@Mark Johnson
Thank you for another beautiful daughter board - Milpitas !
Thank you for another beautiful daughter board - Milpitas !
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A possible cold solder on the black component?
(and it seems there are solder on the area with screws so ..this part seems weird. But not clear on the picture)
(and it seems there are solder on the area with screws so ..this part seems weird. But not clear on the picture)
I’m assuming Mark’s PCB screen shows that the resistor body should be at the circle? Plus possible cold joint? 
(I understood the welding close to the screw: this is for the quick connection, better shown on the amplifier pictures above)
could it be possible to give a bit if gain to the milpitas IPS so to avoid gain transformer? lets say 6db would be ok for my speakers
It is not possible to give gain to any of the input cards. They are buffers, and the transformer is gain.
This is the point of M2x. If you want no gain transformer, build a different amp.
This is the point of M2x. If you want no gain transformer, build a different amp.
Someone here mentioned that he used FE2022 as a front end for M2X instead of the buffer(s) and the Edcor.
Search through the thread and you should find it.
If not found here try a general search.
The someone you refer to might be me, although my build is based on the Tea Bag M2 boards, not the M2x. I'm happy to provide details if you are interested, @marconi118.
He's been kicking the tires of M2x for six and a half years -- see post #40 of this thread -- but hasn't actually built one yet.
Any current builders planning to use the Reichelt D Sub connectors for the daughter boards? I have an extra channel A board that I’ve soldered 4 female D Sub connectors to for the purposes of aligning the Male connectors and daughter boards. Worked great, and I’ll have no use for it going forward. U pay shipping and all yours! FCFS.. Cheers..
Hello,
I have some silly (maybe) question.
I use Ian Canada DAC and it has a symmetrical output too. I was wondering if a daughter card with a symmetrical input could be made for the M2x or would it almost certainly oscillate?
Maybe the op. amps are would be dual versions ? Milpitas uses LT1122 and LM7171, but neither of them have a true dual version.
Substitute dual op amps could be the OPA1611 (LT1122) as well as the OPA2828 (LM7171)?
I don't mean direct opm.amp replacement of course.
Thank you the answers
I have some silly (maybe) question.
I use Ian Canada DAC and it has a symmetrical output too. I was wondering if a daughter card with a symmetrical input could be made for the M2x or would it almost certainly oscillate?
Maybe the op. amps are would be dual versions ? Milpitas uses LT1122 and LM7171, but neither of them have a true dual version.
Substitute dual op amps could be the OPA1611 (LT1122) as well as the OPA2828 (LM7171)?
I don't mean direct opm.amp replacement of course.
Thank you the answers
M2x daughter cards have four electrical connections to the motherboard, one connection per M3 bolt hole.
I think it's likely that "a daughter card with a symmetrical input" would need more than four electrical connections. That means it would not actually be an M2x daughter card.
If you and your colleagues design an interface circuit which takes Ian Canada DAC symmetric input, and which has an output that can drive the auto-transformer of an M2x, you can physically mount your interface circuit wherever you like. It doesn't NEED to use the four bolts on the M2x motherboard; that's just a convenience which lets builders perform board swaps quickly, without soldering.
I think it's likely that "a daughter card with a symmetrical input" would need more than four electrical connections. That means it would not actually be an M2x daughter card.
If you and your colleagues design an interface circuit which takes Ian Canada DAC symmetric input, and which has an output that can drive the auto-transformer of an M2x, you can physically mount your interface circuit wherever you like. It doesn't NEED to use the four bolts on the M2x motherboard; that's just a convenience which lets builders perform board swaps quickly, without soldering.
Those can oscillate... which can manifest (the perceived sound quality) as specious, easy-to-listen sound. Hook the oscilloscope and check for oscillations - do it before the transformer.
We have glorious music folks!
Ok, it's just music as its playing through old Bose satellite acoustimass test speakers, but having music play feels pretty glorious. It was not without a couple issues, but I'll cover my lessons learned in another post.
A new M2x is born today. Chassis is Modushop 4U Deluxe with linear PSU using Antek AS-4220 and @rhthatcher stereo PCBs w/ rectifier snubber boards. Wire is all 16Ga BNTECHGO with XHF heat shrink twist wrap (input wire is Mogami W-2381). Current IPS is the Mtn View. I purchased the main boards prebuilt with the IPS from @deafbykhorns a year ago and all I did was add the 9240/240 FETs for the amp boards.
I just wrapped up bias check and setting DC offset after cooking for over an hour, then verified music would play.
I'll follow up with listening impression(s) and lessons learned post when time allows.
Thank you to Papa and @Mark Johnson for this great design. I also must thank @ItsAllInMyHead for lots of support with my silly noob questions along the way.
I gotta give a special shout out Thank You! to @6L6 for all the great build pics, thoughtful advice, and amazing support to help troubleshoot a couple issues I ran into.
Feels so good to finally have music playing. It's a Festivus Miracle!
Ok, it's just music as its playing through old Bose satellite acoustimass test speakers, but having music play feels pretty glorious. It was not without a couple issues, but I'll cover my lessons learned in another post.
A new M2x is born today. Chassis is Modushop 4U Deluxe with linear PSU using Antek AS-4220 and @rhthatcher stereo PCBs w/ rectifier snubber boards. Wire is all 16Ga BNTECHGO with XHF heat shrink twist wrap (input wire is Mogami W-2381). Current IPS is the Mtn View. I purchased the main boards prebuilt with the IPS from @deafbykhorns a year ago and all I did was add the 9240/240 FETs for the amp boards.
I just wrapped up bias check and setting DC offset after cooking for over an hour, then verified music would play.
I'll follow up with listening impression(s) and lessons learned post when time allows.
Thank you to Papa and @Mark Johnson for this great design. I also must thank @ItsAllInMyHead for lots of support with my silly noob questions along the way.
I gotta give a special shout out Thank You! to @6L6 for all the great build pics, thoughtful advice, and amazing support to help troubleshoot a couple issues I ran into.
Feels so good to finally have music playing. It's a Festivus Miracle!
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It looks like you've been going to wire twisting school at night. Are these plastic wire standoffs an invention of yours? I have never seen neater wiring than that! Congrats!
