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. 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
Ahhhh. Didn't know that, but it helps to explain why it seems to be a level above their previous offerings.
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.
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.
Well, PV might well have just solved my problem for me
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.
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)
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.
“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.
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.
Well, PV might well have just solved my problem for me
Good to hear. Anand does good work. You'll be impressed!
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.
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
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.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.
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?
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)
Perfect!
One Power-86 will be fine. If you'd like a bit more (OK, twice as much) reservoir capacitance, use the Power-686.
Tom
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
Tom
Yeah. The THAT1203 and THAT1206 have different gains. -3 dB and -6 dB, respectively. This means the inputs should be allowed to swing past the ±17 V supply rails. Installing the zener diodes allows this to happen. If you never exceed 17 V peak on the input, you can leave the wire links in.
Tom
Tom
This is also DIY, so if you don't like the zener diodes, you're free to leave them out. Just install a wire link instead. As long as the input swing on each wire in the differential pair is within ±17 V, that setup will work just fine. Naturally, the differential voltage also needs to be such that the amp doesn't clip for good performance.
Tom
Tom
I'm pretty sure I just responded to you by email. Either that or someone else asked the exact same question in email a moment ago.
Anyway. If you're using the THAT1200 or you choose to pluck the THAT chip from the socket and hack a single-ended input, D1, D6, and R11 should be wire links (or 0 Ω resistors if you prefer).
Tom
Anyway. If you're using the THAT1200 or you choose to pluck the THAT chip from the socket and hack a single-ended input, D1, D6, and R11 should be wire links (or 0 Ω resistors if you prefer).
Tom
Just an update on my Modulus build. I originally used the SMPS PS but it would cut out when I turned up the volume. I ordered a transformer and linear PS PCB but never installed it. Went to a fellow audiophile's house this weekend to listen to his new Forte III's and to be honest, the Modulus was the star of the show! I think I may just keep the SMPS in and not listen so loudly!
The other amps used were an Eastern Electric MiniMax and a Musical Fidelity A3CR. Source was Tidal streaming through a Chord Qutest.
The other amps used were an Eastern Electric MiniMax and a Musical Fidelity A3CR. Source was Tidal streaming through a Chord Qutest.
Just an update on my Modulus build. I originally used the SMPS PS but it would cut out when I turned up the volume. I ordered a transformer and linear PS PCB but never installed it. Went to a fellow audiophile's house this weekend to listen to his new Forte III's and to be honest, the Modulus was the star of the show! I think I may just keep the SMPS in and not listen so loudly!
That's awesome! Thanks for sharing.
As you've noted the SMPS-86 is limited in its output current, so if you like to crank the music loud, you're better off with the Power-86 and a transformer. The Modulus-86 will sound just as good on a transformer-based supply as it does on a switching supply (and vise versa).
Tom