Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 10

[Bass 45]

Originally Posted by JimmyM

Dang, that's hot and semi-local. Wife would kill me since she's already approved the Heritage SVT.

Are you getting the whole rig - or just the head?

[JimmyM]

Whole rig with the 810, though depending on the price and cost of shipping I may have to space them out with head first.

[Bass 45]

Exciting!

[JimmyM]

Ya, I'm stoked. Totally a vanity purchase when I have the king daddy of vintage SVT rigs already, but my wife can sell it and make some money when I croak so it's all good

[johnnyt]

That's awesome Jimmy! I also wanted to let y'all know I put a freshly reconed JBL D130 in my '66 B-15 and it sounds great! I have a bit of baffle rattle but I'm gonna try some felt, etc. Up next I'm gonna try a cerwin vega 18" in the B-18 cab and SS rectifier. Thanks everyone for the tips!

[Apex_speed]

Originally Posted by gjbassist

I'm wanting to replace the foam gasket for the lid of my B-15T cabinet. Is this the best stuff to use?
http://www.fliptops.net/catalog/p-10...portaflex-amps

I want it to look as close to original as possible so I don't want to use foam weatherstripping.

Yes, this is the correct stuff and I just used it in a restoration that is what I would call museum quality which means I am super anal!

The text is confusing...an order of 1 comes with enough foam to do the entire gasket. You will have to scrape the old gasket out of the recess that it is in with a small screwdriver and then vacuum out the bits. When it is all cleaned out, work the gasket into the gasket slot. It is much easier to do with the gasket turned at a 45* angle and using a screw driver to compress and work it in. When you are all done, secure the top with the latches for several days to get it fully compressed and seated. It will look and work just like the factory gasket after you are all done.

[shadven]

Originally Posted by JimmyM

Dang, that's hot and semi-local. Wife would kill me since she's already approved the Heritage SVT.

Wow, we are twins In the last month or so I received approval and took delivery of a 2007 SVT VR (it was a ebay find, new old stock made in the USA, never sold item from a music store in Nashville) and a brand new SVT 810 AV, and I snuck in the back door a new SVT 410HLF. She hasn't noticed the new 410 cab

You will love the SVT! I really want the SB-12. But, I just can't justify it since I have a nice B-15n already, but damn....

[JimmyM]

Originally Posted by shadven

Wow, we are twins In the last month or so I received approval and took delivery of a 2007 SVT VR (it was a ebay find, new old stock made in the USA, never sold item from a music store in Nashville) and a brand new SVT 810 AV, and I snuck in the back door a new SVT 410HLF. She hasn't noticed the new 410 cab

LOL! I don't have the guts to try that on my wife

[gjbassist]

Thanks for the info Apex. Sounds like that won't work for my cabinet though. The B-15T cab doesn't have a recess that the foam fits in to. The foam on mine has an adhesive backing. I'm having a hard time finding images of this amp with the top off, so honestly I don't even know for sure if it is original or if it was added later.
Here is mine:


It's hard to tell from this photo but there is a thin foam gasket running around the top of the cabinet.

[Apex_speed]

Originally Posted by gjbassist

Thanks for the info Apex. Sounds like that won't work for my cabinet though. The B-15T cab doesn't have a recess that the foam fits in to. The foam on mine has an adhesive backing. I'm having a hard time finding images of this amp with the top off, so honestly I don't even know for sure if it is original or if it was added later.

It's hard to tell from this photo but there is a thin foam gasket running around the top of the cabinet.

I am not an expert on the different variations but FlipTops should know what you need if you call them. Mine looked very thin and only applied to the surface until I went to remove it and then discovered that it was sitting in a channel so yours may or may not be the same.

[beans-on-toast]

Originally Posted by kuratacus

Well my guitarist is happier than happy with the 63' SS rectifier B15. has it running through an old marshall on half and it sounds amazing. meanwhile my tube 63' is happy with a second double baffle cabinet.

oddly enough the SS 63 cab still has the old foam behind the grill. and you can see a square outline where it is. when i took the grill off the visible pieces crumbled as i cleaned out the dust

I like running amps through a Marshall 412. It doesn't take a lot of power to get a good sound out of them. The B-15N/Marshall combination must sound really nice.

Your amp must have been taken care of really well to have the foam still intact like that.

[coreyfyfe]

Originally Posted by gjbassist

It's hard to tell from this photo but there is a thin foam gasket running around the top of the cabinet.

I pick up weather stripping from the hardware store and just use that. You get a big long spool for less than the cost of the fliptops stuff. In your case, where people are probably a little less concerned with originality it would work very well (and actually looks like exactly what's there). For my B15, it doesn't fit in the groove, but I just laid it over what was in the groove. I need it to be tight, not look period-perfect

[beans-on-toast]

Originally Posted by gjbassist

The B-15T cab doesn't have a recess that the foam fits in to. The foam on mine has an adhesive backing. It's hard to tell from this photo but there is a thin foam gasket running around the top of the cabinet.

It can be hard to find in the right thickness. I would check at a hardware store as Corey said, you can also try an automotive store. They use closed cell tape for gaskets to seal airflow on vehicles.

A 1/8" thick foam tape like this might do. They sell 1/16" windshield gasket tape here.

[gjbassist]

Originally Posted by beans-on-toast

It can be hard to find in the right thickness. I would check at a hardware store as Corey said, you can also try an automotive store. They use closed cell tape for gaskets to seal airflow on vehicles.

A 1/8" thick foam tape like this might do. They sell 1/16" windshield gasket tape here.

Great idea on the auto parts store! I want something like that with closed cells instead of the stuff used around windows which is typically less dense.

[Thunderbucker]

A little assistance please, Thunderbucker here, working on Cataldo's B15, which went down with a shorted PT primary. Ouch. While schematic searching, I found that it wasn't built according to any schematic I could find. Not even to the schematic pasted on the bottom of the amp. According to the schema on the amp, power supply filtering is done by a 40-40-20-20uf can cap with the first 40uf serving the 6L6s, 1Kohm later the next 40uf serves the screens, then the two 20s serve the preamp and phase splitter, respectively.

What's weird is that Cataldo's has a 4 X 40uF 500V can cap (huh, bet that's hard to find these days) and it's been rewired so that the 6L6s are served by 2-40s in parallel. Since that leaves us one cap short for the various filtering apps, another discrete 20uF cap has been hand-added in to serve as one of the preamp filters.

Check out the pictures. The first cap cap sections are jumped, then paralleled. The added cap goes to the pads where one of the can cap sections would have attached, but there is no solder on that pad. Was this done at the factory?

Odd. And there is the question that 80uF (40X2) is more capacitance than the 5AR4 is rated for (unless the current draw is low, YMMV etc)

So now I'm hoping some expert will chime in and knowingly opine "Ah yes, that mod went in from October 13 1964 to January 15, 1965, caused by a massive fire at the capacitor factory that caused them to do a running mod....This makes this the most desirable and rare of all the B15NCs...."

[coreyfyfe]

That tab is unsoldered on my B15 of similar vintage. My amp has a 40/40 can and two 22uf caps inside. Sorry I can't answer any of your other questions, but I'm sure David or one of our other resident tech experts will be along shortly.

[kuratacus]

Originally Posted by beans-on-toast

I like running amps through a Marshall 412. It doesn't take a lot of power to get a good sound out of them. The B-15N/Marshall combination must sound really nice.

Your amp must have been taken care of really well to have the foam still intact like that.

i think it's due to having the original dust cover. though the bottom edge took a beating with out the dolly. you can see the faint square lines of the foam framing the the lower half of the baffle. more noticeable in person. I'm on the edge about trying to clean it, leaving it as is. or making a new front baffle for both my cabs so they they match and the originals stay original.

[kuratacus]

Originally Posted by JimmyM

LOL! I don't have the guts to try that on my wife

My Gf and i have an agreement. i can buy amps, she can buy cook books and kitchen appliances... it's a win win for me, she's a great cook ahhahaha

many a night over dinner "soooo i bought another.........." is over heard

[beans-on-toast]

It isn't unusual to see a schematic pasted in that has some differences from what is presented in the amp. It is also common to see wiring variations of the same circuit. At times it can be hard to distinguish between what was done at the factory and what was done after the fact.

There were a number of power supply revisions and different values of caps were used. 40/40/40/40 was one of them, as was 40/40/20/20.

I've never seen one wired as you described. Maybe the cap can is not original and whoever installed it was aiming to connect two 40uF caps in series to get 20uF at a higher working voltage. This was commonly done but you can't do it with a cap can because all the commons are connected to the metal can. Often the first cap is a larger cardboard tube made up of two series caps. I assume that the amp was working but 80uF would have caused a problem. Something odd seems to be going on.

I would test the capacitance of the sections in the cap can. I'm wondering if maybe the 40uF caps are well below spec and that allowed them to wire it that way. If the cap can label is wrong and they might have connected the two 20uF caps in parallel. In that case I would expect to see another external cap being used to make up for the missing 20uF. You said they had an extra cap.

[Thunderbucker]

[quote=beans-on-toast;13845173...
There were a number of power supply revisions and different values of caps were used. 40/40/40/40 was one of them, as was 40/40/20/20.

I've never seen one wired as you described. Maybe the cap can is not original and whoever installed it was aiming to connect two 40uF caps in series to get 20uF at a higher working voltage. This was commonly done but you can't do it with a cap can because all the commons are connected to the metal can. Often the first cap is a larger cardboard tube made up of two series caps. I assume that the amp was working but 80uF would have caused a problem. Something odd seems to be going on.

I would test the capacitance of the sections in the cap can. I'm wondering if maybe the 40uF caps are well below spec and that allowed them to wire it that way. If the cap can label is wrong and they might have connected the two 20uF caps in parallel. In that case I would expect to see another external cap being used to make up for the missing 20uF. You said they had an extra cap.[/QUOTE]


good stuff, thanks guys. I will test the cap can capacitance, planning on changing it anyway, 50 year old electrolytics don't get better like fine wine.

fliptops only has 40-40-20-20, any reccs on ideal power supply filtering for these? I'm more of a guitard myself, so don't know bass amps too well.