Yamaha M-70 Thread

Discussion in 'Yamaha' started by Bratwurst7s, Jan 17, 2018.

  1. zaibatsu

    zaibatsu Well-Known Member

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    Thanks James,
    I actually meant the ones you used in this post:
    http://audiokarma.org/forums/index.php?threads/yamaha-m-70-thread.805670/page-10#post-11497534
    They looked thicker than the 3296 I've used in the past (I liked the idea of that because the 3296s can rock / bend a bit easy if bumped, just my OCD), but I realise now you shared the model already (3299-Y). It might just be my eyes and they're actually the same width? I'll check the spec sheet.

    Also I just noticed the finished pictures of the speaker posts, stunning work!
     
    Last edited: May 1, 2018

     

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  2. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    You are correct. I just looked at the datasheets and the 3299 body is 6.1mm thick (including the small stand-offs) and the 3296 are 4.85mm.

    Concerning the speaker posts, Thanks! I'm really happy with how they turned out. I just bought some 6mm² speaker wire to replace the 4mm² that I've been using. I just have to decide if I'm going to use bannana plugs, cable shoes or bare wire and then they will get switched.

    I just got notice that the MX-1 will finally ship today. He said that the shipping weight is 32kilos, so I have a feeling that DHL will decide that I wasn't home and deliver straight to the post office for pick-up.

    Cheers,
    James
     
  3. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So, finally. After 4.5 weeks and the single most aggravating ebay experience yet, the MX-1 arrived today.

    The seller was a complete jerk concerning shipment (went on vacation and didn't see to it that the package was picked up). But he did do a very good job of packaging. I'm only posting 1 pic here, the rest of that story will be told in the soon to be started MX-1 thread.

    DSC05319.jpg

    So now I can finally move forward with finishing the M-70. I've been enjoying it a lot the last month. As soon as I get the MX-1 opened up and finalize my cap choices I will finally dig back in with the '70.

    Cheers,
    James
     
  4. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    That MX-1 looks to be in great condition, nice pickup.
     
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  5. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Thanks! After only one song played I'm already thinking that it will never leave.

    My son asked what I'm doing with the M-70 now that I have the MX-1. I told him that it's going to a friend that wants it. I didn't lie. My son is a friend and I can tell that he wouldn't object to having the amp. ;)

    Cheers,
    James
     
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  6. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    No doubt it sounds excellent with plenty of headroom, l really like that simple yet stylish look also. I think all Yamaha's from this era with the slightly curved faceplates look very good.

    Exactly, no lie at all. Bet he will love it.
     

     

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  7. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    I placed a large order with Mouser today that included several different types of LEDs for the power switch. Orange, yellow and amber. I can't say that I fully understand the major difference between yellow and amber but will have both to try out. And since they have the Bourns 3296Y trimpots I bought some of them also.

    Cheers,
    James
     
  8. zaibatsu

    zaibatsu Well-Known Member

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    Stealth outside, serious business inside!

    Excited to see what's going into it.
    Also it sounds like your son wants the M-70, maybe if you string him along a little longer he'll buy his own and you can keep both. ;)
     
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  9. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Nah. I wouldn't know what to do with both of them. Besides, I'm running out of room.

    Cheers,
    James
     
  10. zaibatsu

    zaibatsu Well-Known Member

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    Kidding, suspect if that actually happened the family amp restoring expert would just end up with more work.

    Was meant to go in the MX-1 thread, oops!
     
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  11. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    I understood anyway somehow. The dancing LEDs of the M-70 brought back a lot of good memories of sitting in front of my old M-50 with friends and jamming to great tunes. But in truth they can be a bit distracting. I do like the quiet understated looks of the later CX/MX/AX gear. Just sits there looking like "Who? Me?". And then creates thunder and lightning. The M-70 has just a tad more sizzle on the upper end tho.

    Cheers,
    James
     
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  12. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    I now have a pile of 3x types of orange LEDs, 3x types of amber and 2x of yellow to play with, as well as some 20 turn trim-pots.

    Work has been brutal. Our little elevator dept is a 3 man shop. The foreman is seriously sick and has been out for 3 months now. The 2nd in command was sick for 3 weeks and just made it back to work. So I've been busyier than a 1 legged tap dancer.

    So I've been looking over at my workbench from time to time and thinking, "Yep. I'm gonna get busy with that thing real soon. Yep. Mebbe after I have another beer. Or tomorrow."

    Cheers,
    James
     
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  13. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    I finally started testing the LED's today. Again, I just used my bench PSU and pushed them into the switch glove. All of the orange ones are far too orange, almost getting into red. And the yellow ones actually look deep orange also. I've settled on a choice between 2x amber ones. They look pretty good, a light to medium orange. I'll make my choice tomorrow and take/post some photos.

    Cheers,
    James
     
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  14. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    OK. So this was a sucess concerning the power switch LED.

    The 2 finalists were both Cree oval amber, C566C-AFE-CU0W0252 and C566D-AFE-CV0X251. They are actually almost identical with the exception that the 1st one is 2500 mcd 70x35° and the 2nd one is 3200 mcd 70x30°. Both are 2.1v 20mA. And one nice thing, both of them don't have a flange that would have to be removed to let them fit full depth in the rubber glove. Their being oval didn't seem to make any noticeable difference in illumination. I used a 470 ohm 1/2w Vishay metal film resistor.

    https://www.mouser.de/ProductDetail...=sGAEpiMZZMtmwHDZQCdlqbg3pWP5pDcoxmiffd2FAUQ=
    https://www.mouser.de/ProductDetail...mwHDZQCdlqVFlG8iQtBnfJZFkxsXEIyfk2tXptEqoTA==

    DSC05490.jpg DSC05492.jpg DSC05493.jpg DSC05494.jpg DSC05497.jpg

    I ended up using the C566C-AFE-CU0W0252. It looks real nice in person, better than the photo shows.

    I wanted to get a lot more done today but ended up using most of the day removing our old dishwasher, oven and cooktop and cleaning the kitchen in prep for the new ones arriving tomorrow.

    LOL. I took the week off to decompress and play with some audio goodness. I've been working 9 hours+ a day building a cabinet bed, rearranging rooms, cleaning and etc. But at least I'm getting some extra points built up in the WAF account.

    Cheers,
    James
     
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  15. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Very nice, that amber looks spot on :thumbsup:.
     
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  16. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So I finally replaced the trim-pots for the meter (1k ohm) and ZDR (500 ohm) adjust, Bourns 3296Y-1-102LF and 3296Y-1-501LF respectively. I measured the old ones after removal and pre-set the new ones before installing them. There's no turning back now, tomorrow I'll have to hook up the heat sink and will start with setting the meters.

    While I was in there I decided to remove the KMH 18000µF filter caps and re-install the 22000µF ones. I didn't have any problems with the traces.

    The photos didn't turn out all that great but here they are fwiw.

    DSC05516.jpg DSC05518.jpg DSC05519.jpg DSC05521.jpg DSC05524.jpg

    Cheers,
    James
     
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  17. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    So setting the power output indicator LED's wasn't so hard. I had already bought a 75 ohm BNC->RCA cable so hooking up my frequency generator was straightforward. I did have to run it's output up to 5v to get enough gain to run the amp up to 40v. Using the speaker attenuator pots proved a bit tricky to tweak them to 40v. I had to accept 39.99v to 40.01, my fingers weren't able to get it any finer.

    Actually adjusting the indicator pots took little effort. I ran them down until the 200w LED went dim and then back up until it just turned bright. They were very close to begin with so having pre-set the pots before installing them proved to be very helpful. The were actually so close that I could have left them as they were but now I know how to adjust them. I also now know that I can run the amp up to full power without it blowing up. :)

    The amp heat sinks did get pretty hot by the time that I was done, and I'd say that it only took 1 to 2 minutes or so per channel to do the adjustment. My load heat sink barely got warm at all, but then it wasn't loaded for very long. I did have a couple of 12v fans ready to use but they weren't needed. I would have just hooked them up to my bench PSU if needed.

    I only took a pic of the left channel voltage, the right was at 39.99v.

    DSC05525.jpg DSC05526.jpg DSC05527.jpg

    Now I just need to do the ZDR pots. I have to admit that I haven't done anything with the QA400 analyzer up to this point except find and download the software and users manual pdf and the MS network driver needed. I'm reading through the manual and installing the software on my laptop this afternoon.

    Cheers,
    James
     
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  18. Oldsansui441

    Oldsansui441 AK Subscriber Subscriber

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    Nice job, looks like you have a great setup.
     
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  19. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    Thanks! I'm slowly getting there. I'd still like to buy an O-scope sometime this year.

    No new photos at the moment but this is my progress so far:

    I have the MS .net v4 package installed, as well as the QA400 software. It's been a while since I've done much of anything with Windows so when the device/usb dirvers didn't install automatically after plugging the analyzer in I was a bit stumped until I remembered to go to Device Manager and manually find/install the driver.

    After that the calibration went easy and I got the thing hooked up to the amp. But I am now very happy that I decided to buy that 2nd Fluke (79) meter because it's true RMS and that is needed to accurately measure/set the calibration.

    So. 3 things. First, because the analyzer is outputting in pulses it's impossible to exactly set the amp gain because that is also pulsing. Second, even using the differential probe the analyzer is showing clipping by the time that I raise the amp gain to roughly 10v, and I don't want to destroy the thing. Third, even at that level I don't believe the numbers that I'm seeing, it's showing roughly 49% THD, regardless of the gain level.

    The manual doesn't mention the differential probe at all and I haven't been able to find any documentation on it.

    So I have some things to figure out. ;)

    Cheers,
    James
     
  20. Bratwurst7s

    Bratwurst7s In The Frying Pan Subscriber

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    OK. I found one big problem. It's embarrassing, I'd rather sweep it under the rug than admit it but if what one sees can't be believed it's time to check the connections. Yep. I had the output going correctly to the right channel amp input but got dumb and had the diff probe hooked to the left channel analyzer input. Facepalm. :confused:

    I'll try it again tomorrow.

    Cheers,
    James
     

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