I was really into this FIR and Rephase business a while ago, but the urge to get flat linear phase EQ/XO seems to have subsided once I found out how cumbersome it will be to have to reprocess the FIR convolution each time I make a change in the PEQ. Although once dialed in should not be too bad. More importantly though, the way that flat phase is achieved is through manipulation of the impulse response via pre-ringing. I have heard that this produces audible artifacts in giving it an un-natural sound. So take the lesser or the two evils? As Bwaslo has said, he is not so sure all this flat phase (waveform accurate) ability is all that important from a sound quality standpoint. I am actually pretty happy with how the Trynergies sound at this point and will take more time to listen and enjoy them. I figured out how to get a subwoofer going again without a second minDSP: use a passive line level XO to achieve a 12dB/oct low pass filter at 100Hz and use my old Yamaha class A/B amp to drive the sub from the CD line level outputs - now just need to order a pair of 160nF and 16nF caps and 10k/100k resistors for the PLLXO parts for a 47kohm inputt impedance amp). The miniDSP is driven by the headphone output (which gives me volume control).
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Great you got sub back with tools on hand and you happy the point they at now, good listening.
Regarding the FIR my suggestion was NOT meant to get system linear phase, just neutralize the 4. orden 360º HP/LP in middle of Trynergy which do not need measurement because we know the slope, horn thereafter still minimum phase bandpass and can be IIR EQ'ed as wanted. It was to get closer to levels of XO phaseturn as Legis, and at same flexible cause bypass convolution or use another player and playback is as now.
Regarding the FIR my suggestion was NOT meant to get system linear phase, just neutralize the 4. orden 360º HP/LP in middle of Trynergy which do not need measurement because we know the slope, horn thereafter still minimum phase bandpass and can be IIR EQ'ed as wanted. It was to get closer to levels of XO phaseturn as Legis, and at same flexible cause bypass convolution or use another player and playback is as now.
That is indeed different to use just to neutralize the 360 deg phase shift of the XO at 375Hz and still have the miniDSP PEQ there to play with. I like to play from a CD player and would need to do the convolution in hardware and I believe the higher end nanoDIGI 2x8 can be used to implement IIR. So Jriver and DSP would not work for me (that would still require a 4-channel sound card). Thanks for the suggestion though. Btw, I don't have the sub back yet, still need the parts to build the circuit.
Yes stupid me you right we need multichannel sound card for this, for some reason forgotten your sub that sits at parallel line level.
A suggestion from my experience on this is to find a used SoundBlaster Audigy (2 ZS) card on eBay, and install it into the machine of your choice. Then, go to the Official kX Project Site and download the drivers on there for it.
You can program the DSP in there with various plugins and routings for multi-channel scenarios. I'm going to use that approach once I have the Trynergies built, and all of the processing runs on the cards' DSP, so it's in hardware.
Is a Soundblaster Audigy less than $100? That is the cost of the miniDSP with shipping. Also, I don't use desktop chassis but laptops only now so that would be a problem for a PCI card. I am going to try out my PLLXO for the sub and see how that works. Lucky for me the sub is the channel that requires zero time delay so there is no need to have a fancy all pass delay.
Did you know that if you only needed mono, you can do a 2-way active biamp DSP for no cost by using built in stereo sound device and software like Jriver?
http://www.diyaudio.com/forums/multi-way/261506-using-stereo-sound-card-create-mono-2-way-active-crossover.html
An interesting way to try out an active 2 way setup to see if you like it before taking the plunge and ordering an Audigy or miniDSP etc. I tried this and it really works.
I read that thread, very interesting.
The Audigy Soundblaster card I have only has one 'out' 🙁
But.....
My onboard Asus card has 2 ins and 4 outs, 3 of these are stereo so a while back I dl'd the Foodsp plugin but have never managed to get it to work - father used to say 'Use the right tool for the job, if you aint got that tool, buy it'.
Guess I'm gonna have to splurge on a Minidsp.
The Audigy Soundblaster card I have only has one 'out' 🙁
But.....
My onboard Asus card has 2 ins and 4 outs, 3 of these are stereo so a while back I dl'd the Foodsp plugin but have never managed to get it to work - father used to say 'Use the right tool for the job, if you aint got that tool, buy it'.
Guess I'm gonna have to splurge on a Minidsp.
miniDSP and a pair of TPA3116D2 amps is one of the best DIY tools I have ever bought. A total gamechanger as far as the types of speakers you can take on once you have it. For about $140 you can make nice sounding 2-way speakers without being a pro at XO design. Highly recommended.
😀😀😀
I've just figured foodsp out.
Now all I need is a cheap second amp, make a lead and remove the networks from an old pair of tower speakers lurking in my back room...... I know it's no where near as powerful as 'real dsp', but it will provide fun and maybe some 'magic smoke letting'.
But:
Yes, I see what you and others are doing with miniDSP, thrifty amps or not and it does seem the way to go.
I shall drop hints to swiso (she who is sometimes obeyed) that I need dsp for xmass.
I've just figured foodsp out.
Now all I need is a cheap second amp, make a lead and remove the networks from an old pair of tower speakers lurking in my back room...... I know it's no where near as powerful as 'real dsp', but it will provide fun and maybe some 'magic smoke letting'.
But:
Yes, I see what you and others are doing with miniDSP, thrifty amps or not and it does seem the way to go.
I shall drop hints to swiso (she who is sometimes obeyed) that I need dsp for xmass.
If you want some inexpensive amps that actually sound good try these so-called "lunch money" amps. About 12 clean watts very nice sounding. $5 and change shipping included. How can you go wrong?
Online Shop AC/DC12V TDA7297 Rev A Low Noise Audio Amplifier Board 2*15W Dual-Channel Digital Stereo free shipping|Aliexpress Mobile
I have a couple and really like them for experimenting and for most moderate applications where you don't need the 40 watts of the 3116.
Online Shop AC/DC12V TDA7297 Rev A Low Noise Audio Amplifier Board 2*15W Dual-Channel Digital Stereo free shipping|Aliexpress Mobile
I have a couple and really like them for experimenting and for most moderate applications where you don't need the 40 watts of the 3116.
If this (nanoAVR HD | MiniDSP) does what I think it can, combined with a basic 7.1 home theater receiver and an HDMI source (such as a raspberry pi running volumino). It could make a compact 3 way fully active and customizable setup
That sounds like a very nice and capable solution. The nanoAVR provides 8 in and 8 out, and if you have the HT 7.1 amplifier sounds like you are set for a 3 way system with sub.
Rather than 8-in/8-out, I'm hoping it will also do 2-in multiplexed into 8 out. I have a rather nice sounding low powered marantz HT receiver that would be perfect for a multi-way wideband horn setup without needing to mess with a tangle of patch cords.
Just wanted to post a quick update (I haven't time to upload pictures at the moment). The woofers are screwed on, so now I've got to make a temporary mount for the 3" speaker.
UnaHM,
Great progress there. For the flange for the 3FE25, I chamfered a small 0.25in radius roundover on the edge facing the driver to prevent a sharp edge at the horn throat. Also try to make the transition from the throat piece's square opening to the horn's throat as smooth as possible. That is, match the size as best as you can to avoid and discontinuities in duct walls. It is more important to be smooth in this critical area of the first 3 inches or so then to be correct on size of 2.0x2.0 inches. The 3FE25 will need a sealed back chamber lined with foam and stuffing to work properly. Little details like keeping it smooth will help to ensure a smoother HF output on the horn from 6k on up.
Good luck!
Great progress there. For the flange for the 3FE25, I chamfered a small 0.25in radius roundover on the edge facing the driver to prevent a sharp edge at the horn throat. Also try to make the transition from the throat piece's square opening to the horn's throat as smooth as possible. That is, match the size as best as you can to avoid and discontinuities in duct walls. It is more important to be smooth in this critical area of the first 3 inches or so then to be correct on size of 2.0x2.0 inches. The 3FE25 will need a sealed back chamber lined with foam and stuffing to work properly. Little details like keeping it smooth will help to ensure a smoother HF output on the horn from 6k on up.
Good luck!
Sadly, nothing new yet. I've been mulling over the smoothing subject though.
I remember someone saying earlier in the thread that creating what is effectively a parabolic horn at the beginning of the 3fe25's path wasn't desirable.
What are your thoughts on this? I know it's one of the most crucial parts of the design; I just want to do what works best in the end, regardless of construction complexity 🙂
I remember someone saying earlier in the thread that creating what is effectively a parabolic horn at the beginning of the 3fe25's path wasn't desirable.
What are your thoughts on this? I know it's one of the most crucial parts of the design; I just want to do what works best in the end, regardless of construction complexity 🙂
The horn shape is a tractrix from the throat on down. I am just saying that the flat piece with a square hole in it where the driver mounts should transition to the main horn as smoothly as possible. That is, it should be the same cross section and maybe 0.5 in deep if you see using half inch plywood. On the flange side facing the driver take a knife or rasp and round off the sharp corner a bit. Try it first without it, it may be just fine. There is no parabolic profile to make for the mounting flange.
Look at the photo of how I did it.
Look at the photo of how I did it.
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