TOPIC:

frogsizzler wrote:

I have been getting ready to re-do my system, although it will take some time for speakers to arrive and get time to install, but... another config change that I will do for added safety - in addition to changing the gain structure, will be this...

I had all amp hardware crossovers turned off as they were 'unnecessary'.. however most likely in future I will turn them on but set them up a good notch outside the level of crossover in the DSP but still in effect. This at least will leave some hardware barrier to the sub and tweeters seeing full bandwidth, should the DSP "lose it" for a moment or otherwise have a failure...

That will work, however remember that any filter will have an effect on phase. Stacking crossovers, even ones that are far outside the effective bandwidth of the of the *functional* crossover point can make tuning more difficult. It may take quite a few iterations of tweaking the *safety* crossover point to avoid getting undesirable results of steep rolls of phase across the functional bandwidth. It's less of an issue with high bandwidth drivers like mids & tweeters, but can be very pronounced with low bandwidth driver like woofers and subs.


I would suggest perhaps something like WinISP or other similar software that can simulate the effect of multiple stacked filters and show the resulting changes in phase,.. having a sub with a phase swing of 1000°+ between 20-100hz can sound somewhat... odd.

Simulating can help you choose the least offensive combination of orders and freq combinations with less guesswork and time involved.

Yes this was exactly your point elsewhere about intentionally stacking out of band filters for phase tricks wasnt it?

frogsizzler wrote:

Yes this was exactly your point elsewhere about intentionally stacking out of band filters for phase tricks wasnt it?

Yes, precisely.

Following this as my C-DSP also has produced random static blasts at high volume, although my amp went into protection mode immediately after the blast. I immediately turned down the volume and a few seconds later everthing turned back on as normal. It appears that no components or speakers were damaged, however, I haven't turned the volume up since then.

I'm glad I ran across this post so that I can also figure out the cause for the blast and hopefully correct it. For now, I will adjust the gains and see if that minimizes the chances of this happening again.

Thanks for posting, glad to hear another report (makes me feel less crazy/unlucky).

DevTeam has been really good about this and sent me a unit with some debug firmware. Perhaps if you contact them (log a support ticket) they can put you on the same debug firmware - it logs to the microSD so when you have an "event" you can send them the logs and they can try to diagnose what might have happened.

@ daluv16

Please start a tech support asap with our team. At this stage, we don't have any ticket under your name. We do want to get to the bottom to this event asap. We have few CDSP now setup by the engineers running non stop. We must put ourselves in the exact same setup (i.e. potential undercurrent, monitoring of commands potentially sent via remotes?, type of presets currently loaded.. )

Anyway, please get in touch with our team asap through our portal (minidsp.desk.com)

devteam wrote:

@ daluv16

Please start a tech support asap with our team. At this stage, we don't have any ticket under your name. We do want to get to the bottom to this event asap. We have few CDSP now setup by the engineers running non stop. We must put ourselves in the exact same setup (i.e. potential undercurrent, monitoring of commands potentially sent via remotes?, type of presets currently loaded.. )

Anyway, please get in touch with our team asap through our portal (minidsp.desk.com)

The undercurrent/undervoltage question is excellent one - my condition at the time was daytime, no lighting load on the car, no AC on, volume not high so audio system not drawing a lot - have a brand new alternator and this car has relatively robust electrical system, so should not have been any chance of a voltage drop. Only slight thing would be as mentioned I was pulling around into a parking lot so perhaps RPM's sagged for a minute but the car has a very large battery and voltage sag is not typically an issue. My C-DSP is wired parallel ground/power directly back to a large power distribution panel right at the battery with fairly heavy gauge wire, probably only about a meter of it or so. .

I'll reply to my ticket w/ this info as well so it goes into the file hopefully.

Following this thread: A thought I had was that I haven't experienced this issue... not to say that I won't. In my current installation I am NOT using the remote as I have yet to modify it for my needs.

Making an assumption that the remote is USB protocol over RJ-11 wiring. RJ-11 is not twisted or shielded as per USB specifications. If my assumption is correct then one could reasonably point towards the interface cable between the C-DSP and the remote as the source of errant commands from EMI.

Perhaps on your test bench it might be in line to wrap the remote cable around a high EMI noise source to see if errant commands can be detected.

Kowalsker wrote:

Following this thread: A thought I had was that I haven't experienced this issue... not to say that I won't. In my current installation I am NOT using the remote as I have yet to modify it for my needs.

Making an assumption that the remote is USB protocol over RJ-11 wiring. RJ-11 is not twisted or shielded as per USB specifications. If my assumption is correct then one could reasonably point towards the interface cable between the C-DSP and the remote as the source of errant commands from EMI.

Perhaps on your test bench it might be in line to wrap the remote cable around a high EMI noise source to see if errant commands can be detected.

Kowlalsker that is exactly one of the topics DevTeam is pursuing on my ticket. I have the RJ and USB cables both running in cabin, shouldn't be too near anything but but isn't out of the question and we are discussing it and they are looking into it as well. Aside from a rare logic glitch inside the unit, memory leak or something crazy like that, I think that plus the voltage question would seem to be most plausible to me. They have run my configs for days and days as I understand it on their bench rig with no sign of a problem so far but are still looking into other possibilities..

Update - Or not much of one. After contacting the development team a replacement C-DSP was sent; however, upon delivery I noticed something was definitely loose inside the unit and was not able to install it. I'm currently waiting for a replacement C-DSP to replace the original replacement C-DSP, but that won't happen until next week. For now, the static blasts and noise have not reappeared since switching channels 1 and 2 outputs to 7 and 8 and turning off 1 and 2. I did this becuase I was getting engine noise in all the channels and the static blasts appear to have come from channels 1 and 2. My guess is that there is some internal connection issues with channels 1 and 2, but I'll leave this up to the development team to figure out.

In all, the team at MiniDSP has been very helpful and supportive, the C-DSP is a great product and everything is going well (other than having my trunk disassembled until I replace the C-DSP).

I'll return to this post only if the static blasts return after the C-DSP is replaced.

Replying to an old thread, but unfortunately my C-DSP 6x8 just did this as well, twice in one day.

I've had the unit for just over a year (ordered new from Parts Express), absolutely no issues. First instance was while the car was running (at idle, no other electrical loads) and second instance was while the car was off and battery was on a tender. Could be coincidence, but the second instance happened as soon as I touched the case with a USB cable to plug in. I do not have a remote connected and use RCA in/out. I've run the audio system numerous times while on the same charger without issue. 

Like other posters in this thread, head unit volume was on zero for the first one with no media connected (nothing playing). Only stopped when I turned off the head unit which killed the remote signal to the DSP. Second instance music was playing at a quiet volume, had to fully shut down to get it to stop. The first instance was enough to blow the tweeters. 

Recently added a sub (mono amp, 2 more channels into the DSP, 2 more out) and switched to controlling remote for the other amps through the DSP to eliminate a popping sound when the head unit remote turned amp and DSP on at once. I DID open the case to verify the jumper was setup for this (it was). Opened, verified, closed. Touched nothing. I've put a few hours on this setup after opening the case without issue (enough to make a new config, do some tuning, drive around, etc.). Did have the block heater plugged in earlier the same day, but not while the stereo or car was on.