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Official Ampeg Portaflex Club

#1,661
Bluesbob said:
Is it wrong for me to want a B15 even though I have (and am perfectly happy with) my SB12?
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only if the kids are starving because of it. otherwise, not at all!

dl, haven't tried the neos, but on paper, the kappalite 3015 looks better than the deltalite for the 15, and the deltalite 12 looks better than the kappalite 3012ho. honestly, i have no clue whether they would work or not, but if you know the internal dimensions of your cab, you could probably get one of the speaker gurus on here to give you an idea of how they'd work.
 
#1,662
I have a "Vintage Blue" cabinet that kills. it's loaded with the California ceramic 12 Weber with paper cone as recommended by Ted Weber. I am just wondering how a lightweight neo would sound. If it won't sound as good as the weber I am not interested, but if it sounds as good...or perhaps better (more highs due to 6lbs less mass?) then I might do it
appreciate any input on this from anyone who has tried such a thing with a 15
 
#1,663
JimmyM said:
only if the kids are starving because of it. otherwise, not at all!

dl, haven't tried the neos, but on paper, the kappalite 3015 looks better than the deltalite for the 15, and the deltalite 12 looks better than the kappalite 3012ho. honestly, i have no clue whether they would work or not, but if you know the internal dimensions of your cab, you could probably get one of the speaker gurus on here to give you an idea of how they'd work.
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I've had this one for nearly 20 years and (I hope this thought doesn't disqualify me for membership) lately I'm considering replacing the original, square magnet speaker with a 3015 -- to goose it a little.

Anyone done it? Any thoughts?

Link Removed
 
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#1,666
What's my number Jimmy?

1959 Model 835 Comboamp (I'll get photos up as soon as I get it back from the tech).
B15R
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#1,670
Thanks Tom. My 835 is having some work done by Rob Fowler in Cambridge Ontario. After all these years, the entirely stock amp finally needs caps.

I took dozens of detail pics of that amp because it's so cool inside, but I realized today that I don't have a single picture of the whole amp! I'll fix that when it comes back from Rob.

My B-15R was delivered today. I bought it from Brian at The Low End in Nashville. Special thanks to Ken Smith for helping me find it. The amp is in very nice condition, as you can see in pics.

By the way, Brian absolutely rocks. I can't believe how well he packed this amp for shipping.
 
#1,671
My first impression of the B-15R...

Overall, I love the amp. Some minor quibbles I have after about 4 hours of playing it...
1. I'm not sure I like the 6L6 tubes. I never liked them in any bass amp. To be fair, they're Groove Tubes, so they're not exactly the best quality 6L6 tubes. I'll likely switch it over to a set of Winged C EL34s.
2. Not sure I like the stock speaker. I'm considering getting an extension cab from Fliptops in Buffalo. They put the Eminence Delta 15A in their cab, so I'm wondering if I should put one of those into the amp. Has anyone tried this speaker in the the B-15R?
 
#1,672
first housecleaning:

#133 Crackpot
#134 derridiandrift

then yelling at the kids:

derri, how dare you post only close-up porn of the 835! don't you know us true amp porn freaks need some full frontal action!

now i can be fun daddy:

i wish i knew more about what speakers work in what combos. but all i know is that the 70's b-15n is rather dark with the cts alnico of that era and a little mid scooped with the delta 15a, and the delta and the 60's cts sound identical and are a perfect match for the smaller cabs. from all descriptions i've heard, the altec 421a is a more mid forward speaker, so if you want a more modern speaker, look for one that's a little more mid forward and it would probably work really well in the bigger thiele cabs of the late 60's and 70's.

and i would be willing to bet money (as long as it's not over a dollar) that the b-15r either has a delta or something very close to it, maybe a beta. so if you get the extension cab from bruce, i would probably wait and see how they work together and do a little ab'ing before dropping $90 on another delta.

wish i could afford to buy all these speakers and try them out. however, if you all want to figure out the internal dimensions of your cabs (measure inside, L x W x H, subtract a little for your speaker and any bracing), and i'll post an open question to the geniuses on here about what neos they think would work.

as for toobz, the 6l6's work really well in the b-15n's. what's to gain by putting el34's?
 
#1,674
JimmyM said:
the 6l6's work really well in the b-15n's. what's to gain by putting el34's?
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I'll make a sweeping generalization and say that EL34s tend to produce bass frequencies (or maybe I'm hearing low-mids, not sure) differently than 6L6 tubes. Any large bass amp that I've used with 6L6 tubes has been lacking that quality that I'm having trouble describing. I don't know about how they sound in old B15 amps.

Regardless of all that, I've been messing with my new-to-me B-15R all day now, and I think I'm just going to use the amp the way it is for a while.

Jimmy, you also made a good point about the speaker. I have no idea what speaker is in this amp, and when I buy the extension cab from Fliptops, I'll do exactly what you suggested before I consider replacing the speaker in the amp.
 
#1,675
I'm pretty keen to convert my SB-12 to a 230v transformer (or at least a dual 110v/230v tranny) to save me lugging around the separate voltage inverter that is half the size and weight of the SB-12 and very unattractive.

I've had a good look at the 29 different transformers on the fliptops.net website, but nothing jumps out at me as being obviously the one I need to buy. Can someone point me in the right direction for a 230v tranny that is a direct replacement for an SB-12?
 
#1,676
Aussie Mark said:
I'm pretty keen to convert my SB-12 to a 230v transformer (or at least a dual 110v/230v tranny) to save me lugging around the separate voltage inverter that is half the size and weight of the SB-12 and very unattractive. Can someone point me in the right direction for a 230v tranny that is a direct replacement for an SB-12?
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Ampeg lists the power transformer part number as PT-114 for the 7868 based SB-12, and PT-114A for the 6L6 model. Their schematics show the PT-114 used with both models so I assume either model will work. My info does not list a 240V export model as being available for the SB-12. I have one schematic that indicates that the B+ is 370-0-370 with a 117VAC primary voltage, the Ampeg part number is listed as 8930060. I haven't been able to confirm if the 370 spec is correct.

Since fliptops lists a 117VAC version for the SB-12, I would contact them and see if they can order an export model. Some of their transformers are made by Heyboer ([This invalid link has been removed]). You could contact them directly and enquire about having one made. Mercury Magnetics lists an SB-12 transformer for $175USD and can wind an export model (http://www.mercurymagnetics.com/pages/mainframe.htm).

As for a less expensive alternative, you can check out hammond (http://www.hammondmfg.com/guitarLinePWR.htm). They do not sell a drop in replacement but do offer some possibilities such as the 290BEX.

When looking for a substitute transformer, it is good if you can at least match the impedance that the tube rectifier sees (this can be calculated from the direct current resistance specs - see the 290BEX spec sheet to see what I mean by the DCR readings) and the secondary voltage and current specs.

If you feel comfortable working with lethal voltages ... You can unplug your amp and with the tubes removed, measure the transformer DC resistance values with a good ohm meter. Then plug in the transformer and measure the unloaded B+, 5V, and 6.3V secondary tap voltages. All these specs will give you a guide as to what to look for when selecting a replacement transformer. Not a straight forward task. Sometimes it is easier to pay more and buy a transformer that has been designed specifically for your amp.


David
 
#1,677
Thanks David. I got an email reply from Bruce from fliptops who says they don't stock a PT-114/114A transformer in export voltage, but he can get one custom wound for me with a 6 week waiting time.

I'm not comfortable working with lethal voltages, so all I'm planning on doing is buying the transformer and taking it to a tube amp tech here to install.

The rest of the restoration is coming along nicely. I've managed to remove all of the remaining glue residue that was under the black tolex that was glued and stapled over the top of the blue diamond cloth, and I have a Jensen C12N, script logo, new latches and new corners arriving any day now from fliptops.

Fortunately, most of the glue was on the back of the cabinet, so even though that side of the cab isn't in pristine condition, at least I have it back to original condition now.

Here's a pic from last night when I was half way through the glue removal phase ...

DSC02059.gif


It came up pretty well by the time I'd finished ....

DSC02064.gif
 
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#1,680
derridiandrift said:
Hey Mark. You're probably well aware of this, but I'll over-state the obvious. Be very careful about the size of the transformer that you buy. I've seen a few very ugly flip-tops with a replacement transformer that was too big for the black cover to go back on. Just nasty looking.
Click to expand...

Yes, I know that. The transformer that fliptops sell is the original PT-114, an exact replacement for the SB-12. They will get one of these wound for 240v for me.
 

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