The Modulus-86 PCBs costs a LOT more (around 150$ if I'm not wrong) but BOM is cheap, My_Ref FE PCBs costs 25-26€ per pair but BOM costs starts at around 220€ and, using audiophile parts that cost could double.
Both will sound terrific and cost will be similar using Mouser parts.
The Modulus will measure better while the My_Ref FE, IMHO, will sound better thanks to the parts selection (only relevant if you consider part selection important soundwise).
Pick your poison
Sorry, you will need new transformers, 2x24v secondaries and min. 300VA (single) or 160-200VA (double transformer).
I
Can I use the 280VA for one channel and 200VA for another ?
Borh of them seems to meets the requirements.
Bit not sure if thos setup affect the sound quality.
Can I use the 280VA for one channel and 200VA for another ?
Borh of them seems to meets the requirements.
Bit not sure if thos setup affect the sound quality.
Dario, ciao!
I am more and more convinced that it could be placed even fixed, not even an option. When present, it simplifies greatly the compensation scheme, it could be almost one for all opamp substitutes...
like placing an adeguate pad there, which then can be jumpered or the resistance applied
I am more and more convinced that it could be placed even fixed, not even an option. When present, it simplifies greatly the compensation scheme, it could be almost one for all opamp substitutes...
like placing an adeguate pad there, which then can be jumpered or the resistance applied
jwchan, two different transformers per channel is not maximum of joys.
And the bigger one is a bit dangerous with it's too high secondary voltage.
maybe (maybe!) you could try it, only that +_26V one for two channels, by using diodes with high forward voltage drop (like SiC diodes..)
That way you will have like ~1V extra drop in the rectifier, which would make it look like a 25V trafo.. which is closer to optimal.
But the diodes needed could cost more than a new trafo as suggested by Dario..
And the bigger one is a bit dangerous with it's too high secondary voltage.
maybe (maybe!) you could try it, only that +_26V one for two channels, by using diodes with high forward voltage drop (like SiC diodes..)
That way you will have like ~1V extra drop in the rectifier, which would make it look like a 25V trafo.. which is closer to optimal.
But the diodes needed could cost more than a new trafo as suggested by Dario..
So the mod reduces/eliminates ringing, particularly with reactive loads. I'm wondering if it has more loop gain for distortion reduction in the treble as well?
Dear Dan, first of all wished to thank for trying! I am happy for your reporting back.
About the effect of this mod on loop gain: this mod lets the local loop compensation cap (5pF) to do it's job with less unwanted influence from the input filter cap (220pF).
Doing so it means loop gain is slightly less at high frequencies. Stability is increased at the price of loop gain..
But. Loop gain in the Myref topology is an interesting topic.. just recently it came in mind to simulate also some well known composite amp designs and do a comparison in this sense, loop gain reserve at high frequencies.
I got surprised I saw a substantial difference in favor of the myref topology.. But then realized there are good reasons for it. We are only applying 5/10pF in the local loop for the control opamp. In other designs it's higher.. Also no loop gain is burned up in the form of gain attenuation between stages. All this results in a visible positive difference in loop gain reserve...
(this with OPA828 in place)
About the effect of this mod on loop gain: this mod lets the local loop compensation cap (5pF) to do it's job with less unwanted influence from the input filter cap (220pF).
Doing so it means loop gain is slightly less at high frequencies. Stability is increased at the price of loop gain..
But. Loop gain in the Myref topology is an interesting topic.. just recently it came in mind to simulate also some well known composite amp designs and do a comparison in this sense, loop gain reserve at high frequencies.
I got surprised I saw a substantial difference in favor of the myref topology.. But then realized there are good reasons for it. We are only applying 5/10pF in the local loop for the control opamp. In other designs it's higher.. Also no loop gain is burned up in the form of gain attenuation between stages. All this results in a visible positive difference in loop gain reserve...
(this with OPA828 in place)
So removal of ringing at the expense of slightly worse THD in the treble. However THD - or at least loop gain - is already very good relative to similar offerings,
The first amplifier that I built many years ago now was an 80W MOSFET design by John Linsley-Hood. An experienced designer, he prioritized stability over achieving the very lowest THD. To my ears at least if was a very fine sounding amp.
The first amplifier that I built many years ago now was an 80W MOSFET design by John Linsley-Hood. An experienced designer, he prioritized stability over achieving the very lowest THD. To my ears at least if was a very fine sounding amp.
Actually I'm planing to reused these transformers otherwise, it will be useless...
If not good for the anp, I'll get one from Taobao, any suggestion about the quality of transformer, is it affect the SQ?
So +/-26VAC will blow the chip up?
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it will not blow up, but might generate too much heat which might activate the Spike protections..
26V AC rms is giving 26*1,41 = 36,7V DC max
from this one should subtract two diodes forward drop (1,2V) - 35,5V
Then this max tension will shrink with the growing current consumption, So I would guess the practically present DC level will oscillate between 35V <> 30/32V
All this, IF: the line level is standard (230V or some other standard),
The trafo is really providing only the Nominal 26V AC even in idle state..
Usually the trafo is designed to provide nominal AC voltage at nominal current (4/5A..) So idle voltage is usually 5-7-10% higher.. that could be 28V AC even.. 40V DC..
Add to this 'typical' 40V-1,2V =~ 39V the possible line level excursions and we are approaching absolute max voltage tollerance..
26V AC rms is giving 26*1,41 = 36,7V DC max
from this one should subtract two diodes forward drop (1,2V) - 35,5V
Then this max tension will shrink with the growing current consumption, So I would guess the practically present DC level will oscillate between 35V <> 30/32V
All this, IF: the line level is standard (230V or some other standard),
The trafo is really providing only the Nominal 26V AC even in idle state..
Usually the trafo is designed to provide nominal AC voltage at nominal current (4/5A..) So idle voltage is usually 5-7-10% higher.. that could be 28V AC even.. 40V DC..
Add to this 'typical' 40V-1,2V =~ 39V the possible line level excursions and we are approaching absolute max voltage tollerance..
Thanks, I'm asking this is because I'm also using the amp build from LM3886, if you're intrested you can visit here.
I'm using 26Vx2 and it works well...
I do discovered my old 24Vx2 trasnformer is less heat then this one.
Actually I'm still struggling and hard to decide between Modulus-86 or My_ref FE if only one of these have to build.
I know the measurement maybe means nothing but both of the design measured almost the same and fantastic.
I would like to build My_ref but one thing left unknown to me, if the standard parts from Mouser and audiophile parts measured the same, or the sound quality not that different?
Because some of the audiophile parts is not that easy to obtain in Taiwan or I have to pay more than 10x from standard parts.
Actually I think I'm ready for the first try since the Modulus-86 seems promising but the cost of it still quite expensive compared to My_ref.Hey, think of it: If you feel it does not count, then don't even hesitate, go with the cheapest BOM and you gained already a nice sum of money..
Anyway, do you recommended using MCAP EVO oil on C13?
Originally I suggested (and it's still in the build guide) the gold plated wire from Riken Ohm resistors, long gone and removed from the BOM.
Any copper wire from a 1/2 resistor (or similar copper wire from a capacitor) will do.
The wire form the Amtrans cap will work but it's too much thin in my opinion
Hi Guys! I just wanted to say hello again. I have no excuses. When the forum changed to it's new format, I guess I was busy elsewhere and just assumed that the thread had become very quiet. Only to find out today that I was expected to check the box of the threads I wanted emails from.
I don't have any current Fremen Edition projects, just enjoying the old ones I have already built. But I do have a concept for a new 3 way speaker with an active crossover and FE amps for each driver. In the meantime, I will be lurking in the background and catching up on the latest experiments. Glad to see continued enthusiasm for the FE.
I don't have any current Fremen Edition projects, just enjoying the old ones I have already built. But I do have a concept for a new 3 way speaker with an active crossover and FE amps for each driver. In the meantime, I will be lurking in the background and catching up on the latest experiments. Glad to see continued enthusiasm for the FE.