Modulus-86 build thread

[zman01]

Neat work sgpu!

 

[tomchr]

The pic didn't seem to attach correctly in the last post. Here's another try!

Nice family photo there. Thanks for posting.

Tom

 

[sgpu]

Thanks! There are one or two spots that need some TLC. I'll try and fix them up tomorrow.

 

[henrylrjr]

What would the be better of the following two connection methods for the Mod86?

20 feet of Tom's pseudo balanced ICs running from an Audible Illusion M3A (RCAs only) to the Mod86 (XLR inputs) and 10 feet of speaker cable running to a pair of speakers or 1m pseudo balanced ICs from the AI M3A to the Mod86 and 20 feet of speaker cable running to the speakers?

Thanks,
henry

 

[poseidonsvoice]

My preference has always been short interconnects.

Best,
Anand.

 

[henrylrjr]

That is how I would like to go. My reason is, I prefer to have all the components, for 2nd floor HT room and the speakers in the large 1st floor room, in the 2nd floor closet. Basically I try to hide as much as possible. I'd love invisible speakers.

 

[tomchr]

If you need long cable runs, I strongly recommend using differential signalling. A THAT Driver in a small enclosure will work. It'll need a power supply. A Power-86 with a small transformer will work. My hot-off-the-press SMPS-86 is overkill but will work just fine as well.

Tom

 

[zman01]

Tom,

Any pics of the SMPS-86 ? 🙂

 

[tomchr]

Not yet. I should have boards tomorrow so expect pictures of the SMPS-86 by tomorrow night.

Tom

 

[tomchr]

Open for pre-orders of the final board run of the Parallel-86

I have opened up for pre-orders on the absolutely final board run of the Parallel-86. You can pre-order your boards here: Parallel-86 (Last Chance to Buy)

Please pre-order by July 24th if you are interested in getting in on this last time buy. Four of the ten boards needed for the final board run to start have been pre-ordered. For the latest updates on this last board run for the Parallel-86, please see the Parallel-86 thread in the Group Buy forum.

You can read more about the Parallel-86 here: Neurochrome Parallel-86.

Please do note that the LM4780 is getting harder to source, so please make sure you have a source before placing your board order. Currently, Newark/Farnell and RS sit on the distributor stock available world wide.

Tom

 

[Amnes]

Tom, do you think your Modulus or Done Right amps would work well in a car audio system? What kind of power supply design would be recommended in such an application?

BTW I'm excited to see a SMPS design of your making. They will be quite an incentive to finally order your merch.

Cheers, Maciek

 

[poseidonsvoice]

Re: SMPS-86

Looks like a bipolar +/- 24 DC regulated supply which is nice. Any options for lower voltages? Any option for a single + rail voltage? I ask because there are some other amp designs that do not need bipolar supplies...curious to see if it can reach a wider audience and still have the killer Tom Christiansen design credentials! Great work once again!

Best,
Anand.

 

[tomchr]

The switching modules come in the following voltages: 5, 12, 15, 24, and 48 V. For audio ±48 V is not so interesting due to the 1.25 A output current limit. ±15 or ±24 are the more obvious candidates for audio.

You can remove a resistor (0 Ω link) and float the output. This allows for maximum flexibility.

Thanks for the kudos.

Tom

 

[tomchr]

Tom, do you think your Modulus or Done Right amps would work well in a car audio system? What kind of power supply design would be recommended in such an application?

Sure. A couple of guys are using the MOD86 in their cars, actually. I think they actually ended up inverting the 12 V from the car to mains voltage and stepping back down using a transformer. That isn't the most efficient way of handling the supply, but it does get the job done.

The best is if you can find a switching supply to turn +12 V into ±20 to ±28 V.

BTW I'm excited to see a SMPS design of your making. They will be quite an incentive to finally order your merch.

Thank you. Yeah... Transformers are really inconvenient and expensive. I do like the international mains voltage in -> ±24 V out concept. With the Modulus-86, you'll get the same performance with the switching supply as with a linear supply, so it has everything going for it.

Tom

 

[poseidonsvoice]

Tom,

That's fantastic! Make sure you mention those options on your website so your SMPS-86 boards will have a wider appeal. For example, there are several DIY'ers who are into LOW powered single ended Class A designs that only need a +V supply. Some of these designs have mediocre PSRR. So a well regulated supply (even if it's switching), can be a boon for these guys. Make a table with all the PS voltage possibilities and peak current availability for the various voltages.

Best,
Anand.

 

[billshurv]

My preference has always been short interconnects.

Best,
Anand.

It all comes down to preference in the end, but from a signal integrity perspective short speaker cables are best and make the interconnect longer. Even with a single ended drive you get over 80dB CMRR using a Mod-86 if using interconnects as per Tom's instructions.

I doubt if you compared the two scenarios with real world stuff you would hear a difference, but if you went out of your way to come up with an edge case you would see a loss in fidelity with the longer speaker cables 🙂.

 

[tomchr]

In the scenario Henry presented with an upstairs equipment closet and downstairs listening space, I'd definitely prefer to have the amps right behind the speakers for the shortest speaker cable run. This way the high currents run in the shortest wire -> lowest droop.

I'd also use differential signalling. A THAT Driver is pretty inexpensive. Alternatively, use pseudo-differential cables.

You can always go pseudo-differential at first. If you like it, great. If you don't quite get enough CMRR, lob off the RCA connectors and solder on an XLR connector. Recall that the pseudo-differential cable uses a shielded cable with two conductors - just like a differential cable.

Tom

 

[Amnes]

The best is if you can find a switching supply to turn +12 V into ±20 to ±28 V.

This looks like it would do the trick for 2 (or possibly 4 channels if not driven to the limit) worth of Neurochrome 3886 in a car application: 300W Boost Converter for Car Audio TL494 | eBay

Transformers are really inconvenient and expensive. I do like the international mains voltage in -> ±24 V out concept. With the Modulus-86, you'll get the same performance with the switching supply as with a linear supply, so it has everything going for it.

I agree wholeheartedly.

 

[poseidonsvoice]

In the scenario Henry presented with an upstairs equipment closet and downstairs listening space, I'd definitely prefer to have the amps right behind the speakers for the shortest speaker cable run. This way the high currents run in the shortest wire -> lowest droop.

I'd also use differential signalling. A THAT Driver is pretty inexpensive. Alternatively, use pseudo-differential cables.

You can always go pseudo-differential at first. If you like it, great. If you don't quite get enough CMRR, lob off the RCA connectors and solder on an XLR connector. Recall that the pseudo-differential cable uses a shielded cable with two conductors - just like a differential cable.

Tom

Ok! Something for me to ponder. My speaker cables are ~ 20 ft long (low capacitance) and my speakers are 96 dB efficient. I don't know if that makes any difference from a "lowest droop" standpoint.

From a psychoacoustic standpoint I dislike the concept of having your equipment in the same room, let alone between the speakers. I listen in the dark, and find the experience far more pleasurable! I am not one of those audiophiles that likes gawking at my equipment with all the lights and gizmos!

Thanks billshurv for your input as well 🙂

Best,
Anand.

 

[billshurv]

If you like knowing that just your speakers (and some control method) are in the room, then that will over ride any audible effect. note if you make your own power amps you don't have to have lights on them!