I have the daughter cards, I hadn't got around to building any of them yet. May I ask what, "tweaks" you made Mark?
Yup, sorry had a late night with mom and the hospital...
TA, what tweaks if I may ask?
JT
I put the IFI Ican in front of the M2X, so the chain is PC Elfidelity AXF-100 ULTRA III to SIngxer to HoloSpring Kitsune DAC to Ican to M2X to Modded Takton DIs
That's a fun little box the Ican, I have to running in partial tube mode bass off 3d off. It's sounds pretty damn amazing. The bass is nuts and the mids are very nice Tektons do that well especially with the external crossovers I built.
That's a fun little box the Ican, I have to running in partial tube mode bass off 3d off. It's sounds pretty damn amazing. The bass is nuts and the mids are very nice Tektons do that well especially with the external crossovers I built.
Mtn View tweaks
I posted this a while back to show how I built my own IPS proto boards. The Mtn View was the first platform for my experimentation with the M2x.
I was initially looking for an alternative to the red LED, which seemed to be difficult to obtain outside of N. America. I built my original Mtn View PCBs using the recommended LED, then went off to play a little. First, I substituted a 2.048V voltage source for the LED, and adjusted the current setting resistors accordingly. I allowed more total current supply for the voltage source, and the two current sources that are used for the input and output transistors. With the original J112 still in place, I somewhat preferred the sound of my proto boards to the original PCB build. Once I started playing with substitutes for the J112, I happened to like the Linear Systems 2N4416, and left that in the board.
I posted this a while back to show how I built my own IPS proto boards. The Mtn View was the first platform for my experimentation with the M2x.
I was initially looking for an alternative to the red LED, which seemed to be difficult to obtain outside of N. America. I built my original Mtn View PCBs using the recommended LED, then went off to play a little. First, I substituted a 2.048V voltage source for the LED, and adjusted the current setting resistors accordingly. I allowed more total current supply for the voltage source, and the two current sources that are used for the input and output transistors. With the original J112 still in place, I somewhat preferred the sound of my proto boards to the original PCB build. Once I started playing with substitutes for the J112, I happened to like the Linear Systems 2N4416, and left that in the board.
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I picked up a few of these boards - if people are looking, just shoot me a PM. And for those not comfortable with SMD work, I would be happy to use my hot air station and set their opamp in place.
and if anyone has a spare Norwood board - happy willing and able to relieve you of it
..dB
I know they're a bit (okay a lot) different, but I've used the Micro iTube as a pre-amp in a few cases or just in the chain with no gain as a buffer. Similar results and fun!
That Micro has some very good reviews as well... It's fun to play with stuff like that. It's also nice because of how fast you can AB something. When you have to shut stuff down and then work with IC, by the time you get back, for me, I have a harder time discerning changes.
I finally finished up my M2x build in monoblock configuration, and had a short listen tonight. I am traveling today and over the weekend. Pictures next week.
Plitron 225VA transformers (well I had the pair of them already) + DIYStore capacitor board
M2x set from DIY store with silly boutique parts + Fairchild FQA mosfets. I used the heretical advice from Mark Johnson regarding offset R6 and RV1. Had no trouble with adjusting offset. I have a set of speaker protection boards in the case, but bypassed while I finalize offset correction.
Running the Mountain View cards currently. Have a set of Ishikawa cards to try. I should finish the Tuscon shortly, as the DIP sockets arrived today. I have made arrangements for Norwood card assembly, and parts for the Austin boards arrive today.
Initial listening last night was spectacular. Compared to my Aleph J, its a bit more delicate, but I really noticed that in addition to side to side sound field, there was front to back layering, that I have not experienced before.
Pictures, and more to come.
Plitron 225VA transformers (well I had the pair of them already) + DIYStore capacitor board
M2x set from DIY store with silly boutique parts + Fairchild FQA mosfets. I used the heretical advice from Mark Johnson regarding offset R6 and RV1. Had no trouble with adjusting offset. I have a set of speaker protection boards in the case, but bypassed while I finalize offset correction.
Running the Mountain View cards currently. Have a set of Ishikawa cards to try. I should finish the Tuscon shortly, as the DIP sockets arrived today. I have made arrangements for Norwood card assembly, and parts for the Austin boards arrive today.
Initial listening last night was spectacular. Compared to my Aleph J, its a bit more delicate, but I really noticed that in addition to side to side sound field, there was front to back layering, that I have not experienced before.
Pictures, and more to come.
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The only person who can definitively answer that question is the original circuit designer, Nelson Pass.
Any other guesses, speculations, conjectures, postulations, surmises, and theorizings, are simply the opinion of the writer.
Having said that, I now will offer my own opinion:
I think a better question might be, why use a shunt-zener bias circuit in the F4, rather than the optocoupler based bias design of the M2?
I don't have an answer but I do feel it is a better question.
I don't have a good answer, and I am not qualified to give any sort of definitive answer, but in my experience simulating the respective circuits in LTSpice, I have struggled to set up the optocoupled design to work with paralleled devices, where each device has low-ish Iq compared to the single pair of the M2. I think this is due to the forward voltage drop of the LED in the optocoupler; without sufficient Iq in each device, source resistors of a reasonable value do not generate enough voltage drop to drive the LED as intended.
I am very interested in more comments on this - the auto-biasing feature of the optocoupler design is very attractive.
In case there are readers here who haven't yet seen it, I attach Nelson Pass's US Patent on optocoupler bias of audio amplifier output stages. Filed 33 years ago. You may enjoy reading his explanation of his circuitry.
Also, I would point out that even in the narrow domain of thru-hole packaged, phototransistor output, optocouplers ...
there exist models with substantially larger Current Transfer Ratio (Icollector / Iled) than the venerable 4N35 used in the M2. The larger the CTR, the smaller the LED current, thus the smaller the "error term" introduced by siphoning LED current from only one of "N" parallel output transistors. Here is one example, with 3600 parts on the shelf ready to dispatch, at a price of USD 0.79, and 6X higher CTR than the 4N35. If it matters.
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Also, I would point out that even in the narrow domain of thru-hole packaged, phototransistor output, optocouplers ...
there exist models with substantially larger Current Transfer Ratio (Icollector / Iled) than the venerable 4N35 used in the M2. The larger the CTR, the smaller the LED current, thus the smaller the "error term" introduced by siphoning LED current from only one of "N" parallel output transistors. Here is one example, with 3600 parts on the shelf ready to dispatch, at a price of USD 0.79, and 6X higher CTR than the 4N35. If it matters.
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Couldn't agree more; the improvement in these areas was profound when I finally got around to going dual mono for my Aleph J.
I'd like to hear more about why dual mono makes such a profound difference. The reason why I ask is that I have four populated M2X amp boards, a UPSV3 and a SLBPS boards sitting on my bench. I'm ready to put on the heat sinks, connect it all up, and see how it sounds. This is the time to decide if I want to make 4 mono blocks, 2 dual PS amps, or 2 conventional M2X amps. I'd like to hear more opinions. FWIW, I have efficient speakers and seldom use much more than a watt or two of power to drive them at quite reasonable listening levels.
bchassy,
Being a board stuffing ex-powerhouse electrician, as such, it seemed to me that if the PS was of sufficient capacity, there'd be plenty to go around for both channels, yeah?
But I kept hearing from guys on the forum whose expertise I've come to trust of the advantages of dual mono power supplies so I went for it, and am glad I did.
If anything, those advantages are the most prevalent at low volumes.
As an infrastructure guy, I place emphasis on the basics of about everything. In the case of music reproduction that includes providing my components with balanced AC. 240VAC is inherently balanced, and what I use for my amp and preamp. I installed a 3KVA dry type transformer for my 120VAC loads to provide balanced (no grounded leg for neutral) power at that voltage. I take great care to avoid ground loops between components, and to ensure proper shielding of signal cables, etc, etc.
Improvement in overall SQ from my system was realized as each of the above listed steps were taken.
Hopefully, my comments will prove to be helpful.
Being a board stuffing ex-powerhouse electrician, as such, it seemed to me that if the PS was of sufficient capacity, there'd be plenty to go around for both channels, yeah?
But I kept hearing from guys on the forum whose expertise I've come to trust of the advantages of dual mono power supplies so I went for it, and am glad I did.
If anything, those advantages are the most prevalent at low volumes.
As an infrastructure guy, I place emphasis on the basics of about everything. In the case of music reproduction that includes providing my components with balanced AC. 240VAC is inherently balanced, and what I use for my amp and preamp. I installed a 3KVA dry type transformer for my 120VAC loads to provide balanced (no grounded leg for neutral) power at that voltage. I take great care to avoid ground loops between components, and to ensure proper shielding of signal cables, etc, etc.
Improvement in overall SQ from my system was realized as each of the above listed steps were taken.
Hopefully, my comments will prove to be helpful.