Good on ya!
I suspect that listener evaluations of Milpitas will more or less turn out to be an "all-or-nothing" distribution: either great, or miserable, but not much in between. I, personally, think that the "Norwood Architecture" when realized with Thru Hole components, results in an IPS that really sings. Milpitas really sings. And I mean, raises hairs on your arms when you play the recordings from these ladies: Joan Diener, Thelma Houston, Marianne Faithfull, Jennifer Warnes, Whitney Houston, Grace Slick, Janis Ian, Mahalia Jackson.
I suspect that listener evaluations of Milpitas will more or less turn out to be an "all-or-nothing" distribution: either great, or miserable, but not much in between. I, personally, think that the "Norwood Architecture" when realized with Thru Hole components, results in an IPS that really sings. Milpitas really sings. And I mean, raises hairs on your arms when you play the recordings from these ladies: Joan Diener, Thelma Houston, Marianne Faithfull, Jennifer Warnes, Whitney Houston, Grace Slick, Janis Ian, Mahalia Jackson.
Hello,
The good news:
I successfully soldered the MilPitas PCB-s.
One of them works.
The bad news:
When installing the other panel in the M2x, I managed to supply the input of the other panel with the rail (23V)... A real amateur accident
. Since then, the side has been very quiet. I'm almost sure that the LT1122 input is gone.
Question:
Is there any chance that the LM7171 has not failed?
I would connect the input to the LM7171 and listen to see if there is a difference in sound.
Would that work?
The signed red dot PCB is the wrong side, but I can't see any difference.
Thank you
Gyuri
The good news:
I successfully soldered the MilPitas PCB-s.
One of them works.
The bad news:
When installing the other panel in the M2x, I managed to supply the input of the other panel with the rail (23V)... A real amateur accident
. Since then, the side has been very quiet. I'm almost sure that the LT1122 input is gone.Question:
Is there any chance that the LM7171 has not failed?
I would connect the input to the LM7171 and listen to see if there is a difference in sound.
Would that work?
The signed red dot PCB is the wrong side, but I can't see any difference.
Thank you
Gyuri
Last edited:
Oops, so sorry to hear that!
Yes I think there's a very good chance that the LM7171 was not destroyed or damaged. I recommend that after you remove the LT1122 chip and before replacing it with a fresh new device: measure the resistance of R4 and R5. Verify that they are still working and still have the correct values. If so, put in a new LT1122 and better luck on the installation!
_
Yes I think there's a very good chance that the LM7171 was not destroyed or damaged. I recommend that after you remove the LT1122 chip and before replacing it with a fresh new device: measure the resistance of R4 and R5. Verify that they are still working and still have the correct values. If so, put in a new LT1122 and better luck on the installation!
_
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Hello,
Mark thank you very much for the quick reply, you were right, the LM op. amp is not broken.
I soldered out the bad LT op amp and reconnected the input cable to the LM7171 3rd leg.
I put it back in and was surprised.
The music was definitely clearer. Maybe crystal clear is a better adjective for it. I liked it so much that I also soldered out the good LT1122 off the other Milpitas PCB (which was not faulty).
There are negatives also: it got quieter and the dynamics decreased somewhat. I haven't tied the Norwood back yet to weigh the pros and cons.
To reduce or eliminate the cons, I now need a good preamp. Currently the signal goes directly from the DAC to the amp.
I think if someone is just starting to build a Milpitas, it is worth building it so that it can be tried without the front opamp (in a socket for example?), especially if you have a good preamp before the M2x.
What is your opinion Mark?
My amp is oscillated when I connected the input cabel to the 3rd leg of the LM7171 and I left the first good opamp in the PCB. I had to soldered out.
Is it possible that the Milpitas will not oscillate if somebody use socket to the LT1122 op-amp?
Of course the signal cable should be soldered to the 3rd leg of the LM.
Here's my solution, I use a dedicated power supply (+/-14.3V) for the Daughter boards, use cables and no metal spacers, and no need for Zener diodes because of low supply voltage.
Thank you
Gyuri
Mark thank you very much for the quick reply, you were right, the LM op. amp is not broken.
I soldered out the bad LT op amp and reconnected the input cable to the LM7171 3rd leg.
I put it back in and was surprised.
The music was definitely clearer. Maybe crystal clear is a better adjective for it. I liked it so much that I also soldered out the good LT1122 off the other Milpitas PCB (which was not faulty).
There are negatives also: it got quieter and the dynamics decreased somewhat. I haven't tied the Norwood back yet to weigh the pros and cons.
To reduce or eliminate the cons, I now need a good preamp. Currently the signal goes directly from the DAC to the amp.
I think if someone is just starting to build a Milpitas, it is worth building it so that it can be tried without the front opamp (in a socket for example?), especially if you have a good preamp before the M2x.
What is your opinion Mark?
My amp is oscillated when I connected the input cabel to the 3rd leg of the LM7171 and I left the first good opamp in the PCB. I had to soldered out.
Is it possible that the Milpitas will not oscillate if somebody use socket to the LT1122 op-amp?
Of course the signal cable should be soldered to the 3rd leg of the LM.
Here's my solution, I use a dedicated power supply (+/-14.3V) for the Daughter boards, use cables and no metal spacers, and no need for Zener diodes because of low supply voltage.
Thank you
Gyuri
I changed all connectors between daughterboard and mainboard as @borlotti did (#3234).
Fortunately there is a local seller of these connectors in South Korea.
It's so easy to change daughterboards.
Thank you! @borlotti
MIX-STG HS D-SUB single contact (part number 131C12029X)
MIX-BUG HS D-SUB single contact (part number 132C12019X)
Fortunately there is a local seller of these connectors in South Korea.
It's so easy to change daughterboards.
Thank you! @borlotti
MIX-STG HS D-SUB single contact (part number 131C12029X)
MIX-BUG HS D-SUB single contact (part number 132C12019X)
Attachments
@Mark Johnson your efforts and expertise are much appreciated. My newly completed cards. 4U is being shipped in so it'll be awhile before the M2x is running. Thanks again,
Jim
Jim
Congratulations on a very tidy build with truly excellent cleanup, @JKiriakis !! Not a speck of flux to be seen anywhere. Good on ya.
Kind of you @Mark Johnson. For the good of the order: I used my brain for a change and swapped my usual small chisel Hakko tip for a pointy one. And used a weighted gantry tool with adjustable padded alligator clips to hold the daughter board while peering at each solder joint through the integrated and adjustable magnifier. Cardas small diameter proper solder. I threaded in all the bits before soldering with the exception of the Opamp sockets. Used blue tape to hold them in place while lastly soldering the sockets. I broke my surface diagonal side cutters recently separating bulk male crimp on mounts so ordered two new cutters which were employed to remove the excess leads, and a toothbrush + isopropyl + linen serviette three passes to clean up the flux. It's fun and rewarding to improve skills and processes. Board design and component fit is just awesome you do great work sir.
Easy to order and though it just arrived seems much nicer than the garden variety from Amazon. Thanks TA!
If anyone wants some more Edcor PC600-15K transformers, as used in the M2x, I'm giving away a set of nine of them for free (but you pay $17 postage). And you have to un-solder them from obsolete PCBs. Here is a link to the message in the Swap Meet.
Thanks Mark for the great designs for the M2X! I'm ordering parts for the Milpitas. Looks like Mouser is out of the LT122DCN8. They still have the LT1122CCN8. In my review of the datasheet specs look the same. Just looking for some reassurance that I'm not overlooking anything here.
I've also acquired parts for the Cedarburg and the IPS7 and realize that I don't have those boards. Does anyone have spares That I could buy before I begin the process of ordering boards? Thanks!
I've also acquired parts for the Cedarburg and the IPS7 and realize that I don't have those boards. Does anyone have spares That I could buy before I begin the process of ordering boards? Thanks!
Free! Two sets of Royal And Ancient M2x PCB sets -- if and only if you accept the boards in person, hand to hand, on Sunday at the 2023 Burning Amp Festival in Petaluma
Send me a Private Message ("Conversation") if you definitely will attend 2023-BAF on Sunday, and want one set of these PCBs. One set per person. First come, first served. If fewer than two people ask for these, I'll donate them to the BAF raffle. A board set consists of ten input daughter boards and a book-matched pair of amp channel "mother" boards.
I call these Ancient because they were built in March of 2018, before this thread was created. {check post#1!!} Before the diyAudio Store ever sold boards. Before I even knew how to order boards in a color that wasn't green. They have single thickness ("one ounce") copper whereas the Store boards have double thickness ("two ounce") copper. If that frightens you, don't take these boards. Get the thicc bois from the Store and sleep soundly.
Send me a Private Message ("Conversation") if you definitely will attend 2023-BAF on Sunday, and want one set of these PCBs. One set per person. First come, first served. If fewer than two people ask for these, I'll donate them to the BAF raffle. A board set consists of ten input daughter boards and a book-matched pair of amp channel "mother" boards.
I call these Ancient because they were built in March of 2018, before this thread was created. {check post#1!!} Before the diyAudio Store ever sold boards. Before I even knew how to order boards in a color that wasn't green. They have single thickness ("one ounce") copper whereas the Store boards have double thickness ("two ounce") copper. If that frightens you, don't take these boards. Get the thicc bois from the Store and sleep soundly.
^question for you all. This morning, hooked up the bridge rectifiers to the power supply and the star ground. UPS grounded to star via CL60 thermistor. Employed dim bulb, powered up the transformer and PS. No funny smells or magic smoke. Measured 48.5V between V+ and V- points on the UPS without the dim bulb.
Is this a normal readout unloaded and disconnected from the M2x PCBs? Thanks!
Is this a normal readout unloaded and disconnected from the M2x PCBs? Thanks!
@Dennis Hui @6sX7 nice progress on left channel. No magic smoke or strange odors with dim bulb. Sans dim bulb voltage on R13 and R14 613mV. Not worrying too much about offset yet until I properly heat it up, but at this stage stable at 018mV. On to the right channel now.