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Heathkit W5M rebuilds

Those 500's are some sweet amps!

I always laugh when I hear the old "tube amps don't have good, tight and low bass." Makes me wonder if those naysayers have ever heard good, tight and low bass!

I don't think anybody that has ever heard my various amps play such content through my Cornwalls, Khorns, A7's, Koss 1020's, University Classics, or even an old pair of EPI 100's that I have has ever said "man, the bass sucks!"

Usually, it's something like "I feel the floor shaking" or "I never knew there was such low bass in that recording and I've heard that tune for years!"
 
ab0ez said:
...my various amps play such content through my Cornwalls, Khorns, A7's, Koss 1020's, University Classics, or even an old pair of EPI 100's ...
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Dang. Feel free to let me know next time you're having a party! I'll bring "Pretzel Logic"!
 
And I forgot to add - those W5's look beautiful. Congratulations. Can't wait to see them lit up. And as for over-compression on modern recordings - you're preaching to the choir here. There's nothing worse than mastering for laptop speakers. Yuck!
 
Dang. Feel free to let me know next time you're having a party! I'll bring "Pretzel Logic"!
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My favorite Steely Dan album of all time. I've GOT to find a copy of it on SACD.

Thanks for the compliments of the W5's. They're 90% done. Once they are checked out and verified running stable, I think I'll christen them with "Pretzel Logic" in your honor.

It's taken years to collect the speakers and I am blessed with a wife who likes good sound. I have, at this moment in time, 8 monoblock tube amps in the living room. She thinks they are cool. I think I am keeping her!
 
university classics

hi,
thanks for you response to my power cap question. I'm curious about your University Classics? I am running a JBL C-37 cabinet with a 130 woofer and a 075 horn with my W-5M for my mono system but would like to explore other vintage speakers in the future. i don't know much about "Universitys".. can you enlighten me? Sorry if this deviates from your thread...
kirk
 
One word to the wise- it may be a good idea to put back those tube shields on the input tubes... these old Heathkits are known for RF issues, and it's probably not a good idea to tempt fate, IMHO...

Regards,
Gordon.
 
W5M Surgistor

Here's a shot of a new surgistor being installed.
 

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New coupling caps

Needless to say, all of the old and most likely leaky coupling caps were given a burial and replaced with Obbligato caps. I retained the original capacitively coupled front end. If it turns out that the amp is bass-shy or rolled off, I will go back to the drawing board and either upsize the input cap or direct couple the input.
 
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Here's a shot of the voltage amp/phase splitter and driver tube sockets with their new components, not quite done yet.
 

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Question on caps sizes.

I went to AES last night looking for caps and see that the replacement caps have a pretty sloppy tolerance; well at least to me. -10%/+50% on the Mallory cans and -20%/+50% on the Illinois caps. I guess more capacitance isn't a bad thing, but I'm just a bit surprised that the tolerances are so, shall we say, wide?? Why list something as a 33 uf when it could vary from 26 to 50 uf???
 
Have used a lot of CEC electrolystic and have found them very unreliable, when new, it's 5% off and after 2 months, it's 12 % !?
Nowadays, I prefers the German's stuff, F&T or JJ's.
 
Driver tube socket replacement

Should have posted these shots a few back.

Here are a couple of pics detailing the driver tube socket replacement. Since we are dumping the 12AU7 theme and going with 6CG7's. a few wiring changes are also necessary on the sockets.

In the first picture, the old components have been clipped away from the old socket and folded back for access. Pictures were also taken before this and now it is a matter of removing the rest of the components one at a time and soldering them in. This helps reduce the chance of soldering something in the wrong spot.....not that I have ever done that before or anything.

The second picture shows pin 9 of the socket soldered to signal ground. This is for the internal shield on real 6CG7's.
 

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And here is a shot of the last part of rewiring the socket for the 6CG7 conversion. Pins 4 and 5 are the filament connection. The rest of the connections have the same pinout as the original 12AU7. Only the heater connections are different.
 

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Output tube coupling caps

The old micamold 1uf coupling caps were removed and replaced with 1uf 630VDC Obbligato caps. The ends at the socket aren't soldered just yet because there are more connections that go there.
 

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Interesting, 1uF is a huge coupling cap. Never realized Heath did it that way. :scratch2:

.1uF -> 1uF is a big difference in the circuit which probably helps nicely with stability.
 
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