If you have a DMM that can test diode Vf you can verify that there are diodes btn pins 1(Anode) and 2(Kathode) as well as pins 6(Base) and 4(Emitter).
I finished my M2x build last night. Many thanks to Mark Johnson et al for all of their hard work designing the M2x PCB's and especially the different input stages. Board layouts were very clear as were the directions in the first few posts in this thread.
The first daughter board I have used is the Tucson with the OPA1611 opamp. All I can say is WOW. The M2x with this input stage sounds incredible with a very big, dynamic, dimensional, dramatic sound with a massive sound stage and exceptional bass and top end. Midrange is very good but perhaps not as sweet as some amps I have listened to but still great. I am also going to try Mountain View, Cedarburg, and IPS7. Perhaps it is simply a case of preferring the most recent build, but for the moment the M2x has displaced the Aleph J as my favorite First Watt amp.
If I can get my hands on another set of the Tucson cards, I would love to try the LT1122 opamp that Mark has talked about liking. If anyone has an extra set of those cards that they would like to sell please PM me.
The first daughter board I have used is the Tucson with the OPA1611 opamp. All I can say is WOW. The M2x with this input stage sounds incredible with a very big, dynamic, dimensional, dramatic sound with a massive sound stage and exceptional bass and top end. Midrange is very good but perhaps not as sweet as some amps I have listened to but still great. I am also going to try Mountain View, Cedarburg, and IPS7. Perhaps it is simply a case of preferring the most recent build, but for the moment the M2x has displaced the Aleph J as my favorite First Watt amp.
If I can get my hands on another set of the Tucson cards, I would love to try the LT1122 opamp that Mark has talked about liking. If anyone has an extra set of those cards that they would like to sell please PM me.
Research the IPS7. Mark Johnson designed this input board, and published the files so you can order them as needed. It fits both single, and dual OpAmps. And if you like trying out new OpAmps, you really should try the Cedarburg input cards, yet another gift from Mark Johnson. The Cedarburg is my current favorite.
If you make another Tucson or IPS7 consider using OPAMP sockets so that you can “roll” OPAMPs. I have found that they have a considerable impact on the sound. My favorite combo so far is the Tucson with Burson Audio Classic, very good all around including mids.
Since OPA1611 is a surface mount device, and since the Tucson board includes a PCB footprint for a surface mounted opamp (in addition to a PCB footprint for a DIP opamp), he probably just soldered the OPA1611 straight to the PCB.
Too bad this isn't May of 2018, there was a Group Buy of Tucson boards back then.
FS: M2x daughter cards, type "TUCSON"
Maybe you can PM each of the buyers, and ask whether they have used every single Tucson they bought -- someone may decide they can spare a couple after all. Not everybody reads every post in the M2x thread after all.
Too bad this isn't May of 2018, there was a Group Buy of Tucson boards back then.
FS: M2x daughter cards, type "TUCSON"
Maybe you can PM each of the buyers, and ask whether they have used every single Tucson they bought -- someone may decide they can spare a couple after all. Not everybody reads every post in the M2x thread after all.
I did deliberately choose and solder the OPA1611 in first with the reasoning that it would be easy to remove and replace with a socketed opamp but I like it so much I can't imagine doing that now. Thanks to dBel84 for his offer to send me more cards.
I have the Cedarburg built so I'll look forward to trying that next and I appreciate the tip about the Burson Audio Classic opamp.
I have the Cedarburg built so I'll look forward to trying that next and I appreciate the tip about the Burson Audio Classic opamp.
I just finished my M2x build and am burning it in listening to all my favorites. This is easily my best sounding amp project to date. I can't believe the liquid midrange and lifelike character of this guy. Prodigious base and delicate highs. I can't wait to hear it after it settles in. Am streaming MQA music masters directly from a Bluesound Node 2i into the M2x feeding Klipsch RPM 600 speakers, supplemented by a SVS powered sub. This is not my primary system, but it is now my favorite. Ive built Bob Latino's M125 monoblocks, the ACA monoblocks. Also used the Dynakit ST35 and Quicksilver monoblocks(with the venerable 8417 obsolete output tubes). This M2x with the Ishikawa input card (jumpered C1) knocks em all back. Setting DC offset was no problem, I used the 37K value for R6 with RV1 at 20K. Waiting on parts to build the Cedarburg. Profuse thanks to Papa, Mark, Jim, and all involved for making this project available for DIY!!!
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Åke,
What is the voltage of the secondaries of your power transformer?
The image you shared earlier of you build in progress shows an SLB power supply on the chassis floor if I am not wrong. The SLB PSU uses the LT4320 ideal bridge rectifier and a capMx, and is very low noise. However there is a voltage drop associated with the cap multiplier.
What is the voltage of the secondaries of your power transformer?
The image you shared earlier of you build in progress shows an SLB power supply on the chassis floor if I am not wrong. The SLB PSU uses the LT4320 ideal bridge rectifier and a capMx, and is very low noise. However there is a voltage drop associated with the cap multiplier.
I have had the pleasure of listening to the M2x with most of the daughter boards except Austin, IPS6 and Black Forest. It has been a ton of fun building and trying all these variations and comparing them to my Aleph J which has been my reference system so far. Having Nelson Pass make the M2 design available and then having Mark Johnson create the M2x version with the initial set of daughter boards was a huge act of generosity and one I am very grateful to them for.
Flipping through the posts, I saw a suggestion that it was possible to run the M2x without any daughter board if you had an input with enough voltage. I recently completed Wayne's BA2018 and I wondered if that would be an adequate source? Also, I wanted to double check that to remove the daughter board you would just jumper Pin/IO 2 and Pin/IO 4 of the main amp board and leave Pins 3 and 4 unconnected?
Flipping through the posts, I saw a suggestion that it was possible to run the M2x without any daughter board if you had an input with enough voltage. I recently completed Wayne's BA2018 and I wondered if that would be an adequate source? Also, I wanted to double check that to remove the daughter board you would just jumper Pin/IO 2 and Pin/IO 4 of the main amp board and leave Pins 3 and 4 unconnected?