Jess Oliver's legacy - AMPEG PORTAFLEX CLUB part 9

[JimmyM]

Originally Posted by lowend81

Hey Jimmy!

I found this guy on the Montreal craigslist while on tour. The serial numbers date it to early 1965. The previous owner bought it off a guy in Philadelphia. It looked at little rough and the shockmounts had worn through, but it worked and it still had the original CTS speaker. I hadn't planned on buying an amp on tour but once I played it I knew I had to have it and the act I was touring with also encouraged me to buy it...she even paid me extra for the previous gig so I'd have no excuse not to buy it.

Attachment 310338

I used it at our gig that night and loved it. When I got it back home to Toronto I spent a few hours scrubbing the dirt out of the tolex and got on Fliptops.net to order a few parts (all cosmetic except for the shockmounts) to get the amp looking like her old self. Once everything was polished up and tightened I used it for a gig with a 4-piece rock band and it kept up just fine. I got a lot of compliments on my tone that night - the B-15N and my Eastwood Classic 4 are a killer combo!

Attachment 310339

Happiness Is A Warm Tone

Nice! Will add you to the list when I get back from my road trip Saturday or Sunday. My list is at home.

[spacebassed]

Originally Posted by beans-on-toast

There is very little known about the NA and NB which is surprising as a different speaker, cab connector, and solid state rectification were major changes. They also put the kibosh on the design changes fairly quickly, they were in production for less than a year. It leaves me wondering what happened to cause the fast turnaround.

The Jensen EM series speakers were used in several amps. Fender used them at one point as well and they are sought after even today. I quite like this speaker. Ampeg dropped them and switched to CTS. Maybe they wanted to be different, perhaps it was a financial issue.

I don't think they really ever meant to make the B15NA, since it is essentially the same as the B15NB. It seems that the NB was supposed to be the next revision, but they made some amps with all of the changes that the NB had except the 4 pin xlr (possibly to use up the stock of octal connectors), then they ended up calling all those amps B15NA's. If you notice, the "A" is handwritten on the schematics and all the B15NA cabinets are labeled B15NB.

Originally Posted by ddbassGA

Interesting to wonder how things might have turned out if Jess had stayed and he and Kager had bought out Hull.

Ken Fischer (of Trainwreck fame) was also there around that time. If those 3 would've taken over the company I think its pretty safe to say the the history of Ampeg would've been a lot different. I certainly don't think we would've seen amps being built in China or Vietnam or some of the quality control problems Ampeg had a while back.

Originally Posted by jnewmark

My whole thing is, I'm wondering if either of those two, or any other 100dB sensitivity driver will get me past noon on the volume dial, or get louder sooner. It seems that, to me, the B15N is just a tad shy of being able to keep up with a reasonable drummer, on it's own.

Using a more efficient speaker won't get you more usable range out of the volume knob, what it will do is get you more apparent volume at the same volume setting. If modern speakers don't get you to where you want to be, you might want to try an old ElectroVoice, those were very efficient speakers - but they're heavy. As David said, making sure your amp is in perfect working order will get you the most out of your volume knob (I think David said he has his amp to where he can get just past 2 o'clock without distortion). You might also want to invest in a plug in SS rectifier. Using something to boost your signal will also get you more volume as well. I have an old Dynacord tape echo that I got with my B15 that I use for a bit of a boost and to brighten things up when i play guitar through my B15, just be careful not to overdo it or you'll overdrive the frontend of the amp.

[jnewmark]

Originally Posted by spacebassed

Using a more efficient speaker won't get you more usable range out of the volume knob, what it will do is get you more apparent volume at the same volume setting. If modern speakers don't get you to where you want to be, you might want to try an old ElectroVoice, those were very efficient speakers - but they're heavy. As David said, making sure your amp is in perfect working order will get you the most out of your volume knob (I think David said he has his amp to where he can get just past 2 o'clock without distortion). You might also want to invest in a plug in SS rectifier. Using something to boost your signal will also get you more volume as well. I have an old Dynacord tape echo that I got with my B15 that I use for a bit of a boost and to brighten things up when i play guitar through my B15, just be careful not to overdo it or you'll overdrive the frontend of the amp.

Thanks. The amp is at my tech right now, so I should know if anything is amiss. As far as a replacement speaker, I might go that route with a JBL K140 as I have some laying around. The SS plug in rectifier is an interesting idea. Are you saying that, it could ruin the front end if I turn it up too much ?

[spacebassed]

Originally Posted by jnewmark

Thanks. The amp is at my tech right now, so I should know if anything is amiss. As far as a replacement speaker, I might go that route with a JBL K140 as I have some laying around. The SS plug in rectifier is an interesting idea. Are you saying that, it could ruin the front end if I turn it up too much ?

A SS rec will give you a bit of a stronger sound, and maybe a little more clean headroom. And I meant that if you decided to used some sort of boost (a pedal, ect.) not to overdo it. The hotter the signal you give to the frontend of the amp the sooner you can cause onset of distortion. You won't hurt anything, its just not what you want as a bass player (well, MOST bass players don't want distortion). With my Dynacord in front of the amp I can get anything from a nice clean volume boost to Marshall crunch territory if I really crank it. I can get a lot more clean volume using a little boost in front of the amp, than trying to crank the volume knob on the amp.

[Ric Vice]

Originally Posted by spacebassed

A SS rec will give you a bit of a stronger sound, and maybe a little more clean headroom..........

J Newmark,

I have a Webber Copper Cap (SS) Rectifier in my B-15N(C). This was recommended to me by other TB members on this thread. As I recall, the Webber is designed to emulate a tube rec. All I can say is that the amp sounds great with the Webber in place.
http://www.webervst.com/ccap.html

Ric

[spacebassed]

The Weber's are nice because they have an inrush limiter, which keeps your power section from being slammed with voltage. A tube allows the voltage to slowly charge the power supply caps, the inrush limiter simulates this. A SS rec is also nice because it doesn't draw heater current like a tube, making your power transformer run cooler - well worth the $20 investment.

[jnewmark]

Originally Posted by spacebassed

The Weber's are nice because they have an inrush limiter, which keeps your power section from being slammed with voltage. A tube allows the voltage to slowly charge the power supply caps, the inrush limiter simulates this. A SS rec is also nice because it doesn't draw heater current like a tube, making your power transformer run cooler - well worth the $20 investment.

Good to know, I think Beans brought this up a few pages ago. Might just go for it to see if it makes a difference. I would really like to just use the B15N without lugging another cab to this little restaurant gig I do every now and then, but the guitar player uses a Fender Super. Just not quite enough gas to keep up without going into fartsville.

[beans-on-toast]

Since your amp is going to be checked out by your tech, he will mention that you want him to pay particular attention to the power supply and you would like the amp to have more headroom and less distortion when cranked. New caps will help if the old ones are in bad shape. So will the Weber solid state rectifier replacement. This might be enough to give you the edge that you need.

A last option that you might want to discuss with your tech is beefing up the power supply. The first power supply cap (C17 on the schematic) is 30uF. This cap running out of capacity is a big reason why the amp farts out when it does. You can consider increasing the value of this capacitor. Some B-15's, including mine, have a 40uF here. The heritage B-15 has a 47uf cap, an inductor, then another 47uF capacitor. The schematic is available on the user's manual on the Ampeg site if your tech wants to look at it. These changes were all intended to give the amp a little more headroom and to extend the onset of distortion. Increasing the value of this cap sometimes requires adding a couple of diodes to protect the tube rectifier. The mods are reversible although tech time cost money.

[jnewmark]

Originally Posted by beans-on-toast

Since your amp is going to be checked out by your tech, he will mention that you want him to pay particular attention to the power supply and you would like the amp to have more headroom and less distortion when cranked. New caps will help if the old ones are in bad shape. So will the Weber solid state rectifier replacement. This might be enough to give you the edge that you need.

A last option that you might want to discuss with your tech is beefing up the power supply. The first power supply cap (C17 on the schematic) is 30uF. This cap running out of capacity is a big reason why the amp farts out when it does. You can consider increasing the value of this capacitor. Some B-15's, including mine, have a 40uF here. The heritage B-15 has a 47uf cap, an inductor, then another 47uF capacitor. The schematic is available on the user's manual on the Ampeg site if your tech wants to look at it. These changes were all intended to give the amp a little more headroom and to extend the onset of distortion. Increasing the value of this cap sometimes requires adding a couple of diodes to protect the tube rectifier. The mods are reversible although tech time cost money.

Could you use the ss rectifier in conjunction with increasing the first power cap to 40uF ?

[Jignant]

First post on TB...Long time poster on The Gear Page & LPF.

Here is my entry to the club, B-15N around 1972. This amp was purchased by my father as a keyboard amp for a Wurlitzer electronic piano back in the day. It was also used by him in his music store for several years while he taught guitar. I have the original price tag that I just found in the cab. $550.00...WOW!

Dad gave it to me in it's original condtion in the late 90s and it has been sitting the majority of that time. I am pimarily a guitar player, but I have been working on bass and getting ready to gig as a bass player in a project with some friends. I am currently struggling with the mic vs. DI issue because I want to use this amp as a gigger. Here she is:









Overall the amp is in great shape. Almost no damage to the tolex whatsoever. Original square magnet speaker (don't know what it is) Metal logo and squared outlines date it to around 1972 which makes sense as that is when I remember him getting it. Playing a MIM Fender Dimension bass (which is somewhat rare in and of itself) thru it. Not the best bass but light weight and fast like a guitar with a decent tonal spectrum.

I have replaced all tubes in the amp except the rectifier tube and have all the originals. Nothing has been modded and I am going to test the original tubes and re install them as I suspect they did not really need replaced. Something Sovtek in it now.

My plan is to either DI with an MXR box AND or mic it with something I need to acquire. I hear a 57 won't do the trick...

Please include me in your elite club...after all I had to fish thru all 7 or 8 incarnations of this thread to find you all here! What is the current favorite mic of choice for one of these and thanks!!!

[jnewmark]

^ Nice , just like mine !

[beans-on-toast]

Originally Posted by jnewmark

Could you use the ss rectifier in conjunction with increasing the first power cap to 40uF ?

Yes, they are two independent things if you are using the Weber WS-1. I have run mine like that. Most of the time I have a 5AR4 installed though.

I threw that capacitor change out there as a last possibility. Most people don't like making changes to their amp. Have your tech check it out and see if he can do anything for it first.

[jnewmark]

Originally Posted by beans-on-toast

Yes, they are two independent things if you are using the Weber WS-1. I have run mine like that. Most of the time I have a 5AR4 installed though.

I threw that capacitor change out there as a last possibility. Most people don't like making changes to their amp. Have your tech check it out and see if he can do anything for it first.

WS1 - diodes and limiter only. What's the difference between this one and the Wz34 and WR4 ? All three could be used in a B15N ? The chart is a little confusing.

[nouroog]

Originally Posted by Jignant

First post on TB...Long time poster on The Gear Page & LPF.

Here is my entry to the club, B-15N around 1972. This amp was purchased by my father as a keyboard amp for a Wurlitzer electronic piano back in the day. It was also used by him in his music store for several years while he taught guitar. I have the original price tag that I just found in the cab. $550.00...WOW!

Dad gave it to me in it's original condtion in the late 90s and it has been sitting the majority of that time. I am pimarily a guitar player, but I have been working on bass and getting ready to gig as a bass player in a project with some friends. I am currently struggling with the mic vs. DI issue because I want to use this amp as a gigger. Here she is:









Overall the amp is in great shape. Almost no damage to the tolex whatsoever. Original square magnet speaker (don't know what it is) Metal logo and squared outlines date it to around 1972 which makes sense as that is when I remember him getting it. Playing a MIM Fender Dimension bass (which is somewhat rare in and of itself) thru it. Not the best bass but light weight and fast like a guitar with a decent tonal spectrum.

I have replaced all tubes in the amp except the rectifier tube and have all the originals. Nothing has been modded and I am going to test the original tubes and re install them as I suspect they did not really need replaced. Something Sovtek in it now.

My plan is to either DI with an MXR box AND or mic it with something I need to acquire. I hear a 57 won't do the trick...

Please include me in your elite club...after all I had to fish thru all 7 or 8 incarnations of this thread to find you all here! What is the current favorite mic of choice for one of these and thanks!!!

Just like mine too, except way cleaner! Speaker is probably a CTS. Have you looked if there's a 137 code on the back of the magnet?
IMHO, a SM57 wouldn't be that bad a choice, it might lack some bottom, but would fit in a live mix.
Following Jimmy's advice, I have tried and adopted the Heil Sound PR40, and like it a lot, in different placements.
Here's a clip I made some time ago with a PB and my 73 Portaflex, recorded with the PR40.
http://soundcloud.com/nouroog/cts-vs...s-weber-pb-cts
Congrats and welcome!

[beans-on-toast]

The WZ34 is a GZ34 emulator. It sags like the tube although not as much. If you want the most clean out of you amp, you want the WS-1 since it has a rectifier and current surge limiter in it but no sag. Yes, you could use either in the amp. The WR4 emulates a 5R4 tube, not the same as the 5AR4 that is used in the B15N. Don't use that one as it would lower the amps power supply voltage too much.

You want a solid state module with a current limiter in it. Not all of them have this. The current inrush limiter provides a slow power turn on. It ramps it up. This allows discharged capacitors in the amp to charge slower than if they were hit with full power. This helps them enjoy a longer service life. Some tube rectifiers do this as well. The 5AR4 rectifier tube that the B-15N uses has this slow turn on feature. Without the current limiter, the current surge could be high enough to blow the amp's fuse. The amount of current draw in this surge depends on the size and health of the power supply caps. A bigger cap like the 40uF will have more of a surge than the original 30uF. That is why I said to get the WS-1.

If you want some sag when the amp is pushed, try the WS-34. The advantage of using a SS rectifier is that there is no heater in the device like a tube has. This saves 1.9A of current at 5V or 9.5 Watts. Your power transformer will run cooler. Just keep in mind, it is intended to act like the tube but is not the same in terms of sagging.

[johnnyt]

I'll let you know the D130 sounds in the '66. I'm gonna try a E140 that I have in the B-15R cab. I figure that's a good place to start.

[jnewmark]

Originally Posted by beans-on-toast

The WZ34 is a GZ34 emulator. It sags like the tube although not as much. If you want the most clean out of you amp, you want the WS-1 since it has a rectifier and current surge limiter in it but no sag. Yes, you could use either in the amp. The WR4 emulates a 5R4 tube, not the same as the 5AR4 that is used in the B15N. Don't use that one as it would lower the amps power supply voltage too much.

You want a solid state module with a current limiter in it. Not all of them have this. The current inrush limiter provides a slow power turn on. It ramps it up. This allows discharged capacitors in the amp to charge slower than if they were hit with full power. This helps them enjoy a longer service life. Some tube rectifiers do this as well. The 5AR4 rectifier tube that the B-15N uses has this slow turn on feature. Without the current limiter, the current surge could be high enough to blow the amp's fuse. The amount of current draw in this surge depends on the size and health of the power supply caps. A bigger cap like the 40uF will have more of a surge than the original 30uF. That is why I said to get the WS-1.

If you want some sag when the amp is pushed, try the WS-34. The advantage of using a SS rectifier is that there is no heater in the device like a tube has. This saves 1.9A of current at 5V or 9.5 Watts. Your power transformer will run cooler. Just keep in mind, it is intended to act like the tube but is not the same in terms of sagging.

Thanks. So if I went with the WS1, and bumped up the first power cap to 40uF, do the additional diodes still need to be added ? BTW, do you happen to know what size nut driver to use for the speaker nuts ? I see nut drivers all the time at garage sales.

[beans-on-toast]

No you don't HAVE to add the diodes with the 40uF cap and the WS-1 but I recommend that you do.

Whether or not the diodes are required depends on the type of caps. Many B-15's have a 40uF cap and no protection diodes. If you install a GZ34 tube and you see a flash when you turn on the amp, you need the diodes for sure. The purpose of the diodes is to protect the tube. You want the amp to be able to be used either the tube or the SS rectifier so if the tube needs them, they won't affect the function if the SS module they are in place.

I add these diodes every chance I get. With the high cost of GZ34 tubes, it is smart to offer the protection. It doesn't affect the amp other than to serve as protection for the tube. It extends what is called the peak inverse voltage of the diode in the tube. The diodes can be mounted on unused terminals on the rectifier socket. Here is how it can be done. The diodes are D1 and D2 on the schematic, there is also a layout drawing further down that shows how they are mounted. Rather than use the diode that Fender used, you can use a pair of 1N4007's or better yet UF4007's as they respond faster and don't cost a lot ($0.41 for the UF4007 vs $0.14 for the 1N4007 at mouser.com). Good insurance for less than a buck.

[AverageWhiteBassist]

Originally Posted by Jignant

First post on TB...Long time poster on The Gear Page & LPF.

Here is my entry to the club, B-15N around 1972. This amp was purchased by my father as a keyboard amp for a Wurlitzer electronic piano back in the day. It was also used by him in his music store for several years while he taught guitar. I have the original price tag that I just found in the cab. $550.00...WOW!

Dad gave it to me in it's original condtion in the late 90s and it has been sitting the majority of that time. I am pimarily a guitar player, but I have been working on bass and getting ready to gig as a bass player in a project with some friends. I am currently struggling with the mic vs. DI issue because I want to use this amp as a gigger. Here she is:









Overall the amp is in great shape. Almost no damage to the tolex whatsoever. Original square magnet speaker (don't know what it is) Metal logo and squared outlines date it to around 1972 which makes sense as that is when I remember him getting it. Playing a MIM Fender Dimension bass (which is somewhat rare in and of itself) thru it. Not the best bass but light weight and fast like a guitar with a decent tonal spectrum.

I have replaced all tubes in the amp except the rectifier tube and have all the originals. Nothing has been modded and I am going to test the original tubes and re install them as I suspect they did not really need replaced. Something Sovtek in it now.

My plan is to either DI with an MXR box AND or mic it with something I need to acquire. I hear a 57 won't do the trick...

Please include me in your elite club...after all I had to fish thru all 7 or 8 incarnations of this thread to find you all here! What is the current favorite mic of choice for one of these and thanks!!!

Great amp! I am waiting on cables from fliptops.net to be able to run a countryman di in between the amp and speaker for full tubeness. This might be a good option for you, but mic'ing the cab grabs the full magic. DIs are easier and what a soundman typcially wants but try to get as much of your tone in there as possible.

[JimmyM]

Originally Posted by Jignant

My plan is to either DI with an MXR box AND or mic it with something I need to acquire. I hear a 57 won't do the trick...

A 57 doesn't have much low end response, but if you use two channels, use the DI for lows and a 57 for the cab, it'll sound great.

Otherwise, my favorite mics are an EV RE 20, Heil PR 40, Sennheiser MD421, and Beyer M88. Haven't tried it but the AKG P6 is a $100 mic that is supposed to sound great on bass cabs.

Also, I will add you when I get home as well.