Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 10

[TheDialog]

I have a '67 BT-15 head for sale.
PM me if you have any interest in it.

[beans-on-toast]

Originally Posted by Apex_speed

Here is a nice tame example with Focal Grande Utopia EM and MBL electronics.

Makes me wonder how it sounds running a bass through the system.

[Apex_speed]

Originally Posted by beans-on-toast

Makes me wonder how it sounds running a bass through the system.

I have visions of a high school kid showing up at his local hi-fi store with melted speakers and a smoldering amplifier saying..."hey man, I only plugged my guitar into it".

In all seriousness, it would be out of this world and like nothing you have ever heard except for one glaring flaw. It would sound EXACTLY like your bass in every way as a $700K system is designed as a perfect reference. The problem with that is we all buy these wonderful old Ampegs for the tone and distortion that adds to the experience we get and creates that signature sound we crave. So what you really need is a B-15 emulator to go between the bass and the system.

I will probably get around to trying it in the near future using an Alembic preamp and SuperFilter I just got to feed the system. The SuperFilter can be set up to sound like just about anything so I could probably dial in a reasonably close B-15 sound with some work.

[beans-on-toast]

Too much honesty can be bad when it comes to musical instrument amplification. But still, if one has the opportunity, you gotta try it.

Years ago, I had the misfortune of auditioning a set of high end speakers and it ruined me. Everything else pales in comparison.

I'd love to build a 300B based B-15. I keep promising myself that someday I'll get to it.

[stiles72]

Originally Posted by Bass 45

Thank you!

The '60 B15 and the '61 B15N did not make the photo.

Yes, there are multiple symptoms of a problem

Not being able to stop looking on Ebay is one of them

Now I have a '67 BT15C on the way. I won on a low bid on that I did not expect to win - as the cab is loaded with two JBL D130f's (I think).

The seller is making me very nervous though - so I am afraid of what I may be actually receiving. Before the auction ended, I asked if there was a JBL in the lower compartment (the photos only showed the top one) and he never responded (I assumed he did not have a clutch head screwdriver). Then, after I won, he sent me an invoice with a padded shipping cost and AZ sales tax added (he is in Florida!). And - I won the item on January 27th and he still has not shipped it. Every few days I get a long winded message from him "updating" me on his shipping process AND HIS CAPS LOCK IS ALWAYS ON!

Anyway - here it is folks:

http://www.ebay.com/itm/VINTAGE-AMPE...vip=true&rt=nc

Nice looking BT15C! I really like mine. Gotta love the light up control panel. I noticed the bat wing power switch has been swapped for a more standard paddle shaped one. One of mine has been replaced as well. Anyone have a source for original or close to original bat wing switches? Fliptops doesn't have them.

[beans-on-toast]

I don't have a source for you but you might find something close at Surplus Sales of Nebraska. Their stock varies so it helps to check them out from time to time. Also worth checking out the Carling toggle switches. They make a switch with a nylon paddle actuator that can be filed down and polished to a desired shape.

For some reason, I've always prefer the bat to the paddle actuator. I have a paddle switch for coil splitting on a Gibson guitar that cuts like a knife when I whack my hand against it.

[Apex_speed]

Originally Posted by beans-on-toast

Too much honesty can be bad when it comes to musical instrument amplification. But still, if one has the opportunity, you gotta try it.

Years ago, I had the misfortune of auditioning a set of high end speakers and it ruined me. Everything else pales in comparison.

I'd love to build a 300B based B-15. I keep promising myself that someday I'll get to it.

Oh yeah, a 300B B-15 would be amazing. That gives me an evil idea, I have an E211 based SET amp that I could run into a vintage B-15 cab using the pre out on the B-15 head. I bet it would be awesome but this could get silly really fast if I found something that I liked.

As to too much honesty, that is a real concern. I would never try something like this with the majority of basses but I think an Alembic would be ideal for the task as the electronics package and pickups approach what I would consider audiophile quality performance.

[ddbassGA]

Catching up on Portafkex posts and this one hit my funny bone:

Originally Posted by beans-on-toast

...
There is a simple test that you can perform that could help locate a problem with the wiring. Get a portable AM radio, tune it between two stations, and turn the volume up. This acts as a crude detector. Hold the radio near an outlet...

Great suggestion! But who still has a portable AM radio?

[beans-on-toast]

True enough. I figure, if anyone has one it would be someone with a 50 year old amp.

I used to love pulling in far away stations that played that rock-n-roll at night. Parents called it noise. Here's what I use as an RF noise detector. From time to time, I still try to pick up distant stations late at night. I think that Radio Shack still sells this model made by good old RCA.

[beans-on-toast]

Chances are, you've seen the PA designed by Bill Hanley and used at Woodstock in 1969. Below is a description of what was in the cabs. They choose to use JBL D130 and D140 drivers.

Two "bass bins" were placed under a pair of high frequency horns, totalling about a thousand pounds and standing roughly 6 feet tall, 4 feet deep, and 7 feet wide. Each of the four upper level bins was loaded with four 15-inch JBL D130 drivers with a loudness maximizer compressing the sound to improve reach. Each of the four lower bins was loaded with four 15-inch JBL D140 drivers for extended bass. The high frequencies were handled by model 1003B, 5x2 Altec multicell horns (300Hz. min freq) and Bill Hanley custom built 2x2 horns, all with Altec 290 compression drivers.

Sometime I use my B-15 to drive one or two EV SH-1502 cabs. A thiele designed cab with a 15" driver and a horn. Wonder if it would work with one of these cabs.

[micahturner]

Never noticed it until recently; when I'm playing around the 5-9th fret, G string on my P-bass, my B18 breaks up and distorts. I have the volume at 9 o'clock, treble at 11, bass at 1. Running it with two B15R cabs. The tubes are the original set. I'm not sure that has anything to do with it.

Thanks for the advise.

[christw]

Originally Posted by micahturner

Never noticed it until recently; when I'm playing around the 5-9th fret, G string on my P-bass, my B18 breaks up and distorts. I have the volume at 9 o'clock, treble at 11, bass at 1. Running it with two B15R cabs. The tubes are the original set. I'm not sure that has anything to do with it.

Thanks for the advise.

It could be a pickup height issue. My HW1 P has a rather tall J Worrell P in it and when I set the action how I like (med high) my G string ends up a tad hotter than the rest, especially in the upper registers when I'm pushing it down closer to the pickup.

[JimmyM]

Originally Posted by micahturner

Never noticed it until recently; when I'm playing around the 5-9th fret, G string on my P-bass, my B18 breaks up and distorts. I have the volume at 9 o'clock, treble at 11, bass at 1. Running it with two B15R cabs. The tubes are the original set. I'm not sure that has anything to do with it.

Thanks for the advise.

Seems a little low, doesn't it? I've had a pre tube issue that caused that before. If they're original, it's certainly within reason to suspect a tube.

[beans-on-toast]

I'd look at the bass first. Does it do this when plugged into another amp? The notes could be causing something to resonate in a pickup. Dripping wax on the back of the pickup to seal it can sometimes help. In these cases you tend to get a feedback but a distortion isn't out of the question. Sometimes certain notes are louder on a bass, the opposite of a dead spot on the neck. If this is the case it could be sending a signal that is too strong to the amp. But with the volume set so low I wonder about that possibility.

Try another bass in the B18 and see how it reacts. Is there anything vibrating in the amp when you hit those notes. Try damping the head, have someone apply pressure to it by lifting it or pushing down while you play.

[micahturner]

I tried it with my fretless, which yielded less distortion. The break up is still slightly present, but my tape wounds are naturally darker than the rounds on my P. Should I start looking into preamp tubes?

[JimmyM]

Maybe -a- preamp tube...doubt very seriously if all of them are like that, although since they're old Magnavoxes that came with it, it might be time to consider new ones. But before you do that, swap V1 and V2 and see if the problem clears up. And if that doesn't clear it up, swap V2 with V3. If I'm not mistaken, V1 is the pre tube for ch. 1 and V2 is for ch. 2 and V3 is a phase inverter.

[micahturner]

Thanks Jimmy. The kid is in bed, so I'll give it a shot tomorrow when I get off work.

[shadven]

I used my new 1967 SB-12 at a rehearsal tonight and it sounded really good. Plenty of volume to keep up with a Fender Champ and a drummer with an 18" kick. I had headroom to spare. I was playing with a P-bass with rounds, treble was at 2 o'clock and bass was at 11 o'clock. It really sounded better then my B-15n. I was surprised, but man, it's a tone machine and so smooth with great mids and lows.

I am recording with it tomorrow. I am planning on bringing the SB-12 and the B-15 and see what works best. I will be playing a 1975 P-Bass with Labella Flats and a newer P-Bass with rounds, and a Gibson T-Bird with rounds. I'll report back how the session goes.

[johnnyt]

Originally Posted by shadven

I used my new 1967 SB-12 at a rehearsal tonight and it sounded really good. Plenty of volume to keep up with a Fender Champ and a drummer with an 18" kick. I had headroom to spare. I was playing with a P-bass with rounds, treble was at 2 o'clock and bass was at 11 o'clock. It really sounded better then my B-15n. I was surprised, but man, it's a tone machine and so smooth with great mids and lows.

I am recording with it tomorrow. I am planning on bringing the SB-12 and the B-15 and see what works best. I will be playing a 1975 P-Bass with Labella Flats and a newer P-Bass with rounds, and a Gibson T-Bird with rounds. I'll report back how the session goes.

Gotta love the SB-12's!!!!!

[johnnyt]

This may be in a previous post, does anyone have the pin out for the octal connector on the cabinet(male)? I'm getting some intermittent crackle and I want to make sure I resolder the connections properly. Thanks!