Modding the Fender Excelsior: before & after recordings

Discussion in 'Ampage Area' started by Michiel, Aug 6, 2012.

  1. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    Hey Folks,

    As some of you know I'm modding Paul Pigat's Fender Excelsior.
    The objective is to give it some tighter bass and clearer, more balanced highs.

    For those interested in the process and the nitty gritty details, the mod-thread is located here (gdp link). It's a bit of a read. The summary of the current list of mods is in post 286. I'll list them again below.

    Here are the before and after recordings.

    Stock circuit, with Tung Sol reissue 6v6gt power tubes and EHX 12ay7 in V1:
    https://docs.google.com/open?id=0B82lBHbq5VHKNnpSRjl1bFJldGM

    Modified circuit, with Tung Sol reissue 6v6gt power tubes and EHX 12ay7 in V1:
    https://docs.google.com/open?id=0B82lBHbq5VHKdTZ4RTJudjNjVjg

    I used the Viking in these recordings (supertrons). The effect / differences are more pronounced when I use filtertrons. So, I guess I'll have to do those recordings again with the Gent.


    So, the list of mods so far:

    Tone Control mods

    1. Replace tone switch with 500k Audio pot - more control over tone - independent mod
    2. Change R9 and R29 to 10k (or add parallel 22k to get 11k effectively) - increases tone pot control range - only mod after adding tone pot.
    3. Change C2 to 720pF (add parallel 360pF) - changes tone control contour - independent mod


    Dynamics & Clarity mods

    1. Swap stock 6v6s with Tung Sol Reissue 6V6gt - improves clarity - independent mod
    2. Swap V1 12aX7 for 12aY7 - reduces gain and extends clean range on the volume dial - independent mod
    3. Add extra 47uF/450V elco parallel to C28 - tightens bass response - independent mod
    4. Change cathode bypass cap C32 from 100uF to 22uF (63V min) - improves responsiveness, more clarity and punch - independent mod.
    5. Bridge together rectifier-side of resistors R22 and R30 - *Reduces sag, tightens up bass response, evens the overal response of the amp (less nasal & honky) - also needs mods 6 & 7 to compensate for higher voltages.
    6. Add 2k2/2W in series with R58 - Reduces voltage to preamp - only needed after doing 5.
    7. Insert 2 x 12V/5W zener from B+ connector to OT center tap - Reduces B+ voltage back to stock - only needed after doing 5.
     
  2. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    Ah, prices...

    Tung Sol 6v6gt matched pair - ~$35
    12ay7 - ~$15

    Pots, caps, resistors, zener diodes ~$10 tops.

    A note on the recordings:
    if you want to evaluate the differences of the mods, open both recordings side-by-side and run one volume setting after another.
    You won't hear much difference otherwise (too many variables, to much time between playing comparable sequences ;)).
     
  3. Tinman46

    Tinman46 Country Gent

    Age:
    50
    Dec 19, 2011
    Kitchener, Ontario, Canada
    Do you need google chrome to hear sound clips? I can't seem to open the sound file. When I try it sends me to some google chrome app site.
     
  4. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    You'll have to download the files before you can play them. But they should download freely for everyone, without apps or logins.
     
  5. polishbroadcast

    polishbroadcast Synchromatic

    990
    Jun 23, 2010
    Chicago
    I had to select which google docs account i wanted to use to download them so you may need a google account, or change the permissions on the files. i've never shared files via Docs. Box.com has an inline player and public sharing.

    On the topic of mods: isn't there a bit of geographic hurdle for you guys or are you just designing them and he is implementing them? Also, it seemed like in Fender amps the transformer is a huge contributor to the sound, will you need to upgrade that?

    Thanks for sharing.
     
  6. jflintmac

    jflintmac Country Gent

    You really need to do that. I could hear some difference between the 2 recordings but the distortion really burried any discernable audio improvements.
     
  7. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    hmmm, weird.
    Yeah, I've seen that before. If goggle recognizes that you have a goggle-ish account (gmail, picasa, utube), it'll force to sign in to get access to docs. That's a nuesance.


    Paul's Excelsior was actually the first Excelsior on European soil, or so the story goes. I'm working directly on his amp.

    By now excelsiors hitting the shops hete in NL, but only in small quantities.

    The amp will definitely benefit from an OT upgrade. I will try that for kick, but since this project is on a tight budget, I can't make that a permanent mod I think.

    The amp will also benefit hugely from a better speaker. Tried it with various Jensens. After trying the C15N, going back to the stock speaker felt like a bit of a let down.
    But the buget is probably not going to allow putting in a C15N.

    My pleasure.:)


    The difference is indeed subtle.
    Someone described it as looking through dirty spectacles when he went back to the stock circuit.

    The most dramatic improvement was actually replacing the tone switch with a tone pot.

    I still have some experiments to do. In may end up doing more modifications still.


    Thanks for you feedback guys!
     
  8. polishbroadcast

    polishbroadcast Synchromatic

    990
    Jun 23, 2010
    Chicago
    Isn't Paul Canadian?

    FWIW, i was never a big believer in little amp tweaks (ie, for the minuscule change in sound, it wasn't worth the money or time) until i swapped the transformer on the Princeton Reverb Reissue: it went from a bargain amp to a real nice Fender sound. I also watched the Mercury Magnetics video where they swapped the choke and OT on a Deluxe Reverb reissue and the sound was significant, even on the camera mic, which i'm assuming they used.

    Not sure what my point is in reference to the topic other than it's cool you have the knowledge to make tweaks like that. Put in one of those digital reverb tanks (that's the mod i'm waiting for)!
     
  9. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    Yep, OTs and Speakers can make huge differences (and WILL on this amp:)).
    But then you're well into the 400-500s including mods.

    My personal goal with this project is to see what can be done with a couple of small tweaks. The tone pot had a big result, stiffening up the power supply had a more subtle effect. But I'm not done with that yet. I'm hoping for more drama with a couple more tweaks coming up.

    After plunking in this big clunker of a switch, ABing has become more easier than before, haha :)

    [​IMG]

    Ah, and yes, Paul -is- Canadian. He used this amp on his recent 2-week tour of the Benelux and Germany.
     
  10. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    This weekend I found time to re-do some recordings.
    Incidentally, I made another modification - the sag resistors are now bypassed completely in the 'modded' mode. This makes for a more 'fenderish' tone I'd say. It also tightens up the drive a bit more.
    In the recordings I set the tone-knob completely open - the recordings are a bit trebly because of that.

    These recordings were done with the Country Gentleman, middle pickup position. The guitar is in dire need of a string change, but the goal here is to show the differences. Even with the new mod they stay relatively subtle. To my ears they are most clearly audible in the 2-tone melody runs.


    stock:
    https://docs.google.com/open?id=0B82lBHbq5VHKU1NSRUtkekZPdzA

    modded:
    https://docs.google.com/open?id=0B82lBHbq5VHKNG13bkI3Z2VfazQ

    Now the way to AB these, is to load them side-by-side (two media player windows, or some kind of multitrack recording software). and switch back and forth between single runs from same volume. If you play the whole thing in one go and then go listen to the next, you won't be able to tell the difference.
    Also, use a good set of headphones.:)

    The setup:
    293199_122498774562405_1247386041_n.jpg
     
  11. ruger9

    ruger9 Country Gent

    Nov 1, 2008
    NJ
    Yeah, I can't get access to the files. Just takes me to a google page asking me to sign up for 5GB free with google drive.
     
  12. Ricochet

    Ricochet Gretschified

    Nov 13, 2009
    Monkey Island
    Michiel, cudos man, it's too bad I can't listen to the soundfiles since I'm back on dialup, but you really seem to know what you're doing. I can almost hear the difference just by your writeup alone.
    You better read up on your Marshall plexi schematics, I've got plans... that is if you're interested. :cool:
     
  13. Dennison

    Dennison Country Gent

    Jul 17, 2011
    Kent, UK
    All files downloaded easily here (MacBook). I thought there was a discernable different (ie. an improvement) on the clean sounds, although I often find that my ears adjust to fairly subtle tonal changes quite quickly and just accept either one as 'the norm' after a few minutes. It's a bit like auditioning a group of hi-fi speakers of similar quality.

    With the overdriven sounds, IMO the distortion tends to mask the before/after differences, not to mention any subtleties in guitar tone, but then again, I'm not really into overly 'brangy' overdriven sounds.
     
  14. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    That's so weird. For some it works really well, for others it seems to be terribly difficult to get access to my files.

    This is what I'm seeing when I try to access one of the links. Are you seeing the same thing?

    download.jpg

    Thanks Ricochet, I'm learning. ;) I love this stuff and I'd definitely be interested.
    PM me if you want to discuss your ideas! I'll start reading up on plexi schematics.
    Dirt is the next thing for me to delve into.:D
    Actually, I'm on that now with the Excelsior.

    How would you describe the difference/improvement you heard?
    I'm looking for words to describe the differences I'm hearing. :)

    I loaded both files into Audacity and I'm switching back and forth between sections. Even in the distorted sounds the difference is pronounced. The balance between the E/B/G strings seems to be a lot more even than with the stock circuit. (that's what the two-tone runs should demo).
    And in the chords, the lowend produces a thick clotted brawl (in a good way:)) that seems to block out definition of the higher strings. With the mods in place, those higher notes are a little better defined, but they sacrifice some of that rounchy low-end 'brawl'. The drive seems to focus more on the mids than on the lows now.
     
  15. Feel Free to PM me with any questions about this.... I'm vacuuming today. I think I will have some fresh dirt for you to reference. I have all kinds of dirt in reserve, but this will be state of the dirt art dirt.

    In fact I'll post a link to my .drt files once they are uploaded...

    On a less absurd note, Michiel, would it be more economical for me to ship you my Excelsior, or get you a return ticket to the states...
     
  16. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    Haha Ishtar, get me all the dirt you can miss!!:p:D

    I fear you could buy a couple of excelsiors for the price of shipping one (or me).:eek:
    And the other guy who is into Excelsior modding, who is in the states, is practically on the other side of your continent.:rolleyes:
     
  17. Dennison

    Dennison Country Gent

    Jul 17, 2011
    Kent, UK
    I think there's greater clarity with the modded version. And I think clarity is an important attribute in an amplifier when playing a Gretsch — the inherent tone and character of the guitar come through much more.

    I don't know what I can add about the overdriven sounds — I've heard far more expensive amps sound much worse than the unmodded Excelsior. It's just not really my thing.
     
  18. Michiel

    Michiel Friend of Fred

    Age:
    45
    Jul 29, 2009
    The Netherlands
    Thanks Dennison. That's what I'm hearing too. Great to have that confirmation.

    After tweaking, tinkering and noodling with the amp so much, I'm beginning to doubt my own judgement sometimes. Am I -really- hearing a difference? Or do I WANT to hear a difference after all that work? ;)
     
  19. polishbroadcast

    polishbroadcast Synchromatic

    990
    Jun 23, 2010
    Chicago
    Less low-mid in the modded version (which people are hearing as clarity). It is extremely subtle though Both have very agressive mids which i'm guessing is the essential character of the amp.

    BTW, you need a Google account to access the files. Why not put them on SoundCloud? It is free and will open it up to a wider audience.
     
  20. Dennison

    Dennison Country Gent

    Jul 17, 2011
    Kent, UK
    "I'm beginning to doubt my own judgement sometimes. Am I -really- hearing a difference?"

    Ah, Michiel, therein lies the problem. I've tinkered around with different brands of tubes and wondered if I'm hearing a difference. And if I do hear a difference, is it so marginal that after five minutes the 'new' sound becomes the norm? And is it really all that different from what I had before?

    And don't start me off on speakers. Yes, there's an obvious difference between what is rubbish and what is pretty good, but I always feel there's a very wide middle ground where I don't know if Speaker A is actually better or worse than B, C or D because after five minutes listening my ears become accustomed to what I'm hearing and I'd be quite happy with any of them.

    Saxophone players must have an easy life — just get a decent horn, select a reed of choice and you're set for life.