It must be the high drive capability of HA-5002 that makes Norwood special?
https://www.renesas.com/eu/en/document/dst/ha-5002-datasheet
1300V/us and -+200mA current drive.
The op-amps I have looked at for IPS6 board is about 50mA of output current. Many of those are made to drive 600 ohm for professional audio. But should be sufficient to drive the Edcor.
IPS7 may be the only board that can compete with 200mA current drive?
I think I will try out the IPS6 boards anyway now I have 6 pairs of them.....even that Norwood and IPS7 may be the preferred.....
IPS7 does not have a name?
https://www.renesas.com/eu/en/document/dst/ha-5002-datasheet
1300V/us and -+200mA current drive.
The op-amps I have looked at for IPS6 board is about 50mA of output current. Many of those are made to drive 600 ohm for professional audio. But should be sufficient to drive the Edcor.
IPS7 may be the only board that can compete with 200mA current drive?
I think I will try out the IPS6 boards anyway now I have 6 pairs of them.....even that Norwood and IPS7 may be the preferred.....
IPS7 does not have a name?
MJ said :
"Because they're not part of the Store family of M2x boards, I didn't give these cards formal names like Ishikawa or Norwood. Instead these are just plain old IPS6 and IPS7."
Did you get your noise/hum issue sorted? I may have missed it. I hope so. 😀
If you have it fixed, what was the root cause?
If you have it fixed, what was the root cause?
The conclusion is that the Mountain View card has a louder 100hz hum. It is a matter of PSRR. It has higher power requirements. Ischikawa and Tucson are much quieter and can play . I hope that the mumetal cover will improve something else. Any possible changes to the wiring don't help.
My experience with Edcor shielding with mu-metal is that it will dampen 50Hz magnetic coupled noise from transformer. I did not see any other improvements by shielding Edcor.....in my case.
I can confirm I had similar experiences with @darrr - Montain View being noisier than Tucson or Norwood (possibly because of the differences in PSRR?). My power supply may be not ideal (I used only 8 x 15000uF capacitors, not 22000 as many others 😉 thought it should be enough if that was fine for Papa 😉). I ended up using Norwood in my M2X.
Also, putting steel cover over the toroid helped. After that I did not notice big improvement after covering Edcors with mu-metal.
I saw somebody commented that Ishikawa should also be good with PSRR - could somebody knowledgable confirm or dissaprove that? I did not made Ishikawa as I decided to keep the matched quad of jfets for my F5 that I am going to build soon. But if Ishikawa is really good with PSRR, then I would like to build one.
And then one more related question - does anyone in Europe has matched jfet quad to share? Sending just this from the diyAudio store becomes way too expensive. Or perhaps somebody knows good source for matched jfets in Europe (or any other place with decent shipping costs)?
Also, putting steel cover over the toroid helped. After that I did not notice big improvement after covering Edcors with mu-metal.
I saw somebody commented that Ishikawa should also be good with PSRR - could somebody knowledgable confirm or dissaprove that? I did not made Ishikawa as I decided to keep the matched quad of jfets for my F5 that I am going to build soon. But if Ishikawa is really good with PSRR, then I would like to build one.
And then one more related question - does anyone in Europe has matched jfet quad to share? Sending just this from the diyAudio store becomes way too expensive. Or perhaps somebody knows good source for matched jfets in Europe (or any other place with decent shipping costs)?
The Ishikawa is the original input to the M2 so it works well with the standard firstwatt power supply. So it has to be quiet and it is.
Also, I have some problem with my Tucson card - one of them has much higher noise floor than the other (-105dB compared to the normal -135dB). I could not hear this, but I saw this when measuring. I am sure this is the faulty card, these measurements were repeatedly confirmed with this one particular card.
Did anyone had any time similar problem with OPA1611? Could it be a faulty opamp? Or did I fried it when soldering? I hope I did not, but that was some first experience with the hot air gun. There are just so much parts on Tucson, so I suspect opamp first.
Pictures attached if somebody would like to comment.
Did anyone had any time similar problem with OPA1611? Could it be a faulty opamp? Or did I fried it when soldering? I hope I did not, but that was some first experience with the hot air gun. There are just so much parts on Tucson, so I suspect opamp first.
Pictures attached if somebody would like to comment.
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What if you swap the boards......is it same situation?
This just to try to isolate the problem to the input board or the amp board itself?
This just to try to isolate the problem to the input board or the amp board itself?
I did that exercise a couple of month ago and got a few extra pairs to be sent out in Europe. So if you only need a pair of each then I have a spare pair of each I can ship to you in beginning of 2021. A pair of each is already in Croatia, Norway, UK and Germany.
I assume this is about my Tucsons. Yes, I tried to swap the boards. The problem is always on the channel with the faulty daughter card. So, I am pretty sure the problem is in the buffer. I only wonder what part could be faulty on it.
If you have checked that solder connections are ok then I would check if opamp gets correct -+10V. It is powered via two 10V zener diodes. If both plus and minus voltage is correct I would replace the opamp and see what happens. You need a Gnd reference at amp board. If measured at board only you should measure about 20V but I think better to check via a Gnd-ref at amp board. Be sure not to short anything during measurement 🙂
You could also build a "test bench" for input boards and test board as "stand alone". I did that.
You could also build a "test bench" for input boards and test board as "stand alone". I did that.
yes,i´ll wait a couple of days to se if theres any interesst.if not then I´d like to have boards from you.
🙂
I have not installed the shield on mine too. I hear very faint hiss and maybe a 120 Hz. hum when my ears are ~2-3 inches to the cone of the driver (98dB min.) and definitely a non-issue as I sit 3 to 4 meters away when I play my stereo.
When I was building the amp, during testing, I did not mount the trafo (400VA 18-18) permanently and connect the speakers out to an Altec 416-8B (98 dB)drivers. I then experimented on the transformer positioning for what I perceived as quiet. My brother who was building the Aleph J at the time did the same and we end up mounting the trafo, with shield, as shown. I will probably try the mu metal shield later on. But at this time, I have no inclination to do so. M2"N" (Norwood) on the left and F4 on the right.
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Thank you for posting that layout. I am just assembling an M2X with Mark Johnson's soft start board--the only difference I see is my switch led is RED-BLUE. My question is how do you secure the transformer in the upright position? I don't see a bracket. For my last build I attached it to a vertical riser panel. Works ok but doesn't satisfy my need to overbuild.
BTW, I used the Mu-metal box around the Edcor and steel case around the Antek 300VA xformer and there is zero hiss or hum.
BTW, I used the Mu-metal box around the Edcor and steel case around the Antek 300VA xformer and there is zero hiss or hum.
Hello Bruce!
There's a metal bracket holding the trafo. I bought it at the local hardware store (Lowe's) for $2.00 use for securing joist.
What speakers are you using? On my other speakers, with Fostex 167E at 94dB eff., 0 hum.
