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Old 18th July 2019, 04:49 AM   #4721
tomchr is offline tomchr  Canada
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As long as you have the ±30 V version of the SMPS300R, I see no harm in trying. I have only tried the SMPS300RE version. The 'RE' contains extra filtering on the output. That aside, the two supplies are identical. The SMPS300RE works very well in a stereo Modulus-86 amp.

Tom
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Old 18th July 2019, 04:51 AM   #4722
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by poseidonsvoice View Post
I just ordered too many boards from Tom!
What?! There's no such thing! Then again, you have yet to try the Modulus-686, so maybe it's a good thing to let the Parallel-86es move on. Those are pretty rare.

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Originally Posted by poseidonsvoice View Post
Let me see, ... I’ve built 16 channels of amplification from Tom’s designs...you can say I am a believer...but I am not the only one
Thank you for your vote of confidence.

Tom
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Old 18th July 2019, 03:41 PM   #4723
dwk123 is offline dwk123
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Originally Posted by tomchr View Post
I like it. Then again, I designed the analog sections in the SHD for MiniDSP, so maybe I'm biased. The analog sections were designed to get the full performance out of the DACs and ADCs.
Ahhhh. Didn't know that, but it helps to explain why it seems to be a level above their previous offerings.

Quote:
All that said, I still haven't had time to put the SHD on the bench and measure it. One of these days...
In case you're not aware, Amir measured it here: Review and Measurements of miniDSP SHD DAC, DSP And Streamer | Audio Science Review (ASR) Forum

Good performance aside from a few jitter spikes that I assume are due to the SRC. This is my only concern - I currently have a NanoDigi (spdif input/output unit), and I've managed to convince myself that it's not audibly transparent even in pass-through mode - this would seem to imply that the SRC is impacting the signal. I really have to do a more controlled listening test though - and maybe some measurements. If I can get over that mental hurdle, the SHD seems to be the best fit for my application.

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Linux.... Sssss... Yeah... I won't stoke that fire. I've run Reaper and ReaEQ on the 2010 MacBook Pro that's my music machine. That worked very well.
I used Reaper/ReaEQ (on Windows) as my first 'production' DSP system as well. The attraction to Linux is that I like the idea of an 'appliance' style unit - power it up and it just works with no interaction aside from switching inputs and volume. I 'think' I know how to do this on Linux, but not on Win. Making it bullet-proof is the challenge.

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The real question is whether you can find a genuine LME49710HA for less than it would cost you to replace the boards with the current revision. It may be possible. Just make sure you get a genuine part. The Modulus-86 relies on the characteristics of the LME49710 to work.
Well, PV might well have just solved my problem for me :-)

Quote:
For multiway systems optimized for power, I generally recommend running a ±35-36 V power supply. That gives the maximum output power, but you have to select the amplifier modules according to the drivers:
8 Ω drivers can be powered by a Modulus-86 or -186.
4 Ω drivers can be powered by a Modulus-286 (or -686 if you need more power).

If that blows your budget, I recommend running a ±28-30 V supply and using Modulus-86 or -186 everywhere.

Tom
I actually think I have an xformer left over from an old ClassDAudio amp that might work for this - I think it resulted in a 36V supply which is high for a single Mod-86 into 4Ohm, but should be OK for a Parallel/286. I'll have to dig through some boxes to see if I can come up with it, though. Still not sure on the design of the speakers - the most likely candidate is 8 Ohm, but the backup plan is 4, so having a Parallel/286 would give me more flexibility. For your current completed modules the 286 is so close in cost to the 686 that it would make sense to just go with the 686, but if PV's offer of the Parallel-86's comes though, I actually think that could be ideal.
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Old 18th July 2019, 03:43 PM   #4724
dwk123 is offline dwk123
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Originally Posted by poseidonsvoice View Post
dwk123,

I have a pair of Parallel 86 boards fully built (sans LM4780 which I have here as well), with all genuine parts, etc...and tested. They are ready to be attached to some heatsinks. Give me a holler if interested. I just ordered too many boards from Tom! Let me see, ... I’ve built 16 channels of amplification from Tom’s designs...you can say I am a believer...but I am not the only one

Best,
Anand.
Cool - PM sent.

And yeah - my Mod-86 was a revelation when I swapped it into my system. I live in the budget space and so don't have any top-tier units, but it was still a bit of a surprise that it was that much of an improvement (even though I'm driving it SE from a JDS Atom at the moment)
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Old 18th July 2019, 07:52 PM   #4725
Studley is offline Studley  United Kingdom
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DWK123 said
“Good performance aside from a few jitter spikes that I assume are due to the SRC. This is my only concern - I currently have a NanoDigi (spdif input/output unit), and I've managed to convince myself that it's not audibly transparent even in pass-through mode - this would seem to imply that the SRC is impacting the signal. I really have to do a more controlled listening test though - and maybe some measurements.”

A while back I did an experiment with a 4x10 HD. I first used this audio chain:
Streamer>DAC>amp>passive speakers. Then I inserted the 4x10HD (digital in and out) between the streamer and the DAC. The 4x10HD was set to perform no manipulation, so the signal was just passing through ie the only processing being undertaken was by the SRC. I compared the sound quality before and after. There was a significant degradation with the 4x10HD in the chain. Was it night and day? Well, actually, yes it was. OK no measurements, no double blind testing, but the difference really was unmistakable. So my conclusion at the time was that the SRC was adversity affecting the signal.
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Old 19th July 2019, 04:57 AM   #4726
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by dwk123 View Post
Ahhhh. Didn't know that, but it helps to explain why it seems to be a level above their previous offerings.
Thanks for noticing.

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Originally Posted by dwk123 View Post
In case you're not aware, Amir measured it here: [...]

Good performance aside from a few jitter spikes that I assume are due to the SRC.
Saw the review and the jitter issues. I find those odd. "One of these days" I was going to put the SHD on the bench and measure it. Both for an actual review, but also to see if I could tease out that jitter. If it's in the DSP code, a firmware update could fix it.

That said, upsampling by a fractional ratio will likely always result in some jitter, especially as the fraction approaches an integer boundary. At least that's the case in fractional-N PLLs. One possible fix would be to only upsample by integer rations. So upsample to 88.2 or 176.4 kHz for a 44.1 kHz input.

I've played with upsampling on the sound card (Focusrite Saffire) that I used to use for a DAC. I always found that integer ratio upsampling sounded better than fractional ratio upsampling.

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Originally Posted by dwk123 View Post
Well, PV might well have just solved my problem for me :-)
Good to hear. Anand does good work. You'll be impressed!

Quote:
Originally Posted by dwk123 View Post
I actually think I have an xformer left over from an old ClassDAudio amp that might work for this - I think it resulted in a 36V supply
As long as it's ±36 V, that'll work. The Parallel-86 is basically a precursor to the Modulus-286, so it'll share many specs. You can find the description of the Parallel-86 in the Support section of my website: Parallel-86: High-power composite amplifier achieving 0.00012 % THD.

Quote:
Originally Posted by Studley View Post
A while back I did an experiment with a 4x10 HD. I first used this audio chain:
Streamer>DAC>amp>passive speakers. Then I inserted the 4x10HD (digital in and out) between the streamer and the DAC. The 4x10HD was set to perform no manipulation, so the signal was just passing through ie the only processing being undertaken was by the SRC. I compared the sound quality before and after. There was a significant degradation with the 4x10HD in the chain.
The noise floor of the 4x10HD is not great. 45 uV RMS (20 Hz - 20 kHz, unweighted) if I recall correctly. That's a lot for a preamp.

Tom
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Modulus-86, 186, 286, 286 Kit, & 686: 40-240W (8Ω) at <-120dB THD.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 19th July 2019, 01:36 PM   #4727
dwk123 is offline dwk123
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Quote:
Originally Posted by tomchr View Post
Thanks for noticing.

Saw the review and the jitter issues. I find those odd. "One of these days" I was going to put the SHD on the bench and measure it. Both for an actual review, but also to see if I could tease out that jitter. If it's in the DSP code, a firmware update could fix it.

That said, upsampling by a fractional ratio will likely always result in some jitter, especially as the fraction approaches an integer boundary. At least that's the case in fractional-N PLLs. One possible fix would be to only upsample by integer rations. So upsample to 88.2 or 176.4 kHz for a 44.1 kHz input.

I've played with upsampling on the sound card (Focusrite Saffire) that I used to use for a DAC. I always found that integer ratio upsampling sounded better than fractional ratio upsampling.
Yes, a 2:1 process makes more sense, which is why I was so surprised that 96kHz got all the momentum as 'we' moved past 44.1 - 88.2 would have made so much more sense. Unfortunately, AFAIK none of the MiniDSP plugins work at 88 - they're all 96 (or 48). I am hoping that since it's a SHARC based unit, the SHD might use a higher quality SRC solution than the NanoDigi or 4x10 which I believe just use the SRC built-in to the ADAU chips. The jitter spikes in the measurement aren't ideal, but since they don't exceed -120dB it's still possible that they aren't audible.

Quote:

As long as it's ±36 V, that'll work. The Parallel-86 is basically a precursor to the Modulus-286, so it'll share many specs. You can find the description of the Parallel-86 in the Support section of my website: Parallel-86: High-power composite amplifier achieving 0.00012 % THD.
Found the xformer. Antek AN3225 which I think is 300VA @ 25V, which seems basically ideal for a Parallel86/286. I don't seem to have the power supply board though. Is a single Power-86 OK for a Parallel86?


Quote:
The noise floor of the 4x10HD is not great. 45 uV RMS (20 Hz - 20 kHz, unweighted) if I recall correctly. That's a lot for a preamp.

Tom
Note that he was running all-digital in that test, so analog noise wouldn't factor in - basically just the SRC (and, I suppose, the quality of the spdif xmitter)
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Old 20th July 2019, 04:10 AM   #4728
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by dwk123 View Post
Found the xformer. Antek AN3225 which I think is 300VA @ 25V, which seems basically ideal for a Parallel86/286.
Perfect!

Quote:
Originally Posted by dwk123 View Post
I don't seem to have the power supply board though. Is a single Power-86 OK for a Parallel86?
One Power-86 will be fine. If you'd like a bit more (OK, twice as much) reservoir capacitance, use the Power-686.

Tom
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Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 21st July 2019, 12:56 PM   #4729
kberge is offline kberge  Norway
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Default Mod-86 2.4

One change from 2.3 to 2.4 is R11 when looking at some pictures at the Neurochrome site?
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Old 21st July 2019, 09:31 PM   #4730
tomchr is offline tomchr  Canada
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Yeah. You're right. I left the 0 Ω resistor (R11) on the BOM in Rev. 2.4. I normally delete it as I don't see a point in paying 20 cents for a "resistor" that can easily be replaced by any of the wire clippings you'll have left over after assembling the board. On Rev. 2.4, I forgot to delete it before I uploaded the BOM to mouser, so I ended up with 0 Ω resistors in the bag. Might as well use them...

Tom
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