Official Ampeg Portaflex Club

[Ric Vice]

We have meetings here whenever necessary.

I do remember those Dyna Kit Catalogs, in high school. Everyone was trying to score the cash, for the Dynaco to use it as a Bass Amp

I wish I could sill gig with it, but it struggles a bit with cleans since bumping up our volume, so the V4B is the better choice for me these days. May take it to our next gig just to see what happens, though.

I gigged for about two years, with my B-15N(C), but even in 1974-75 it was tough to keep up with a Hammond B-3, and a drummer in the small clubs and lounges I used to do. I moved to a Walter Woods MI-100-8, but still used two orphaned Portaflex
B-15N cabinets, the one off the B-15N(C) was a double baffle, and I had one of a B-15N(D) that was a single baffle. It was a really nice sounding smaller rig running 100 watts, just like your V4B. I always loved the V4B head, but that cabinet was a really challenge
to play through. What you heard on stage was, not what the audience heard. Great for them, not so great for you.

Ric

 

[jbd5015]

I wish I could sill gig with it, but it struggles a bit with cleans since bumping up our volume, so the V4B is the better choice for me these days. May take it to our next gig just to see what happens, though.

Filthy dirty amps past 2 or 3 o'clock! i run it at 1-2 o'clock (3 when i need some fuzz...pedal coming soon) which is great considering the tone and reasonable volume levels for even small clubs. I use my EQ pedal as a scoop to clean it up when i need it to be for some of the country-bumpkin tunes we do. Ive been switching between pick and pluck a lot more recently which has been a HUGE help in tone shaping!

 

[59Pan]

Took a bit of time after I got home this evening, to remove and replace both C14 and R32. Connected all cables and warmed the amp. I suppose that I should have taken voltage readings, at that point. But, the speaker came alive for the first time, in a while. Mainly the noise was from the open chassis sitting under the bench fluorescent lamp. Very loud hum, as the volume pots were at full. Switched the lamp off and the amp became remarkably quiet. And, no shields on any tubes. I will try to remember to snap an overhead picture with a 6" ruler next to the tubes. They are close.

And, the 1M resistor still reads open. I twisted the leads a bit, but no change. And, it has no outward appearance of being defective.

So, I turned the volumes down, put all other pots at 12 o'clock, and retrieved my little Supro guitar. Tried each channel at half volume, only strumming chords, and my wife tells me that I've got to take that out of the house. I now have my amp back. And, better. I don't think that it was this loud before. Tremolo has good range and sounds good. The Reverb sounds really good, too. I will wait until I have it all back together, before playing with the Tone controls. It goes to Church for sure, this Sunday. The speaker that I'm using is a 12" Eminence Wizard, 8 ohms impedance, that I put in one of my really nice Bell & Howell speaker cabinets. This cabinet will go with the amp when I carry it on Sunday. I will keep it fairly active through Saturday, just to be sure no other issues arise.

Tomorrow, I will take complete voltage readings and save them to the voltage chart on my drawing(s). I'll also take another set of bias readings. I'll post the updated drawings, by the weekend.

I'll post more as I am closer to finish. And, I need to run by the drug store tomorrow and see if I can put my hands on some of those little brushes, and give all the tube sockets a good cleaning, and put a touch of No-Ox on them. Thanks, David, for all your help, comments, and suggestions. You may have another to ponder, when I open the PA-100X. There will definitely more to come. Have a good one.

Jack

 

[beans-on-toast]

Sounds like you got it Jack. Your meticulous approach made it easier to pinpoint the problem.

When you take your voltage readings, you can measure the voltage across the 1M resistor and calculate the current through it. It won't be much. I would check the other resistors on that tube just to ensure that they are within spec. Also check the 100R screen resistors on the power tubes, R42 and R43.

 

[pedrodelawasp]

You're right. The PF500 isn't a quiet head. Can't blame you for keeping an eye on the bottom line, that's for sure. The AK's are pretty good cabs.

Just added (ordered, anyway) another PF head to the stable: a PF-350. I'll be using it at rehearsal to emulate my SVT-CL, which is the gig and home practice head.

I think so, too. I've had the PF-500 and the PF-800, but for my current needs, the 350 better fits the bill. Plus, at $170 new, I can't beat the price.

Having kept an eye on this thread, I think I have come to a decision...

I need a head soon, but the bottom line is at a premium. However, once the New Year comes by I will have more disposable income (well, smaller bills). So, the plan is a PF350 on its own just now - a great value, good sounding and super portable head that will cover most gigs comfortably enough.

Next year: two 115 cabs purchased at convenient times, followed by the PF800. The more powerful amp will become my main gigging weapon whilst the 350 can be my home and rehearsal head.

I had the opportunity to take my bass and pedalboard along to Guitar Guitar and try both heads - not at full gigging volume, but they let me crank it enough to know I like the sound of both amps. I really like the sound. I tried the 350 through a 115HE and the 800 first through a pair of 115 LFs then a 115 paired with a 210HE. All combinations sounded very pleasant, but I think my initial inkling for a matched pair of 115s will be the way I'll go.

When I get the 350 I'll be able to take it to the rehearsal rooms and try it through all manner of different cabs, the place is really well stocked and the guys running the place are great when it comes to accomodating swapping things about. They have lots of Ampeg, some Hartke, SWR and properly old Marshall bass cabs [plus a few Trace combos].

I think this plan makes sense... Shall TB offer affirmation or talk me out of it?

 

[beans-on-toast]

Having kept an eye on this thread, I think I have come to a decision...

I vote Yea for the plan. The PF350 will serve as a good practice amp and backup.

 

[59Pan]

Warmed the amp up this morning and took another complete set of readings. The reason for this is that I installed a thermistor on the primary of the PT, influenced by the Ampegs of the time. It dropped my secondary voltages a bit, but overall, not much change. I really like watching the gradual increase in glow from the power lamp and the tube filaments. I figured that it would a lot better on the old components to slow the inrush current a bit. It's rated for 3 amps. The amp is fused for the same, anyway. I positioned it so that it would not touch anything, as I know how hot they get.

And, the original picture of the front, before repairs:

Channel 1 does not have the gain that Channel 2 does. I'm thinking that it's because the signal passes through the LDR, before heading for the next stage. I did not test either above half volume, this morning, and they are both plenty loud. Wish that I had thought to take a picture of the LDR/Lamp holder. Appears to have been made from a pistol cartridge case. The LDR is glued into a drilled hole in the case bottom. The lamp is fitted into a hole, drilled across the case, and very close to the LDR. The end is crimped flat and maybe soldered. Some kinda neat setup.

I've attached the updated drawing, but kept the same revision. No changes other than voltages.

David -

I think that I calculated .3mA across R32. Very small.

Anyway, I'm going to play with it for the next couple of days, and then carry it to Church for my buddy Don to give a workout. I'll carry the nice old Bell & Howell cabinet with the 12" Eminence Wizard. Sounds really good with this amp.

 

[Pentatonic]

There is a 1960s Ampeg M-15 for sale near me for $450. Looks to be in very good physical condition and am told it was recently repaired (not sure what for yet). I was thinking this would be a great guitar amp and also a good bass amp for practice at low volumes. Does anyone have any experience with this vintage Ampeg model?

 

[Dadagoboi]

I've enjoyed reading about your exploits, 59Pan, great job!

Here's my PF500, bought off the Guitar Center used website after being given a heads up by a fellow TBer a few years ago. I replaced a preamp tube, 2 6V panel lights, got a repro handle, built a dolly, and gave it a good cleaning. Fantastic amp! Channel 1 is very B-15 like, channel 2 is more Fenderish. Lift motor is non functional but everything is there.

Before:

 

[beans-on-toast]

Here's my PF500, bought off the Guitar Center used website

Very nice Carlo. It looks like new. One remarkable thing about the Oliver amps is that they are very much like the Ampeg amps of the same era. Circuilt boards with cutouts on the top of the chassis, covered by aluminum plates. This Oliver amp has massive transformers helps make it sound so good.

 

[beans-on-toast]

There is a 1960s Ampeg M-15 for sale near me for $450. Looks to be in very good physical condition and am told it was recently repaired (not sure what for yet). I was thinking this would be a great guitar amp and also a good bass amp for practice at low volumes. Does anyone have any experience with this vintage Ampeg model?

The M15 is a good guitar amp and you can use it for bass at lower levels.

Same power amp as a B-15. The power supply caps are a bit smaller than that of the B-15 but not a lot. What you would expect to see in a guitar amp to give you some distortion. The tone controls are voiced differently, again, not a big issue.

 

[Ric Vice]

Very nice Carlo. It looks like new. One remarkable thing about the Oliver amps is that they are very much like the Ampeg amps of the same era. Circuilt boards with cutouts on the top of the chassis, covered by aluminum plates. This Oliver amp has massive transformers helps make it sound so good.

+1 It's said that the bigger the iron sled is, the better the amp sounds, those old Macintosh mono power amps had big cajones (big trannies?) The one thing that's different for me between the Oliver's and Ampeg (Oliver's) is the stunning look of the B-15N's light up logo, chrome chassis, and exposed tubes, offset against the two transformers, with the chrome logo, on a field of blue check.
By contrast the Oliver's look more 70's modern, not nessicarily a bad thing, but the Ampeg's are really kind of Art Nouveau, kind of the Frank Lloyd Wright of Amplifier designs.

Ric

 

[beans-on-toast]

Warmed the amp up this morning and took another complete set of readings.

Channel 1 does not have the gain that Channel 2 does. I'm thinking that it's because the signal passes through the LDR, before heading for the next stage. I did not test either above half volume, this morning, and they are both plenty loud. Wish that I had thought to take a picture of the LDR/Lamp holder. Appears to have been made from a pistol cartridge case. The LDR is glued into a drilled hole in the case bottom. The lamp is fitted into a hole, drilled across the case, and very close to the LDR. The end is crimped flat and maybe soldered. Some kinda neat setup.

I've attached the updated drawing, but kept the same revision. No changes other than voltages.

Thanks for the updated schematic Jack.

Such a small current flow difference to give you the desired voltage on the tube but it sure shut the 6AN8A down.

When you have a chance, turn off the tremolo and try setting the tremolo intensity knob at one end and then the other and see if the setting affects the sound of channel 1. The LDR is in parallel with the pot that the channel 1 signal flow through. When the intensity is on full, the pot is shorted and the LDR in the circuit should not be an issue.

 

[beans-on-toast]

+1 It's said that the bigger the iron sled is, the better the amp sounds...

Big iron translates into less low end distortion and better low end frequency response. Also more lower back pain.

 

[59Pan]

Thanks for the updated schematic Jack.

Such a small current flow difference to give you the desired voltage on the tube but it sure shut the 6AN8A down.

When you have a chance, turn off the tremolo and try setting the tremolo intensity knob at one end and then the other and see if the setting affects the sound of channel 1. The LDR is in parallel with the pot that the channel 1 signal flow through. When the intensity is on full, the pot is shorted and the LDR in the circuit should not be an issue.

I'll give that a try, tomorrow. Looking at the drawing, I have no doubt that you are right, as to testing the gain.

Taking a quick look at my PA-100X board, it appears to be different from the mainboard in the G-300. Similar, but the traces don't appear to be the same. I'll draw up one for this one, at some point. If it passes the lamp limiter and tube test, I may put off drawing for awhile. It's pretty intense to make these layout drawings.

Jack

 

[JimmyM]

There is a 1960s Ampeg M-15 for sale near me for $450. Looks to be in very good physical condition and am told it was recently repaired (not sure what for yet). I was thinking this would be a great guitar amp and also a good bass amp for practice at low volumes. Does anyone have any experience with this vintage Ampeg model?

I don't but a Mercury is a guitar amp, and I'd be just a little skittish to pump bass through it as I recently blew a speaker in my 73 Super Reverb by doing that.

 

[JimmyM]

Having kept an eye on this thread, I think I have come to a decision...

I need a head soon, but the bottom line is at a premium. However, once the New Year comes by I will have more disposable income (well, smaller bills). So, the plan is a PF350 on its own just now - a great value, good sounding and super portable head that will cover most gigs comfortably enough.

Next year: two 115 cabs purchased at convenient times, followed by the PF800. The more powerful amp will become my main gigging weapon whilst the 350 can be my home and rehearsal head. <snip>

I think this plan makes sense... Shall TB offer affirmation or talk me out of it?

Good plan, although if you're like me, you might just stick with the PF350 Only reason I got a PF800 is because a soundman accidentally broke my PF350. Glad I did because it's awesome, but had it not happened, no doubt I'd still be using the PF350 with nary a thought to the PF800.

 

[pedrodelawasp]

Good plan, although if you're like me, you might just stick with the PF350 Only reason I got a PF800 is because a soundman accidentally broke my PF350. Glad I did because it's awesome, but had it not happened, no doubt I'd still be using the PF350 with nary a thought to the PF800.

You could be right! As you've pointed out, the old SVTs were less powerful, plus there's the fact I'm generally mic'd and/or DI'd for FOH so the extra power isn't quite so necessary. GAS may still rear it's cheeky head all the same

 

[Ric Vice]

Big iron translates into less low end distortion and better low end frequency response. Also more lower back pain.

+ very true, but in the case of my solid state Kasino 200 all I got was the lower back pain.

Good plan, although if you're like me, you might just stick with the PF350 Only reason I got a PF800 is because a soundman accidentally broke my PF350. Glad I did because it's awesome, but had it not happened, no doubt I'd still be using the PF350 with nary a thought to the PF800.

Once you get something you're really happy with, you need look no further, When I did a "guitar center" comparison between the PF350 and the PF500 I really preferred the EQ section of the PF350 it's simpler and has a little more in common with the B-15N, where the PF 500's and 800's
seem to be SVT based pre amps. Neither is better mind you, and having the extra watts is very nice, in a pinch. I'm just more comfortable with it's simpler EQ section.

 

[Pentatonic]

The M15 is a good guitar amp and you can use it for bass at lower levels.

Same power amp as a B-15. The power supply caps are a bit smaller than that of the B-15 but not a lot. What you would expect to see in a guitar amp to give you some distortion. The tone controls are voiced differently, again, not a big issue.

Thanks a lot, I've put it on hold and I'm going to check it out shortly.

Thanks.