Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 9 - Page 29

jnewmark · #**561** 12-20-2012, 09:09 AM

Quote:

Originally Posted by beans-on-toast

Not quite, with the 8 ohm extension cab connected you have a 16 ohm load.

The amp has both 8 ohm and 16 ohms taps on the transformer. You don't have access to these at the back of the amp. When the 8 ohm internal speaker is connected, it is connected to the 8 ohm transformer tap. The impedance is matched. When you plug an external 8 ohm cab into the ext. spkr. jack on the back of the amp, the wiring is shuch that the internal speaker is connected in series with the external cab (8 ohms + 8 ohms = 16 ohms) and this is switched to the 16 ohms transformer tap. This switching is done internally when you plug into the ext spkr jack. So now your speaker load totals 16 ohms and is connected to the 16 ohm transformer tap. Again the impedance is matched.

You are correct, with tube loads it is better to go to lower impedances than it is to go to higher impedances. Either way there is a price to pay in doing so and matching loads is optimal.

Got'cha, thanks. Here is a shot of the speaker mag. Does the " 69 " indicate the year ?

portaflexer · #**562** 12-20-2012, 09:20 AM

I'm not an expert at those date codes, but I believe 432 is the manufacturing line and 7150 is the date. That would be read as the 50th week of 1971. Again... I'm no expert.

beans-on-toast · #**563** 12-20-2012, 09:40 AM

Yes as portaflexer said, the 4327150 looks like an EIA speaker code: 432 is Long Engineering, Inc., Waveland, IN, 71 is the year, 50 is the week.

Sometimes CTS would subcontract another manufacturer to help fulfill their orders. Long Engineering made speakers and, like CTS, was also located in Indiana. The speaker would have the same specs as the CTS, sometimes even assembled with the same parts, just produced at a different site.

If the resistor codes turn out to be earlier, perhaps it is a replacement speaker. Other B-15's have turned up with drivers from Long Engineering though so it could be original.

There may be other numbers on the rim where the mounting screws are located. A CTS speaker would start with a 137 code.

coreyfyfe · #**564** 12-20-2012, 09:43 AM

The 69300090 number is the ampeg part number for those speakers. 432 is the EIA code for Long Engineering as best I can tell (pdf) and 71 50 would be 50th week of 71 as said above. I've seen speakers with a few different codes conforming to the same CTS look in the early 70s amps. Either ampeg or CTS would contract out to other vendors to make the speaker to the same spec when speaker production output couldn't keep up with amp production demands.

jnewmark · #**565** 12-20-2012, 10:33 AM

Quote:

Originally Posted by coreyfyfe

The 69300090 number is the ampeg part number for those speakers. 432 is the EIA code for Long Engineering as best I can tell (pdf) and 71 50 would be 50th week of 71 as said above. I've seen speakers with a few different codes conforming to the same CTS look in the early 70s amps. Either ampeg or CTS would contract out to other vendors to make the speaker to the same spec when speaker production output couldn't keep up with amp production demands.

Thanks. Next time I'm in Boston, I'll buy ya a clam roll !

gimp · #**566** 12-21-2012, 09:42 AM

I swear I asked this before, and I think I know the answer, but I can't see to find it.

I have an orphan B-15NF head. Will this fit in the newer PF cabinets? Ultimately, I'd like to go original or Vintage Blue, but I thought I'd check my options.

**Bass 45** · #**567** 12-21-2012, 09:49 AM

I think it would if the hf horn was removed.

coreyfyfe · #**568** 12-21-2012, 11:14 AM

I don't think so. The newer cabs have extra internal bracing that would also have to be removed. At least in the 2x10, I'd have to look at a picture of a 1x15 to know if they have the same setup inside. Try stalking ebay and craigslist, sometimes orphaned cabs do pop up.

For example, this is not exactly what you want, it's a copy of an ampeg cab with a CTS speaker, but it could do the trick for less than the cost of a VB or fliptops cab for now.

http://www.ebay.com/itm/Bass-Speaker...item35c2bb1662

**Bass 45** · #**569** 12-21-2012, 12:02 PM

I should have specified that I was referring to the PF115HE only. I am pretty sure that would work with the horn removed. There is no internal cross brace like the 210 has.

I cannot verify for sure though. I have been selling off some of my stuff (including the Ebay listing you showed)as I am moving into a smaller place and my PF115's are gone

JimmyM · #**570** 12-21-2012, 12:07 PM

I have not tried flipping my B-15 head into my PF115he, but aside from the tweeter, you have to consider that the speaker is mounted to one side, and that will likely cause the output tranny to bang into the speaker frame.

gimp · #**571** 12-21-2012, 12:07 PM

No problem. I appreciate the heads up. I may have to measure my '67 BT-15 cab and head to Guitar Center with a tape measure.

jnewmark · #**572** 12-21-2012, 03:31 PM

Picked it up today. Really a well preserved B15N, with a little tolex damage on one side, but otherwise, in great shape. It also came with a zippered, black vinyl cover, no Ampeg logo. I'm wondering if this was a custom job, or did Ampeg supply generic covers at this point ( 1971 ) ?

jnewmark · #**573** 12-21-2012, 03:32 PM

And another one.

JimmyM · #**574** 12-21-2012, 03:36 PM

Quote:

Originally Posted by jnewmark

Picked it up today. Really a well preserved B15N, with a little tolex damage on one side, but otherwise, in great shape. It also came with a zippered, black vinyl cover, no Ampeg logo. I'm wondering if this was a custom job, or did Ampeg supply generic covers at this point ( 1971 ) ?

That's one hot looking B-15N! Not sure about the covers, but the V4B/810 I bought from my cousin's ex-husband in the 70's came with a zippered cover for the 810 with no logo.

jnewmark · #**575** 12-21-2012, 03:37 PM

One more.

**Bass 45** · #**576** 12-21-2012, 03:39 PM

Nice score!

I would recognize an original cover if you post a photo.

Edit: Judging by the looks of your amp, the cover has been there all along.

JimmyM · #**577** 12-21-2012, 03:46 PM

I miss my 77 B-15N now.

jnewmark · #**578** 12-21-2012, 03:56 PM

Quote:

Originally Posted by Bass 45

Nice score!

I would recognize an original cover if you post a photo.

Edit: Judging by the looks of your amp, the cover has been there all along.

Ask, and ye shall receive. Pics with the cover unzipped. No writing anywhere, inside or out, a thin felt lining on the inside.

**Bass 45** · #**579** 12-21-2012, 04:02 PM

Quote:

Originally Posted by jnewmark

Ask, and ye shall receive. Pics with the cover unzipped. No writing anywhere, inside or out, a thin felt lining on the inside.

Well shoot, that looks a little different than I am used to seeing - specifically the seam being up past the shoulders, a smaller zipper (maybe) and different pattern around the handles.

That being said, it looks era correct and I don't think there were a bunch of custom cover places back then like we have now.

I think it is original - but I am not 100% sure like I thought I would be.

Ric Vice · #**580** 12-21-2012, 04:43 PM

Quote:

Originally Posted by jnewmark

Picked it up today. Really a well preserved B15N, with a little tolex damage on one side, but otherwise, in great shape. It also came with a zippered, black vinyl cover, no Ampeg logo. I'm wondering if this was a custom job, or did Ampeg supply generic covers at this point ( 1971 ) ?

J Newmark,
Wow, that one's showroom fresh. I don't think the Ampeg covers ever had logos. The Blue Checked ones just matched the cabinet covering. My recollection is that the newer ones just had a black vinyl cover. I had a friend who owned one of these amps, and I think his cover just slipped over the cabinet, but it's been awhile, so I could be wrong. That amps in beautiful condition. I had forgotten that the newer ones, had their speaker connections, at the rear of the cabinet, that's interesting

Ric