Modulus-86 amp

xsb7244 · « **on:** 21 Jan 2015, 06:47 pm »

richidoo,

I want to hear about the Modulus-86 amp you are working on and pictures please. It looks like a terrific amp for the money.

richidoo · « **Reply #1 on:** 21 Jan 2015, 07:45 pm »

I am building a pair, with the Power86 PS. The boards are good quality, the design is excellent, support from the designer is excellent. What's not to like? Soon we will know if it sounds good too. Then it will probably get pretty popular. It's not really a kit, but a very thorough plan with PCB. You buy your own parts which is made easy with his Mouser parts list so you can buy all the parts with a couple clicks. The build instructions are very well written, thorough and educational. Theory is explained in layman's terms to assist making project decisions like transformer.

My amps are finished, I just need to wire it up and attach to heatsink. I was working on a DIY box, but my first design isn't right so I'll probably just run the amps on a test board. Some pics at diyaudio.com

He is also designing a LM4780 version to run two 3886s in parallel for double the current.

richidoo · « **Reply #2 on:** 3 Feb 2015, 05:20 pm »

I got my Modulus-86 amps running yesterday. They sound really good. I am pretty surprised at how good they sound. I normally don't like the opamp used here, but now after listening I have no desire to change it in this circuit.

They are very detailed and powerful sounding, not your grandfather's tube amp. It is revealing of lesser components upstream, and lesser quality recordings. But the tone is very dense, dead quiet, great transient response (slam) so it is musically involving, easy to ignore flaws. And easy to find flaws to upgrade.

Not sure the Mod86 is the best choice for a first electronics project because there is a lot of small parts soldering (though no SMD) but if you can solder pretty well and can get by with solid 30Wpc then I highly recommend this amplifier. The instructions are extremely comprehensive and written for laymen, so you'll not have any questions if you read them thoroughly. If you do have questions the PCB designer Tom Christensen answers emails immediately and he closely monitors his projects' threads on diyaudio. So you shouldn't have a problem if you want it to succeed.

Price per channel all finished is probably about $300/ch? including a box and trannies, connectors etc. Can be done for less, or much more. Imo, nothing can touch this amp's performance for that price, new or used.

jtwrace · « **Reply #3 on:** 3 Feb 2015, 05:22 pm »

Nice job. How about a picture or two? Look forward to the next GTG.

richidoo · « **Reply #4 on:** 3 Feb 2015, 06:22 pm »

Thanks Jason. Me too!

No box yet, always listen to DIY before cosmetics!

Folsom · « **Reply #5 on:** 3 Feb 2015, 06:31 pm »

What are the blue caps?

richidoo · « **Reply #6 on:** 3 Feb 2015, 06:57 pm »

That's the bipolar PS board, blue caps are storage. ~20kuF, I think? The PS PCB is called Power86, unregulated. It is good for at least 2 Mod86 amps, or more with bigger caps if you have tougher load. My load is 7ohms so the chips don't even get warm to the touch. The amps have onboard 317/337 regulators for the opamps. The 3886/4562 composite amp has extreme ripple rejection, like 120+dB? so unregulated supply is fine.

The tranny is 300VA because I will also be putting a Tiwsted pear Sympatico amplifier on this same heatsink with 2 Mod86 amps. Sympatico is 100W from 4780 chipamp. It has built in power supply on the amp board, all in one, just needs AC.

xsb7244 · « **Reply #7 on:** 3 Feb 2015, 09:54 pm »

Where will you get your enclosure from?

goskers · « **Reply #8 on:** 3 Feb 2015, 10:00 pm »

I don't belong in this region anymore but I will continue anyways.

I plan on starting this project tonight. Have most parts minus some connectors, heat sink and transformer in house.

Will post some pics once progress is made.

richidoo · « **Reply #9 on:** 3 Feb 2015, 11:55 pm »

Quote from: xsb7244 on 3 Feb 2015, 09:54 pm

Where will you get your enclosure from?

I'm building 2 three channel boxes from 1/16" aluminum sheet, 1/4" plywood and 3/4" plywood to fit some salvaged heatsinks.

Goskers you are always welcome in Carolina Circle!
Good luck with your build! I think you'll like it.

poseidonsvoice · « **Reply #10 on:** 4 Feb 2015, 01:59 am »

I'm building a bridged version right now. Will post when all done, hopefully with measurements and subjective comparisons to NCore 400, LM3875, UCD 400HG HxR, and SKA designs. And if I have enough time this year perhaps an F5 Turbo V2.

I agree with Richidoo...this isn't a 1st timers project as far as the soldering is concerned, the designer has done an impeccable job in shortening traces, and minimizing excessive inductances. And he is eminently knowledgeable in analog design while maintaining very high value.

Best,
Anand.

xsb7244 · « **Reply #11 on:** 19 Mar 2015, 02:46 am »

poseidonsvoice,

Looking forward to your review.

StevenZ · « **Reply #12 on:** 17 Aug 2016, 01:58 pm »

Any update from you guys who have been using this amp for a while???

poseidonsvoice · « **Reply #13 on:** 17 Aug 2016, 02:15 pm »

Quote from: StevenZ on 17 Aug 2016, 01:58 pm

Any update from you guys who have been using this amp for a while???

Unfortunately, my final build was delayed this summer due to family responsibilities & vacation. I'm currently working on it now and should be done this week. Then I can make subjective and objective comparisons. I know Richidoo had completed his and has been pleased with the design over and above the Twisted Pear Sympatico.

Best,
Anand.

StevenZ · « **Reply #14 on:** 17 Aug 2016, 02:30 pm »

Thanks for the reply, Anand! I had Peter Daniel build me up one of his integrated amplifiers and it's en route currently. I'm hoping to compare his integrated with a Modulus 86 eventually, though it might be a while until I can save up enough to buy the Modulus parts. From what I'm reading it seems the Modulus might just blow the AudioSector integrated out of the water. Perhaps it's not the best idea to compare them. LOL!

poseidonsvoice · « **Reply #15 on:** 17 Aug 2016, 02:49 pm »

Quote from: StevenZ on 17 Aug 2016, 02:30 pm

From what I'm reading it seems the Modulus might just blow the AudioSector integrated out of the water. Perhaps it's not the best idea to compare them. LOL!

Yes. And I have measurements that prove that...however, there are enough in this hobby who WILL NOT make a move on this design until a detailed subjective review is published and that is what I am going to try to do in the Critics Circle.

Stay tuned.

Best,
Anand.

StevenZ · « **Reply #16 on:** 17 Aug 2016, 02:55 pm »

Ooooh, exciting! Maybe I can shoehorn in the Modulus boards into the AudioSector amp instead. Hahaha! Please link to your review in this thread when you're done. I don't want to miss it.

richidoo · « **Reply #17 on:** 17 Aug 2016, 04:48 pm »

Hi Steven
I have 4 channels of Mod86 running for a year or so, all version 1. I like them very much. Very detailed, very alive, very incisive. It has such low distortion because it uses a high feedback opamp to control the chip amp via another external feedback loop. This gives microscopic distortion and an ultra clean dryness to the sound. But there is no trace of the suffocating closed-in sound typical of poorly designed high feedback amps. Mod86 is extremely open sounding. Every detail of tone and space comes through easily. Some might call it sterile, but it doesn't sound actively "sterile" to me, it just sounds like nothing. It is not "aggressively" low distortion like some class D amps that put pressure in the room and attack with their cleanliness, Mod86 has a safe, easy, passive, nothing is there harmlessness. The lack of good or bad distortion allows the most minute and subtle tonal detail and texture to come through. You've never heard a solo violin like this, or classical guitar. Well recorded female vocals are incredible. It's easily the most detailed and well balanced amp I've ever heard. You hear it the instant you first turn it on. Wow! like that. I also have Audio Research tube amps so I go back and forth between clean SS and luscious tubes to maintain context and appreciation of each.

My Mod86 are currently out of service, as I inserted passive line level crossover filters between the input IC and the driver IC in the Mod86s. I adjusted the global feedback resistor for attenuation to match the driver levels. It worked technically OK but not great and dialing it in was too inconvenient so I bailed. I'll be removing the filters, resetting the gain and putting them in chassis to use them with dsp crossover and new multichannel USB and DAC that I just got from diyinhk.com

Mod86 has adequate power for 88dB 4ohm speakers, imo. Mine are 85db 8R with the passive crossover. When I play loud I occasionally hear the "spike" protection sound. But as active amps they are more than adequate power beyond pain threshold driven with professional balanced signal level >5V! Impressive little amps, incredible value. Assembly isn't too hard. The manual is very helpful and detailed. Tom is very helpful, and there is an active build thread to help with the slightest question. If you don't like it, easy to sell since many people won't DIY but would like to hear it.

I think you'll be happy with the AudioSector. Let us know how you like it!
Rich

StevenZ · « **Reply #18 on:** 17 Aug 2016, 05:26 pm »

Thanks for the informative reply, Rich!

wushuliu · « **Reply #19 on:** 5 Dec 2016, 06:33 pm »

Thanks for the review. Hard to find in depth reviews of this amp. Might give it a go later next year.

Anand did you sell yours?