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TOPIC: Re: 4x10 problems in low frequency ranges

Re: 4x10 problems in low frequency ranges 9 years 10 months ago #2846

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@ Nyt,

Engineers will look into it asap, but FYI you just posted this just less than 2day ago over a week end (i.e. less than 24h since our team is aware of it), so I don't want to set expectation too high that we're going to release a new firmware within the next 30min.. :-)

As we already mentioned over email, we're working on understanding the problem and have allocated engineering resources for that matter. We'll let you know once we have a fix for a tested solution(i.e. plug-in release).

Thanks for your understanding.

DevTeam
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #2910

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@ Nyt,

Following quite a lot of hours of brainstorming by our team, here is a quick update. This work is still in progress so please take this information accordingly.

Our team has indeed been able to reproduce the unstable filter in the sub frequency range. Some of the effects being more obvious as you get closer to 10Hz. This quantization problem was most likely missed as these symptoms wouldn't show on our Matlab or UI charting of the plots. The reason being that we are full floating point through out our calculation on the UI. While the main reason for instability being the fixed Point DSP architecture of the unit, its implementation of the IIR filter by the IC and high sample rate (96kHz vs very low frequencies).

At this point of time, a couple of ideas are under progress and being worked out, but none of these are a quick magic wand solving all the problems. They involve some pretty deep math to solve the problem of quantization and the fact that on some coefficients, the effect of one LSB (least significant bit) has a major effect on the response..

With this said, we won't pronounce ourselves on whether we'll be able to solve that issue or not. There are a couple of things we're considering in the mean time.. We'll let you know what comes out of these investigations. Thanks for your patience.

In the mean time, note that a beta version of the miniDSP 4x10 providing REW support is now available. Maybe an alternative that you may want to consider but note that the limitation is not in the software here, but rather the fixed point DSP structure of the current algorithm.

Hoping this information makes sense,

DevTeam
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #2921

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Thanks for the update. Please continue to keep me updated on this problem.

Will this issue also affect EQ done with biquads?
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #3038

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any news?
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #3042

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Still waiting for news, as I still have a MiniDSP that doesn't function as advertised a month later.
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #3047

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Have you tried using the new (beta) plugin and putting in the biquad coefficients directly?
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
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Re: 4x10 problems in low frequency ranges 9 years 10 months ago #3050

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john.reekie wrote:
Have you tried using the new (beta) plugin and putting in the biquad coefficients directly?

Yes, It's broken in exactly the same way. It's been about 4 weeks now and nothing resembling a solution :(
Last Edit: 9 years 10 months ago by nyt.
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3051

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Just to be clear, you calculated the coefficients yourself and entered them directly, and the same thing occurs? So the issue is not with the calculation of the coefficients, but how the chip does the arithmetic?

Unfortunately I don't have time to try for myself although I am curious.

I can't help wondering if you would get a better response if your posts were more helpful instead than complaining. Four weeks in a software development cycle is nothing.
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3053

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john.reekie wrote:
Just to be clear, you calculated the coefficients yourself and entered them directly, and the same thing occurs? So the issue is not with the calculation of the coefficients, but how the chip does the arithmetic?

Unfortunately I don't have time to try for myself although I am curious.

I can't help wondering if you would get a better response if your posts were more helpful instead than complaining. Four weeks in a software development cycle is nothing.


I provided plenty of information in the original post, and they have identified the problem. There isn't anything else to provide. All I can do is wait for a fix for broken hardware that I paid decent coin for that doesn't perform as advertised or intended due to bugs that they have acknowledged.

I used REW to generate the quadratics, they get "processed" correctly by the plugin, and then the actual hardware skews things just like using the PEQ settings.

As a developer myself, I wouldn't leave something broken for so long. If I did, my users would crucify me. Asking for an update after 4 weeks isn't asking for too much. After all, the only relevant communications I've received so far are "we may or may not fix it." I don't really consider that acceptable. I am still holding out for an update, but I will only wait so long before I start looking for better hardware and urging people not to buy MiniDSP products. I can only hope the development team is more reliable than the QC team at this point.
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3054

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I see. What software do you produce?
I am not miniDSP support.

"You must ask the right questions." - Dr. Alfred Lanning's hologram.
-> Have you read the User Manual??
-> Have you drawn and posted a diagram?
-> Have you posted a screenshot?
-> Have you posted your config file?
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3056

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I have been following along and while I can understand the issue here I think the request to fix just isnt the highest priority. Lets face it < .1% of the world requires this type of EQing in the first place.

My LT Circuit does work for my LMS5400 (so far) and anyone building sealed high power designs should just use a natural HPF circuit (box/amp limited)

Yes, there are problems but the assumption that this actual problem is a general issue is a big assumption.

As for software development, since I have owned my own company for 20 years all I can say that if this was my team and I had to allocate resources to it it would not have the highest priority at all. I also suspect its not an easy fix either.

Sorry to nyt but his need isn't going to be the highest priority when others with bass/minidsp solutions do not see this is a 100% failure below 15Hz. But I only have the 2x4 balanced unit though.

btw, as a developer you know all too well that those who complain the most about the same very specific need over and over get push to the bottom of the priority list all the time ;) Patiences is required and even 1 month is nothing in the development world. I see 6 months as a logical time frame for maybe a problem like this one.
Last Edit: 9 years 9 months ago by penngray.
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3057

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Also EQing below 15Hz is just a "look at the flat measurements" process. it has really little to do with < 15Hz in room performance so do we really need to obsess about it daily waiting for a solution??
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3058

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@nyt,

Let me try to give you a bit more background information of how things run inside an engineering company. The fact that we're very open and been very much listening to the DIY community, doesn't mean we're telling you EVERY single task we're up to. Hope you understand that first point.

With this said, from our end, this is what we did do. From day one that you wrote and mentioned the problem, we did looked at it and worked on a solution behind the scenes. From what I'm told (and looking at previous posts), I can see that we did communicate our progress in a long post earlier on. That's where we mentioned that we were working on a fix for a hard issue that was not a "Software bug" but a "Math issue".

Maybe the problem got missed (as I read your last posts where you believe that we could just "fix" the problem like a UI bug or so) so let me try to once again highlight it. The problem has to do with 96kHz + very low frequency on fixed point DSP. It is a Math problem about rounding errors happening on any platform. i.e. even a PC running some rounded coefficients will show the issue. It's not that we're calculating the coefficients wrong, it's the fact that at sub frequencies, the resolution of these coefficients run into so called quantization noise. Many subwoofer processor running at say 32kHz sampling rate for that reason. The 2x8 being the first platform to run at 96kHz, sub filtering (10-20Hz) showing up artifacts not present on earlier platforms. If the platform was to run at 30kHz, you wouldn't know about it. Hope you now understand in bit more details what the problem is here as I strongly believe that it's important to understand it.

Though I could appreciate that it's indeed upsetting to have a problem on a product, but your statements still sound unfair as you didn't even get a chance to let us update you on what we've been up to... I'm also not 100% sure you're going the right direction with your choice of wording (here or on other forums) to get us to find a solution here as Penngray already suggested from his experience. Propose to working "with" people (e.g. beta testing) is typically an easier way than "against"... :-)

What's to remember to all this is that we DID work all this time on finding a solution. We DID read countless AES papers on the issues of High sampling rate and very low filtering. We DID work with the IC manufacturer in getting things moving on their side to see if we could implement a custom piece of code on their IC. We DID contact multiple consultants and even some university professors to see if there was something we could do.. A lot of the suggestions, ended up in this upcoming beta version which is running in a beta form.

So to summarize, tough issues take time to get solved. That's the reality. If it was easy, we would have had a fix for a long time. As I tried to spend time to clearly word this post to explain the issue, it would be worth that you try to do the same to keep this forum a place where we can share ideas, improve products, rather than making statements that could easily be cleared out if we were to properly communicate in the first place.

Thanks for your understanding.

Tony
Co-Founder miniDSP
miniDSP, building a DSP community one board at a time.
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3060

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penngray wrote:
Also EQing below 15Hz is just a "look at the flat measurements" process. it has really little to do with < 15Hz in room performance so do we really need to obsess about it daily waiting for a solution??

That may be your point of view on the subject, but it is not mine. I wanted to trim output below 20hz, and with how things are currently, adding something as simple as a low shelf does not work. Furthermore, the generated responses from say a 1db peak at 15hz results in a what looks like a rising edge trigger with a 7db null and then a 7db peak that requires over 4 times the amount of power to drive. This can damage equipment, and is not something to gloss over lightly. You have a functioning product, your views may not be the same if you had a 2x8. I bought this unit to add a margin of safety to my system. I wanted to trim output in very low bass frequencies and prevent over excursion. I was kind of surprised to see that the unit was actually doing the opposite of what I wanted when I tested it. Thankfully, I didn't test it with the speakers hooked up.

If I make changes to my system, it takes hours to find a correct EQ setting since it is no longer a matter of put in the correct filters and adjust from there, but instead put in semi random filters and see what the output looks like.

An analogy would be like buying a car that's advertised to go 120mph. You first get this car and realize one of the seats are missing, but that's not too big of a deal, the manufacturer sends you a new one. You just have to install it yourself (or in my case, a missing component on the PCB that prevents the unbalanced #1 output from not working). You then take your car out for a drive, and want to see what it can do. So you find a nice straight bit of highway and open it up only to discover that once you pass 100mph, the steering no longer functions. You then contact the manufacturer to see if they'll fix it, and get a response of "maybe we will, maybe we won't". After a month you check back for an update on this and are met with silence from the manufacturer, and other customers responding "who cares, I only drive 80mph in my car, even though it is a completely different car and doesn't have the same problems, you shouldn't care about this."
devteam wrote:
With this said, we won't pronounce ourselves on whether we'll be able to solve that issue or not. There are a couple of things we're considering in the mean time.. We'll let you know what comes out of these investigations. Thanks for your patience.

I was simply asking for an update, since this was where the communications were left at. It would be nice to know if a fix would be available or not in the future.

@devteam,

I appreciate the response and the time spent looking into this. I understand the problem as that part was communicated in the previous response, however that response left it in a state that didn't say whether it would actually be fixed or not. I was simply asking if there were any updates and was met with silence on a board that is actively read by devteam.

As for beta testing, you guys released beta software, I tested it, and reported that it showed the same problem. If you have newer beta version in the works, I'd be happy to test that and report back as well since you seem to be offering this option.

Would you mind clarifying if it is a new beta board, or a software/firmware update to the current 2x8 unit and when it will be available? Thank you for your time.
Last Edit: 9 years 9 months ago by nyt.
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Re: 4x10 problems in low frequency ranges 9 years 9 months ago #3073

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Anyone reading?
If you have newer beta version in the works, I'd be happy to test that and report back as well since you seem to be offering this option.

Would you mind clarifying if it is a new beta board, or a software/firmware update to the current 2x8 unit and when it will be available? Thank you for your time.
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