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Kenwood M2/M2A Restorations, Upgrades, & Mods

ajfink

ajfink

Member
Hi all,

I know there are several of us interested in what's available for these amps. I'm grouping them together since, while there are differences (Sigma Drive in the M2, which the M2A doesn't have, the Super DLD board in the M2A, which the M2 doesn't have), they're very similar amps.

Goals
  • To compile tips, schematics, parts lists, and other resources for easy reference, and provide a thread for ongoing discussion about the above

Existing Resources
Dan at DRM Audio provides further, extensive documentation with his kits, but I will not share them without his permission.
 
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Phaceless56 said:
you are replacing the 5200uf 56v with a 8200uf 63v the capacitance and voltage are higher value whats the benefit in this ? what about the 10,000uf 71v and 100v
Click to expand...

@Phaceless56 I upped the capacitance to...increase the capacitance/storage value of the Super DLD board. Basically, more better. I upped the voltage threshold because I typically like to add further buffer. It isn't necessary. Might help with longevity? Maybe? Given the height limitation for the capacitors on this board (~35mm), any replacements really just need to match the electrical characteristics and be short enough. They don't need to over-shoot.

I haven't replaced the main filter capacitors in my M2A yet simply because of cost. Both sets are relatively high-capacity and high-voltage, and I'd want them to be from brands I trust. I did add some film bypasses, but as with many people I'm unconvinced as to whether or not they matter.

I have fully recapped my M2A, similarly upping the voltage when possible, and the lower-value electrolytics are all replaced with WIMA films. The 1.0uf, 2.2uf, and even 4.7uf MKS2 series are reasonably priced, but they really need to be the MKS2/02 series, since these have the 5mm lead spacing workable as electrolytic replacements.

More to come, time to walk to the market....
 
Thanks for that ajfink this is going to be fun I will start collecting parts, already got the list going and yes I saw the price on the Capacitors size is an issue so let the fun begin
 
yeah I have a good idea what he means I looked at the data sheet it say one positive one negative and two dummy connectors that ground thru the electrolyte I think I read that right so the two I use will have to modify the connectors on the caps or drill out the PCB I will see when they arrive
 
I picked up a Basic M1a this weekend for $80 in very good working order which I will one day do a recap nice amp I was impressed so now I have a few projects that should keep me occupied for a time
 
Hi all,

Swinging back through with some pictures of an in-progress Dan Mattis output kit installation.

New vs old outputs and heatsinks. The old boys are disgusting - I bought this off of eBay and there was zero mentions of this having belonged to a smoker. I've cleaned this thing pretty thoroughly, sitting it on one end andland drenching it with rubbing alcohol from a spray bottle, getting in there with q-tips and paper towels, etc. Dunked the main cover, filter capacitor bracket, and bottom cover grill in soapy water and scrubbed - still has some smell to it. Hoping that the recap helps by getting rid of some surface area that's been contaminated.

This was also previously in a damp environment. There are rusty spots on the inside of the chassis and on the transformer casings. I bought some Fartan rust treatment to help stop these in their tracks, this the brownish look to the transformer side you see here.

Still to go: recap, installing the new pre-drivers, and installing the new heatsink and output ribbons.

Then, a head-to-head with a recapped but otherwise stock M2A.
 

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thanks for the update. i've been very curious how this project was progressing. I've kept an eye out for a M2 or M2a power amp. Don't need it (have a big yamaha and a Citation 22 on the shelf) but I like the M1 and my maggies like power.
 
Well, I did it.

20200625_215022.jpg

My kit was short a silicon insulator, so I snuck in a mica insulator from the original driver transistors:
20200625_215032.jpg

Hey there there new caps:
20200625_215051.jpg

Films where possible. I DO NOT RECOMMEND settling for the huge Panasonic 4.7uf capacitors if the WIMAs MK2's aren't available. Too big, will probably swap these out. One is in physical contact with the heatsink.
20200625_215102.jpg

Also Dan Mattis' wiring is much prettier than mine. Don't judge, let's see how well you do.
20200625_215111.jpg
 
@ajfink, still like your m2a?

I just got one. I checked DC offset, set bias to factory specs, fixed the broken RCA connectors, and general cleanup.

Works on the bench and hope to move it to the main rig tomorrow.
 
rickl said:
@ajfink, still like your m2a?

I just got one. I checked DC offset, set bias to factory specs, fixed the broken RCA connectors, and general cleanup.

Works on the bench and hope to move it to the main rig tomorrow.
Click to expand...

I sure do - it's my daily driver, with some vintage Magnepans attached. I have a second one with original driver and output transistors I need to find a use for.

Do you plan on doing any more restoration work?
 
i was over on Dan's site looking at the various updates he has developed.

I want to listen to it for a bit before any updates. I just wanted it working for now. I did add a grounded IEC connector (amp didn't come with a power cable) so I can't just plug it into my C2 convenience outlet.

I really don't need it with my L mono blocks/Maggies but really wanted see what the fuss is all about. plus I have a big yamaha power amp and a citation 22 if i need a lot of fire power.
 
I think all the basic family amps have the SDLD, I am thinking about getting one, which one is the best
M1
M1A
M1D
M2
M2A
Can you guys help me out ?
 
Hi forgive me for posting this to this old thread, but I'm wondering if anyone has tried recently to reach Dan's site at DRM audio. I keep getting a message saying it cannot provide a secure connection when using the Chrome browser or Safari. I realize you guys aren't administrators for his site but is everybody having this experience? Is there a work around?
 
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