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Modulus-86: Composite amplifier achieving <0.0004 % THD+N.
Modulus-86: Composite amplifier achieving <0.0004 % THD+N.
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Old 1st December 2019, 11:14 PM   #2441
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by Nightpuma View Post
Just a quick question. Will it be a good option to build the Mod-86 with a volume control as an integrated amp?
I think that would be an excellent option for an integrated amp or a desktop amp.

If you want to use a single-ended source with the amp (so have RCA inputs), adding a volume control is easy. Just get your favourite volume control and wire it between the RCA connector and the Modulus-86 input.

If you want to preserve the differential/balanced input on the amp, you either have to use a 4-gang pot and make a differential volume control; or use something like my upcoming Universal Buffer to convert from differential to single-ended before the volume control.
You could tap into the local ±16 V supply on the Modulus-86 to power the UniBuff.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
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Old 1st December 2019, 11:33 PM   #2442
Nightpuma is offline Nightpuma  Norway
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Quote:
Originally Posted by tomchr View Post
I think that would be an excellent option for an integrated amp or a desktop amp.

If you want to use a single-ended source with the amp (so have RCA inputs), adding a volume control is easy. Just get your favourite volume control and wire it between the RCA connector and the Modulus-86 input.

If you want to preserve the differential/balanced input on the amp, you either have to use a 4-gang pot and make a differential volume control; or use something like my upcoming Universal Buffer to convert from differential to single-ended before the volume control.
You could tap into the local ±16 V supply on the Modulus-86 to power the UniBuff.

Tom
Thank´s a lot for the fast answer Tom.
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Old 7th December 2019, 08:50 AM   #2443
spiggs is offline spiggs  United States
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Ordering the BOM for the Modulus-86 and SMPS-86 from mouser and some parts are out of stock. I can find the out of stock items at Digi-key except for the DR127-R47-R inductors. Is there a substitute part?
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Old 7th December 2019, 05:07 PM   #2444
spiggs is offline spiggs  United States
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Originally Posted by spiggs View Post
Ordering the BOM for the Modulus-86 and SMPS-86 from mouser and some parts are out of stock. I can find the out of stock items at Digi-key except for the DR127-R47-R inductors. Is there a substitute part?
Would these do the job?

IHLP6767GZERR47M11 Vishay / Dale | Mouser
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Old 7th December 2019, 08:22 PM   #2445
tomchr is offline tomchr  Canada
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The IHLP... is not the same size. It won't fit on the footprint.

I'd go with the DR127-1R0-R. Mouser has 328 in stock.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
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Old 7th December 2019, 08:44 PM   #2446
spiggs is offline spiggs  United States
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Originally Posted by tomchr View Post
The IHLP... is not the same size. It won't fit on the footprint.

I'd go with the DR127-1R0-R. Mouser has 328 in stock.

Tom
Thanks Tom. Everything is ordered now and on the way. Should be fun. Building this as a replacement for an ACA in my main system powering some fullranger speakers. Going to the other end of the spectrum of amps will be an interesting comparison.
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Old 8th December 2019, 12:55 AM   #2447
tomchr is offline tomchr  Canada
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I compared the Modulus-686 to the ACA last summer on quite a few full range speakers at the Vancouver Island DIY Fest. I think you'll enjoy the Modulus-86.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 22nd December 2019, 05:53 PM   #2448
musicgeek is offline musicgeek  United States
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Hi everyone! I'm planning to build this amp thanks to a very kind forum member.. And looking for some advice!

My friend has recently acquired a 30-0-30v transformer and a built board from diyzone from ages ago for a power supply. We measured output as 39 -0- -39 VDC. I was wondering if I could reuse this power supply on this board?

I've read somewhere in this long thread that it can theoretically run off power supply of 25-40 volts or something like that. I plan to use it with Continuum Ii which I believe are 8 ohms.

What are any potential dangers of using a high voltage, especially if I plan to listen at only moderate volumes? Just want to check if I can get away without getting another power supply.

Thanks!
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Old 22nd December 2019, 06:59 PM   #2449
BrianL is offline BrianL  United States
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Modulus-86: Composite amplifier achieving &lt;0.0004 % THD+N.
In theory you should be OK. The problem is not as much 'volume level' (as heating of the LM3886 amp chips is a somewhat complex function of several factors -- see the Neurochrome web site for more info). The main concern is that the LM3886s' max operating voltage is +/-42V. At the moment, your no-load voltage (assuming that you measured with no load or minimal load) is less than that, but if your AC mains drifts higher than what it was at the time you checked the supply's output, the supply at the LM3886 chips will be correspondingly higher. Generally one should not violate the 'absolute maximum' ratings on an IC's datasheet. I do not know how much 'padding', if any is in the LM3886's spec.

I would advise to proceed with caution and try to better-understand your local power system.
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Old 23rd December 2019, 05:36 PM   #2450
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by musicgeek View Post
My friend has recently acquired a 30-0-30v transformer and a built board from diyzone from ages ago for a power supply. We measured output as 39 -0- -39 VDC. I was wondering if I could reuse this power supply on this board?
The power supply board can probably be reused. I'd swap the transformer for a 2x22 VAC type, though. That will give you about ±28-30 V rectified. If you only plan to use the amp with 8 Ω loads, you can bump it up to 2x25 VAC for ±35 V rectified. You can read about the tradeoffs here: Taming the LM3886: Output Power – Neurochrome

If you don't want to get a new power transformer (though the ones from Antek are very affordable for those in the US), you can use a bucking transformer to lower the primary voltage a bit. The beauty of that solution is that the bucking transformer can be a lower VA model as it only has to supply the primary current.

Quote:
Originally Posted by musicgeek View Post
I've read somewhere in this long thread that it can theoretically run off power supply of 25-40 volts or something like that.
±10 V to ±42 V for the LM3886, actually. The Modulus-86 will run down to ±20 V without modifications. You'll get worse performance above ±35 V (8 Ω load) and ±30 V (4 Ω load) as the internal protection circuits of the LM3886 will engage sooner. More is not always better.

Quote:
Originally Posted by musicgeek View Post
What are any potential dangers of using a high voltage, especially if I plan to listen at only moderate volumes?
Aside from frying the LM3886 and potentially blowing your speakers if your mains voltage is a little high one day? Nah.... Not really...

Unlike vacuum tubes, semiconductors are decidedly unforgiving of over-voltage. I wouldn't push my luck in that regard, even if Someone-On-The-Internet did so and it went "just fine".

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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