^ +1 to both above.
@mspijker - YMMV of course and do what makes you most comfortable. When it's soldered in properly, the pins will not break turning the pot even if bent. My advice... if you have a quality pot, the center pin is easily bent to fit with no issues. I would not wiggle it back and forth 20 times, but a quick fit is no issue. If it concerns you, get a new pot. Your own confidence in the build is a part of the path to success. Why worry. However, I've done it a number of times.
I would not order pots of unknown provenance to get replacements more quickly. Sadly, premium electronics parts (even those of relatively low price) are often copied and will likely be of lesser quality. You're better off bending one pin on a real Bourns than using the correct pin configuration on a copy, IMO.
@mspijker - YMMV of course and do what makes you most comfortable. When it's soldered in properly, the pins will not break turning the pot even if bent. My advice... if you have a quality pot, the center pin is easily bent to fit with no issues. I would not wiggle it back and forth 20 times, but a quick fit is no issue. If it concerns you, get a new pot. Your own confidence in the build is a part of the path to success. Why worry. However, I've done it a number of times.
I would not order pots of unknown provenance to get replacements more quickly. Sadly, premium electronics parts (even those of relatively low price) are often copied and will likely be of lesser quality. You're better off bending one pin on a real Bourns than using the correct pin configuration on a copy, IMO.
The only issue may be if the centre pin is not long enough. But if that's ok then as ItsAllInMyHead wrote, the trimmer should be fine once it's soldered in.
The "W" designation is a straight line pin-out for Bourns I think. (sadly not for BI it seems)
There's nothing magical about the original spec'ed trimmer and there are parts available in the distributors that will work. For
example, Mouser has the old standby 3296W:
https://www.mouser.ca/ProductDetail/Bourns/3296W-1-502LF?qs=zl1BDXJPZVrTnesl5BcuCQ==
Good luck with your build.
The "W" designation is a straight line pin-out for Bourns I think. (sadly not for BI it seems)
There's nothing magical about the original spec'ed trimmer and there are parts available in the distributors that will work. For
example, Mouser has the old standby 3296W:
https://www.mouser.ca/ProductDetail/Bourns/3296W-1-502LF?qs=zl1BDXJPZVrTnesl5BcuCQ==
Good luck with your build.
I’ve had my M2x in service now for about a year now, and I thought I would share some of my insights on the sound. I’ve built and played many different amplifiers, and the M2x is clearly my favorite for its natural, detailed, and lifelike sound. Nelson Pass’ design is pure magic. My set up currently includes a Bluesound Node 2i music streamer, Mytek Brooklyn DAC/Preamp, Autoformer passive volume control, the M2x, SVS SB13 Ultra subwoofer, and Klipsch RP600M speakers.
As far as input buffer cards go, I am listening a lot lately to the Tucson card using the Burson Audio V6 Classic discrete opamp. I’ve been swapping between the V6 Classic and the LT1122 opamp in the Tucson. I’m not sure if having swappable input cards and opamps is a blessing or a curse, as I find myself constantly changing them. For those of you liking the Tucson card, I suggest you give the Burson opamp a go. To my ears, it is noticeably better than the 1122. The soundstage gets wider and deeper, there is a better sense of acoustic space with plenty of sweet detail. Vocals have a richness with the Burson I really enjoy. And I can listen for hours with no fatigue. Images are well defined. In contrast, the 1122 comes across a bit more in your face, and with a flatter 2D soundstage. The presentation is more aggressive, if that’s your thing. Its a bit more hifi sounding, and doesn’t sound as ‘live’. The bass on the 1122 is very controlled and tight, which I do like. The Burson in comparison is a bit recessed in the upper bass region, but is more 3D. To note, I am using a high pass filter on the subwoofer, the M2x is only amplifying 80hz and above frequencies.
My favorite daughter card? That goes to the stripped down version of the Ishikawa. Mine have the C1 shorted and no trimmer pot, loyal to the Pass original design. It has all the great stuff of the Burson/Tucson combo, but a more robust bass. I love live music, and this one gets me there, closer than the rest, its absolutely sublime. I can follow individual instruments like being there with the Ishikawa. The Burson/Tucson combo is a close second. I am still trying to warm up to the Cedarburg card, which has seen some time in the amp. But I always come back to the Ishikawa and Burson/Tucson cards.
Well, thanks for reading thus far. I think the M2x is amazing. I plan on upgrading my speakers in the near future. Maybe some Klipsch Forte IVs. The M2x is a good mix with the Klipsch house sound….its the closest to being there that I have found. Thank you Nelson and the DIY community.
As far as input buffer cards go, I am listening a lot lately to the Tucson card using the Burson Audio V6 Classic discrete opamp. I’ve been swapping between the V6 Classic and the LT1122 opamp in the Tucson. I’m not sure if having swappable input cards and opamps is a blessing or a curse, as I find myself constantly changing them. For those of you liking the Tucson card, I suggest you give the Burson opamp a go. To my ears, it is noticeably better than the 1122. The soundstage gets wider and deeper, there is a better sense of acoustic space with plenty of sweet detail. Vocals have a richness with the Burson I really enjoy. And I can listen for hours with no fatigue. Images are well defined. In contrast, the 1122 comes across a bit more in your face, and with a flatter 2D soundstage. The presentation is more aggressive, if that’s your thing. Its a bit more hifi sounding, and doesn’t sound as ‘live’. The bass on the 1122 is very controlled and tight, which I do like. The Burson in comparison is a bit recessed in the upper bass region, but is more 3D. To note, I am using a high pass filter on the subwoofer, the M2x is only amplifying 80hz and above frequencies.
My favorite daughter card? That goes to the stripped down version of the Ishikawa. Mine have the C1 shorted and no trimmer pot, loyal to the Pass original design. It has all the great stuff of the Burson/Tucson combo, but a more robust bass. I love live music, and this one gets me there, closer than the rest, its absolutely sublime. I can follow individual instruments like being there with the Ishikawa. The Burson/Tucson combo is a close second. I am still trying to warm up to the Cedarburg card, which has seen some time in the amp. But I always come back to the Ishikawa and Burson/Tucson cards.
Well, thanks for reading thus far. I think the M2x is amazing. I plan on upgrading my speakers in the near future. Maybe some Klipsch Forte IVs. The M2x is a good mix with the Klipsch house sound….its the closest to being there that I have found. Thank you Nelson and the DIY community.
To me, Ishikawa is also one of the best cards I tried. It has a different, unique, sound than the rest of the cards. I installed RV1 and C1, connected two DVM across the resistors R1 and R2, then adjust RV1 to have the Vdrop equal across the resistors. I also tried using a soundcard to adjust RV1 and the distortion does not change significantly from end to end of the pot (in my experiment, I see M2X has a dominant H3 in the spectrum).
My preference are as follows: Ishikawa, IPS7, IPS6, Cedarburg, and Norwood. The rest are very good too and after a long time living with the cards and trying one by one every month, I concluded that it is very difficult for me to say that one is better than the others. Building all of the cards however gives you so much fun to try them all and is a very rewarding investment.
Much thanks to Mr. Mark Johnson for giving us the opportunity to hear what the M2X is really about. Thank you Mr. Johnson!
My preference are as follows: Ishikawa, IPS7, IPS6, Cedarburg, and Norwood. The rest are very good too and after a long time living with the cards and trying one by one every month, I concluded that it is very difficult for me to say that one is better than the others. Building all of the cards however gives you so much fun to try them all and is a very rewarding investment.
Much thanks to Mr. Mark Johnson for giving us the opportunity to hear what the M2X is really about. Thank you Mr. Johnson!
I have just finished mine with Isihkawa but haven't time for a test drive. I did a test without daughterboard and found the sound extremely detailed but lack the low bass on Cornwall III. I hope the Isihkawa will restore my expectations. I have Tucson on the todo-list. The photo is without buffer.
@Fajimo: you said "stripped down version of the Ishikawa". By that do you mean without RV1 and C1, Pass native buffer?
I hope take some measurements this weekend. I will return with findings regarding H2/H3 fiddling with RV1. RV1 is on long legs and perhaps I cut them.
C1 keep it or loose it? What is the public opinion?
Isihkawa Jfets are linear 7.1mA/7.2mA with 10ohm resistors. With RV1 it's 9.3ohm.
@Fajimo: you said "stripped down version of the Ishikawa". By that do you mean without RV1 and C1, Pass native buffer?
I hope take some measurements this weekend. I will return with findings regarding H2/H3 fiddling with RV1. RV1 is on long legs and perhaps I cut them.
C1 keep it or loose it? What is the public opinion?
Isihkawa Jfets are linear 7.1mA/7.2mA with 10ohm resistors. With RV1 it's 9.3ohm.
Attachments
I can’t find it - to build two Ishikawa M2s (For an active system) which should I go for at the store -
- P Channel Quad (PPPP)
- Toshiba 2SJ74 Quad Idss 6-8mA - $45
- Toshiba 2SJ74 Quad Idss 8-11mA - $50
- NP Quad (NNPP)
- Toshiba 2SK170/2SJ74 Quad Idss 6-8mA - $40
- Toshiba 2SK170/2SJ74 Quad Idss 8-11mA - $45
A quad of each, but the preferred Idss?
Thank you
sov,
Yes, by stripped down Ishikawa, I meant without the trimmer pot, and with C1 shorted per the original Pass design. I also did not use C0 on the mother boards, as I have alot of tubed gear. Best of luck on your build! You will like it.
Yes, by stripped down Ishikawa, I meant without the trimmer pot, and with C1 shorted per the original Pass design. I also did not use C0 on the mother boards, as I have alot of tubed gear. Best of luck on your build! You will like it.
I am using the Ishikawa stripped-down input on my M2x. To me, it has a ”soft-focus” kind of sound — very easy to listen to but maybe not as detailed as I might want. I’m a little surprised, because I‘m usually sensitive to “bright” amps and don’t typically look for more treble. Of the standard M2x input cards, which would users say has a brighter treble Than Ishikawa? I have the amp in a hard to access place and would rather not try them all one by one. (Yes, I realize I’m not being a good DIYer.) Any suggestions would be appreciated.
Of the original set of input stages, I really like Austin. It has a clean, detailed sound that is easy to listen to all day. I like it so much that I adapted it to use as the input stage for my F6, which is running on higher voltage power rails.
Some time ago Burson sent me a couple of their V6 Vivid Dual Opamps to try with the M2x and the IPS7 daughterboard. It took me a while to reconfigure my system to listen to the M2x again and I wasn't able to compare them directly with the V6 Classic Single Opamps that I really liked before. I did set my system up to do a level matched A/B comparison with my Aleph J build.
I felt the M2x IPS7/V6 Vivid combination gave a more expansive soundstage with a more holographic feeling than the Aleph J while offering better definition and separation of the different elements of the music I listened to. Dynamics seemed better and the sound generally seemed like it had less congestion with a more open sound while still being rich. I liked the combination a lot. However, there was just a touch of glare on some tracks of female vocalists or brass instruments that the Aleph J didn't have. I noticed the same thing with a different amp later on and changing some of my cables resolved it so I am not certain the glare was actually due to the V6 Vivid.
Overall, I liked the M2x IPS7/V6 Vivid combination best of the various input stages I have tried and it has become my standard for when I listen with the M2x. One of the great features of the M2x is you can really change its sound signature with the different daughterboards and I have had so much fun with it.
Thanks for updating your listening impressions with the IPS7/V6 Vivid combination. The IPS7 and Cedarburg are intriguing updates to the M2x FE collection.
I have the parts for building a new dual-mono PSU in my old M2x. It was the only one of my FW clones that I built with a common PSU shared by both channels. While I tried several things to improve supply decoupling for the individual channels, it never had the same wide and detailed soundstage that my later builds had. Hopefully that will improve once I get around making the changes. After that, it will be time to try a couple new FE cards.
Some forum readers may have noticed that I am a loud proponent of dual-mono power supplies for new DIY builds. My experience with the M2x is why that is.
I have the parts for building a new dual-mono PSU in my old M2x. It was the only one of my FW clones that I built with a common PSU shared by both channels. While I tried several things to improve supply decoupling for the individual channels, it never had the same wide and detailed soundstage that my later builds had. Hopefully that will improve once I get around making the changes. After that, it will be time to try a couple new FE cards.
Some forum readers may have noticed that I am a loud proponent of dual-mono power supplies for new DIY builds. My experience with the M2x is why that is.
I'm receiving the rev.A PCBs tomorrow, of a VFET front end card that has two DIP sockets, just like IPS7. One of them accepts single opamps (e.g. LT1122) and the other accepts dual opamps (e.g. LME49720), just like IPS7. Each DIP socket sits in the middle of an otherwise empty ~~ 20 x 20mm zone on the PCB, where there's no other components, not even bypass capacitors. That appears to be large enough to accept many, but probably not all, discrete opamps. Either single or dual. (link to adapter idea)
Since the VFET amp's power supply is single ended (+36V, GND) while the IPS7's supply is bipolar (+21V, -21V), I didn't include the IPS7 bootstrapped supply rail concept in this VFET front end card. All of the usual disclaimers apply, including the reminder that it might or might not work, I might or might not decide to throw it away without releasing it, nobody knows the timeline (certainly not me), etc.
Since the VFET amp's power supply is single ended (+36V, GND) while the IPS7's supply is bipolar (+21V, -21V), I didn't include the IPS7 bootstrapped supply rail concept in this VFET front end card. All of the usual disclaimers apply, including the reminder that it might or might not work, I might or might not decide to throw it away without releasing it, nobody knows the timeline (certainly not me), etc.
Dang, if only there were a way for those of us without VFETs to actually build that amp! I'm still hoping Papa releases a design for those THF-51S devices he suggested we buy "while they last" nearly a year ago.
At some unknown date in 2022, "Ship Of Theseus" will be unveiled. It includes amplifier channels that fit in the VFET amp chassis, but use other semiconductor devices that aren't VFETs or SITs. It also includes PSU filter boards to clean up any SMPS grunge, which fit in the VFET amp chassis and replace the filter boards shipped with VFET amp kits. It also includes front end boards that aren't Scourge, Bulwark, Marauder, or Dreadnought. All Theseus boards are electrically compatible & interchangeable with the VFET originals, and fit in the original VFET chassis & bolt onto the original UMS pre-drilled, pre-tapped heatsinks from the original VFET chassis. The Front End card mentioned in #5774 is part of the Ship Of Theseus family, which N.P. managed to talk me into releasing early and standalone.
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You are not alone Paul! I have stashed some Tokins too and eagerly awaiting for the Kraken! 🙂
Hey TungstenAudio,
I'm interested in the dual mono PSU you mention. My current M2x build is the single PSU, single chassis stereo version. I have some background 60hz hum at idle that I have not addressed. Its barely noticeable. Neither my tranny or autoformers are shielded. You've got me thinking about a different layout with the PSU in a separate chassis. If I go that route, I may build dual mono PSUs. A couple questions for you. Do you house the dual mono PSUs in the same chassis? Or is your layout a monoblock, with each channel and PSU in a separate chassis? Any feedback on either style? Also, do you use a separate tranny for each mono PSU, if they share a chassis? I appreciate your inputs!
I'm interested in the dual mono PSU you mention. My current M2x build is the single PSU, single chassis stereo version. I have some background 60hz hum at idle that I have not addressed. Its barely noticeable. Neither my tranny or autoformers are shielded. You've got me thinking about a different layout with the PSU in a separate chassis. If I go that route, I may build dual mono PSUs. A couple questions for you. Do you house the dual mono PSUs in the same chassis? Or is your layout a monoblock, with each channel and PSU in a separate chassis? Any feedback on either style? Also, do you use a separate tranny for each mono PSU, if they share a chassis? I appreciate your inputs!
My rebuild of the M2x is currently in progress. I've attached a couple photos to show the prevous configuration and where things currently stand.
The original build used a single 400VA transformer inside a steel case, with the store's 'Universal' PSU board, a set of 22,000 electrolytics and discrete diode bridge rectification. This did have a noticeable amount of 120 Hz hum with my ear close to a speaker, but was not really noticeable when listening to music. I did try several measures to reduce hum and improve stereo separation, with mixed results. Probably the best improvement was replacing the conventional diode bridges with synchronous bridge rectifiers on separate boards (after removing the diode bridge portion of the PCB).
The new configuration will use a pair of Triad Magnetics 160VA VPT36-4440 transformers and two custom PSU boards that incorporate synchronous rectifiers and other features that I requested. The new PSU boards have a set of 33,000 uF electrolytics supplemented with 2200 uF on the output and 2.2uF film caps after the rectifiers. The component placement study in the second photo shows there is more room to move things around. I'm hoping that the smaller power transformers produce less magnetic interference. The initial listening tests will determine if more work is needed to reduce hum.
Note that the channel boards are placed toward the rear of the amp, in an attempt to reduce magnetic interference between the power transformers and the Edcor signal transformers. This chassis is 2.5U high (105mm internal) by 400mm deep, 365mm wide. Overall, I find it somewhat simpler to build a dual-mono supply in the same chassis as the rest of the amp. This approach worked well for my Aleph J and F6 builds. It is now time for the M2x to be brought up to date. When it came to build a linear PSU for my VFET lottery amp, an external chassis was necessary, as well as an umbilical power cord between the two. That also worked very well, as my VFET amp is completely silent when no music is playing.
The new chassis being introduced by Modushop will be worth considering if you want to try separate mono chassis. Otherwise, the closest single chassis would be the Dissipante 3U, 400mm deep.
The original build used a single 400VA transformer inside a steel case, with the store's 'Universal' PSU board, a set of 22,000 electrolytics and discrete diode bridge rectification. This did have a noticeable amount of 120 Hz hum with my ear close to a speaker, but was not really noticeable when listening to music. I did try several measures to reduce hum and improve stereo separation, with mixed results. Probably the best improvement was replacing the conventional diode bridges with synchronous bridge rectifiers on separate boards (after removing the diode bridge portion of the PCB).
The new configuration will use a pair of Triad Magnetics 160VA VPT36-4440 transformers and two custom PSU boards that incorporate synchronous rectifiers and other features that I requested. The new PSU boards have a set of 33,000 uF electrolytics supplemented with 2200 uF on the output and 2.2uF film caps after the rectifiers. The component placement study in the second photo shows there is more room to move things around. I'm hoping that the smaller power transformers produce less magnetic interference. The initial listening tests will determine if more work is needed to reduce hum.
Note that the channel boards are placed toward the rear of the amp, in an attempt to reduce magnetic interference between the power transformers and the Edcor signal transformers. This chassis is 2.5U high (105mm internal) by 400mm deep, 365mm wide. Overall, I find it somewhat simpler to build a dual-mono supply in the same chassis as the rest of the amp. This approach worked well for my Aleph J and F6 builds. It is now time for the M2x to be brought up to date. When it came to build a linear PSU for my VFET lottery amp, an external chassis was necessary, as well as an umbilical power cord between the two. That also worked very well, as my VFET amp is completely silent when no music is playing.
The new chassis being introduced by Modushop will be worth considering if you want to try separate mono chassis. Otherwise, the closest single chassis would be the Dissipante 3U, 400mm deep.
