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Turn the normal channel of you old Fender into a Plexi

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    Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Originally posted by Alvin Lee Fan
    Kent, sorry, can't upload the schematic for the Deluxe Reverb II. The file is too large. Let me know if you still want it and I can mail it to you. It's not that big, only about 950K, but the upload limit here is 100K.
    Forgot about that ... I'll check with up a bit later on it, thanks.

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    To further tweak the reduced effect of the tone controls in Scott's gain mod ... replace the 250k-A bass pot with a 500k-A pot with the wiper connected to the CCW lug unlike the present condition. Replace the mid cap (.047uF) with a .1uF cap, and the bass cap (.1uF) with 1nF(1,000pf); add the 120pf cap in parallel with the 250pF treble cap (either straight in parallel or as previously explained). The controls will now have a bit more effect the treble control is the main control, while the bass control trims of lower bass from about 120Hz. down (subtle about 6dB or so). The bright switch can be saved for a sensitivity switch or a contour/treble cut option. This will help make the tone controls more useful. The bass control will also function in the correct manner (unlike the reverse manner caused by lifting the ground resistor).
    Kent S.
    Volume Enhanceologist
    Last edited by Kent S.; 07-15-2004, 03:36 AM.

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  • Guest
    Guest

  • MrHeavyMetal
    Guest replied
    Re: Turn the normal channel of you old Fender into a Plexi

    I own a 100-watt Marshall 1959SLP Reissue with all Mullard tubes and a 4X12 w Vintage 30's. This thing is SO DAMN LOUD that I can start a riot in a 3 block area. Beware the Plexi. MrHM.

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  • Alvin Lee Fan
    Toneologist

  • Alvin Lee Fan
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Kent, sorry, can't upload the schematic for the Deluxe Reverb II. The file is too large. Let me know if you still want it and I can mail it to you. It's not that big, only about 950K, but the upload limit here is 100K.

    Leave a comment:

  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    And the second ...

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Here are a couple comparisons, some old Bandmasters and some Bassmans, I tried to eliminate some clutter by simply saying cathode follower at some points (if that's not specified then you know its a common cathode) ... again one big draw back is that the CF is a lot lower in gain (hence on all the designs additional stages following (not shown here of course). Using one without additional stages might result in a situation where you can't get your lead tone loud enough compared to your clean tone. Anyway, here are some interesting options tonally in regard to your tone stack.

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Scott ... I'm currently (read this to mean :when I get time) working up a comparison of the circuit differences between various Fender Bandmasters and Bassmans ... time permitting I'll post them to the board ...

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Originally posted by mmguz
    Could this modiffications works in a fender hot rod deluxe amp?
    Again, check the schematic ... I've got about five things going on at once ... post a schematic and I'll be able to advise you better ...

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  • mmguz
    Tone Member

  • mmguz
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Could this modiffications works in a fender hot rod deluxe amp?

    Leave a comment:

  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Originally posted by Lewguitar
    Kent, you are a real asset here. Thanks again for all the details.
    Well people have called me everything froman asset o an ^%$ minus the *et*, and everything in between ...

    I have an original 5F6-A Bassman from about 1959 or 60. I think it's one Fender used as a factory demo or something. It was recovered once (I think at the Fender factory maybe 40 years ago) with the original tweed so it looks original. There's no white lettering whatsoever on the chassis panel, but it's a stock Fender 5F6-A. It's the best amp I own, but it's so loud I don't play it much. It's remarkable how similar the feel of this amp is to my Marshall...and how crunchy it is when it's cranked up above 4. I only hear that particular style of crunch from a 59 Bassman or Marshall...amps with the Bassman style preamp and cathode follower. My other amps overdrive beautifully, but that Plexi/Bassman crunch isn't quite there. Gotta go...heading for the high country again today. Climbed South Arapahoe Peak yesterday: 13,500 feet! I'm thinking I'll head up to Rocky Mountain National Park today...it's only a one hour drive from where I live.

    Take care, Lew
    I'll have to check up on differences around those models, like I said some of the bassmans and especially the bandmasters were a bit odd to say the least in regard to the tonestack ... A lot of the various models had different preamp tube plate voltages as well ... another interesting twist in the mix.
    Be safe in your climb, and enjoy!

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  • Guest
    Guest

  • Lewguitar
    Guest replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Kent, you are a real asset here. Thanks again for all the details.

    I have an original 5F6-A Bassman from about 1959 or 60. I think it's one Fender used as a factory demo or something. It was recovered once (I think at the Fender factory maybe 40 years ago) with the original tweed so it looks original. There's no white lettering whatsoever on the chassis panel, but it's a stock Fender 5F6-A. It's the best amp I own, but it's so loud I don't play it much. It's remarkable how similar the feel of this amp is to my Marshall...and how crunchy it is when it's cranked up above 4. I only hear that particular style of crunch from a 59 Bassman or Marshall...amps with the Bassman style preamp and cathode follower. My other amps overdrive beautifully, but that Plexi/Bassman crunch isn't quite there. Gotta go...heading for the high country again today. Climbed South Arapahoe Peak yesterday: 13,500 feet! I'm thinking I'll head up to Rocky Mountain National Park today...it's only a one hour drive from where I live.

    Take care, Lew

    Leave a comment:

  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Originally posted by Lewguitar
    Scott, Kent, and everyone:

    About the Orange Utah speaker...Is it labeled Utah? Or is it labeled Radio Shack? Some of those orange Radio Shack speakers for guitar are pretty darn good! They were made by Pyle I believe...Ted Weber would know.
    I don't know much about the Utah at all, however I had a Gibson G-30, my first amp,(no longer have it unfortunately) it was 30 watss, 1x12 combo, S.S. hi, lo inputs volume, reverb, treble, bass, speed, and intensity, and a foot switch jack for the reverb and tremolo ...it was clean and loud ... remiminded me of a Roland JC 120, but warmer, the Gibby speaker was crap, so I replaced it with a Plye Driver 12, 150watt ... that didn't sound that good, so I changed it to a Plye 90 watt, and that was very JBL like, that thing would chime like a twin but warmer ... straight clean but what an amp for a S.S.. Talk about loud, the thing would drown a drummer at 3. Man I wish I had that thing, for someone that could get their tone from and overdrive/distortion pedal ... that would be a perfect gigging amp. Built like a tank to.

    As for the Tremolux, the tweed version from the 50's is fairly similar to a 5E3 Deluxe. I had one for a while...got it free! Bruce and I were remodeling kitchens for a living about 1980 and we were driving into the dump to drop off the remains of a kitchen we'd just torn out and looked at the truck ahead and there was a tweed Fender amp bouncing around on top of the junk!

    We followed the guy in and even tho you're not supposed to scavenge, you can bet I scavenged that old amp right up!

    It was a nice tweed Fender Tremolux from about 1958 or 59. Worked too!
    Man, I never have luck like that ...cool indeed!


    That's the other thing that can be done to beef up the tone of 60's or 70's Fender amp with reverb: There's a resistor and cap that is the reverb recovery circuit. Can't remember the value, but it's a big resistor...maybe 3.3 meg.
    Lew

    Lew
    Yeah that's right it's a 3.3Meg in parallel with a 10pF cap, I think it balances/mixes the reverb return with the direct signal off the preamp.
    Concerning the deluxes the one with out reverb had a .033uF mid cap, hey changed that on the Deluxe reverbs to a .047uF cap, also the vibrato channel had a 47pF cap across the volume control as a subtle Bright boost.
    The bassman's had and interesting layout to their tone stacks, a bit different with that .01uF mid cap arrangement. I was looking over some of the older amps that fender made, and for guitar players looking for a bit more control from the eq some of the older stuff is really different than the standard BF/SF eq. I'm not just talking about the earlier E series eq either, some of the bandmasters had some neat stuff, a bit perplexing with the *tap* connections on some of the pots, and the deep switches where cool on some of the bss channels ... I remeber the schematic but not what model it went to ... To much to keep track of, cool nonetheless. Thanks fro the update on the tremolux Lew ... but you never did tell me, how was it at overdriving at lower volumes? And to the guy that asked about the Vibrolux, yeah I looked at the schematic, it's the same as what Scott has, just follow that little schematic that I posted. You know I can't remember which model it was, but one or two of the fenders had a 4k7 mid resistor insted of the 6k8 ... for some reason that's bugging me that I can't remember. The Tweed bassman had the cathode follower arrangement though, that's the one I was trying to remember for Scott.That's not on the ampwares site, thats at ...
    www.muzickicentar.co.yu/scheme/sheme.php under fender amps of course, that site only has a couple, but some aren't on the other site.

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  • Guest
    Guest

  • Lewguitar
    Guest replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Scott, Kent, and everyone:

    About the Orange Utah speaker...Is it labeled Utah? Or is it labeled Radio Shack? Some of those orange Radio Shack speakers for guitar are pretty darn good! They were made by Pyle I believe...Ted Weber would know.

    As for the Tremolux, the tweed version from the 50's is fairly similar to a 5E3 Deluxe. I had one for a while...got it free! Bruce and I were remodeling kitchens for a living about 1980 and we were driving into the dump to drop off the remains of a kitchen we'd just torn out and looked at the truck ahead and there was a tweed Fender amp bouncing around on top of the junk!

    We followed the guy in and even tho you're not supposed to scavenge, you can bet I scavenged that old amp right up!

    It was a nice tweed Fender Tremolux from about 1958 or 59. Worked too!

    I fixed it up and sold it...bought my first Deluxe Reverb with the dough.

    Anyways, the Tremolux is like a tweed Deluxe with vibrato. They never had reverb...even when Fender brought out the blackface version in '63 or '64, they didn't add reverb.

    Generally, I only love blackface Fenders with reverb and vibrato...the reverb beefs up the tone even if you don't use it and adds some gain and balls to the tone.

    That's the other thing that can be done to beef up the tone of 60's or 70's Fender amp with reverb: There's a resistor and cap that is the reverb recovery circuit. Can't remember the value, but it's a big resistor...maybe 3.3 meg. Change it to a smaller resistor and you'll get more balls out of the amp and add some gain...just don't overdo it. You'd need to change the cap too...experiment.

    Lew

    Lew

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Another thing to, while I'm rambling on about this stuff ...Scott here's an option that reverseable also ... if you wanted to you could at least have the cathode follower ... you wouldn't have to change that much ...AND the volume would come in between the triodes, so to some degree you could control the drive of the cathode following section (crunchy), while still controlling the overall overdrive from the guitar volume, the now convoluted tone stage would take care of basic low end trim, and subtle tone colouring, and contouring of the guitar itself (I'll e-mail you an emf graph of the tone curves if you'd like ... hey I got curious myself okay ... Let me know on that).
    If you interested I'll lay out the changes for you and post to board (like the last thing I did). Bear in mind that a cathode follower will be lower in volume so you won't find that channel as loud, but it will overdrive more. You mind find it worth running that channel (CF) into the other channel (in which case you wouldn't want reverb added any way). That's more complicated though, and I think you're not looking to totally reverse engineer the amp, that CF is viable and fairly simple too though ...

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  • Kent S.
    Volume Enhanceologist

  • Kent S.
    replied
    Re: Turn the normal channel of you old Fender into a Plexi

    Originally posted by wixomwhat
    would this plexi thing work with a SS fender amp?
    like this one

    http://www.musicgoround.com/store/in....asp?id=269623
    You need to download a schematic for it, and compare the way the gain is done ... some tone circuit in those opamp based amps are done with an inverting opamp, an opamp has tremendous gain, much more than a tube circuit (you also run the risk of burning something up) ... this really is a tube thing, all Scott did is put back a bunch of midrange (and hence available gain) that the fender tone stack takes out, he didn't alter the gain stages per se'. To do that he'd have to alter the bias of the preamp tubes (cathodes) and the low cut-off frequency of the gain (that cap that's in parallel with the cathode resistor). BTW the ADA MP-1 it's clean tube, and distortion tube mode ... that's exactly what it does, it changes the bias on the preamp tube and the low end cut-off Fc, so in distortion mode the tube gets pushed into clipping on almost anything you play.
    What Scott is referring to isn't a plexi mod per se', he just means that the amp now has more overdrive and more mid character, hence compared to a typical fender, well ... I can see the comparison. I think his new lead channel still cleans up nice to. In the case of and S.S. amp though, you'd be better off cahnging the gain controlling resistors around the opamp that regulates it's gain (just like on a pedal), sometimes you can change out the gain pot for a higher value (depending on the circuit) for more gain. The short answer is you'll probably get a gain boost, but as far as the sound ... although I can't say with certainty ... ah ... NOT. If you're really curious though, you'll have to get a schematic from fender for it, or check here to see if they have it for download at www.ampwares.com check under fender field amp guide.
    Kent S.
    Volume Enhanceologist
    Last edited by Kent S.; 07-07-2004, 07:53 AM.

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