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  • Amplifier Dude Crossover DSP and Amplifiers

    Wow that’s a lot of parts in the signal path! The biggest upgrade I ever experienced with the Purifi 6.5X and Bliesma T34B tweeter was when I took out all the passive components from the signal path and replaced them with a solid piece of Furutech Alpha-OCC copper wire.

    End result from the listening position with this 2 way monitor in a 3L sealed cabinet.

    Click image for larger version

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    https://www.maverickaudioforum.com/

  • #2
    With no crossover? That's interesting...

    And that is why some of those parts in the path are a bit pricey...


    Of course, what I figure is that you're using a DSP based crossover setup, and direct connection on your drivers.

    The problem I've found with that approach is the quality of the DAC's used in DSP based systems, and the overall digital train- no place for re-clocking or a rubidium clock in there, and typically delta-sigma DAC chips, compared to standalone high end DACs and digital signal train. And if you room EQ for one listening position to get a very flat response, it can create issues with the response everywhere else in the room, because the actual system power response is changed from whatever nominal flat or acoustic voiced character exists for the speaker to something else.

    I ended up recommending an NAD M33 to a friend/forum member who wants to try that path- it comes with a 500Hz and down version of Dirac, which for small dollars can be upgraded to the full version.

    But by all means, you should do whatever makes YOU happy!

    I prefer acoustic solutions to acoustic problems. This is a rental home with no acoustic solutions in place, (moving in March/April) so with a long enough measurement window for capturing the bottom end, there are quite a few reflections.
    the AudioWorx
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    Resistance is not futile, it is Volts divided by Amperes...
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    • #3
      Originally posted by JonMarsh View Post
      With no crossover? That's interesting...

      And that is why some of those parts in the path are a bit pricey...


      Of course, what I figure is that you're using a DSP based crossover setup, and direct connection on your drivers.

      The problem I've found with that approach is the quality of the DAC's used in DSP based systems, and the overall digital train- no place for re-clocking or a rubidium clock in there, and typically delta-sigma DAC chips, compared to standalone high end DACs and digital signal train. And if you room EQ for one listening position to get a very flat response, it can create issues with the response everywhere else in the room, because the actual system power response is changed from whatever nominal flat or acoustic voiced character exists for the speaker to something else.

      I ended up recommending an NAD M33 to a friend/forum member who wants to try that path- it comes with a 500Hz and down version of Dirac, which for small dollars can be upgraded to the full version.

      But by all means, you should do whatever makes YOU happy!

      I prefer acoustic solutions to acoustic problems. This is a rental home with no acoustic solutions in place, (moving in March/April) so with a long enough measurement window for capturing the bottom end, there are quite a few reflections.
      Yes using DSP. The DAC’s in my DSP system are the best I’ve ever heard using them in a 2 channel passive system. And I’ve made dacs that compete with the MSB Select DAC 2 in the past. Review of one of my old dacs comparing to $100000 MSB Select DAC 2:

      https://www.head-fi.org/threads/poss...rstack.838570/

      However my new dacs used in my DSP system put that DAC to shame. That was 6 years ago.

      Regarding the room correction, my system measures from 40 points in the room. And with these drivers crossed over at 1.5k with a 4th order, the power response from all room positions is pretty amazing. However I did settle on only correcting below 300hz, with mild correction. Because the response is pretty amazing with these drivers without correction.

      Here’s the response with no EQ at all above 300hz. From the listening position 8’ from the speakers in the centre. The room is 18x34’. With hardwood floors and many windows. No carpet or acoustic treatments. And the measurement using no gating at all. All reflections are included.

      Click image for larger version

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      • #4
        A 300 (!!) dB scale? Wow....

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        • #5
          Originally posted by draki View Post
          A 300 (!!) dB scale? Wow....
          Here’s zoomed in more with 1/48 smoothing.

          Click image for larger version

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          https://www.maverickaudioforum.com/

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          • #6
            Is "flat" really where it's at?

            This is more like what I'd expect to see in the room.

            But if you have this much control over your filters, here's a suggestion that's been vetted by quite a few other people, and promoted by Sigfried Linkwitz, too. Several on the forum here have tried the passive filter version I proposed and find that they really prefer the listening experience that way.






            Some specific EQ curves proposed and considered/evaluated by Linkwitz and associates





            Passive circuit simulation and implementation for NAD M22 (or similar power amplifier with input impedance in the 100K range).





            I know of several sets of these voicing filters built up and in use now with members, after their evaluations.
            the AudioWorx
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            Resistance is not futile, it is Volts divided by Amperes...
            Just ask Mr. Ohm....

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            • #7
              When you’re doing listening position measurements in an untreated room I think using 1/12 smoothing is fair. However the first measurement I shared with the +-0.5dB 20-20 from the listening position had no smoothing at all. And that measurement was taken with REW. When the correction was done with completely different software.
              https://www.maverickaudioforum.com/

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              • #8
                Originally posted by JonMarsh View Post
                This is more like what I'd expect to see in the room.

                But if you have this much control over your filters, here's a suggestion that's been vetted by quite a few other people, and promoted by Sigfried Linkwitz, too. Several on the forum here have tried the passive filter version I proposed and find that they really prefer the listening experience that way.






                Some specific EQ curves proposed and considered/evaluated by Linkwitz and associates





                Passive circuit simulation and implementation for NAD M22 (or similar power amplifier with input impedance in the 100K range).





                I know of several sets of these voicing filters built up and in use now with members, after their evaluations.

                I can set the target curve to any shape I want. For this example I set the target curve to flat. However the un-corrected response has no target curve at all. It’s just a simple 4th order Linkwitz crossover at 1.5k and the tweeter gain adjusted 12dB lower than the woofer above 300hz. And that’s how the listening position result turned out. And it sounds damn good! From all positions in the room.
                https://www.maverickaudioforum.com/

                Comment


                • #9
                  As to the DAC's, it sounds like you've got your bases covered, but for a three way system, if your homebrew hits the suggested performance level of the MSB DACs, that would be like using three Berkely Alpha DACs cost wise, which is a LOT more than the price of all the speaker system components including top of the line passive crossover parts. Even the baseline Berkley Alpha DAC is $10K these days, a lot more than I paid for my first one from them. Most of our members have somewhat finite financial resources...

                  I'm partial to R2R ladder DACs these days using precision selected resistors, and with a digital front end re-clocked through a Brainstorm DCD-8 which itself is slaved to a Rubidium 10MHz reference clock for precision and low jitter. A former colleague at the firm I used to work for, based out of Munich, and I spent many years evaluating quite a few solutions in that area, including MSB, and we used both my Audio Precision and his wife as "independent" reference standards for comparing and evaluating bench and listening results. One of the weirdest things we found is that Rubidium clocks don't all "sound" the same; when we were comparing what we thought were the best candidates, his wife could tell the difference and identify each one; and the "best" one for imaging and tonality and minimum grain was not the most expensive one.

                  Everyone I know of that has build some of these passive designs, like the Wavecor Ardent, has commented on how well they respond to source and component upgrades. So, for now, at the level of expenditures they can afford, I don't think they're getting short changed by passive crossover components. And for me, there's no money in it for me anyway, this is just a labor of love, driven by my past life as a professional musician and my experiences as an engineer in a variety of areas. Including electronics for audio.

                  So, let's just say we're using different paths and different levels of resources to get to what we individually conceive of as audio nirvana...
                  the AudioWorx
                  Arvo Pärt
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                  M8ta
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                  SMJ
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                  Ardent D

                  In Development...
                  Isiris Mk II updates
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                  Resistance is not futile, it is Volts divided by Amperes...
                  Just ask Mr. Ohm....

                  Comment


                  • #10
                    Originally posted by JonMarsh View Post
                    As to the DAC's, it sounds like you've got your bases covered, but for a three way system, if your homebrew hits the suggested performance level of the MSB DACs, that would be like using three Berkely Alpha DACs cost wise, which is a LOT more than the price of all the speaker system components including top of the line passive crossover parts. Even the baseline Berkley Alpha DAC is $10K these days, a lot more than I paid for my first one from them. Most of our members have somewhat finite financial resources...

                    I'm partial to R2R ladder DACs these days using precision selected resistors, and with a digital front end re-clocked through a Brainstorm DCD-8 which itself is slaved to a Rubidium 10MHz reference clock for precision and low jitter. A former colleague at the firm I used to work for, based out of Munich, and I spent many years evaluating quite a few solutions in that area, including MSB, and we used both my Audio Precision and his wife as "independent" reference standards for comparing and evaluating bench and listening results. One of the weirdest things we found is that Rubidium clocks don't all "sound" the same; when we were comparing what we thought were the best candidates, his wife could tell the difference and identify each one; and the "best" one for imaging and tonality and minimum grain was not the most expensive one.

                    Everyone I know of that has build some of these passive designs, like the Wavecor Ardent, has commented on how well they respond to source and component upgrades. So, for now, at the level of expenditures they can afford, I don't think they're getting short changed by passive crossover components. And for me, there's no money in it for me anyway, this is just a labor of love, driven by my past life as a professional musician and my experiences as an engineer in a variety of areas. Including electronics for audio.

                    So, let's just say we're using different paths and different levels of resources to get to what we individually conceive of as audio nirvana...
                    You can’t beat a DAC slaved directly to a local clock at the native frequency of the audio signal. The PLL generators alone add loads of phase noise. But that’s a discussion for another thread.

                    Yes I know that there’s no commercially available solutions this good on the market. Which is why I spent 6 years making my own. Which is commercially available now.

                    https://www.maverickaudioforum.com/f...eaming-dsp-amp

                    Here’s the types of components I use for reference when comparing to the DSP. Sounds like cotton is in my ears with the passive parts. And the soundstage is on another planet. Active. Same with the dynamics at all listening levels.

                    Click image for larger version

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                    https://www.maverickaudioforum.com/

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                    • #11
                      OK, now I understand- you are posting here because you have a product you would like to sell more widely.

                      You've already directly posted a link to your site- if you want to reach more people, I suggest you start a thread here about your project hardware, and the example implementation, and post bench test evaluations in the "On the Bench" forum section- measurement evaluations such as what John Atkinson does would help you make your points.

                      This forum section "Mission Possible DIY" is a forum for home construction DIY, not for products for resale. We don't have any "bans" on mentioning services or products for resale, but you're not really posting in the right place, if I understand what you're doing correctly. Given that it doesn't sound like a DIY project, it seems that promoting and describing it in a more commercial setting would be appropriate and more useful for you. .
                      the AudioWorx
                      Arvo Pärt
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                      SMJ
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                      Ardent D

                      In Development...
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                      Resistance is not futile, it is Volts divided by Amperes...
                      Just ask Mr. Ohm....

                      Comment


                      • #12
                        That’s not why I posted. I just wanted to share some results using almost the same drivers you’re using for the mid and tweeter, and DSP. But since you mentioned the lack of commercially available solutions on the market to do things right, I thought I’d let you know that there is some available. Usually people are interested in the kind of equipment used to obtain the shared results. So I hope that I won’t be disqualified for chatting about speaker designs, simply because I happen to make electronics.
                        https://www.maverickaudioforum.com/

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                        • #13
                          No, you wouldn't be, but I'd suggest posting a thread about your complete design- the speaker and the crossover system. Focus on the acoustic design issues and how they were implemented if you want to put that in the Mission Possible forum section- And I suggest posting some bench testing on the bench forum section- if you wish, explain your design choices in as much detail as you're comfortable with, and document test results as usually done commercially. And for the two way speaker project (I'm guessing you're using one of the PuriFi woofers, not the midrange as is in this current thread update) document the design, and how you handled the driver time origin offset with what ever features your DSP solution provides (LR4 normally assumes coincident sources in the Z axis).

                          And it would probably be helpful to explain how you support both digital and analog sources. And document the performance.
                          the AudioWorx
                          Arvo Pärt
                          Isiris MLBL
                          Modula MT
                          Natalie P
                          M8ta
                          Modula Neo D CC
                          Ardent
                          Modula MT XE
                          Modula Xtreme
                          Isiris
                          Wavecor Ardent

                          SMJ
                          Minerva Monitor
                          Calliope
                          Ardent D

                          In Development...
                          Isiris Mk II updates
                          Calliope CC
                          Obi-Wan
                          Saint-Saëns Symphonique
                          Modula PWB
                          Calliope CC Supreme


                          Resistance is not futile, it is Volts divided by Amperes...
                          Just ask Mr. Ohm....

                          Comment


                          • #14
                            I could do that at some point. I made this system for my own internal use. In active in-wall speakers. But decided to put together a system in a nice case that could be used with regular speakers.

                            The 2 way is actually a local speaker manufacturers product. That he brought over to hear what I could do with my DSP system. He was so blown away that he’s done with passive now for good.

                            Regarding the Purifi midwoofer vs the pure mid, the results would be essentially identical above 300hz. Other than slightly less gain attenuation on the tweeter amps to match levels.

                            Regarding acoustic, and cabinet design attributes, that’s no different when you go active vs passive. Any speaker that is great with a passive crossover, can only be made better going active. And the main thing is getting all the trash out of the signal path. And you would be shocked how much power passive crossovers gobble up as well. With the amps putting out the same wattage, I’m getting 15dB more SPL’s from these monitors compared to running them with the passive crossover he brought over with them. So the 450w amps are like having 2000w+ amps powering the speakers through passive crossovers. And the dynamics! It’s another world. Especially at super low levels. The tonal density at whisper levels is just amazing. With passive crossovers at low levels the crossovers absorb most of the energy before the signal has a chance to make it to the drivers. Think of it like a fire hose going into the passive crossover, and a garden hose coming out.
                            https://www.maverickaudioforum.com/

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                            • #15
                              If what you report about the difference in active versus passive crossover for SPL at the same amplifier power, his crossovers are quite problematic. That's the polite way of putting it, because the insertion loss for designs usually posted here are well under 1 dB.

                              As with everything engineering, solid documentation is key.
                              the AudioWorx
                              Arvo Pärt
                              Isiris MLBL
                              Modula MT
                              Natalie P
                              M8ta
                              Modula Neo D CC
                              Ardent
                              Modula MT XE
                              Modula Xtreme
                              Isiris
                              Wavecor Ardent

                              SMJ
                              Minerva Monitor
                              Calliope
                              Ardent D

                              In Development...
                              Isiris Mk II updates
                              Calliope CC
                              Obi-Wan
                              Saint-Saëns Symphonique
                              Modula PWB
                              Calliope CC Supreme


                              Resistance is not futile, it is Volts divided by Amperes...
                              Just ask Mr. Ohm....

                              Comment

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