ShortScale.org

dots wrote:my god that's a beautiful amp.

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Looks nice! Here's what's apparent from these pics:

1) cathode bypass caps original. You may leave them if you like the way the amp sounds. If one channel starts acting funny down the road, that would be the firs thing I'd be looking at. It's unlikely that both channels' bypass caps would go down at the exact same time.

2) Screen resistors and grid resistors on power tube sockets have both been replaced. But you knew that already. This is good preventative maintenance.

3) You have one of the later "chocolate drop" reddish-brown caps. It's about the fourth large cap from the right, immediately east of the orange Mallory tubular double cathode bypass cap. It's a .1, and it's the coupling cap between the first and second 12AX7s in the "Bass instrument" channel. Lots of people don't like these caps, but a single one won't make a bit of difference. You could change it to something nicer if you wanted, but I'd leave it alone. If I had a whole amp full of them I might consider changing them, but even then, maybe not. I'd definitely leave it alone in this amp since you like the way it sounds. Don't want to upset the balance!

4)The rest of your caps are the vaunted Mallory "blue hot dog" caps. Some people just rave about these-- I think they're good, but I don't buy into the notion that they're anything special. Don't get me wrong, I'd leave them there, but to me they sound like old orange drops-- which is not a bad thing at all, just very 'neutral.' They won't impart color like, say, an old Astron paper-in-oil cap would. I have a few of them sitting around. I know it's really anal, but I decided to try something else for the last two coupling caps in my Deluxe... I put mojotone "vitamin T" oil filled caps in there, and I liked what they did. But the blue Mallories are good caps. I suspected my old ones had drifted anyway, so it was maybe not a fair fight.

5) Your amp is VERY clean inside. This thing spent most of its life indoors and out of the basement, so to speak, and doesn't look to have ever been overheated. Lots of time the cloth insulation on the twisted pairs of green filament wires that go from tube to tube will turn dark when it gets hot and/or moist. Yours is still a bright, vibrant green. Doesn't mean anything, but it's nice to piece together the history of your amp.

6) Are those two pemcil dates on the chassis behind the "bass instrument" channel's pots? Maybe dates when the amp was in for service? (cap job?) If so, that's good to know when the amp was last serviced. I make a habit of writing the date under the cap pan whenever I do a cap job. Should the amp end up in someone else's hands, they will then be able to find out how old the caps are.

7) I see the three-prong cord has been added and grounded with a lug to a PT chassis bolt. This is good.

8 ) I can see that the bias cap has been replaced with a recent production Sprague Atom. This is good. It means the rest of the caps under the "doghouse" under the chassis have probably been replaced, too. But you knew that already.

9) The original rectifier diodes are there. These may be old Selenium rectifiers which aren't as durable as modern silicon diodes. If one should happen to fail, it will fill the room with foul-smelling and mildly toxic smoke. Should you want to replace them preventatively (I would be inclined not to bother, but I'm not as scrupulous as some dudes), then you could use regular silicon 1N4007 diodes.

10) Other than that one mysterious white wire, the amp appears to be immaculate, in "serviced-but-original" condition! The way you want it! I'd say you did really, really well. Without looking inside, it's hard to know what you're getting, so vintage amps can sometimes be a crapshoot. This one is the way you want it!!!

James wrote:Well that was certainly worth doing. From those pics someone just wrote this up for me

Looks nice! Here's what's apparent from these pics:

1) cathode bypass caps original. You may leave them if you like the way the amp sounds. If one channel starts acting funny down the road, that would be the firs thing I'd be looking at. It's unlikely that both channels' bypass caps would go down at the exact same time.

2) Screen resistors and grid resistors on power tube sockets have both been replaced. But you knew that already. This is good preventative maintenance.

3) You have one of the later "chocolate drop" reddish-brown caps. It's about the fourth large cap from the right, immediately east of the orange Mallory tubular double cathode bypass cap. It's a .1, and it's the coupling cap between the first and second 12AX7s in the "Bass instrument" channel. Lots of people don't like these caps, but a single one won't make a bit of difference. You could change it to something nicer if you wanted, but I'd leave it alone. If I had a whole amp full of them I might consider changing them, but even then, maybe not. I'd definitely leave it alone in this amp since you like the way it sounds. Don't want to upset the balance!

4)The rest of your caps are the vaunted Mallory "blue hot dog" caps. Some people just rave about these-- I think they're good, but I don't buy into the notion that they're anything special. Don't get me wrong, I'd leave them there, but to me they sound like old orange drops-- which is not a bad thing at all, just very 'neutral.' They won't impart color like, say, an old Astron paper-in-oil cap would. I have a few of them sitting around. I know it's really anal, but I decided to try something else for the last two coupling caps in my Deluxe... I put mojotone "vitamin T" oil filled caps in there, and I liked what they did. But the blue Mallories are good caps. I suspected my old ones had drifted anyway, so it was maybe not a fair fight.

5) Your amp is VERY clean inside. This thing spent most of its life indoors and out of the basement, so to speak, and doesn't look to have ever been overheated. Lots of time the cloth insulation on the twisted pairs of green filament wires that go from tube to tube will turn dark when it gets hot and/or moist. Yours is still a bright, vibrant green. Doesn't mean anything, but it's nice to piece together the history of your amp.

6) Are those two pemcil dates on the chassis behind the "bass instrument" channel's pots? Maybe dates when the amp was in for service? (cap job?) If so, that's good to know when the amp was last serviced. I make a habit of writing the date under the cap pan whenever I do a cap job. Should the amp end up in someone else's hands, they will then be able to find out how old the caps are.

7) I see the three-prong cord has been added and grounded with a lug to a PT chassis bolt. This is good.

8 ) I can see that the bias cap has been replaced with a recent production Sprague Atom. This is good. It means the rest of the caps under the "doghouse" under the chassis have probably been replaced, too. But you knew that already.

9) The original rectifier diodes are there. These may be old Selenium rectifiers which aren't as durable as modern silicon diodes. If one should happen to fail, it will fill the room with foul-smelling and mildly toxic smoke. Should you want to replace them preventatively (I would be inclined not to bother, but I'm not as scrupulous as some dudes), then you could use regular silicon 1N4007 diodes.

10) Other than that one mysterious white wire, the amp appears to be immaculate, in "serviced-but-original" condition! The way you want it! I'd say you did really, really well. Without looking inside, it's hard to know what you're getting, so vintage amps can sometimes be a crapshoot. This one is the way you want it!!!

benecol wrote:Was that "thetaman" (not sure how to type a theta character - looks like a row of 000000000s) over at offestguitars? He's a true don, that fella.

Mike wrote:I bet you're happy as a clam after that.

James wrote:

benecol wrote:Was that "thetaman" (not sure how to type a theta character - looks like a row of 000000000s) over at offestguitars? He's a true don, that fella.

Yeah that's the one. I was even thinking "should I bother posting this over at offset?", but doing it was probably a smarter decision than buying the amp.