Fender Supersonic 60 combo Question

[gtto]

First let me state that my electronics knowledge is very low so forgive any mistakes I may make in trying to explain this. I wanted to bring my US Fender Supersonic back to Thailand so I had the power transformer changed to a Hammond 290 VEX. Since the change everything was working great. Recently I noticed a severe drop in power which I suspect are the tubes since the present tubes are quite old. While doing some research about bias and plate voltage I saw on a schematic that the 110v version had a 3 amp fuse while the 220/240 had a 1.6A fuse. I also saw that on the 100/120V version there was a .1 250VAC capacitor, C97, between the black and white wires coming from the power line in but this cap is absent in the 220/240V version. I will change the fuse but do I need to do anything with this cap? I have no idea what it does or doesn't do. Thanks for any help you can give me.

[Leo_Gnardo]

the 110v version had a 3 amp fuse while the 220/240 had a 1.6A fuse. I also saw that on the 100/120V version there was a .1 250VAC capacitor, C97, between the black and white wires coming from the power line in but this cap is absent in the 220/240V version. I will change the fuse but do I need to do anything with this cap? I have no idea what it does or doesn't do. Thanks for any help you can give me.

Neither the fuse nor capacitor has anything to do with your power loss.

Fuses are chosen to break the connection to power source should the amp draw current well in excess of normal levels. It's perfectly normal to see fuse ratings for 220/240 V lines to be half what they are for 110/120V. The fuse choice is made, predicated on what power draw the amp designer reckons will be "trouble zone", and power is voltage times current. Double the voltage, half the current to arrive at the same result.

Capacitor across the AC line is an attempt to reduce high frequency noise on the AC line which may show up in your audio. It's optional whether your line is 220/240 or 100 or 110/120V. You often find these in "power conditioners", sometimes built in to outlet strips. It's debatable whether they help much. For instance, if my neighbors are using motor appliances such as kitchen mixer, power saw, hedge trimmer or similar, I can hear the motor whine in my guitar amps whether there's a cap across the AC line or not.

[gtto]

Leo,
Thanks for the answer. I didn't mean to imply that I thought the fuse or capacitor was my problem. I just wanted to make sure that the capacitor was OK even in a 220/240 situation. I really appreciate the help.

[Leo_Gnardo]

I'm sure the cap will be all right rated at 250 VAC. You can always select a higher rated part for safety margin.

Super 60 is one of my favorite "sleeper" amps - still available relatively cheap because 1) most people don't know how good it sounds and B: no rock star has yet been photographed or video'd playing one. I hope yours perks up with a fresh set of tubes.

[gtto]

Believe it or not Jeff Beck actually played one on American Idol many years ago. Strange but true. What about just removing the cap?

[Leo_Gnardo]

Believe it or not Jeff Beck actually played one on American Idol many years ago. Strange but true. What about just removing the cap?

You could do just fine I'm sure without that cap across the line. Many amps have a cap from one side of the power line to chassis - not much use especially in amps that are safety grounded through the power cable & plug. Across the line, might help relieve some noise but I've never found it to really help much.

Jeff Beck on American Idol???? Missed that, I have no TV, no cable. About 6 years ago he played a local show using a Blues Junior covered in Miami Vice aqua blue. Although he's an incredible guitarist somehow what Jeff plays doesn't seem to move prices on gear. Jack White on the other hand seems to be responsible for a price uptick in old Sears Silvertone amps over the last couple years. Go figure...

[Justin Thomas]

Jeff Beck doesn't move gear because he sounds amazing with anything he plays on, and NOBODY sounds like him, even if he just hands the guitar yo the next guy. It's incredibly frustrating to go out and clone his rig and get disappointing results. And you probably can't play like him, anyway!

Loved his work on Roger Waters's Amused To Death.

Justin

[Leo_Gnardo]

Jeff Beck doesn't move gear because he sounds amazing with anything he plays on, and NOBODY sounds like him, even if he just hands the guitar yo the next guy. It's incredibly frustrating to go out and clone his rig and get disappointing results.

Goes without saying - but you said it!

And you probably can't play like him, anyway!

Not me. But I do have a customer who's learned some of his moves and uses them well. And doesn't clone the JB rig. It's in the brain-hands-guitar connection.

Loved his work on Roger Waters's Amused To Death.

"Roger" that. Absolutely heartbreaking.

Some more Beck treats for your ears, if you haven't already heard. Jeff Beck & Jed Lieber's soundtrack cues for Frankie's House, here's the youtube link:

https://www.youtube.com/playlist?lis...34kzyukarErE-d

[g1]

Just for the record (and OCD sake), the Super-sonic 60 and Super 60 are quite different amps.

[Leo_Gnardo]

Just for the record (and OCD sake), the Super-sonic 60 and Super 60 are quite different amps.

Ahh, WOOPS! Mark me an "F" in reading comprehension... I am a fan of the Super 60.

The Super-sonic, yes the overdrive department is formidable. And once I was asked to follow some cookie-recipe mods for a customer, that worked out well too. Yes both good, but definitely different.

Now back to our Jeff Beck worship service.

For further cornfusions, there is another SuperSonic, made in 1939 (!) looky here:

https://www.youtube.com/watch?v=tlyaRNNSHDE

I bet Jeff Beck would like that one!

[Justin Thomas]

I heard the Super-Sonic is a less expensive & glitzed-up Prosonic wannabe... Chuck H, you listening? I know you have thoughts!

Justin

[eschertron]

Ahh, WOOPS! Mark me an "F" in reading comprehension... I am a fan of the Super 60.

Yeah, I remember that. I picked up a Super 60 off eek!bay for salvage, and you helped endear it to me.

Now back to our Jeff Beck worship service.

[xtian]

Just to assist in the derail: I am super digging Jeff Beck's new album with Rosie Bones. Great stuff.

[gtto]

OK so I finally got around to biasing the SuperSonic. First time I ever tried this. Plate voltage was 425V which is lower than I have heard it should be. I don't know if this has anything to do with the power in Thailand or the fact that the power transformer was swapped for a 220 version. According to the Weber calculator 6L6GC bias at 70% should be 49mA. When I check the bias with a multimeter set to mV at TP49 and 50 I get a max of around 32 if I turn the trimpot as far as it will go. Am I missing or doing something wrong here? Thanks.

[g1]

32mV is the correct bias according to the schematic.
If the plate voltage is that low (should be about 480V), this is probably why it won't bias any hotter.
You will need to figure out if the plate voltage is low because of the power transformer.
Does the heater voltage measure 6.3VAC at the pilot light? Does TP10 measure 27VAC? 180VAC at TP1 ?