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
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.
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!
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!
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.
I would advise to proceed with caution and try to better-understand your local power system.
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.
±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.
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
Sadly both Mouser and Digikey are out of the Aavid heat sink I specify. Mouser says they'll ship in April...
You could fashion a heat sink from a small piece of aluminum. Make it as wide as you can without bumping into any components, drill two mounting holes aligned with the holes on the board, and bend it into an L shape using a vise and a hammer. Then just use two machine screws to hold it in place. A 1.0-1.6 mm thick aluminum piece would be great. You can usually find a suitable piece at a local scrapyard or metal recycler.
Tom
You could fashion a heat sink from a small piece of aluminum. Make it as wide as you can without bumping into any components, drill two mounting holes aligned with the holes on the board, and bend it into an L shape using a vise and a hammer. Then just use two machine screws to hold it in place. A 1.0-1.6 mm thick aluminum piece would be great. You can usually find a suitable piece at a local scrapyard or metal recycler.
Tom
Those of you who are on the fence about the SMPS-86 might consider getting off the fence and onto the internet. I have three boards left and will likely not make more of them. It's a pretty slow seller and there are many more SMPS options available now than when I designed the circuit.
The SMPS-86 is an excellent candidate for a desktop LM3886-based amp, such as the Modulus-86. With that supply, an LM3886-based amp will deliver 28 W into 8 Ω and 28 W into 4 Ω. However, due to the current limit of the switching power supplies used on the SMPS-86, you will only get 2x14 W into 4 Ω if you build a stereo amp.
Thus, the SMPS-86 is mostly suited for mono blocks, for amps driving 8 Ω speakers, and desktop amps.
The SMPS-86 provides ±24 V @ ±2.5 A by default. It can be built for ±5 V (±10 A), ±12 V (±5 A), and ±15 V (± 4 A) as well. Many use it to power preamps and it would be an excellent, albeit a bit overkill, power supply for my Universal Buffer.
To see the current stock levels, please see my website. The current stock is indicated just below the price.
Tom
The SMPS-86 is an excellent candidate for a desktop LM3886-based amp, such as the Modulus-86. With that supply, an LM3886-based amp will deliver 28 W into 8 Ω and 28 W into 4 Ω. However, due to the current limit of the switching power supplies used on the SMPS-86, you will only get 2x14 W into 4 Ω if you build a stereo amp.
Thus, the SMPS-86 is mostly suited for mono blocks, for amps driving 8 Ω speakers, and desktop amps.
The SMPS-86 provides ±24 V @ ±2.5 A by default. It can be built for ±5 V (±10 A), ±12 V (±5 A), and ±15 V (± 4 A) as well. Many use it to power preamps and it would be an excellent, albeit a bit overkill, power supply for my Universal Buffer.
To see the current stock levels, please see my website. The current stock is indicated just below the price.
Tom
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Power-686 has twice the capacitance so you'll get half the rail sag on a heavy transient. This translates to a few extra watt before the amp clips. So an amp powered by the Power-86 might deliver 40 W at the onset of clipping, but that powered by the Power-686 would deliver, say, 41-42 W under the same conditions.
Tom
Tom
Hi Tom. I'm having a lockdown splurge on amps for my soon so be completed 3 way system. The Modulus-86 as far as I can see is the peak of its amp type.
I was wondering would you recommend the Modulus-86 for any particular frequency range? in my case - up to 200hz - 200-2000hz - 2000hz +
Cheers
I was wondering would you recommend the Modulus-86 for any particular frequency range? in my case - up to 200hz - 200-2000hz - 2000hz +
Cheers
It was a really slow seller and many better options exist in the market now. So I'm rather hesitant to make the circuit more broadly available. I can make you a custom run at custom prices, though...
Thank you. Yep. It's a very good amp indeed. I'm actually back on the Modulus-86 as my main amp as I sold the last of my Modulus-686 amps. I can make more, though. I know a guy...
I'd recommend the Modulus-86 from DC to about 85 kHz.
My only reason for recommending a different amp (including my Modulus-286 and -686) would be if you need more power. Let's say you needed 400 W in the bass for some room EQ (or whatever) then going with a Purifi 1ET400A for the subs and Modulus-86 for everything else would make sense.
Tom