Paging mulveling... your W5s are running!

GordonW

GordonW

Speakerfixer
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Mike brought in his Heathkit W5s... they'd never been re-capped. And, from the looks of the Sangamo 1uf coupling cap in one, they were in definite need!

Also, someone had put in the wrong rectifiers (5U4s are a definite NO-NO, from the aspect of allowable capacitor voltages AND the fact that the extra B+ is also an undue burden on the OPTs!), and one amp had different output tubes than the other (I found him a matching pair of GE 7581s to go with the nice pair of 7581s that were in one of the amps)...

If you look carefully, someone sort of did a partial "bootleg recap" in one of those. The two Nichicon caps just strung across open space wasn't much of a confidence-inspirer!

In the other amp, the original builder made a pretty questionable decision... there was a pretty dangerous exposed-wire "extension" on the end of one of the heater wires to one of the output tubes (the wire obviously was just a little too short... the original builder just spliced a bit of extra wire on, but didn't bother to insulate the joint! Needless to say, some soldering and some heatshrink later... it's MUCH better).

But, overall, I have to say, the original builder didn't do too badly...

Before re-cap:

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After re-cap:

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We're planning to do the 6CG7 mod (replacing all the 12AU7s with 6CG7s), which should make it better... but it doesn't suck now!

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Nice, huh? :thmbsp:

Regards,
Gordon.
 

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WhiteSE said:
those are nice...if he doesnt pickem up....how much??..lol
Click to expand...

Not a chance... he already saw them running last night. :D

I will be doing the input tube mod (taking out the 12AU7s, installing 6CG7s, changing the heater wiring to do so) within the next few days... then, these should be seriously stunning.

AFAIK, Mike's going to use 'em to run his Tannoy Kensingtons. How about that for a setup?

Regards,
Gordon.
 
before you do the 6CG7 mod, try out some 12BH7s instead. I have a friend with a pair of W5s that he runs 12AU7s with. I keep trying to convince him to run the 'BH7 but he never does - just curious about the results since I've had good luck with the 'BH7 with my Dynaco Mark IIIs (with Poseidon boards).
 
Great job Gordon! The W5M is one of my favorite tube amplifiers...
I did the 6CG7 swapout on mine and the difference was dramatic. I'm using vintage GEC KT66 tubes for the output.
You may want to change out the resistors around the new 6CG7's when you do the tube swap. I was having quiet crackle sounds in one amp and I ended up changing out a bad resistor by a 6CG7. A month or so later I had the same problem with the other amp and ended up changing out all the small carbon resistors on both. They have been fine ever since :thmbsp:
 
dividebytube said:
before you do the 6CG7 mod, try out some 12BH7s instead. I have a friend with a pair of W5s that he runs 12AU7s with. I keep trying to convince him to run the 'BH7 but he never does - just curious about the results since I've had good luck with the 'BH7 with my Dynaco Mark IIIs (with Poseidon boards).
Click to expand...

One of the members here tried both the 12BH7 swap first and then went to the 6CG7's and he said he prefered the 6CG7's. I've never tried the 12BH7's in mine so I can't say which I prefer...
 
Didn't have four 12BH7s... had a pair, so I tried putting one 12BH7 in the diff amp position (the second tube) in each amp, and a pair of 5814s, one in the first tube position of each amp.

Definitely better. More dynamics, and the bass is cleaner. Think we got rid of at least some of the compression and distortion, that was inherent in the 12AU7s.

I'm going to hunt up a second pair of 12BH7s. Even if I wind up with the 6CG7s, it'll be interesting to hear what, if any, the difference is, with all 12BH7s...

Regards,
Gordon.
 
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Already shaping up to be NICE amps

As Gordon mentioned, their "baseline" performance is already very very sweet indeed - great work on the recap/rewiring! Glad I got to hear them last night - the only problem is that now I'm itching to get them home...

It's a bit of a vanity, but I think I'm really going to like how the gold paint matches up with the hardware details on the Kensingtons :D
 
That was me who tried the 12BH7's in my W-5M's then changed them out for the 6cg7's...I like the 6CG7's! but one always thinks every improvement is a step up! plus going back is a pain to rewire. But I think the 6cg7's sound more natural or neutral? if that makes any sense, the 12BH7's did add more punch over the 12AU7's. That said I'm interested in your opinion, I'm fairly new to tubes so a more trained ear is welcomed.
Kirk
 
So far, the 12BH7s in the diff amp and the 5814 in the input amp/phase splitter is a very entertaining sound.

As I said, though... I'm going to try 12BH7s in both positions in both amps. If it makes it this good, there may not be any reason to re-wire the amp... he can use 12BH7s and the original 12AU7s without me having to go back in the amp...

And, yes... it was more punch and leading-edge dynamics that was needed. It's definitely better now...

Regards,
Gordon.
 
GordonW said:
So far, the 12BH7s in the diff amp and the 5814 in the input amp/phase splitter is a very entertaining sound.

As I said, though... I'm going to try 12BH7s in both positions in both amps. If it makes it this good, there may not be any reason to re-wire the amp... he can use 12BH7s and the original 12AU7s without me having to go back in the amp...

And, yes... it was more punch and leading-edge dynamics that was needed. It's definitely better now...

Regards,
Gordon.
Click to expand...

I just heard these, after hearing them the other day with the 12AU7s in place. The setup with the 5814/12BH7 is simply a different amplifier, period.

I have never heard a simple tube substitution make this much of an improvement in ANY amplifier/preamplifier I've heard, EVER.

If you have one of these, you owe it to yourself to start looking for good 12BH7s, period.
 
BrassTeacher said:
I just heard these, after hearing them the other day with the 12AU7s in place. The setup with the 5814/12BH7 is simply a different amplifier, period.

I have never heard a simple tube substitution make this much of an improvement in ANY amplifier/preamplifier I've heard, EVER.
Click to expand...
Wow! I like where this is going :D
 
Gordon!! Call me as soon as you see this, I found my other two 12BH7s!! I knew I had more, now we can try the amps with ALL 12BH7s in place!
 
BrassTeacher said:
I just heard these, after hearing them the other day with the 12AU7s in place. The setup with the 5814/12BH7 is simply a different amplifier, period.

I have never heard a simple tube substitution make this much of an improvement in ANY amplifier/preamplifier I've heard, EVER.

If you have one of these, you owe it to yourself to start looking for good 12BH7s, period.
Click to expand...

Listen for a while but consider the 6CG7 change...i feel this is even better than the 12BH7. I agree the 12BH7 is a major step up, it is like a whole new amp, still I have no desire to turn back to the 12BH7. The 6CG7 rules. At present I'm running RCA clear tops.
Cheers,
Kirk
 
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