1. Please take 30 seconds to register your free account to remove most ads, post topics, make friends, earn reward points at our store, and more!  

Official Ampeg Portaflex Club

Discussion in 'Amps and Cabs [BG]' started by JimmyM, May 25, 2008.


  1. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    It changes the input impedance at the first stage. Use whatever sounds the best with your bass. Probably stick with the magnetic setting. Back then, pickups were not standardized so Ampeg offered different options. Even the early B-15N has three different input impedances. Crystal microphones were used with standup basses so they had a setting for that.
     
  2. bftbassman

    bftbassman

    Aug 23, 2014
    Ephrata PA
    Forgot To post
    PF50t
    SVT210av cab
    Very impressed. Have some live rigs but man this records so well. Also has me just plugging in more often cause it fits anywhere & playing at level that brings out some nuances . So many sounds in this thing. It is very touch sensitive & learned to enjoy that in tone shaping in attack. The circuit does reveal the bass character nice & clear. pf50t (2). pf50t2 (2). PF50t3.
     
  3. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Looks to be in very good shape.

    The black silkscreen can get delicate with age and flake off quite easily if you rub it.
     
    bobyoung53 likes this.
  4. I would expect it to make the sound thin when switched to crystal, right? When I said it doesn't seem to do anything I meant it doesn't do anything.:laugh:
     
    beans-on-toast likes this.
  5. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    The problems is, there were so many options on these bassamps. You never know how the components were wired, or have been modified since the amp was manufactured, or if the components are working at all or are up to spec.

    A crystal input impedance is usually higher than the typical 1M input impedance of a magnetic pickup. It may or may not sound any different with a magnetic pickup.
     
    bobyoung53 likes this.
  6. ShaunNecro

    ShaunNecro

    Aug 1, 2007
    Houston, TX
    Don't exactly have a matching cab for this yet, but I have two 60 year old Jensen P15Rs in this dually-esque cab, and while it isn't that loud (these speakers must not be very efficient) it is definitely the best tone I've ever had.

    20190803_150605.
     
    Last edited: Aug 7, 2019
  7. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Cool work on the grille cloth.
     
    chupacerveza likes this.
  8. ShaunNecro

    ShaunNecro

    Aug 1, 2007
    Houston, TX
    Thanks! The green tolex and nebula grill cloth is my aesthetic for stage stuff. I'm in the middle of retolexing my VT22 for the same thing.
     
    chupacerveza and beans-on-toast like this.
  9. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    I like having amps that look different from the others on stage.

    Notice how the front frame tolex on your cab separates at the forty five degree cuts. This tends to happen with age.

    It helps to tint the wood under the cut using a sharpie of the same color as the vinyl or darker. It doesn’t affect the adhesive. In the case of the VT22, the metal corners will pretty much cover those cuts.
     
    chupacerveza likes this.
  10. TinIndian

    TinIndian

    Jan 25, 2011
    Micco Florida
    Good tip!
     
    chupacerveza and beans-on-toast like this.
  11. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    That tip comes from Mark at Vintage Blue.
     
    TinIndian likes this.
  12. TinIndian

    TinIndian

    Jan 25, 2011
    Micco Florida
    Not surprised. Very Helpful guy.
     
    beans-on-toast likes this.
  13. mattysaurus

    mattysaurus

    Mar 21, 2019
    Hey folks, reposting this relevant bit of my post in this thread on the suggestions of tinIndian:

    Tldr: 1960 Ampeg B-15, major overhaul but still getting whooshy sounds in input 1 and “Stereo” when changing volume or using pickup selector on my guitar. Input 2 is fine. Stereo makes sense since it’s suppose to be a combo of 1 and 2.

    My current issue is this: I'm getting some DC leakage on input 1. Input 2 measures .10mV, while Input 1 is measuring -.5V. I've rolled the 6SL7's around in different spots and the issue is still there, which presents itself as a whooshing sound when I turn the volume knob, or a small pop sound when I change the pickup selector on my Strat.

    Obviously this isn't a huge deal since I think input 2 sounds better for guitar, but it doesn't seem quite right to me. I talked to the amp tech and he says that from his notes, the inputs resistors were different than the schematic (per the color bands), but didn't want to change them because we'd heard Ampeg had a tendency to change things on the fly. Specifically, while input 1 resistor is supposed to be 1M, it was actually 5.6M (reading 4.9) and while Input 2 is supposed to be 5.6, it's actually 2.2 (reading 2.6) These specs are similar to the b-15N, and he'd already found another resistor on the board that was incorrect spec for the b-15 schematic, but correct for the b-15n.

    Any thoughts on what could be causing this issue and how to fix it?
     
  14. beans-on-toast

    beans-on-toast Supporting Member

    Aug 7, 2008
    Old amps can be noisy. If you want to fix the issue...

    I would copy what was used as the input in the B-15NC for example. There should be a grid stopper resistor added at the input on channel 2. To reduce noise, use a shielded wire grounded at the jack end only, the grid stopper at the tube pin end.

    The carbon composition resistors used at the input are usually noisy. A metal film is way better.

    Schematics | TalkBass.com

    Channel 1 has a grid stopper. In this schematic, channel two does not have a grid stopper. It’s better to have one.

    Odd noises described in the wiki: Technical - Amplifier | TalkBass.com

    Technical - Amplifier | TalkBass.com
     
    TinIndian and chupacerveza like this.
  15. BassJuju

    BassJuju Supporting Member

    Jul 9, 2016
    Kentucky
    Someone told me a while back that Ampeg was the way to go. I can’t say that I really listened at that time, but I’m listening now. I played through an SVT with an 8X10 and just loved playing in front of that rig. As good as it sounded, just a little large for the bedroom.

    The choice from there was easy for me. PF-50T with a flip top cab. I’ve played it for 30 minutes total, but the tone variety is astounding. I first played in a very Jamerson like way with plenty of gain and bass and virtually no treble or mids. It was like I went back in time. Then, I put everything at noon Oh my! Like P Bass heaven.

    All that is to say, I’m digging it and can’t wait to continue my tonal exploration. There is only one photo at this time. Are numbers still available?

    AB7D2E2D-C709-48A3-9538-42F6BE5F53D2.
     
    Ed Byrnes, Zbysek, JimmyM and 4 others like this.
  16. ShaunNecro

    ShaunNecro

    Aug 1, 2007
    Houston, TX
    I kinda wanna pick up a pf50t for it's DI capabilities. Was thinking about getting either that or a REDDI, but I'm leaning PF50T.
     
    Zbysek likes this.
  17. BassJuju

    BassJuju Supporting Member

    Jul 9, 2016
    Kentucky
    I have both now. I really like the REDDI, but it can’t be overdriven without another source. I too liked the DI capabilities of the PF-50T. I’m not sure how things will turn out, but I do have options.
     
    Zbysek likes this.
  18. ShaunNecro

    ShaunNecro

    Aug 1, 2007
    Houston, TX
    I plan on doing a lot of reamping for my next album, so I have plenty of options for dirt, but I just wanted a really good DI to get a good start, and you can get a PF50T for the price (roughly) of the REDDI, so it just makes sense to go down that path for me.
     
    Zbysek likes this.
  19. JimmyM

    JimmyM Supporting Member

    Apr 11, 2005
    Apopka, FL
    Endorsing: Ampeg Amps, EMG Pickups
    Sorry man...we ran completely out of numbers last week.

    :D

    #710 BassJuju

    I'm of two minds about that...I love my REDDI and its simplicity of plug in and rip and let the sound tech or engineer do the rest, plus it's 10 lbs lighter and fits in my accessories bag with everything else. But I love having control of things as well, and I love tube overdrive, and the PF-50T is great for both, plus when I set the knobs at noon and keep it clean, I think it sounds like the REDDI. Bottom line, I have lots of respect for both products and I choose one or the other based on my needs. But then again, I can :D
     
    PillO, Zbysek and JIO like this.
  20. farace

    farace

    Jul 9, 2016
    Connecticut USA
    Can't seem to post a link to the listing on Facebook Marketplace, but there's a blue-check Ampeg Portaflex empty cab (maybe was once a full amp?) in Middletown, NJ, listed as a '74 Guild (and for some reason has a Guild logo). $60. If I lived closer, I'd be there, but . . . I'm sure someone here needs this for an orphaned head. Listing title is "Shop cleanout sale! Cabinets, amps, etc". It's a bit rough, but not beyond redemption.
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.