TOPIC:

Hi Kids,

I've been meaning to get to this for awhile, and finally found time to do it. The original Full Gonzo setup (full active 5.2, using dual nanoAVRs) has been doing a great job, but it's not without its quirks ( as summarized here ). In the time since I originally put it all together, miniDSP has introduced the nanoAVR-HDA, and with it the upgrade kit for owners of the original nanoAVR-HD. I recently performed this upgrade on both of my nanos, which has allowed me to remove the dual Yamaha AVRs, which were really only providing D/A conversion and level control. The nano HDA analog outputs are connected directly to the inputs of my 2 Outlaw Audio 7075 7-channel power amps. I've been living with version 2.0 for about a week now.

THE GOOD

I immediately made two discoveries that were completely unexpected. The first is that all the HDMI / HDCP handshaking glitches I was experiencing with the old setup have disappeared! I always had to deal with this any time there was a sample rate change in the incoming audio, like when switching from music to movies. I'd lose one half of the rig or the other, or part of one, or something - with no pattern, rhyme or reason. This would require resetting the HDMI splitter, or rebooting the AVRs, or both. It always came back with a few button pushes, but it was still a pain in the butt. With the new setup, it just works. There is a brief glitch in the audio when the incoming sample rate changes, but that's it. Looks like the AVRs were causing the confusion, and running the nanos "headless" is working really well. This was quite a pleasant surprise to say the least, but it was only the first...

The other thing I'm happy to report is that the IR remote volume control is tracking perfectly between the 2 nanoAVRs. I can run the volume up and down for days (literally), and every time I fire up the laptop and check the plugins, the 2 boxes are at exactly the same level. So far, the only way I've found to knock them out of sync is to wave my hand right in front of the remote while I'm holding the volume button down! And even then, it only takes a few seconds to run it all the way down to -125 dB (or whatever it is) and back up, and they're back together again. But seriously, this is the only time I've had to do this!

I'm a little embarrassed that I haven't even tried this feature on the nanos before now. But I always figured they would behave similarly to my 2 Yamaha AVRs, which would go out of sync fairly easily. Of course it was easier to keep track of this since the Yamahas also had front-panel volume readouts, which brings us to:

THE BAD

It is definitely frustrating to no longer have a solid readout of the volume setting anywhere on the hardware with the new setup. The only way I can see it now is to boot up the laptop and check the plugins. With that said, it's not as bad as I thought it would be, for the reasons described above. I've discovered that there is a dependable 1.5 dB volume step with each single button press on the remote, so that keeps things somewhat predictable. I also downloaded an SPL meter app for my phone, so I can at least make sure my listening levels aren't creeping up over time (I live in an apartment building).

I could be wrong about this next part, but I think the reason the nanos track the IR commands so well is ironically because they are responding to every single code they receive! I know others have complained about this, that these units "run away" in a hurry if you hold the remote volume buttons down, but I believe this little miniDSP quirk is inadvertently producing the tight tracking that occurs. I'd wager that the more gradual, "normal" response of my Yamaha AVRs is the result of their IR receivers having been programmed to skip codes if they're coming in too fast - and it's precisely that "feature" that introduces the asynchronicity between them, and subsequently the volume tracking problems I was experiencing with them - even thought both were essentially the same model.

It's occurred to me that I could exploit the above behavior by building a simple Arduino box that would sit on top of the nanos, catch the same IR codes they do, and produce a volume readout on a 3-digit signed 7-segment display that would match the settings on the nanos. If the display box could be made to respond the same way, it should stay in sync with them, and be resettable in the same way if necessary (volume all the way down & back up). I've started learning to program in C in my spare time, so this will be my first Arduino project as soon as I'm up to speed.

The other thing I miss from Gonzo v1 is analog volume control. I understand the misconceptions that many seem to have about digital volume, and I'm not hearing any degradation in the actual music - it's as lovely as ever. But as near as I can calculate, the system noise floor has come up about 10 dB. Even this is not as bad as it sounds, since I still can't hear any noise at the listening position - I have to have my ear about a foot away from a tweeter to hear anything at idle. But that distance used to be more like 2 or 3 inches.

The thing that concerns me more (and I don't see this discussed as much) is the safety cushion provided by analog, post-conversion level control. Previously, using the Yamahas (which use multichannel analog ICs for master volume), at normal listening levels the volume indicators would read in the -10 to -12 dB attenuation range. With the nanos, I'm at roughly -14 to -16 when I check levels in the plugins. This lines up, since I measured roughly 4 dB more level out of the nano HDA compared to the Yamaha pre outs, for a given input. But here's the thing: A few weeks ago, I managed to temporarily "crash" one of my nanoAVR boxes, and it seemed to go into some sort of a test mode, producing a 1 KHz sine wave at what sounded like 0 dBFS at each output. For a conventional system with passive speakers, this would not necessarily be cause for panic. But with an active setup, I had a fairly loud 1 KHz connected directly to my dome tweeters! Fortunately this occurred with the old setup, so there was that -14 dB or so of analog attenuation between the nano full-scale output and my speakers, and no damage occurred. But with digital level control, that cushion is gone - full-scale is full-scale, and if anything like this happens again, I doubt I'll be so lucky. Speaking of which:

THE UGLY

Both of my nanoAVR HDAs produce a loud crack on the outputs when powered down. This is very disappointing to say the least, especially when these units are used in a full-active system. I really wish you guys would try a little harder to get this right - and "just turn your power amps off first" is not an acceptable solution. I know my Peerless tweeters aren't the best in the world, but they're damn good, and they're not made anymore, and if I lose any of them as a result of this, I'm gonna be very unhappy. As it stands, I'm just leaving the nanos powered up 24/7 until I can install a power sequencer, but of course even that will not completely eliminate the possible consequences of this behavior. If this is not normal for these units, I'd welcome any suggestions on how to correct it.

To summarize, and avoid ending on a sour note: Overall, I'm very pleased with Gonzo v2. Any worries I had about the quality of the DACs in the HDA upgrades were unnecessary; they sound beautiful. And hey, I'm finally learning C!

-- Jim

@ Jim

What an update! I think that you're maxing out our forum text size limits.. ahahah
Thanks again for the update on this great setup. We do know others who are following your footsteps.. Great stuff!

- IR control: Glad to hear that it's synching well.
- Arduino box: Indeed it could be a trick to have a little panel + send some IP commands to each box. We can help you with the commands that you need to send for the master volume control. It's easy..
- Another way is to wait for our new Android/iphone app release that will soon "link up" units for both volume control and presets?. Maybe a trick if you get a little cheap tablet?
- Pop noise: that indeed shouldn't happen. I wonder if it's related to the HD to HDA upgrade you did. Maybe let's confirm the following:
a) You're running the latest firmware on both units
b) You can email to our tech support team some pics so we can help review them for you. (minidsp.desk.com)

DevTeam

devteam wrote:

- Arduino box: Indeed it could be a trick to have a little panel + send some IP commands to each box. We can help you with the commands that you need to send for the master volume control. It's easy..

I was talking about IR (infrared) control, but if you guys can really tell me how to do volume control over IP (network), that would be even better. How can I obtain this information?

- Another way is to wait for our new Android/iphone app release that will soon "link up" units for both volume control and presets?. Maybe a trick if you get a little cheap tablet?

So the new app will allow control of multiple units simultaneously? Cool! I'll definitely watch for that.

- Pop noise: that indeed shouldn't happen. I wonder if it's related to the HD to HDA upgrade you did. Maybe let's confirm the following:
a) You're running the latest firmware on both units
b) You can email to our tech support team some pics so we can help review them for you. (minidsp.desk.com)

Yes, firmware is current, just downloaded & installed last week. I'm going to do a little more troubleshooting at this end. I'll email you as soon as I have more info about this.

-- Jim

Cool!! Interesting that the remotes track so well.

Hi John,

john.reekie wrote:

Cool!! Interesting that the remotes track so well.

It has really made the difference between useable and not with this setup in its current form. I was expecting intermittent remote behavior similar to the Yamahas, and having no longer any sort of volume readouts, that just wouldn't have worked.

I really believe the nanoAVR's rather simplistic IR receiver behavior is actually the reason this works so well. They seem to just catch and use every single code. As others have observed, this can be a bit of a nuisance for remotes that repeat codes very rapidly, like all the old Sony remotes I have lying around seem to do. But in this case, this "bug" has turned out to be a "feature."

-- Jim

Update:

Tonight I got to thinking: Since the HDMI problems seem to have disappeared, I wonder if I could replace the fancy resettable HDMI splitter I've been using with the little cheapo 2-way no-frills model I pulled out of the closet way back at the beginning of this whole ordeal? The fancy one made things work a lot better in Gonzo v1, but it has all these really bright red LEDs on the front panel that are kind of distracting.

Well, the little cheapo splitter didn't work as well - it worked BETTER. I cued up a bunch of different types of audio files on Foobar2000 - different sample rates, bit depths, stereo or multichannel - and it switched back and forth between them flawlessly! No audio glitches - it didn't even cut off the beginning of the song! Amazing. I'd grown so accustomed to screwing around with this crazy HDMI stuff, I didn't even think it was possible for it to work this well!

Then I got cocky...

What the hell, I thought. Let's try adding an HDMI switcher, so I can add my little Sony Blu-Ray player to the mix, and see if I can get my SACDs to play! (This player has worked before with the old setup). So I hooked everything up - no joy. Tried changing settings on the player, went back to the fancy splitter, nothing worked. And THEN, somewhere in the midst of this, I managed to produce a HUGE BLAST OF NOISE through the rear speaker pair, which immediately roasted both tweeters.

(Sigh...)

By an amazing stroke of luck, I think I've found a couple of replacements online. They're the 8 ohm version (mine are 4). Hopefully this will only mean a difference in sensitivity, which will be easy to adjust for. But I won't believe I actually found these things until I'm holding them in my hands.

Lessons learned:

1. No more attempts to hook up the crappy little Sony SACD player. (Hell, I only have 5 or 6 SACDs anyway, GRRR!!)

2. Start researching tweeter protection schemes. Pico-fuses, capacitors...? (Good thing I have plenty of cheap dome tweets in the closet for sacrificing I mean, testing.)

3. Take a deep breath, relax and enjoy some gorgeous 2-channel music while waiting for the replacements to arrive. After all, it could be worse - could've been all 5 of them. <shudder>

-- Jim

Hi Jim, there were no caps in series with the tweeters?

That is correct.

I did do the math awhile back, and couldn't come up with a solution that didn't involve electrolytics, lots of phase shift, or high cost. Of course I'm paying even more now, but this seems to be my approach to life in general...

-- Jim

I'm not sure anymore that the advice to size the cap octaves below the crossover is the best way to do it. If you size it for the crossover frequency, you can take it into account in the active high pass.

Also, Dayton/PE have film caps at pretty good prices. Not like the "old" days.

I wouldn't be opposed to a combined active / passive approach, but I don't understand how to remove a single pole from the active high-pass filters. (I'm using 48 dB L-R alignment.) Is it possible to do something like this with a custom biquad?

-- Jim

Another update: The new tweeters have been installed. They seem to sound essentially the same as the originals, despite being the 8 ohm version instead of 4. There is definitely a step down in sensitivity; I ended up with them padded up +2.4 dB from the others. I'll have to haul the speakers down to the shop one of these days and take some good measurements to see how close they really are.

In the meanwhile, I've decided to go back to analog master volume. I will also decide on some sort of tweeter protection scheme that is sonically unobtrusive enough for my needs, but I also really want to have that final gain adjustment to be in the analog domain - I'm just more comfortable with that concept.

For example: I've now had two events where the nanoAVRs have seemed to "crash." The first one was when they appeared to go into some sort of test mode, where it sounded like they were producing a full-scale 1 KHz sine wave at each output. At that time I was still using the Yamaha AVRs so there was approximately -14 dB of analog attenuation occurring downstream. and no damage occurred. The second time was this latest one where one unit suddenly started producing the full bandwith noise at all outputs. This time the Yamahas were not in the circuit, and the tweeters were dispatched in very short order.

I know there are considerable differences between the two events, but my point is that there are times when it is possible to get some "undocumented" output from these little black boxes, and given my experience so far, I'd rather have as much attenuation as possible between the nanos and the power amps.

I'm returning to my plan for a multichannel analog volume control based on the Texas Instruments PGA2311 IC; I'll report back when I have it up & running.

The other problem I now have is with those damn SACDs. I don't want to risk connecting the player directly to this system again. It never did work; the only thing it did manage was to wreck my stuff. I've never liked SACDs anyway, since it's so much more difficult to rip them to a server setup. (Also, I remain skeptical regarding the claimed sonic benefits of DSD.) But as we all know, there are a lot of great titles on SACD that you can't get any other way. So I'm thinking of a scheme that may solve both of my problems in one go. It involves a USBStreamer Kit, a Yamaha AVR, and one of these:

AK4128A 8ch 216kHz / 24-Bit Asynchronous SRC

Dunno yet if I'm smart enough to make this work, but if it does, I'll let you know.

-- Jim

Hi Jim, that will be a lot of PGA2311s! Have you considered using an 8-channel chip e.g. Crystal CS3318. I have no idea what involved in implementing any of them but definitely interested to hear how it works out.

john.reekie wrote:

Hi Jim, that will be a lot of PGA2311s! Have you considered using an 8-channel chip e.g. Crystal CS3318. I have no idea what involved in implementing any of them but definitely interested to hear how it works out.

I did look at several of the multichannel chips including the 3318, but from what I've been reading they can be a bit more tricky to get working well. I couldn't find any boards for them (besides the sketchy Ebay stuff), and I'm not confident enough in my own board layout skills. The thing that sold me on the 2311s was this:

IR High Fidelity Remote Volume Controller Chip with LCD support

This site has been around for quite awhile now, but I've received kits from this guy within the last year, so he's still up & running. I even asked, and he didn't have a problem with me providing a link here. I'm impressed with the boards - they follow the recommendations on the data sheets regarding ground planes etc. I expect they will allow maximum performance from these excellent ICs. It's also designed to be expandable to 12 channels (or even 18 or 24, if you don't need individual balance adjustments). He doesn't share his controller code, but I plan to use his chip until I get up to speed on that stuff; then I'll sub in my own so I can add my own features.

To house this project, I dug out of the closet (I love my closet!) an old Peavey Autograph. It's got the right front panel controls & display for the job. All I have to do is clamp the big main board into my miter saw and "excuse" the power supply from the rest of it. That should be fun.

-- Jim

Jim wrote:

IR High Fidelity Remote Volume Controller Chip with LCD support

Nice find! Somewhat tempted myself.

All I have to do is clamp the big main board into my miter saw and "excuse" the power supply from the rest of it. That should be fun.

Yikes