- Apr 3, 2003
- 35,518
- 19,954
- Disclosures
- Editor-in-Chief, Bass Gear Magazine
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Official Ampeg Portaflex Club
- Thread starter JimmyM
- Start date
I like the industrial look of that Ashdown amp. It reminds me of an arc welding machine.
http://img2.tradeget.com/Jerry8257\W3TR6NRB1mig200big.jpg
I don't think the wife would be as thrilled to see that sitting by the door between gigs.
http://img2.tradeget.com/Jerry8257\W3TR6NRB1mig200big.jpg
I don't think the wife would be as thrilled to see that sitting by the door between gigs.
Some Schematics I found for Portaflexs while looking for more info on them
Invalid Link Removed
Invalid Link Removed
Wolf brings up a good point. Does anyone know where I can get the schematic for the B-15R? I checked and it's not on the drtube.com site.
Further on the same topic, does anyone know if the B-15R is a fixed bias circuit or a self-biasing circuit? My guess is that it's fixed.
Further on the same topic, does anyone know if the B-15R is a fixed bias circuit or a self-biasing circuit? My guess is that it's fixed.
I posted this on another forum, but since we have so many B-15N lovers here:
I had some free time today to get into the amp:
Here's an overview of what it looked like to start:
It's a pretty clean and easy amp to work on. Probably one of the easiest I've been in.
I replaced the 2-prong cord with a grounded 3-prong, I replaced the electrolytic capacitors in the power supply, as well as the carbon composition resistor in the power supply, I replaced a number of the coupling capacitors and I generally cleaned up the interior a bit, cleaned the pots, etc.
Here are some pics for those interested in these things:
I replaced the death cap/2-prong power cord with a grounded 3-prong power cord:
See the big white death cap:
It has been removed and the green ground wire from the new power cord ties into the chassis where the cap once did:
You can see the partially cooked carbon composition resistor on the right:
Here is it's replacement (also note the two replaced electrolytics):
Here's a shot of the four original 0.1 uF caps (aqua blue) in the preamp:
and their replacements (silver):
Here's a shot of the three original 0.022 uF caps (aqua blue) in the preamp:
and their replacements (yellow):
If you refer back to the first picture, you'll see a large cylindrical green electrolytic capacitor in the power supply that has been replaced by a large black cylindrical cap:
I didn't take any pics of the cap can that sits up by the tubes on the exterior of the amp, but it was replaced as well.
There is only one small issue left with the amp and that is the volume pot on channel 1. When dialed all the way down, it jumps a bit and lets through some volume. As soon as it is turned up a small amount, it acts normally and isn't an issue. Since I don't have a replacement pot sitting in my drawer, I didn't address it today. I may never get around to it as it doesn't affect the performance of the amp in any way other than having a bit of volume leak with the pot rolled to one extreme.
Then I had some time to play - sweet. This is me enjoying my first Sunday off in a long time.
I had some free time today to get into the amp:
Here's an overview of what it looked like to start:
It's a pretty clean and easy amp to work on. Probably one of the easiest I've been in.
I replaced the 2-prong cord with a grounded 3-prong, I replaced the electrolytic capacitors in the power supply, as well as the carbon composition resistor in the power supply, I replaced a number of the coupling capacitors and I generally cleaned up the interior a bit, cleaned the pots, etc.
Here are some pics for those interested in these things:
I replaced the death cap/2-prong power cord with a grounded 3-prong power cord:
See the big white death cap:
It has been removed and the green ground wire from the new power cord ties into the chassis where the cap once did:
You can see the partially cooked carbon composition resistor on the right:
Here is it's replacement (also note the two replaced electrolytics):
Here's a shot of the four original 0.1 uF caps (aqua blue) in the preamp:
and their replacements (silver):
Here's a shot of the three original 0.022 uF caps (aqua blue) in the preamp:
and their replacements (yellow):
If you refer back to the first picture, you'll see a large cylindrical green electrolytic capacitor in the power supply that has been replaced by a large black cylindrical cap:
I didn't take any pics of the cap can that sits up by the tubes on the exterior of the amp, but it was replaced as well.
There is only one small issue left with the amp and that is the volume pot on channel 1. When dialed all the way down, it jumps a bit and lets through some volume. As soon as it is turned up a small amount, it acts normally and isn't an issue. Since I don't have a replacement pot sitting in my drawer, I didn't address it today. I may never get around to it as it doesn't affect the performance of the amp in any way other than having a bit of volume leak with the pot rolled to one extreme.
Then I had some time to play - sweet. This is me enjoying my first Sunday off in a long time.
Proud Portaflex owners: I'm currently searching for a mid 60's B-15 (cab only). If you happen to come across one please PM me.
Thanks
Thanks
kindness, thanks for those pics. i have to do that to two guitar amps i have. actually, i think one of them has already been done but some nimrod cut the ground off the plug before i bought it.
Aussie Mark
I come from a land down under
- Oct 26, 2002
- 1,161
- 206
- Disclosures
- Endorsing Artist: Fender; O'Neill Amps; Cave Passive Pedals
My SB-12 came with the original latches long gone, so I've bought two new latches from Fliptops.net, but they came without screws/bolts or whatever is used to attach them to the cab.
Could someone post a photo of what is used on an original SB-12 to attach the latches? The two holes on the latch look tiny, so I'm wondering how any screw or bolt that small is going to be able to take the weight of the cab when lifting it by the top handle.
Oh, and I'm wondering about the orientation of the baffle panel. Mine has the vertical port on the right, and I noticed others with the vertical port on the left. Photos on Google have them both ways. Is there a "correct" side to have the port? (I realise the baffle panel is easily flipped)
Thanks in advance.
Could someone post a photo of what is used on an original SB-12 to attach the latches? The two holes on the latch look tiny, so I'm wondering how any screw or bolt that small is going to be able to take the weight of the cab when lifting it by the top handle.
Oh, and I'm wondering about the orientation of the baffle panel. Mine has the vertical port on the right, and I noticed others with the vertical port on the left. Photos on Google have them both ways. Is there a "correct" side to have the port? (I realise the baffle panel is easily flipped)
Thanks in advance.
- Feb 13, 2008
- 1,251
- 1,923
- Disclosures
- Owner, Vintage Blue (repro cabinets)
Mark - here's a photo of an original SB-12 latch:
They used the same mounting hardware as the B15's and others used, a #10-24 machine screw and a #6 wood screw. I'm going from memory on the machine screw so it may have been a #10-32, I'm just too lazy to go find one and check!
Ampeg used to punch an extra hole in their latches to accomodate the larger machine screw:
None of the replacement latches come with that hole punched. If you want to try to match the original hardware/holes you need to add the hole yourself. You can punch it or drill it but be careful if you drill it - the bit can grab as it goes through and pull the latch out of your hand. You can also do what I do on my cabinets. I use a #6 x 1/2" pan head sheet metal screw in the upper hole, much like Ampeg did. However, instead of punching a new hole I use the existing lower hole and fasten it with a #4-40 x 1" binding head machine screw and nut. The head style isn't critical, but you want as low a profile as you can get. Fastening this way is plenty strong enough - the reality is that the latch itself will break first anyway. Because of that you may want to avoid lifting the whole unit by the top handle if you can.
Most of the SB-12's I've seen had the port on the right (as you look at the cabinet) but, as you've noticed, they seem to have been assembled both ways.
They used the same mounting hardware as the B15's and others used, a #10-24 machine screw and a #6 wood screw. I'm going from memory on the machine screw so it may have been a #10-32, I'm just too lazy to go find one and check!
Ampeg used to punch an extra hole in their latches to accomodate the larger machine screw:
None of the replacement latches come with that hole punched. If you want to try to match the original hardware/holes you need to add the hole yourself. You can punch it or drill it but be careful if you drill it - the bit can grab as it goes through and pull the latch out of your hand. You can also do what I do on my cabinets. I use a #6 x 1/2" pan head sheet metal screw in the upper hole, much like Ampeg did. However, instead of punching a new hole I use the existing lower hole and fasten it with a #4-40 x 1" binding head machine screw and nut. The head style isn't critical, but you want as low a profile as you can get. Fastening this way is plenty strong enough - the reality is that the latch itself will break first anyway. Because of that you may want to avoid lifting the whole unit by the top handle if you can.
Most of the SB-12's I've seen had the port on the right (as you look at the cabinet) but, as you've noticed, they seem to have been assembled both ways.
OK - I just took a quick look at mine. I'm not sure if the latches are original or not, but I wouldn't call them the pinnacle of engineering. The latch base is attached to the box by two screws - one apparently goes all the way through the box and the little insulated lip the amp sits on and is fastened with a locknut and nut. The actual latch isn't attached to base at all - it's held in place by tension and can fall off when you release the tension. 
The business end of the latch hooks over squarehead bolts that protrude from the amp base. The latch base that is attached to the box also sports a ring that will "lock" the latch in place once it latched - I slip a hex bolt and wing nut through it whenever I move it to keep the latch locked.
Lately I haven't been carrying it by the handle much anyway, I just kind of hug it. It's olde and precious to me.
EDIT - and now that I see those pics, mine doesn't look like that, so it was either a different production run or some previous owner didn't like the originals a long time ago....
PPS - mine is right-ported too.
The business end of the latch hooks over squarehead bolts that protrude from the amp base. The latch base that is attached to the box also sports a ring that will "lock" the latch in place once it latched - I slip a hex bolt and wing nut through it whenever I move it to keep the latch locked.
Lately I haven't been carrying it by the handle much anyway, I just kind of hug it. It's olde and precious to me.
EDIT - and now that I see those pics, mine doesn't look like that, so it was either a different production run or some previous owner didn't like the originals a long time ago....
PPS - mine is right-ported too.
Aussie Mark
I come from a land down under
- Oct 26, 2002
- 1,161
- 206
- Disclosures
- Endorsing Artist: Fender; O'Neill Amps; Cave Passive Pedals
Thanks Mark and Bob, that info fills in the gaps for me. The replacement latches that a previous owner put on this SB-12 were a totally different size, with a larger 3 hole baseplate, so my SB-12 has several extra holes already on each side for me to choose from. I'm sure I have some machine screws and nuts in my shed that will work just fine.
