Hi all,
I would like to 'deposit' some public note about a measurement Tom made.
Review: MyRef Fremen Edition / MyRef FE – Neurochrome
I have come here, because I don't know where it is possible to discuss publicly about it. On the original site I did not find access.
First of all, would like to thank Tom for his work. I think he made a very nice and correct assesment, as usual of him.
I do agree with most of the results - and ask to differ with many of the conclusions, but I hope that is permitted democratically..
There is only one thing which bugs me a bit, I would be happy if it could be discussed here, or somewhere else, doesn't matter.
Tom reaches to a conclusion that the Myref amp is having a relatively high noise contribution, with respect to the Mod86.
My problem is, that I see it properly on the contrary, and would like to clarify it, if possible.
From Tom's measurements it results that the Myref produces at 20Hz - 20KHz range, unweighted: 69uV RMS noise on the output;
From his spec's for the mod86, it results that the mod86 produces at 20Hz-20kHz range, unweighted: 40uV RMS noise on the output.
Now Tom' s conclusion is that the Myref is noisy, and one should explore the reasons..
Let me put it differently: the total gain of the Myref is 31,6.
The input referred noise in 20Hz-20kHz, unweighted, RMS is 69uV/31,7 = 2,17uV
The total gain of mod86 is : 10.
The input referred noise in 20Hz-20kHz, unweighted, RMS is 40uV /10 = 4uV
That is ~double of the Myref's input stage contribution, and so the proper question here is: what is causing this in the Mod86?
Apart from this, I really would like to thank again for this effort of Tom.
All the best, George
I would like to 'deposit' some public note about a measurement Tom made.
Review: MyRef Fremen Edition / MyRef FE – Neurochrome
I have come here, because I don't know where it is possible to discuss publicly about it. On the original site I did not find access.
First of all, would like to thank Tom for his work. I think he made a very nice and correct assesment, as usual of him.
I do agree with most of the results - and ask to differ with many of the conclusions, but I hope that is permitted democratically..
There is only one thing which bugs me a bit, I would be happy if it could be discussed here, or somewhere else, doesn't matter.
Tom reaches to a conclusion that the Myref amp is having a relatively high noise contribution, with respect to the Mod86.
My problem is, that I see it properly on the contrary, and would like to clarify it, if possible.
From Tom's measurements it results that the Myref produces at 20Hz - 20KHz range, unweighted: 69uV RMS noise on the output;
From his spec's for the mod86, it results that the mod86 produces at 20Hz-20kHz range, unweighted: 40uV RMS noise on the output.
Now Tom' s conclusion is that the Myref is noisy, and one should explore the reasons..
Let me put it differently: the total gain of the Myref is 31,6.
The input referred noise in 20Hz-20kHz, unweighted, RMS is 69uV/31,7 = 2,17uV
The total gain of mod86 is : 10.
The input referred noise in 20Hz-20kHz, unweighted, RMS is 40uV /10 = 4uV
That is ~double of the Myref's input stage contribution, and so the proper question here is: what is causing this in the Mod86?
Apart from this, I really would like to thank again for this effort of Tom.
All the best, George
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In my experience dual mono is the only way to go.
Although with the PSRR of the modules you would expect it to make no difference to share a power supply, that is not the case.
I have built an 86 amplifier and achieved much better channel separation by converting to dual mono. This led to me converting my 286 to dual mono by shoehorning another psu into the (extended) case with the same result.
You can use a single case or separate, it doesn't matter.
Thanks! I'll go for a dual mono in a single enclosure then. That should give me an endgame amp alright for my efficient speakers.
Now I just have to figure out how to design a case with internal heatsinks to keep it nice looking. I'd like it to compliment my other gear, that is a nice SET tube amp.
I have a couple of pairs of the original Twisted Pear MyRef_C amps. Very "musical" amplifiers. And by musical I mean "easy to listen to".. Last word in amplification, no. Enjoyable for hours, yes.
I would love to hear them side by side with Tom's to see what the difference is between pure accuracy and a musical instrument.
My "guess" is that for a reference system Tom's would be better, for a bedroom system Mauro's. But that is a guess and I haven't heard the FE edition, only the Twisted Pears.
View attachment 914103
I would love to hear them side by side with Tom's to see what the difference is between pure accuracy and a musical instrument.
My "guess" is that for a reference system Tom's would be better, for a bedroom system Mauro's. But that is a guess and I haven't heard the FE edition, only the Twisted Pears.
View attachment 914103
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I'm not interested in an US vs THEM discussion here. I'm curious why you chose to make your 'deposit' in this thread and not in the MyRef FE thread. After all, you seem to want a discussion about the performance of the MyRef FE.
ClaveFremen (Dario) asked me a few years back if I would measure the MyRef FE if he sent me a pair of boards. I agreed and built one of the boards. I finally found time to measure it. I provided the results and my analysis of them. Dario read through the review immediately after I posted it. He provided some feedback, which I integrated. He also asked that I comment on the Build Guide, so I added that section.
You're more than welcome to contact me by email if you'd like to discuss the review. You can do so through the Contact Us form on my website. I'm also happy to continue the discussion in the Modulus-86 or MyRef FE thread.
You're correct that the input-referred noise of the MyRef FE is lower than that of the Modulus-86. That's fine and dandy, but in actual use it's the noise on the output of the amp that matters as that's what you hear as hiss in the tweeters.
The gain matters too. Connect a Modulus-86 to a MiniDSP 4x10HD and you get 136 uV RMS total at the speaker. Connect the same MiniDSP 4x10HD to a MyRef and you get 426 uV RMS total at the speaker. Which would you rather have?
While on the topic of noise, the Modulus-186's input-referred noise is 1.4 uV. The input-referred noise of the Modulus-286 is 1.4 uV as well. The Modulus-686 gets down to 1.25 uV. All numbers RMS, unweighted, 20 Hz - 20 kHz. So if low noise, including low input-referred noise is your goal, I do have options for you.
The Modulus-86 was designed to allow for an optimal gain structure (i.e. the lowest system noise at the speaker). That's why it's a low-gain amp. Naturally, I improved a few things, noise included, on the more expensive -186, -286, and -686.
You can increase the gain on the Modulus-86 by changing a resistor. At 26 dB gain, you can expect the input-referred noise to fall at around 2.0 uV.
Tom
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I agree with Tom, this is not the place to discuss Tom's review (thanks again about it
), better to move the discussion on the correct indicated thread.I am working on my two channel Modulus-86. I have all parts here except chassis!
What would be more appropriate power supply for an 8 Ohm load? +/-28 VDC or +/-34 VDC (21-0-21 or 25-0-25 transformers).
Would separate power supply modules with separate transformers for each channel be preferable?
Thanks!
What would be more appropriate power supply for an 8 Ohm load? +/-28 VDC or +/-34 VDC (21-0-21 or 25-0-25 transformers).
Would separate power supply modules with separate transformers for each channel be preferable?
Thanks!
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I recommend a 2x25 VAC transformer (or 25-0-25) for an LM3886-based amp optimized for 8 Ω. That'll give you about ±35-36 V rectified.
If you intend to drive both 8 Ω and 4 Ω speakers, I recommend a 2x22 VAC transformer. That'll give you around ±30 V rectified.
You can read more about why I make those recommendations here: Taming the LM3886 Chip Amplifier: Output Power – Neurochrome
With the Modulus-86, I do not see the point of using separate transformers for each channel. That said, there's no harm in it either. Well... Aside from the hit to the pocketbook, that is.
Tom
If you intend to drive both 8 Ω and 4 Ω speakers, I recommend a 2x22 VAC transformer. That'll give you around ±30 V rectified.
You can read more about why I make those recommendations here: Taming the LM3886 Chip Amplifier: Output Power – Neurochrome
With the Modulus-86, I do not see the point of using separate transformers for each channel. That said, there's no harm in it either. Well... Aside from the hit to the pocketbook, that is.
Tom
Last week I had the pleasure to speak with Jason Weissman of The Intellectual People Podcast. You can see the first part of our two-part interview here: High-end audio design & PCB layout with Tom Christiansen, Neurochrome & TCA | Part 1 - YouTube
Jason and I meandered through a wide range of topics ranging from circuit design and PCB layout though consumer psychology and marketing, and even touched briefly on some of the neuroscience around gender identities. Perhaps you'll enjoy with your morning coffee... Hey... It's better than watching the news.
Maybe it'll give some insights into who I am and convince you that I'm not just a precision audio bot.
Tom
Jason and I meandered through a wide range of topics ranging from circuit design and PCB layout though consumer psychology and marketing, and even touched briefly on some of the neuroscience around gender identities. Perhaps you'll enjoy with your morning coffee... Hey... It's better than watching the news.
Maybe it'll give some insights into who I am and convince you that I'm not just a precision audio bot.
Tom
...and Part 2 of the interview: High-end audio design & PCB layout with Tom Christiansen, Neurochrome & TCA | Part 2 - YouTube
Tom
Tom
Now you've got the bug! My other diy projects are just for fun, but I know when it's a Christiansen designed product...it belongs in the reference system. Best,
Anand.