I don't have any subs connected for now; just using a bit of hastily-applied Linkwitz transform via parametric EQ to stretch the F3 on the sealed boxes from 80 Hz down to 50.

Mind that I do live in an apartment, with neighbors all around (and a landlord right across the hall!), so my SPL requirements are likely not as demanding as some; but I'm not talking about whisper-quiet levels either. So far the built-in power in my Yamaha receivers is working quite nicely for my needs. This will simplify the Full Gonzo plan significantly.

But I was still having doubts about the top end. Although much better after the switch to active filters & bi-amping described earlier, I was still hearing a bit of 'scratchiness,' and wondering if there was room for more improvement. It was then that I decided to try 48 dB crossover slopes for the first time.

I keep having happy accidents with this stuff. I've been reading for years that you can't just A/B one set of crossover slopes with another without making any other changes - it's an invalid test. And I understand why this is; we're hearing different passbands from each driver, causing changes in the overall frequency & phase response that should really be accounted for and corrected, etc. etc. I get that. I also understand some of the complaints I've read from others about these really steep slopes regarding phase & impulse response. But what can I say - I am LOVING this sound. Without changing anything else (except tweeter balance), this was an immediate, drastic, long-term improvement. And by long-term, I mean one of those deals where you don't realize how long you've been enjoying the music until the sun starts coming in the windows!

Of course this has so far been all listening and no measuring. I will get to the latter as soon as I have time. And while the sound is immensely enjoyable, I have no doubt that measurements will reveal areas where even more improvement can be made. But I think I can see the happy accidents that may have occurred so far:

1. I think my midbasses & tweets must start misbehaving pretty quickly outside of their respective passbands. They are Peerless drivers, but they're also 20-year-old designs. For example, the midbasses have those concave dust caps that were happening back then, which are pretty much the opposite of the phase-plug designs we see these days. And the tweeters are decent, but some sine wave ping tests in the 2-5 KHz range do reveal a fair bit of harmonic distortion - audibly more even than a pair of modestly-priced Tang-Bands I bought recently for another project. By increasing the slopes (further limiting the passbands), I think I've inadvertently reduced distortion in the tweets, and cone breakup/ dispersion trouble in the upper mids. Of course, combined with the bi-amp conversion, all of this has also resulted in a pretty major change in overall frequency response, but not necessarily in a bad way, which leads us to:

2. I also think the passive crossovers in these Sony SS-M3s have deteriorated more than I realized over the years. I discovered during the bi-amp conversion that they used electrolytic caps. These are bypassed (and possibly tuned) with film units, but still - I gotta think that using electrolytics in a tolerance-critical 4-pole passive filter design was probably not a great idea in the long term. With the current combination of active left-right mains and passive center & surrounds, it's easy to hear the difference. Especially with a pink-noise test tone, the actives have a lot more energy in the midrange, and not just in the crossover region. Conversely, the passives sound sucked-out and lifeless in the mids. Which is correct? I'm betting neither at this point. I'm still hearing raw, uncorrected driver response in the actives, and what is probably dried-out crossovers in the passives. Measurements will shed light here. But with all that said, at this time I can subjectively report that the 24 dB passives, which I've been enjoying for decades, now sound like pretty good speakers; whereas the 48 dB actives sound like famous people hanging out in my living room. It's actually startling at times.

OK, enough rambling for now. As for the original topic: It's obvious that another nanoAVR is needed. Time to take this sound from 2 channels to 5. With 3 subs, of course. But right now, I gotta do my taxes...

-- Jim