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DizRotus

MiniDSP NIB $50 shipped.

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EDIT:  11/04/19  Jump to page 4 for details.

 

I use a Pono player to feed a balanced signal to a Texas Instruments TDA3255EVM class-D chip amp which drives a pair of DIY Supers made to @ClaudeJ1‘s recipe.  The balanced output from the Pono player is split to also send balanced signals to a pair of iNuke 1000dsp amps, each of which drives a pair of DIY Exodus Anarchy tapped horn subs.  In my small space, the subs (Lil’Mike says they’re flat to 25Hz) provide plenty of low frequency energy.  Nonetheless, I can’t help but think the delay between the Supers and the subs is something to be avoided.

 

Inserting DSP between the Pono and the 3255 seems problematic, due to the balanced inputs of the 3255.  Perhaps a pair of 2-channel DSP units, one for each balanced channel, would work.

 

I can hear the question being asked, “Why balanced?”  The answer is because I can, and because I think it sounds better.  Everyone, as in ALL, who has listened to both balanced and single ended output from a Pono player using my Sennheiser cans, preferred balanced.  The sound is universally described as “3-D,” wider soundstage, deeper soundstage, better separation and localization of Instruments, etc.  While intuitively such subtleties are likely more apparent using headphones (with no time delay issues) it seems the same benefits would also be observable, albeit to a lesser degree, through speakers.

 

Also you might ask, “Why Pono?”  Despite the complete failure of Neil Young and Pono as a revolution in listening to music, it works very well in my system as a preamp with an excellent ESS Sabre DAC.   While the Pono can provide single ended output to my amps in single ended mode with excellent results, the facts that Pono, 3255s and iNukes are designed to operate in balanced configuration, and that balanced sounds better, at least through headphones, makes it seem a shame to waste that opportunity.

 

Can dsp be inserted in the outputs of the 3225 to delay the signal to allow the TH subs to catch up?

 

Can dsp be inserted in the inputs before the 3255?

 

Any suggestions as to how to implement this?

 

The attached photo shows the inside of the case containing the 3255 and the Meanwell power supply.  Although difficult to see from the photo, the inputs are via XLR terminals (+, -, and shielded ground).  Inside the case, before going to the 3255, those signals are split to send to the inNukes via cables at the rear of the case.  It seems to me that dsp units could be external to the case but inserted into the inputs or outputs in such a way was to delay the upper frequencies to be aligned with the subs.

 

What do you think?  Is it even a problem?

 

TPA3225EVM.thumb.jpg.f97482699864649f59c534ceac680069.jpg

 

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What's the length of the horn?  Where's its low-pass frequency?  Ought to know that so's to make a determination.

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4 hours ago, mboxler said:

If you spread the amp/PS further apart, would one of these fit in between?

 

https://www.minidsp.com/products/minidspkits/2-x-in-4-x-out-bal

 

That could work.  The case is big enough; it might require some shuffling.

 

I see the unit requires a 12v power supply.  That probably can’t fit in the case also.

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4 hours ago, ClaudeJ1 said:

I'll get back to you on this.

 

No hurry.

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50 minutes ago, glens said:

What's the length of the horn?  Where's its low-pass frequency?  Ought to know that so's to make a determination.

 

I’ll calculate the length of the path from the front of the driver to the mouth and post that later.  However, since these are tapped horns, it seems to be complicated by the energy coming off the rear of the drivers closer to the mouths.  The attached photo of one of Carl’s @CECAA850 identical subwoofers is helpful to understand the situation.

 

The LPF can be set wherever by the dsp in the iNukes.  It’s presently crossing at 60Hz.  The HPF is set at 20Hz, but it too is variable in the iNukes’ dsp.

 

FEFA2A61-F3CE-49CA-84D6-0F7F0EA9FD0E.jpeg

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I'm confused....which is nothing new when it comes to the digital domain. Is there some physical constraint? I'd think you could put whatever DSP you desire right before the amp(s). That is what I do with my bi-amped 2-way system. Source >> Passive or Active pre >> DSP >> Amp(s). An additional set of cables is all you need, in my mind, to put DSP in its proper place. What exactly am I missing here? Pono>>DSP>>Chip Amp

 

Are you trying to account from driver alignment via delay? If so one thing I learned from @Chris A was that you can't/should not delay a horn low end. I've had Khorn/Belle/LS for the bass bins with my large horns up top, when I switched to an open baffle H-frame for my Bass bins I was concerned about the distance between drivers but did not want to "delay" the bass drivers which were well in front of the high end. Chris said no problem with direct radiators, but not to with horn loaded bass. I'm paraphrasing our conversation, but that was the take away for me.

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12 minutes ago, rplace said:

I'm confused....which is nothing new when it comes to the digital domain. Is there some physical constraint? I'd think you could put whatever DSP you desire right before the amp(s). That is what I do with my bi-amped 2-way system. Source >> Passive or Active pre >> DSP >> Amp(s). An additional set of cables is all you need, in my mind, to put DSP in its proper place. What exactly am I missing here? Pono>>DSP>>Chip Amp

 

Are you trying to account from driver alignment via delay? If so one thing I learned from @Chris A was that you can't/should not delay a horn low end. I've had Khorn/Belle/LS for the bass bins with my large horns up top, when I switched to an open baffle H-frame for my Bass bins I was concerned about the distance between drivers but did not want to "delay" the bass drivers which were well in front of the high end. Chris said no problem with direct radiators, but not to with horn loaded bass. I'm paraphrasing our conversation, but that was the take away for me.

 

You seem to understand my confusing questions.  I’m asking about the feasibility of inserting a DSP between the preamp (Pono) and the 3255 chip amp.  The balanced signal would be split to bypass the DSP and chip amp to proceed unmolested to the iNukes.  You seem to suggest it’s OK.

 

I’m not trying to delay the subs, but rather to possibly delay everything else to let the subs catchup, or Ketchup for Steve @BigStewMan.

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6 minutes ago, DizRotus said:

 

You seem to understand my confusing questions.  I’m asking about the feasibility of inserting a DSP between the preamp (Pono) and the 3255 chip amp.  The balanced signal would be split to bypass the DSP and chip amp to proceed unmolested to the iNukes.  You seem to suggest it’s OK.

 

I’m not trying to delay the subs, but rather to possibly delay everything else to let the subs catchup, or Ketchup for Steve @BigStewMan.

Why split the signal to the iNukes? DSP everything, get rid of the passive networks, flatten them out, cross them where you want to, delay as necessary. Ha, look at me I could almost fool myself into thinking I know what I am talking about.

 

To think I once was hoping and praying @Coytee or @babadono would stop by my Xilica ramblings. Chris is the Oracle of all things DSP....accept no substitutes. Take my suggestions with the necessary grain(s) of salt.

 

FWIW, I think you are on the right path to delay the others and not the sub.

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@rplace  said:

 

“Why split the signal to the iNukes? DSP everything . . . FWIW, I think you are on the right path to delay the others and not the sub.”

 

I think you answered your first question with the last sentence.

 

 

 

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3 minutes ago, DizRotus said:

Does anyone here have any experience with this company’s products?

 

https://www.minidsp.com/products/minidspkits/2-x-in-4-x-out-bal

 

There's a lot of happy minidsp users here on the forum.  The HD versions are supposed to work very well and have a low noise floor.  That's the first balanced offering I've seen from them.

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10 minutes ago, DizRotus said:

Does anyone here have any experience with this company’s products?

 

https://www.minidsp.com/products/minidspkits/2-x-in-4-x-out-bal

 

I use the 4X10 HD ahead of my LXmini speakers.  You will need a Mac or Windows PC to configure.  Once configured, no need for the PC.

 

I have an extra 2.5mm 5.5mm chassis mount DC connector I'd be happy to send you.  Then the 12 volt PS could be located outside your chassis.

 

Mike

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1 hour ago, mboxler said:

I use the 4X10 HD ahead of my LXmini speakers.  You will need a Mac or Windows PC to configure.  Once configured, no need for the PC.

 

I have an extra 2.5mm 5.5mm chassis mount DC connector I'd be happy to send you.  Then the 12 volt PS could be located outside your chassis.

 

Mike

 

Thanks for the offer.  Since Radio Shack disappeared, I’ve stockpiled electronic bits, and pieces, which I think includes what you’re kindly offering.  If I don’t find one in inventory, I’ll take you up on your kind offer.

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Is “Minidsp” a brand name?  I always assumed it was a generic description of a small dsp.

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I have no personal experience with the miniDSP hardware but I have read it is easy to overdrive the inputs. So no reason it cannot be used but you will have to be mindful of that. miniDSP website says max input for the unit you linked to is 2 Vrms which is only about +8dBu.

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2 minutes ago, DizRotus said:

Is “Minidsp” a brand name?  I always assumed it was a generic description of a small dsp.

Yes, brand name.

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1 minute ago, DizRotus said:

Is “Minidsp” a brand name?  I always assumed it was a generic description of a small dsp.

Yep miniDSP is a brand out of HongKong I believe. Hardware is prolly produced on the mainland.

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The 2x4 HD is a good piece of equipment (and I'm currently running one bi-amping/EQing my surrounds with excellent results).  But I don't recommend the "miniDSP 2x4".  It apparently has the problems with lack of dynamic range/gain that was mentioned above.

 

Chris

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