Heathkit W5M rebuilds
- Thread starter ab0ez
- Start date
Ah, I thought that might be the one you were talking about. I almost posted that link last night.
Seemed like the best of a sizable crop of Williams upmod articles. Much of it above my current
skill level, but a nice reference to have should I ever actually learn my way around a bench.
Seemed like the best of a sizable crop of Williams upmod articles. Much of it above my current
skill level, but a nice reference to have should I ever actually learn my way around a bench.
That's neat stuff in the paper. I'm relearning my basic electronics after having turned into a basic ham appliance operator over the years and I'm starting with studying and understanding the W5M schematic and how it all works.
Then I have to decide my next step. With the end goal of getting two of my monoblocks working well, and assuming I'm going to pull the 6146s out and go back to original KT66s (or similar), I see a couple of directions.
1. I could restore the circuit per Heathkit specs.
2. I could restore it with minor changes like some of those in the referenced Williamson circuit paper.
3. I could strip the chassis and start it as a 'new' kit.
As a start, and to understand the process better I'm leaning towards #1. Conventional wisdom seems to indicate that most/all of the caps need to be replaced, as well as anything else that appears to be faulty including some older sockets. On the other hand, I read in a blurb somewhere in my Internet search that it's really not always necessary to change out a lot of components just because of age. Considering the relatively small number of parts in the amp I'm thinking that replacing a lot of these things is relatively cheap insurance.
I'll be digging in to one of the Amps over the next week or so and see how it appears, and go from there. I haven't even taken the base plate off yet ;-)
Bill
Then I have to decide my next step. With the end goal of getting two of my monoblocks working well, and assuming I'm going to pull the 6146s out and go back to original KT66s (or similar), I see a couple of directions.
1. I could restore the circuit per Heathkit specs.
2. I could restore it with minor changes like some of those in the referenced Williamson circuit paper.
3. I could strip the chassis and start it as a 'new' kit.
As a start, and to understand the process better I'm leaning towards #1. Conventional wisdom seems to indicate that most/all of the caps need to be replaced, as well as anything else that appears to be faulty including some older sockets. On the other hand, I read in a blurb somewhere in my Internet search that it's really not always necessary to change out a lot of components just because of age. Considering the relatively small number of parts in the amp I'm thinking that replacing a lot of these things is relatively cheap insurance.
I'll be digging in to one of the Amps over the next week or so and see how it appears, and go from there. I haven't even taken the base plate off yet ;-)
Bill
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I've read in a few places (including post #2 here) that new sockets (especially
the rectifier) can save you lots of migraines down the road.
"...could not get the regulated voltage...to stabilize... Changing all
the components in the circuit did nothing. Changing the socket did. Lesson
learned. Although it looked fine to the eye, the dielectric in the tube socket was breaking down."
the rectifier) can save you lots of migraines down the road.
"...could not get the regulated voltage...to stabilize... Changing all
the components in the circuit did nothing. Changing the socket did. Lesson
learned. Although it looked fine to the eye, the dielectric in the tube socket was breaking down."
DanO55
Radar - BSFR
I would, but that is just me.
Option one is were I would start too. Unless there has been a safety related correction on a particular amplifier I usually go for a "factory" level restoration first then go from there. However and comma, if I have already done a few units of the same model before, I will go ahead and make the "improvements" as I rebuild. IMO just because someone has come up with a modification it isn't always a good one in my book. For example: The Dynaco Stereo 70 probably has more modifications, improvements, changes, etc. than just about any amplifier on the planet. If my stereo 70 was my main rig and I used it everyday, I too would probably change out the original board, do away with the 7199s, add this or take away that, you know. But and comma, there is something to be had in keeping a unit "as designed".
The 70 is by no means the greatest amplifier every made. However, when they hit the market they brought "Hi-Fi" to the great unwashed masses such as myself. Of course, swap out old electros, change out the coupling caps to newer and improved ones with better sonic characteristics, dump any out of tolerance resistor, etc. I kinda like my 70 sounding like, well, a Dynaco Stereo 70. Also, sometimes a darn near mint condition dynaco with factory labeled tubes can fetch much more on the sale market then one that has been modded big time. Of course others will disagree, but since I have over 25 amps to swap in and out of my listening systems, I am the only one I have to please.
Option one is were I would start too. Unless there has been a safety related correction on a particular amplifier I usually go for a "factory" level restoration first then go from there. However and comma, if I have already done a few units of the same model before, I will go ahead and make the "improvements" as I rebuild. IMO just because someone has come up with a modification it isn't always a good one in my book. For example: The Dynaco Stereo 70 probably has more modifications, improvements, changes, etc. than just about any amplifier on the planet. If my stereo 70 was my main rig and I used it everyday, I too would probably change out the original board, do away with the 7199s, add this or take away that, you know. But and comma, there is something to be had in keeping a unit "as designed".
The 70 is by no means the greatest amplifier every made. However, when they hit the market they brought "Hi-Fi" to the great unwashed masses such as myself. Of course, swap out old electros, change out the coupling caps to newer and improved ones with better sonic characteristics, dump any out of tolerance resistor, etc. I kinda like my 70 sounding like, well, a Dynaco Stereo 70. Also, sometimes a darn near mint condition dynaco with factory labeled tubes can fetch much more on the sale market then one that has been modded big time. Of course others will disagree, but since I have over 25 amps to swap in and out of my listening systems, I am the only one I have to please.
Kegger
R.I.P. 1/12/1966 - 6/1/2017
Also keep in mind any mod you do is reversible. 
As long as you don't cut up the chassis anything you do to the amp/amps can be put
back to "stock" if you wanted to for resale or any other reason you may wish later on.
(just keep any boards or non cap/resistors parts removed an save them)
--
Also if what you're going to do to the piece improves it from your point of view there's
really nothing I see reasonable that should hold back from making those improvements
over keeping something stock just for sake of keeping it stock, I never got that whole
"keep it original" deal, IF there is room for improvement I want the improvement.
But I'm a tinkerer, and feel nothing is as best as it could be, there's always something
that was a cost cutting move or design that wasn't quite tweaked as best it could be.
Wanting to hear something in original form first though to compare is a fine way to go.
Then go ahead and make any changes/improvements so you have a baseline, for some
though that means rebuilding it twice, and it's not always financially or time conducive.
As long as you don't cut up the chassis anything you do to the amp/amps can be put
back to "stock" if you wanted to for resale or any other reason you may wish later on.
(just keep any boards or non cap/resistors parts removed an save them)
--
Also if what you're going to do to the piece improves it from your point of view there's
really nothing I see reasonable that should hold back from making those improvements
over keeping something stock just for sake of keeping it stock, I never got that whole
"keep it original" deal, IF there is room for improvement I want the improvement.
But I'm a tinkerer, and feel nothing is as best as it could be, there's always something
that was a cost cutting move or design that wasn't quite tweaked as best it could be.
Wanting to hear something in original form first though to compare is a fine way to go.
Then go ahead and make any changes/improvements so you have a baseline, for some
though that means rebuilding it twice, and it's not always financially or time conducive.
vinylkid58
Super Member
It's nice to get a good variety of feedback. Looks like I WILL go to option 1. As a couple of you said, I can always mod from there if I want/need to. I like the idea of doing the basics (again, my learning curve) and then checking out the "what if" ideas.
I've been through this with a couple of cars... at first I wanted my old Alpine to be stock original. Then I decided I didn't want to mess around with the dual-carb setup and opted for a single barrel Weber. At that point I realized, "who cares?" It's my car and the "original" police aren't established yet! So the same will go for my W5Ms, I guess. Make ME happy first, then we'll see how it goes.
Now, back to boning back up on basic electronics theory. When I first studied it in the 60s it was only pass my ham tests. I just wanted to operate - not one of the tinkerers. I've forgotten almost all of it, but now that I'm interested it's making more sense to me. Only 50 years too late
I've been through this with a couple of cars... at first I wanted my old Alpine to be stock original. Then I decided I didn't want to mess around with the dual-carb setup and opted for a single barrel Weber. At that point I realized, "who cares?" It's my car and the "original" police aren't established yet! So the same will go for my W5Ms, I guess. Make ME happy first, then we'll see how it goes.
Now, back to boning back up on basic electronics theory. When I first studied it in the 60s it was only pass my ham tests. I just wanted to operate - not one of the tinkerers. I've forgotten almost all of it, but now that I'm interested it's making more sense to me. Only 50 years too late
Capacitor sources
Now that I'm beginning the teardown of one of my W5Ms (one of the ones that was butchered up to take a 6L6), I'm looking for the replacement parts. I really want to try and maintain some semblance of originality at this point, just so I have a good reference for sound and so I can have some experience before I tackle the other ones. I see that some of the caps are difficult/impossible to get, but maybe I'm not looking in the right places.
The most obvious source seems to be Antique Electronic Supply, but are there others to choose from?
Has anyone looked at or used this circuit board?
http://www.quadesl.com/pdf/w5m_board.pdf
Bill
Now that I'm beginning the teardown of one of my W5Ms (one of the ones that was butchered up to take a 6L6), I'm looking for the replacement parts. I really want to try and maintain some semblance of originality at this point, just so I have a good reference for sound and so I can have some experience before I tackle the other ones. I see that some of the caps are difficult/impossible to get, but maybe I'm not looking in the right places.
The most obvious source seems to be Antique Electronic Supply, but are there others to choose from?
Has anyone looked at or used this circuit board?
http://www.quadesl.com/pdf/w5m_board.pdf
Bill
soundmotor
super modified
No, not with that part. However, my experience with Sheldon is that anything he's done has a ridiculous amount of effort & evaluation put into it.
Ridiculous good, I'm hoping?
phoenixjazz
New Member
Big Thanks to AB0EZ and all the rest for this thread!
Not sure if AB0EZ still checks in here but if you are reading this I'd love to get your schematic and any new thoughts you have on this subject these few years on....
I've just obtained a pair of these that have been sitting idle for 20 years or more. All the iron checks out good and I've been looking into the work to do a restoration/mod project right and this is the best resource I've found so far.
As part of the deal I also picked up a pair of Altec 9844a monitors which I can't wait to get hooked up and running on the restored amps.
I promise, Steely Dan Pretzel Logic will break them in....
Thanks again folks.
Chris
Not sure if AB0EZ still checks in here but if you are reading this I'd love to get your schematic and any new thoughts you have on this subject these few years on....
I've just obtained a pair of these that have been sitting idle for 20 years or more. All the iron checks out good and I've been looking into the work to do a restoration/mod project right and this is the best resource I've found so far.
As part of the deal I also picked up a pair of Altec 9844a monitors which I can't wait to get hooked up and running on the restored amps.
I promise, Steely Dan Pretzel Logic will break them in....
Thanks again folks.
Chris
ab0ez
AB0EZ
Hi Chris,
I've been away for a while getting a new left titanium & teflon shoulder. Now I'm rehabing the arm/shoulder and just now able to get back into the swing of things.
http://www.audiokarma.org/forums/showthread.php?t=553493&highlight=Heath+W5M
Here's a thread on W5M amps I'm about 90% done with that has some changes vs this build. What are your goals with your amps, Chris?
I've been away for a while getting a new left titanium & teflon shoulder. Now I'm rehabing the arm/shoulder and just now able to get back into the swing of things.
http://www.audiokarma.org/forums/showthread.php?t=553493&highlight=Heath+W5M
Here's a thread on W5M amps I'm about 90% done with that has some changes vs this build. What are your goals with your amps, Chris?
He's baaa-aack!! I'm glad this thread got a nudge. 
Showed up in my
notifications and steered me to the new thread ab0ez mentions - which
I'd been unaware of. :tresbon:
I've been sitting for a couple years on a pair of
later W5-M's that, by the look of things under the hood, shouldn't sound
too bad but are, in fact, pretty underwhelming.
Not horrible, but
my Pilot 232's blow them out of the water sideways (even the un-restored
one). Maybe in a couple of years when my back-order of round tuits gets
in, I'll try doing something about these W5's. Meantime, I keep lurking
and learning from threads like these. :thmbsp:
ab0ez, I hope your shoulder is shaking down OK and the therapists aren't
too sadistic.
Showed up in my notifications and steered me to the new thread ab0ez mentions - which
I'd been unaware of. :tresbon:
I've been sitting for a couple years on a pair of
later W5-M's that, by the look of things under the hood, shouldn't sound
too bad but are, in fact, pretty underwhelming.
Not horrible, butmy Pilot 232's blow them out of the water sideways (even the un-restored
one). Maybe in a couple of years when my back-order of round tuits gets
in, I'll try doing something about these W5's. Meantime, I keep lurking
and learning from threads like these. :thmbsp:
ab0ez, I hope your shoulder is shaking down OK and the therapists aren't
too sadistic.
ab0ez
AB0EZ
Hey Hannibal, I'm kinda-sorta back. Still under weight restrictions on the left arm, etc. I'm doing all of my arm rehab at home. The doc that did the surgery at the University of Washington and I got to know each other pretty good and he realized I am a pretty hardcore (and old) athlete and I would push myself to the limit with the new shoulder. Apparently, the worst thing possible to do after this kind of a surgery is to not do enough. No problem there!
In the meantime, I'll start working on the schematic for the latest version of the W5M in the newer thread I previously linked to. That version is the bomb. Done right, these are extremely capable amplifiers and eminently listenable for hours on end.
In the meantime, I'll start working on the schematic for the latest version of the W5M in the newer thread I previously linked to. That version is the bomb. Done right, these are extremely capable amplifiers and eminently listenable for hours on end.
