Modulus-86 build thread

Public service announcement

Just injecting that the Modulus-86 board can be used with the LM3876 as well.

I'm listening to a Modulus-86 in >>>STEREO<<< where one channel is LM3886-based and the other LM3876-based. The supply voltage is ±15 V. This is intended as a low-power build to drive a pair of computer speakers.

I stand by my previous comment that if the amp sounds good in mono, it will sound amazing in stereo. It really does sound amazing. I'm spinning Eric Clapton, "Unplugged"; Dire Straits, "On Every Street" and "Brothers in Arms". I'm seriously impressed. The speakers are Alpair 6P in an enclosure designed by Planet-10. The enclosure is originally designed for the metal cone version of the driver, but take the center port fill out and it'll work with the paper cone version.

I actually can't tell any difference in sound quality or measurements between the LM3886 and the LM3876 channels. I'm sure I can measure a few minute differences, I just haven't gotten there yet. I was a bit eager to get the contraption hooked up to my speakers... :)

~Tom
 
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For low power needed (10/15 watt) with low voltage (12/18 volts), maybe it's a good way ?

I'm running mine at ±15~16 V using an Antek AN-0512 (2x12 V, 50 VA) and a Power-86 board with 2x33000 uF, 25 V caps. Works great!

To run at low voltage, you need to swap a couple of resistors on the MOD86 board to ensure proper regulation of the on-board voltage regulators. That's now described in the design doc.
If you need the latest doc, just email me. List the email address you used to buy the boards so I can find you in my records.

~Tom
 
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Looking good Dominique!! Good way to ease into the build!

Annoying. Hope you can sacrifice something to the cause. Not even a ratshack near you?

I need 100 feet of ICs for 3way active and for WAF gear placement, so I ordered a wad of cheapo from redco.com, Gotham GAC2 foil shield, only .20/ft! Gotham is good stuff but this version has minimum shielding, which I don't really need anyway. Balanced, twisted and foil shield should be plenty for home use. I've used unshielded SE cables before with no prob.

Edit: Glad it still sounds good in stereo Tom! :D
 
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Some of the headline specs of the LM3876 are better than those of the LM3886. SNR, for example. I also suspect some builders like the idea of the lower current limit on the LM3876 as a "safe & sane" approach to give some protection against speaker blow-out. There are probably others who simply have a personal preference for the LM3876 over the LM3886, or maybe have a large stock of the LM3876.

Perhaps we can entice Phil to elaborate on his reasons for using the LM3876...

Aside from the lower output current, hence, possibly lower output power, I doubt there'll be any measurable difference between a MOD86 using the LM3886 and one using the LM3876.

~Tom
 
My own, standard, non-composite LM38xx gainclone had no trouble revealing the "accuracy of the source signal" - but it achieved this by using an industrial strength power supply, and lots of subtle, point to point optimising - this would be very rarely done elsewhere. Lots of extremely ordinary audio gear out there use the same chip, implemented in an exceedingly mediocre way; hence, mediocre sound.

What you put into it, in terms of effort, is what you get out ...