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Dayton Audio's DSP-LF Low Frequency DSP Controller

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  • Dayton Audio's DSP-LF Low Frequency DSP Controller

    This could be very appealing at it's price. Has anyone used one of these yet? The software is a mobile app on your iphone and uses the internal microphone. The manual doesn't show provisions for using a separate microphone. My first question is, what is the frequency response of the microphone on an iphone? If it doesn't reach 20hz or so, this device would have very limited use. Has anyone measured one?

  • #2
    Just saw that thing today... disappointed it doesn't have a high pass output for a quickie DSP bi-amp system. Cool for sub tuning though. As for phone mics, they're little electret types that do usually respond that low. You could also plug in a iMM6 I imagine. I got the impression from the picture that it's taking a close mic measurement, then measurements in the room to determine delta and adjust, so mic accuracy may not be an issue.
    Electronics engineer, woofer enthusiast, and musician.
    Wogg Music
    Published projects: PPA100 Bass Guitar Amp, ISO El-Cheapo Sub, Indy 8 2.1 powered sub, MicroSat, SuperNova Minimus

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    • #3
      Some interesting design designs were made with that. Like the use of 3.5mm jacks instead of the more common RCA jacks. And 5V rather than 12V power (I can easily see this being used in a car audio environment).

      I'd love to see some of its features (dynamic EQ, compression / limiting) be included in the next software update for the DSP408 BTW...
      Last edited by Brian Steele; 03-10-2020, 08:11 PM.
      Brian Steele
      www.diysubwoofers.org

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      • #4
        I saw it too and thought about trying it with the little sub I am starting.

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        • #5
          I got suckered in to ordering one today... If it works as advertised, it should be a pretty sweet little doodad. Easy way to turn a Crown XLS into a fancy DSP unit! While I don't necessarily like all things be controlled via a phone, this should be convenient. The advanced app is only $5. It's half the price of a MiniDSP so for sub duty I'm excited to see what it can do. I wonder if it will have provisions for using a Dayton iMM-6?

          In my unofficial testing, an iPhone XR mic is good down to ~22hz; 20hz didn't make a blip, 22hz was a little weak, 25hz was solid. But, this was using headphones in close proximity to the microphone for a couple of reasons. I know the headphones play the 20hz test tone as I can hear it. But don't take that for gospel.

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          • #6
            Looks interesting but how come there are no detailed specs? Where's the PC based software?

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            • #7
              True, with PC based software, you could run a real mic off a laptop. And my fat fingers and poor eyesight work much better on a PC than my phone!

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              • #8
                I received my DSP-LF the other day. Had a little time to fiddle with it this evening and was slightly underwhelmed. BUT, I later figured out that my kids had pushed a bunch of random buttons on the receiver that fiddle with the sound field so I didn't give it a fair shake.

                A few things though:

                - The mic on the iPhone XR does absolutely nothing below 25 hz. I'm not sure it does much below 30 hz either but there's literally nothing on the measurement graph below 25 hz even though I can hear/feel useful content below that on the sweep.

                - I downloaded the iWoofer Pro app; I didn't feel the free version was worth much.

                - The measurement graph displays from 10hz and up but since the phone mic lacks the ability to listen that low, I'm starting to agree with ya'll above - kind of wishing there was a PC app. I'm tempted to put it on an iPad and see if it makes a difference. I KNOW it will make a difference in the ability to edit the response, which brings me to the third point -

                - Manual equalization is quite clumsy. I'm sure I need to use the tool more to figure out how to better utilize it.

                - EQ only goes down to 20 hz even though the measured sweep is supposed to go down to 10 hz. I know, I know, this is nit-picking and nobody adds EQ below 20 hz. Well, on occasion, I have. But I wish it would. One of the clumsy things is trying to disable the HP filter set at 20 hz. That one is most likely user error but maybe not... I like that infrasonic fun

                - Lastly, I started having issues with the app towards the end. Initially, it would sweep up past 100 hz (not sure what helps it determine the window, but it appears to be automatically selected from the short bursts it sends out initially (much like automatic room calibration from an AVR that sends out rapid white noise burst at an increasing volume to measure each speaker in the room). The DSP unit then measures a prolonged, stepped sweep (maybe 20 seconds) and graphs the response. This part is dead easy; it also allows you to average several different measurements (I had it average center of the cone, halfway between cone and port, and at port). The problem is that it didn't do anything to EQ my room not at 40 hz, but instead attenuated everything above 60 hz. Almost like a low pass filter at 60 hz. I tried running the wizard a few times but it either got worse or shortened the measurement window to 10-60hz.

                Anyways, I'll give it another try another day but for now, I have disconnected it and am running un-EQ'd. My new receiver lacks some functions that the old Yammy had - like the ability to select EQ frequency and Q. The new Pio only has 32, 60, 80, and 120 hz and no Q option so that room node can't be dealt with from the receiver like my Yammy could do. Oh well. I suppose I can use the DSP-LF on other projects with smaller, less beefy drivers...

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                • #9
                  Played with the DSP-LF for a few more minutes today. First, I pulled out the iMM-6 measurement microphone to see if it would work; whuddyaknow - it did! It improved and extended the response measurement, though it is still only measuring down to 20hz. I suppose that's actually a limitation of the DSP-LF even though the response graph starts at 10 hz. Looking at the spec's for the iMM-6, Dayton says it's good down to 18hz.

                  Here are a set of measurements using the iPhone's built-in microphone. Notice the drooping response from about 40 hz and down, and the non-existent response below 25hz.


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                  Compare this to the iMM-6 measurements. Green was measured at the cone, Red measured at the port. Note the port resonance just below the 100 hz, just as predicted in WinISD. As for THD, I'm really not sure how they derive that, but it can easily be manipulated with the amplifier gain and the mics proximity to the sub. So, for now, I'm ignoring it.


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                  The issues I was having earlier was from following the directions. Guess I need to quit reading them.. The very limited amount of paperwork and directions included with the DSP-LF suggests using the "Boomy Region" room compensation setting. From the manual, "We recommend the "Boomy Region" selection since it maintains the high energy peaks of the low frequencies while creating a linear response for the mid-range." IMO, this is just a bad, bad idea. It leaves most of what is below 45 hz, adds some boost at 45 hz, attenuates everything from 45 to 70, then flattens it out from there at 10 or 15db below the average. Here is the room correction that the DSP-LF applies.


                  DASHED LINE: Projected Response
                  BLACK LINE: Corrected Response

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                  If you use the "Linear" setting, this is what you get. Much better but I still don't like the rising response from 30 down to 20 hz. Well, I mean, I do, but that's not what I'm aiming for here.

                  DASHED LINE: Prospective response curve
                  BLUE LINE: Corrected Response, In-room

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                  I really wish that it was easier to change the prospective curve. As is, I don't see any way to edit it directly. Instead,I have to go in to the Xover, add some DSP here and there, then go back, remeasure, see what happens, go back to the Xover editor, edit the filters using by dragging up/down, left/right to change frequency and amplitude, the pinch gestures to edit the Q, then hope those changes are sufficient. Rinse, dry, repeat. But I have yet to figure out how to edit the rising tail from 30 hz down to 20 hz. This sub doesn't need the extra boost down there; it makes plenty as is.

                  A few more things about the DSP-LF:

                  - On-screen prompts were clearly written by a non-native english speaker. They were translated and make enough sense to know what's going on, but are not great.

                  - I really wish the sweep would start and measure below 20 hz. Strange, since the the graph starts at 10 hz AND the phase settings start at 10hz.

                  - I don't really understand some of the slider settings - phase being one of them. I understand phase, but I'm not sure why the phase setting is a slider from 10 to 30,000 hz. I'm sure there is an explanation, but it doesn't seem intuitive to me.

                  - One fun little item in the programming is a SubHarmonic Synthesizer (SHS). It reminds me of that one button on old receivers that added extra low bass that was fun to turn on for a few songs until it gave you a headache. It generates harmonics an octave lower than the original frequency. However, this function is useless to me.

                  - I like the ability to add up to 25 different filters.

                  - After collecting a set of measurements, then selecting the correction curve, the program calculates the corrective measures then informs you that the settings can be saved. However, I don't see any save button or any way to change the preset. Hmmm....

                  - The measurements automatically set the level. The level actually adjusts on the fly so it isn't absolute, meaning you can't even compare one sweep to another, just take each sweep

                  As much as I'm complaining about it, for half the price of a MiniDSP, you get a reasonable measurement system with the loads of EQ in the palm of your hand with a few finger swipes. I'm not sure if it will meet my needs, but is certainly a viable, budget-oriented option. I'll play with it some more and see what more I can figure out. It might work perfectly for my system upstairs.

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                  • #10
                    Has anyone tried 2 or 3 of these on each sub? Also what do I have to do for the setup of the Dayton iPhone mic? I think it’s the imm-6 mic Sent from my iPhone using Tapatalk

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                    • #11
                      I have one, it works well.The operating instructions are gosh awful. I did the setup manually, feeding my system with pink noise, seeing the result of the adjustments I made (using my Android pad) in real time on my computer with an RTA. In a multiple sub arrangement you'd want one on each sub, but the more subs you have the less need you'd have for DSP, as using multiple subs smooths out the room response.
                      www.billfitzmaurice.com
                      www.billfitzmaurice.info/forum

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                      • #12
                        Instead of getting 3 of them you might be better off getting the Dayton DSP 408. It's more than 3 individual units but a lot less cables to deal with and it has a PC interface

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                        • #13
                          Curious why you would think to try and use two or three on a single sub? I suppose if you wanted an EQ band every 5 hz it might work?? Otherwise, I guess I'm missing the plan for multiples...

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                          • #14
                            I believe he meant using two or three of them as in one each with two or three subs.
                            www.billfitzmaurice.com
                            www.billfitzmaurice.info/forum

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                            • #15
                              That makes more sense. In the which case, it would be beneficial to use one DSP-LF per sub for placing the subs in different parts of the room and being able to EQ them individually. Higher-end home theater receivers have this function built in for the .2 subwoofers outputs, which I find to work pretty well.

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