I'm going to build a new amp...suggestions?

[Tube60]

I'm going to build a new amp!

Hi everybody
I've been given a fried Yamaha M-60 amplifier, and my plan is to gut it and do my own design, saving the cool output meters, that is if they still work! My plan is to do a tube design, using 4 or 6 6550's per channel, with Plitron power and output transformers. I'm indecisive about the front-end circuitry though. Currently I'm considering a triode front-end, but pentode or even MOSFETs run class-A would be a consideration. Thoughts? I'll be driving my Sequels with it.
Update: this is now a work in progress! Pics and updates as she goes! Still open to suggestions though!
Regards,
Ross

 

[Tube60]

Update:
Here's what I've got to work with. I started gutting it last night. So far so good!

 

[Tube60]

I've removed the output devices and the power transformer. I've left the main board in place for now, so I can pin-out the needed power, ground, and signal feeds for the output meters which I'll be saving. For the circuit itself, I've settled on 4 x 6550s per channel, with a triode front end. Minimal feedback and simplicity of the audio pathways will be the rule here. I'd love to direct-couple the drivers to the outputs, ala Loftin-White, but that's a little out of my league!
For what it's worth, recycling old dead stuff is a lot of fun, and keeps said stuff out of the landfill!

 

[Tube60]

My plan for recycling the output meters has come to naught. I found out last night that when the main board brewed up, the meters went with it. No big deal though. I can use aftermarket ones. No pics today since an empty shell isn't too exciting!

 

[Tube60]

My plan for recycling the output meters has come to naught. I found out last night that when the main board brewed up, the meters went with it. No big deal though. I can use aftermarket ones. No pics today since an empty shell isn't too exciting!

Gad! I'm quoting my own replies!
I took another look at the output meter board last night, and the damage isn't as bad as I thought. I'll make repairs and power it up in the next few days. Tonight I measure for the chassis plates and tube socket locations, so the water jet cutter operator can digitize them and load into the cutter. Hopefully I can take a photo of the cutting machine. It's pretty impressive.

 

[Jeff Zaret]

I guess quoting yourself is ok, as is talking to one's self. I think it may become an issue is where you argue with yourself and lose.

Jeff

 

[Tube60]

I guess quoting yourself is ok, as is talking to one's self. I think it may become an issue is where you argue with yourself and lose.

Jeff

"That's not the way to do it!!"
"Yes it is!!!"
"Shut up and let him talk! Mother always liked you best!!"
Like that?

 

[Jeff Zaret]

"Yes that would be it"
"No its not"
"Yes it is"
"Who said that?"

 

[Tube60]

Update:
The same friend who gave me the dead M-60 has also given me his equally fried M-80 as well. They both have pretty much identical chassis, and the front panels are exactly the same. My plan is to build a pair of 280w monoblocs, using a (possibly much) modified version of the amp design in the book Principles of Power by Kevin O'Connor. For those familiar with the book, it's on illustration 5-35 in the Design Pool section of the book. I like the circuit because it's dirt simple, but I'm going to configure the power supply to my tastes, and I may change the front-end circuit altogether. Not sure yet on that one. I had new chassis plates cut from 304 stainless sheet to go where the original circuit board used to be.
That's all for now, and once things get interesting I'll post some pics as I go.

 

[benleeys]

Update:
The same friend who gave me the dead M-60 has also given me his equally fried M-80 as well.

Your friend good at frying banana fritters too?

 

[Tube60]

Your friend good at frying banana fritters too?

:rocker: His elderly cat peed through the vents of the M-60, where said cat was having a nap. Incontinence and all that......
For the M-80, the small-value capacitors used as parasitic snubbers in all the (many) gain stages failed, which sent THAT amp up in smoke, although not quite so dramatically as in the M-60's case, not to mention a highly agitated cat not sailing across the living room!
To let ya all know, I ordered the power and filament transformers today! I'll be cutting metal and soldering stuff next week! Wish me luck!:cheers:

 

[MotorToad]

:rocker: His elderly cat peed through the vents of the M-60, where said cat was having a nap. Incontinence and all that......
For the M-80, the small-value capacitors used as parasitic snubbers in all the (many) gain stages failed, which sent THAT amp up in smoke, although not quite so dramatically as in the M-60's case, not to mention a highly agitated cat not sailing across the living room!
To let ya all know, I ordered the power and filament transformers today! I'll be cutting metal and soldering stuff next week! Wish me luck!:cheers:

NEAT! I can't wait to see it.

 

[benleeys]

T........o let ya all know, I ordered the power and filament transformers today! I'll be cutting metal and soldering stuff next week! Wish me luck!:cheers:

Good luck with the effort, Tube. In my younger days, I diy some too. Nothing like the satisfaction of seeing your sweat and tears turn out wonderfully successful.

Oh, by they way, I hope your friend wasn't half as mad as I was when my old tabby urinated on my precious Telefunken radiogram in the 60s. If not for my sainted mother I would have sent him to the gallows.

 

[IWalker]

Can't wait to see the pictures!!! and hear the build story. I haven't braved an amp project yet, so hopefully I can learn a lot from this.

 

[Tube60]

Can't wait to see the pictures!!! and hear the build story. I haven't braved an amp project yet, so hopefully I can learn a lot from this.

My philosophy is this: If you can, or learn how to, solder, and read a road map, anybody can build their own amp. And in the process go down a path of life and experience that one would not expect, and not many people these days would bother to do. Besides, here's the drill: What would a pair of 280 watt tube amps cost these days, if one just went down to a high-end audio store and plonked down an Amex card for the instant satisfaction? Maybe it's my Scottish heritage, but I'm very willing to go through the trouble of making my own to save the money!