I would say.. as it is, it is already optimized for 8ohm speakers, first of all..
In fact, the high rail voltage, the fact of only one current pump (lm3886), the choice of bypass, the diodes..
All converge for giving the best with higher load impedance.
The current pump (voltage controlled current source) is loaded by the speaker. The speaker converts the current back into voltage, which is then taken for the composite feedback loop.
This way also the loop gain is higher with higher load impedance..
In fact, for lower impedances the double current pump version is more ideal ( original evolution design by Penasa).
The doubled current pump gives a higher 'gm', if we leave R3 invariant. This higher gm then compensates for even the lower load impedances.
Ciao, George
I can confirm what George explained. I enclose the impedance graphs of two different speakers built by me and playing together with My_Ref FE evo A compensation. The first speaker, the Volkspeaker - 3.2 Ohm, sounds great and is well controlled by the amplifier. But the second, the Funspeaker, with its minimum impedance of 6.1 Ohm, thanks also to greater efficiency, literally flies together with the My_Ref. In the aperiodic version, same speaker with only a little dacron in the port, things are even better. But I want to emphasize that even with the first speaker there are no problems.
Personally I don't like modern commercial speakers with 5-6 inches, 3 Ohm, 87dB midwoofers. They solve space and WAF problems, but in order not to mortify the My_Ref think about bigger woofers, higher efficiencies and better impedances. Musical realism will thank you.
Ciao
Giacinto
Only european source for the stunning W2944 I've been able to find is audiophonics, with a price MUCH higher than the supplier Jac linked...
And for the also stunning W3173 AES cable to be used as interconnect only Audioteka in Italy.
Edit:
W2944:
Cable audio, video et informatique – CONECTOR
Distributor (spools only and 3173 by meter):
cma audio GmbH
And for the also stunning W3173 AES cable to be used as interconnect only Audioteka in Italy.
Edit:
W2944:
Cable audio, video et informatique – CONECTOR
Distributor (spools only and 3173 by meter):
cma audio GmbH
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I like Sommer analog cables. Several online sources in Germany. The Red Zilk and Black Zilk microphone cables are my faves. Used to prefer the Carbokab, but the Zilk cables are cheaper, easier to terminate, and may be better. There is a top line SC-Albedo cable but I prefer the Zilk.
Just build some 10 meter cables yesterday. Needed a Star Quad type. Used some Gotham GAC 4/1 quad mic cable I found in the attic. Did not enough Canare Star Quad for two 10 meter runs.
The Gotham was better anyway; thinner, more flexible, and easier to terminate. Has the double served shielding like Mogami. The Canare cable has braided copper shielding. It is a pain to unbraid for connecting to the shield.
I like playing with cables. Cheap when you build your own. Even reuse the connectors and the cabling sometimes.
Just build some 10 meter cables yesterday. Needed a Star Quad type. Used some Gotham GAC 4/1 quad mic cable I found in the attic. Did not enough Canare Star Quad for two 10 meter runs.
The Gotham was better anyway; thinner, more flexible, and easier to terminate. Has the double served shielding like Mogami. The Canare cable has braided copper shielding. It is a pain to unbraid for connecting to the shield.
I like playing with cables. Cheap when you build your own. Even reuse the connectors and the cabling sometimes.
Picture
This is the hillbilly rig cable I built yesterday. It is used to bridge a stereo amp with single ended inputs to a balanced mono. Needed a quad cable for the two RCA connections.
Will build my next amplifier with two FE boards per channel as a balanced mono. WOD.
This is the hillbilly rig cable I built yesterday. It is used to bridge a stereo amp with single ended inputs to a balanced mono. Needed a quad cable for the two RCA connections.
Will build my next amplifier with two FE boards per channel as a balanced mono. WOD.
Attachments
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Disclaimer (take things with a pich of salt)
Just a note...
While W2944 is an incredibly good cable for internal cabling in general and will be part of the recomendations for the Fremen Edition it's not so for the W3173.
W3173 is very very good FOR THE PRICE, very balanced but not the last word in detail definition, there are better cables and anyway it's still under evaluation and scrutiny, don't rush to buy it.
Just a note...
While W2944 is an incredibly good cable for internal cabling in general and will be part of the recomendations for the Fremen Edition it's not so for the W3173.
W3173 is very very good FOR THE PRICE, very balanced but not the last word in detail definition, there are better cables and anyway it's still under evaluation and scrutiny, don't rush to buy it.
Is it worth using dual power switch in dual mono? In this case there will be some short delay between powering each transformer. I understand, that it is not as effective as soft start circuit. Anyway it is “free” feature, but does it make any good for amplifier?
Attachments
Could you add photos of your build?
Here or in specified thread:
Fremen Edition My_Ref Amplifier – Completed Projects and Photos
What is the lowest voltage rating that can be used for this cap?
Parts Connexion has it in 25V.
I have used Nichicon KZ in other builds with good results but I seen this in the build tutorial:
KZ will sound good but it will not sound how a My_Ref Fremen Edition is supposed to.
I guess you are saying that a KZ at 50v may be a better choice than a Cerafine at 25v?
I tried kz /35v and cerafine /35v caps , to be honest I did not hear any difference . But I remember Mario was insisting on Elna silmic ll/50v , you could find those on eBay .
Digikey has the first class shipping option for very small packages , I would buy from them before buying from eBay.
Digikey has the first class shipping option for very small packages , I would buy from them before buying from eBay.