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Official Ampeg Portaflex Club
- Thread starter JimmyM
- Start date
+1 better safe than sorry, I blew a JBL E140 once, using a Walter Woods (100 watt) MI-100-8. Found out later, that the previous owner, had re-coned the speaker with an cheaper aftermarket kid, that used round wire in the voice coil, instead
of flat copper that was the spec. re-cone for the E140. The voice coil was actually rubbing against the housing.
Ric
Great job with the restoration. What manner did you clean and finish it? Looks really good.
Jack
- Jul 1, 2005
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Thanks! Dish soap with a scrub brush, black marker for dings, naval jelly for rust. Superglue for loose seams and finally Armorall .
Here are some more M-15 pics. It sounds awesome with my Hofner CT Viola bass with flats, very crisp and precise compared to my B100R which seems more a bit muddy. I don't currently have a guitar but the M-15 sounded pretty good in the store with an Epiphone Casino. I got a great deal with a 15% off gift card and store pays the sales tax promo, out the door it was less than $400! 
I feel like I saved a classic amp today.
I feel like I saved a classic amp today.
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Wow you really did well on that purchase!
Looking at the gut shot, the power supply caps have been replaced and a three-conductor power cord has been installed. This is a big plus and saved you on the cost of having it done. It is very rare to see an intact 63 handle, they often break and replacements are impossible to find. Best that you don't lift the amp by the handle, bear hug the amp to carry it. The tolex is excellent. The Ampeg logo is there. As I said above, the Jensen Concert is a very good speaker.
Looking at the gut shot, the power supply caps have been replaced and a three-conductor power cord has been installed. This is a big plus and saved you on the cost of having it done. It is very rare to see an intact 63 handle, they often break and replacements are impossible to find. Best that you don't lift the amp by the handle, bear hug the amp to carry it. The tolex is excellent. The Ampeg logo is there. As I said above, the Jensen Concert is a very good speaker.
Thanks a lot. I had a sense it was a pretty good deal when I first saw it so I jumped on it. I was told the repair it needed was just a tremolo footswitch issue and it works fine now. The tolex overall is excellent, the back side tolex is damaged/missing on the lower back corners likely from tilting back over the years, I'll clean that up as best I can with glue and paint. One of the inputs hums for some reason as if it is not grounded properly, but there are 5 others to choose from so really no big deal.
Thanks for the heads up on the handle.
Can you tell what was done to the unit based on the handwritten additions on the left side of the schematic? The handwritten notes on the right side are funny as well, call this number when its ready or if there are any issues . . . .
I can't read the schematic. Could you post a higher resolution image? If it is easier, post left, middle, and right side images.
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You really did save an amp that I guess more guitar players would have had some exposure. I've never seen one. I know they built lots of guitar amps like the Gemini and the VT 22, but I've never seen this amp in a store. It's pretty unique in it's more traditional tube and tone stack placement, that's similar to the other guitar amps built by Fender and Vox, but it has all the nice Ampeg appointments. The tube compliment looks identical to a B-15N, that should set it off from the other guitar amps of the period.
Ric
Thanks. Unit runs pretty warm to the touch with the tubes and transformers on the bottom. Does this tend to lead to premature electronic component failure as compared to a B-15 type design with the tubes and transformers on top?
Thank you.
It isn't clear what the handwritten entry is about. Are there three 6SL7 preamp tubes in the amp plus the power tubes? If yes, then maybe they were outlining an additional gain stage but the scratchings are incomplete and not of much value.
You can always blow a small desk fan into the back of the amp to help cool it. Allow enough space in the back of the amp for air to circulate. Don't put it too close to a wall.
You can always blow a small desk fan into the back of the amp to help cool it. Allow enough space in the back of the amp for air to circulate. Don't put it too close to a wall.
Thanks a lot for looking at that for me. There are 3 6SL7 tubes, all Russian made, the 6LSs are also Russian made, and the 5U4 is Sylvania, this one looks older than the others, might be original or NOS.
Thanks for all your help, the amp sounds terrific!
Thanks for all your help, the amp sounds terrific!
Well, I'm sure that heat is often a very significant contributor to component failure. If you've ever touched the top of the tube cage on a B-15N (I only did it a couple of times, before. I realized it wasn't a good idea!) you know that it runs very hot. Having those same tubes, placed the more traditional way they are in the M-15, would have to be a bit warmer, but every Fender Bassman I've ever seen, does it that way, so it must work. My educated guess is that the way a B-15N cools it's components, contributes significantly to it's component longevity, when compared to other amps. David will chime in here with some excellent info. My only consideration would be, that the M-15 was designed as a guitar amp, so when using it as a bass amp, you would have to be a little more careful about volume levels and overdriving the power section. Just my take.
Ric
Here are some more M-15 pics. It sounds awesome with my Hofner CT Viola bass with flats, very crisp and precise compared to my B100R which seems more a bit muddy. I don't currently have a guitar but the M-15 sounded pretty good in the store with an Epiphone Casino. I got a great deal with a 15% off gift card and store pays the sales tax promo, out the door it was less than $400!
View attachment 474641 View attachment 474642 View attachment 474643 View attachment 474644 View attachment 474645
Wow, she's a beaut, and a hell of a price.
I don't know if I can add much to what Ric said about the amp cooling other to say that it was designed to work that way. That doesn't mean that it was designed well. They did what Fender and others did.
The amp was originally intended to be operated with a wall voltage of 117 VAC. Operate the amp at 120 or 125VAC as is common in some regions today, the voltages inside the amp are going to be higher and the amp will run hotter than it would have back when it was made. Heat is going to rise and be trapped which is why a quiet desk fan is a good idea. Heat that isn't dissipating is hard on the transformers and the capacitors.
The amp was originally intended to be operated with a wall voltage of 117 VAC. Operate the amp at 120 or 125VAC as is common in some regions today, the voltages inside the amp are going to be higher and the amp will run hotter than it would have back when it was made. Heat is going to rise and be trapped which is why a quiet desk fan is a good idea. Heat that isn't dissipating is hard on the transformers and the capacitors.
This should be an easy fix. It is often a bad ground connection that causes this type of hum.
Take the nut and washer off the jack. Better to use a socket or wrench for this as pliers can scratch the chassis. From the inside of the chassis, carefully pull out the jack. I say carefully because the wires are fragile and they can break if you bend them too much. Look for signs of corrosion on the jack and the chassis where they come into contact. There is often a big star washer inside the chassis around the jack collar. The washers helps lock the connection and keeps it tight. They also oxidize and turn a green color. Any corrosion has to be cleaned, there has to be a good clean metal to metal contact. The washers are available individually at a place like Home Depot and it is easier to replace them rather than clean them. The best way to clean the corrosion is with a product like deoxit. If you don't have any, scrape it clean, use to alcohol to degrease the area. Reassemble the connection and tighten the nut well.
Don't forget to clean the jack/plug contacts as well.
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