to xrk971 #2397
Hello xrk971,
I reply to your post in #2379.
I agree with you. M2X + B1 NUTUBE - Preamp can be pretty sweet. This depends on your adjustments in the B1 NUTUBE. If you start to play with the
trimpots in the B1 NUTUBE, play with polarity at the output of your poweramp (B1 NUTUBE is inverting polarity)
(positive/negative H2) and then you change the inputboards of your M2X -
this is a big playground!
I prefer to drive my M2X with my BA-3 Preamp or the good old ALEPH P1.7.
But this is my personal taste. But I also like my B1 NUTUBE!
Play around with this beautiful amp and -
Enjoy the music!
Greets
Dirk
Hello xrk971,
I reply to your post in #2379.
I agree with you. M2X + B1 NUTUBE - Preamp can be pretty sweet. This depends on your adjustments in the B1 NUTUBE. If you start to play with the
trimpots in the B1 NUTUBE, play with polarity at the output of your poweramp (B1 NUTUBE is inverting polarity)
(positive/negative H2) and then you change the inputboards of your M2X -
this is a big playground!
I prefer to drive my M2X with my BA-3 Preamp or the good old ALEPH P1.7.
But this is my personal taste. But I also like my B1 NUTUBE!
Play around with this beautiful amp and -
Enjoy the music!
Greets
Dirk
Hello xrk971,
I reply to your post in #2379.
I agree with you. M2X + B1 NUTUBE - Preamp can be pretty sweet. This depends on your adjustments in the B1 NUTUBE. If you start to play with the
trimpots in the B1 NUTUBE, play with polarity at the output of your poweramp (B1 NUTUBE is inverting polarity)
(positive/negative H2) and then you change the inputboards of your M2X -
this is a big playground!
I prefer to drive my M2X with my BA-3 Preamp or the good old ALEPH P1.7.
But this is my personal taste. But I also like my B1 NUTUBE!
Play around with this beautiful amp and -
Enjoy the music!
Greets
Dirk
You mean post 2397? I do not have the Korg B1, just commenting on Elwood's data.
Looks like an awesome system & what are those speakers?
On the MQA thing: sorry to nitpick but MQA is not 24bits. MQA is a lossy codec that at best provides 15-17bits and no more than 48k resolution.
It's been marketed as a high-resolution streaming solution equivalent to true 24/96 and higher resolutions but technical analysis has shown these claims to be untrue.
More info on MQA can be found here:
MQA: A Review of controversies, concerns, and cautions - Reviews - Audiophile Style
Currently only Qobuz offers true uncompressed high-rez streaming and afaik it's available in the US now.
Speakers are OBL-15 by Troels Gravesen:
OBL-15
I am very happy with the system as is right now.
When I used an external DAC and let the streamer node do the MQA decoding in software then most often the 24/96 LED was "active". So the playback was at least 24 bit in most cases. But if the "true resolution" is less then the "extra" bits are "filled in" by the decoder. We will probably hear more about that…….what is true and false. The streamer node I use now has a MQA hardware decoder so it can go to 24/192 but it does not indicate the resolution.
Often the same "CD" is available in both CD and MQA quality. I have tried A/B listening test but would not be able to pass a blind test.
I will have a look at Qobuz.
More about MQA here…..which of course is not objective:
MQA
It should be a "quality" which is "authenticated" by the performers and is sold as being studio quality.
OBL-15
I am very happy with the system as is right now.
When I used an external DAC and let the streamer node do the MQA decoding in software then most often the 24/96 LED was "active". So the playback was at least 24 bit in most cases. But if the "true resolution" is less then the "extra" bits are "filled in" by the decoder. We will probably hear more about that…….what is true and false. The streamer node I use now has a MQA hardware decoder so it can go to 24/192 but it does not indicate the resolution.
Often the same "CD" is available in both CD and MQA quality. I have tried A/B listening test but would not be able to pass a blind test.
I will have a look at Qobuz.
More about MQA here…..which of course is not objective:
MQA
It should be a "quality" which is "authenticated" by the performers and is sold as being studio quality.
The following articles are not for arguing purposes nor comments, just for information reading :
Here read the 1st post :
24bit vs 16bit, the myth exploded! | Headphone Reviews and Discussion - Head-Fi.org
Here is just an article :
24/192 Music Downloads are Very Silly Indeed
Here read the 1st post :
24bit vs 16bit, the myth exploded! | Headphone Reviews and Discussion - Head-Fi.org
Here is just an article :
24/192 Music Downloads are Very Silly Indeed
You think so ? Not my intention at all ! Lets move it somewhere else then or cancel it all together.
I think one of the reason my M2X mono blocks is a success is that it is easy to drive using a passive pre and this gives me the perfect amount of amplification. When passive pre is set to 2-o'clock it plays quite loud when playing blues, jazz, rock etc. and perfect loud when playing classical music. So depending of mood and time of day the vol. settings is from 11 o'clock to 3 o'clock which is perfect. Then I don't add additional noise from an active pre. If I should experiment I could try just a B1-bufffer but I don't feel the need for it in the moment (it will just add noise). It is very dynamic as is. I have never felt that a passive pre "kills" the "dynamic". My RCA cables are also on the short side (75 cm) and my Bluesound node has a good output driver. I like RCA connectors that you can "twist lock" (like WBT). I have experienced bad RCA connectors even on quite expensive cables. The Supra cables I use are just perfect (price/quality).
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I have a Korg. He is "sleeping" in the moment. It sounded really good with MoFo but with M2X the amount of amplification was way too much. The 10k 24 step Goldpoint attenuator is a much better combination. Input board in M2X is Tucson with OPA604. Next input board to try will probably be Norwood. Until now Tucson is the only one I have tried.
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Talk about a Zen design, the board looks empty. This amp is so cool! This is one project where listening to the end product is so? Smile worthy? It has replaced my McIntosh as the primary amplifier, no contest, I now use the Mc for preamp inputs since it has a built in tuner and phono and DAC.
I have had my M2X running for a couple of months now, it replaced a Copland CSA29 integrated hybrid.
I use a B1 mesmerise ten years after pre.
To be totally honest, I have not heard my stereo sound so good ever.
Speakers are 92dB sensitivity and an easy 8 ohm load.
Using a valve gain stage for the TT, CD is good as is gain wise.
Thank you so much all of those involved with the design and sharing of this fantastic amp.
I think my total cost was around $1500 aussie.
I use a B1 mesmerise ten years after pre.
To be totally honest, I have not heard my stereo sound so good ever.
Speakers are 92dB sensitivity and an easy 8 ohm load.
Using a valve gain stage for the TT, CD is good as is gain wise.
Thank you so much all of those involved with the design and sharing of this fantastic amp.
I think my total cost was around $1500 aussie.
I've been getting ready to build a few additional FW designs, but the M2x is still getting a ton of play time. Since it was my first speaker amp project, I've been a bit paranoid about monitoring how well it holds up (related to my build quality).
I am currently swapping out C2 for the recommended Nichicon cap, and I was swapping over to the Austin boards from Norwood. Every time I get inside the amp, I check everything over. I started with the left channel. Since I had to remove the boards from the heatsinks to swap the caps, I checked for continuity between all three legs of the 9240s and the heatsinks after remounting the board. My observations trouble me. Since memory is a tricky thing, I need some help, please.
It may help if I denote the 9240s Q1R, Q2R, Q1L and Q2L. Keratherm pads and the mounting kit from DIY store were used, and the amp has been a total delight with no issues to this point.
1) Observations after re-mounting the left channel (after the cap swap).
The drain leg of both Q1L and Q2L are shorted to the center bolt / washer holding the FETs to the heatsinks and thus to the ground on both the amp boards and chassis ground. I see no holes in the Keratherm or anything that would give me pause.
2) Observations for right channel. This channel was untouched and has been running this way for months. I have not unmounted the board.
The drain leg of ONLY Q2R is shorted to the bolt / sink / etc. Q1R shows no continuity to the heatsink / center bolt.
I went through all my build notes, and could not find the appropriate section... but I thought NONE of the pins should short to the heatsinks.
Could someone please confirm and/or comment. I do not want to proceed w/o furthering my understanding. Any thoughts for troubleshooting are greatly appreciated. It seems odd to me that the amp has been functioning without flaws and sounding great for months with this potential "defect". I know I checked for continuity during final assembly.
With thanks as always.
Edited to add - if it helps, the resistance between the mounting bolts and the GND 0 tab on the boards is roughly 11 Ohms for the 3 FETs showing a short.
Edited to add again - SHEESH - I hope my goofs help some others. Because I didn't want to disconnect everything to take out the boards, I left the output signal wire and the PSU attached to the boards. DOH! I found my notes, and I checked continuity BEFORE powering up the boards and hooking up the power supply and outputs. So, looking at the schematic explains the drain to ground continuity. However, any reasons or concerns that Q2R drain does not show continuity like the left channel with the amp wired to operate (with PSU and output connected)? Thanks again!
I am currently swapping out C2 for the recommended Nichicon cap, and I was swapping over to the Austin boards from Norwood. Every time I get inside the amp, I check everything over. I started with the left channel. Since I had to remove the boards from the heatsinks to swap the caps, I checked for continuity between all three legs of the 9240s and the heatsinks after remounting the board. My observations trouble me. Since memory is a tricky thing, I need some help, please.
It may help if I denote the 9240s Q1R, Q2R, Q1L and Q2L. Keratherm pads and the mounting kit from DIY store were used, and the amp has been a total delight with no issues to this point.
1) Observations after re-mounting the left channel (after the cap swap).
The drain leg of both Q1L and Q2L are shorted to the center bolt / washer holding the FETs to the heatsinks and thus to the ground on both the amp boards and chassis ground. I see no holes in the Keratherm or anything that would give me pause.
2) Observations for right channel. This channel was untouched and has been running this way for months. I have not unmounted the board.
The drain leg of ONLY Q2R is shorted to the bolt / sink / etc. Q1R shows no continuity to the heatsink / center bolt.
I went through all my build notes, and could not find the appropriate section... but I thought NONE of the pins should short to the heatsinks.
Could someone please confirm and/or comment. I do not want to proceed w/o furthering my understanding. Any thoughts for troubleshooting are greatly appreciated. It seems odd to me that the amp has been functioning without flaws and sounding great for months with this potential "defect". I know I checked for continuity during final assembly.
With thanks as always.
Edited to add - if it helps, the resistance between the mounting bolts and the GND 0 tab on the boards is roughly 11 Ohms for the 3 FETs showing a short.
Edited to add again - SHEESH - I hope my goofs help some others. Because I didn't want to disconnect everything to take out the boards, I left the output signal wire and the PSU attached to the boards. DOH! I found my notes, and I checked continuity BEFORE powering up the boards and hooking up the power supply and outputs. So, looking at the schematic explains the drain to ground continuity. However, any reasons or concerns that Q2R drain does not show continuity like the left channel with the amp wired to operate (with PSU and output connected)? Thanks again!
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