Modulus-86 build thread

[tomchr]

I just updated the doc. If you don't see the change when you download it again, please email me. Add @neurochrome.com to my username here to get my email address.

Tom

 

[wpas]

Thanks Tom! Glad to hear it wasn't going crazy. I seem to have reached my download limit for the doc so will shoot you an email.

 

[tomchr]

I've bumped up the limit. You have docs.

I'm looking forward to seeing your build pictures. Best of luck with your build.

Tom

 

[pistollero]

Hello Tom ,
I have the 2.20 version.
Can you tell me the main difference between 2.20 and 2.30?
Tks

 

[tomchr]

2.2 -> 2.3 adds another pole in the RFI filter, so you get a little better filtering on the input. 2.3 also allows you to use my custom wound output inductor. I still give you the specs so you can wind your own, but if you'd rather skip the hassle, I do offer the output inductor as a component.

Tom

 

[zgtc]

Hey Tom, very OT but since you also sell a tubes amp... would you recommend a tubes preamp to match the modulus? Or adding distorsion (even if just harmonics) would be considered a sacrilege?

 

[tomchr]

Personally, I've come to really appreciate the clean amps, so my choice for a preamp would be a solid state one.

I honestly haven't looked at the tube preamp designs enough to be able to recommend one over the other.

Tom

 

[zgtc]

Personally, I've come to really appreciate the clean amps, so my choice for a preamp would be a solid state one.

I honestly haven't looked at the tube preamp designs enough to be able to recommend one over the other.

Tom

Fair enough, thank you again. If anyone else reading this has any experience with a tubes preamp previous to a modulus power amp, I'd appreciate any insight.

 

[MrKettle]

Fair enough, thank you again. If anyone else reading this has any experience with a tubes preamp previous to a modulus power amp, I'd appreciate any insight.

As per upstream, I have got a Parallel 86 amp running with a World Designs Pre 3 using balanced connections, which given the location in Europe may be an option for the next few weeks anyway...

Works very well from my point of view, but be prepared to drop the Modulus gain with a That1203 or 1206 depending on sources, speakers and listening levels.

 

[zgtc]

As per upstream, I have got a Parallel 86 amp running with a World Designs Pre 3 using balanced connections, which given the location in Europe may be an option for the next few weeks anyway...

Thank you for sharing the experience, didn't know about that one, looks good.

Works very well from my point of view, but be prepared to drop the Modulus gain with a That1203 or 1206 depending on sources, speakers and listening levels.

Yup, I actually saw that mod in the documentation just last week and had this in mind. Thank you

 

[tomchr]

Of the two, the THAT1206 will provide the best performance as it has slightly lower noise than the 1203.

Tom

 

[Alesi]

Hi, today I finished my 2-channel modulus-86 build... well actually not finished, because I am missing THAT1206 (its on a way), so i at least wanted to try to connect RCA into the input of LME49720. So I hardwired it on top of R23 because that was very convenient place to solder it on (dont need filters just for testing...) The amplifier came life without any problems - and it plays... But I am not so pleased with sound. I am playing into Dali Ikon 2 speakers with good cables that vere tested on very good amplifiers so I know they sound great.

It sounds a little better then LM3886 alone, but the sound is actually a little unpleasant, stage is not bad, but the instruments are not divided as i expected them to be (and as they are on some otgher amplifiers), soudn is unpleasant on bigger volume (which is always good indication it is distorted in some way or another)...

So my question is - did i do something wrong elsewhere or is connecting rca straight into LME49720 just not good idea because ths happens?

 

[tomchr]

R23 forms a lowpass filter with a capacitor. I think you're capacitively loading your signal source, which it probably doesn't appreciate very much.

I recommend that you build the circuit as designed before passing judgement.

Tom

 

[Alesi]

Well sure, I am.judging output of current connextion, nothing more. i was impatient and not sure what happened, now I know, thanks.

 

[zarandok]

Hi all,

I have two questions to the new versions of Modulus design regarding to the older ones:
- why had been omitted the DC-servo circuit, and placed some electrolytic (b.p.) caps there into the signal path?
- why had been omitted the THAT1200 diff. receiver and realized an instrumentation amp schematic with LM49720 ICs?

I simply do not understand it...🙂

 

[tomchr]

The THAT1200 is the dominant noise source in the Modulus-86. To get lower noise floor, I had to design it out.

The DC servo adds about $10 worth of components. That may not sound like much ... until you build 100 of them. With a little bit of creativity in the design, I was able to get good DC performance without the DC servo, so I chose to save the money, board area, and assembly cost of the DC servo by getting rid of it.
The one electrolytic capacitor in the signal path is a bipolar type made by Nichicon. As you can see in all my measurements for the Modulus-186, -286, and -686, the cap is sonically transparent and allows the amps to provide world-class performance.

Tom

 

[zarandok]

Thank you Tom!

 

[TioFrancotirador]

For the reference. Just another way of building Mod-86.

An externally hosted image should be here but it was not working when we last tested it.

Thanks. Tom.

 

[sercan85]

Dear Tom;
Can you put the stereo purchase option for Modulus 86 and do the Mirror finish PCB for L-R channels?

 

[zman01]

For the reference. Just another way of building Mod-86.

An externally hosted image should be here but it was not working when we last tested it.

Thanks. Tom.

The image is not displaying.