• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Official Ampeg Portaflex Club

#14,684
I use searchtempest.com to search Craigs List for the Portaflex listings.

[Invalid or Expired Link Removed] posted 11/18, Serviced and reconed

[Invalid or Expired Link Removed] posted 11/18,

[Invalid or Expired Link Removed] posted 11/06, w/JBL D123

[Invalid or Expired Link Removed] posted 11/17

[Invalid or Expired Link Removed] posted 11/05 w/ATA flight case
 
#14,686
Bass 45 said:
@beans-on-toast

"Are there any issues with heat from the amp with the case?"

Maybe I've been lucky, but I have used this model for about 7 years in un-vented racks with no issues - sometimes even with the sun hitting it in extreme Phoenix heat. Still - I created a bit of extra space all around the amp for piece of mind.
Click to expand...

Nice job!

I remember having the same concern when I build mine, specially because SVT4 dissipate heat from sides, but as you said, traditional fly cases leave less space in the amp, I build mine to match the 26" cab width, so I ended up giving more inches than regular 19" cases.

Paso-03Ensambladodepartes-1.jpg


DSC00863_zps57ac4c5e.jpg
 
  • Like
Reactions: Vintage-Blue, beans-on-toast and JimmyM
#14,687
beans-on-toast said:
Always nice to see how an old amp is still carry its own weight.

No question that the vintage portaflex design was a tip of the hat to high end hi-fi gear available at the time. The potted transformers, the chrome chassis, even the script logo.

The fist amp is a circa 1955-61 McIntosh model MC60A, the second is a 1961 MC75.

Click to expand...

Wow nice McIntosh! I think the B15s is closer to the sound of mating a a hi fi tube pre and mono block than anything else. (I did a couple of rigs using hopped up Dyna MkIII and Stereo 70's using Dyna and Demeter pre's ) I could have saved my time and just got a B15s. The B15s was a successful design I think, the components are high quality. My tube amp guru tells me they are a pain in the rear to work on though. After popping the lid and looking, it sure looks like it is. The supply caps are huge, lots of current being tapped there. The original B15 is very service friendly by comparison.

B15s is a heavy amp. My back hurts. :-) I dig the preamp arrangement and eq curve. I like the impedance switch on the rear, 8-4-2ohm. The power section has way more muscle than the original B15, the cabinet is larger, it's just bigger sounding like a B18 is. As a matter of fact it looks like you could retrofit it for an 18" , LOL!
 
  • Like
Reactions: beans-on-toast
#14,688
The dynakit stereo 70 has an ultra-linear output transformer. They work well in hi-fi applications but I don't think that the dynakit ones are suitable for a bass amp. It depends on the design of the ultra-linear transformer. UL designs run clean, bass amps need at bit of dirt.

Those big cap can be difficult to fit under a chassis. You have to find the right caps.

The B15S was a bit of a departure design wise but the do sound good.

McIntosh amps go for crazy prices but they look so cool.
 
  • Like
Reactions: MR PC
#14,689
MR PC said:
Wow nice McIntosh! I think the B15s is closer to the sound of mating a a hi fi tube pre and mono block than anything else. (I did a couple of rigs using hopped up Dyna MkIII and Stereo 70's using Dyna and Demeter pre's ) I could have saved my time and just got a B15s. The B15s was a successful design I think, the components are high quality. My tube amp guru tells me they are a pain in the rear to work on though. After popping the lid and looking, it sure looks like it is. The supply caps are huge, lots of current being tapped there. The original B15 is very service friendly by comparison.

B15s is a heavy amp. My back hurts. :) I dig the preamp arrangement and eq curve. I like the impedance switch on the rear, 8-4-2ohm. The power section has way more muscle than the original B15, the cabinet is larger, it's just bigger sounding like a B18 is. As a matter of fact it looks like you could retrofit it for an 18" , LOL!
Click to expand...

A few years back I picked up a B15S cab from my local Craigslist that had been modded with an 18 inch speaker. I can't remember what the speaker was, but I think it may have been a Peavey. It sounded great, but I did not hang on to it long as I also had an Ampeg SVT 18E at the time that sounded just like it - and was a bit lighter. The B15S is a very heavy cab that was built to last. Isn't it braced with a 2x4 in there?
 
  • Like
Reactions: MR PC
#14,690
The Stereo 70 worked really well for bass with channels bridged. The Mark III was beefier for sure. It was the Dynakits (MK III and MK VI) that the original Sunn Tube bass amps were built with...the guy was literally buying kits and making his own pre amp and putting them in boxes. Always sounded great to me, and very different from the fliptops and Fenders of the era. Yes, "cleaner" sound overall. Though my tech hipped me to ways of using the test socket with jumper wires to change the negative feedback loop which not only changed the tone, but the apparent volume. It was a nice option, plus the different taps on the transformer made for subtle but powerful differences in player feel too.

And yes, that B15s cabinet has a some serious bracing in there involving the use of 2 x 4's and what looks like 5/8" ply for the interior baffles..haven't looked at it closely though. Did I mention that it's heavy? :-)
 
#14,693
Yes, I had the B15R too..I liked the 2 power tube watt setting, the 4 power tube setting was muddy by comparison ime. Too many bells and whistles there for me. And bulky too. I was glad to snag a '66 B15 with a JBL right after I sold that one. As great as that '66 model amp was for me, it still wasn't to my liking as my original point to point early '60's B15 with the 421a I installed.
 
#14,694
[Posted this in another thread, but it seems to have slipped away…]

Do you guys get a 60 cycle hum through your PF-500s?

I recently exchanged my PF-350 for a "factory restock" PF-500 and picked up a used Fender Bassman Neo 410 (YES!) to go with it. The cab just arrived; I unboxed it and set everything up. This is the first chance I've had to try the PF-500 and right away I'm getting an annoying and somewhat loud hum through it, even at low volumes.

Moving my light switch dimmer affects it, and touching my strings or bridge cuts it way down. I tried swapping power cords. I tried plugging into different outlets. I tried playing another bass through it. Nothing helped. There are no pedals in my chain—just a heavy duty shielded cable connecting bass to amp.

My other (home practice) amp is an Ashdown Electric Blue 180, and there's no hum through it. The Peavey Mark III I'm borrowing at rehearsals is also dead quiet when I'm not touching my bass. (I'm playing a Nate Mendel Fender P.)

Could my PF-500 have a bad/faulty ground, or do they all sound this way?
 
#14,699
Jables said:
Do you guys get a 60 cycle hum through your PF-500s?
Click to expand...

Like jimmy said, I would contact Loud. This isn't normal.

The light dimmer will cause hum as will single coil pickups. Touching the strings and finding that the hum is reduced indicates a ground issue somewhere between the bass and the input. You tested the bass and the instrument cable into another amp which eliminates them. This tells me that noise is being picked up at the input of the amp. So the first place that I would look is the input jack on the amp. Check with you fingers that the nut on the input jack is tight. I would reflow the solder joints at the jack.
 
Last edited:
  • Like
Reactions: Jables

Latest posts

Top Bottom
Back