Am I the only one thinking about using replaceable daughter boards, M2x-style?
With Toshiba Jfets being largely unobtanium, it means we can use input stages with different, more readily available components. Shouldn't be difficult to adapt the concept to Tea-bag's boards. Just add female headers and plug in a board.
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With Toshiba Jfets being largely unobtanium, it means we can use input stages with different, more readily available components. Shouldn't be difficult to adapt the concept to Tea-bag's boards. Just add female headers and plug in a board.
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You'd want to avoid the Osborne effect, or else the sales pipeline could be full of last generation PCBs, whereas customers only want the next generation PCBs. Somebody will have to eat the cost of all of that unwanted inventory. Somebody (else?) will have to cough up the NRE cost of developing the new PCB, then prototyping and testing it.
I was thinking DIY daughter boards to fit Tea-bag's boards, Mark. To me that means "home made" and maybe even p2p construction since some are so simple with low parts count.
Can't see how that should influence any production boards of Tea-bag's or yours (M2x).
The diyAudio forum is full of suggestions for improvements. Why would my idea be any different? Unless you feel that your M2x daughter board circuits shouldn't be copied for private use.
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Can't see how that should influence any production boards of Tea-bag's or yours (M2x).
The diyAudio forum is full of suggestions for improvements. Why would my idea be any different? Unless you feel that your M2x daughter board circuits shouldn't be copied for private use.
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Ah, I misunderstood; I thought you proposed to re-layout the M2clone and make it a motherboard. Do whatever you like, with applause (but not technical support) from me. There is an ancient and noble tradition of "air wired" modifications to audio equipment going back at least to the 1950s, if not earlier. Today most of it is a PCB full of SMD discretes that plugs into a dual opamp socket, or an LM7815 voltage regulator footprint.
I suspected as much.
But, it's reassuring to have your blessing to use your ideas and circuits, Mark. You're doing exceptional work and I respect you for that. Fact is, you announced the M2x barely an hour after I pulled the trigger on buying Tea-bag's boards. Had I waited a bit, I would most probably have ordered M2x boards!
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A 3U 300mm is just on the edge of being too small. 3U 400 would be fine. 4U 300 is considered normal.
The difference with making it successful is having sufficient ventilation above and below the heatsinks. Elevate the amp 30mm+ up from the surface it's set on and have 100mm+ of space above the heatsinks and the natural convection will happen unhindered.
The difference with making it successful is having sufficient ventilation above and below the heatsinks. Elevate the amp 30mm+ up from the surface it's set on and have 100mm+ of space above the heatsinks and the natural convection will happen unhindered.
follow up heatsink question...
mini dissipante 200mm 2U is sufficient for 34W from 24V ACA 1.6.
So 300mm 2U should be OK for 50% more (~50W)
M2 with 0.56 ohm source resistors and 19.5V rails will pull 1.1A and mosfets will generate 41W per channel. so this should be OK...
Will the boards fit a 2U chassis?
Am I missing anything here?
mini dissipante 200mm 2U is sufficient for 34W from 24V ACA 1.6.
So 300mm 2U should be OK for 50% more (~50W)
M2 with 0.56 ohm source resistors and 19.5V rails will pull 1.1A and mosfets will generate 41W per channel. so this should be OK...
Will the boards fit a 2U chassis?
Am I missing anything here?
Just a quick update for my build:
I keep forgetting to order the right amount or always missed some parts. Thus...no testing yet.
I reused my humongous 10uF red Wima from the other project. (almost as big as the Edcor transformer)
I am tempted to try Gold/silver oil for 0.1uF and 1uF bypass caps after listening to my friend's Whammy headphone amp which was equipped with 2 expensive Gold/Silver oil caps.
That really shocked me: extreme clarity, 3D feel, romantically beautiful; only that the bass is a bit too much for my age.
The boards are very nice; my solder gun might be too hot and made some brownish burn marks around.
That's it! more to come later.
I keep forgetting to order the right amount or always missed some parts. Thus...no testing yet.
I reused my humongous 10uF red Wima from the other project. (almost as big as the Edcor transformer)
I am tempted to try Gold/silver oil for 0.1uF and 1uF bypass caps after listening to my friend's Whammy headphone amp which was equipped with 2 expensive Gold/Silver oil caps.
That really shocked me: extreme clarity, 3D feel, romantically beautiful; only that the bass is a bit too much for my age.
The boards are very nice; my solder gun might be too hot and made some brownish burn marks around.
That's it! more to come later.
Attachments
I don't want to discourage anyone from tweaking. It took me some tweaking to come up with the recommended components I listed.
I did not find changing the input caps around in the M2 to alter the sound too much. I am not certain why. I assume the Edcor dominates the signature sound. Changing the Mosfets was big, signal resistors a little. The Wima bypass I used over the Elna 10uf may have brought a little more air to it. It may be that the Elna and Edcor are both a little lush, so kind of adds to the smoothness, but may harm resolution ??
I know this. Because of hot weather, I took the M2 out of office system (which I use a yamaha 9.1 receiver on currently.) and went to use the speaker outputs off the Yamaha....Such a loss of sound quality, its sterile tone deaf and generally uninvolving. It does however keep the M2 from overheating my office space when it is 30c outside.
Thanks for helping us save money! It is good that you have tried so that we won't have to. ;-)
What about opting for the Audio Note tantalum resistors? Will that make a positive impact?
Can't wait to build mine.
Eleven percent greater supply voltage means eleven percent greater power dissipation(*) that the heatsinks must radiate into the air. Do you plan to increase the heatsink area by eleven percent?
(*) since the optocoupler bias circuit used in the M2, guarantees the amplifier's DC bias current remains rock solid and constant. Voltage rises 11% but current remains the same --> power dissipation rises 11%
(*) since the optocoupler bias circuit used in the M2, guarantees the amplifier's DC bias current remains rock solid and constant. Voltage rises 11% but current remains the same --> power dissipation rises 11%
completed the M2 build with 1530/201 mosfets
Thanks Tea-Bag and all the other members for their contributions to making these builds the pleasure it is. Your boards were great to work with. Had the Toshibas around and was glad to use them. Geez! the slam and drive. I am using the M2 for the low end and an Aleph J for the highs. Lowther/emminence on a OB. Just fantastic sound. Want to shift them to hear the M2 on top. Thanks again for all your effort.
Thanks Tea-Bag and all the other members for their contributions to making these builds the pleasure it is. Your boards were great to work with. Had the Toshibas around and was glad to use them. Geez! the slam and drive. I am using the M2 for the low end and an Aleph J for the highs. Lowther/emminence on a OB. Just fantastic sound. Want to shift them to hear the M2 on top. Thanks again for all your effort.
Excellent. It does have suprising bass. Do try on top.
Your speaker system sounds like mine, I use an OB Lowther.
Can you publish all resistor changes here for reference, now that it is working?
I want to edit the BOM if possible for these changes. It gets asked of me frequently.
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