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Behold: The PolyClone!

Discussion in 'Amps, Mics & Pickups [DB]' started by svenyonson, Jul 23, 2018.

  1. svenyonson


    Jun 16, 2009
    Boulder, CO
    As every double bassist out there knows, it is SO hard to get a good amplified sound. I've played through a Fender 25 watt 10" and a Raven PMB-1 preamp for the last 20 years or so. Then I borrowed a friends PolyTone MiniBrute III for a few months and realized I needed an upgrade. Finding an old PolyTone in decent condition proved difficult, so I decided to build my own. It sounds awesome!

    • 15" Eminence speaker w/neodymium magnet (3015LF)
    • Gallien Krueger MB200 Class D amplifier (200 watts).
    • PZP-1 Piezo Buffer installed inside of the amplifier for impedance matching
    • Size-wise it is modeled on the Polytone Mini-Brute MKIII.
    • Weighs in at 27.5 lbs - about the same weight as my little Fender 10" 25 watt amp.
    • Baltic birch construction - all 1/2" except the front which is 3/4"
    • Tigerwood grill
    • Duplex outlet on back with USB charge ports for my iPad


    Selim, basmansam, Reiska and 7 others like this.
  2. bassburner

    bassburner Supporting Member

    Dec 8, 2008
    It's looking at me...
    Maple, Microbass and BassmanPaul like this.
  3. Ben B

    Ben B

    Jul 13, 2006
    San Diego, CA
    Nice work. 1/2 inch ply is so much lighter than your average retail cabinet or combo.
  4. Omega Monkey

    Omega Monkey

    Mar 8, 2015
    I don't know if I would have gone with the LF driver, especially for upright. But it certainly looks cool, especially the louvered grille. Very 60s.
    Kro and agedhorse like this.
  5. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    I don't see how you could get a reasonable tuning in that small of a (sealed) cabinet with the LF driver.

    You have given up all the performance benefits of that driver, there are better and less expensive options or upright IME.
  6. Passinwind

    Passinwind I know nothing. Supporting Member Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    How did you handle ventilation for the amp?
  7. Bob_Ross

    Bob_Ross Supporting Member

    Dec 29, 2012
    Well, that's sort of the problem with the original MiniBrutes also: The enclosure is way too small for accurate low-frequency reproduction

    ...but that doesn't necessarily mean they can't sound good. I've been using a MiniBrute III on and off since 1980, and every time I pull it out and play a few notes I think "blech, that sounds kinda nasally, no bottom end!" And then the rest of the band joins in and within 16 bars I'm like "Oh yeah, that's why I still use this little amp!" The sound just seems to work.
  8. Lance Bunyon

    Lance Bunyon

    Jul 17, 2018
    You had me at 27 lbs! Plus the buffer. And when you consider upright gigs usually don't require big buckets of volume, the GK head should give you plenty of headroom.
    Plus it's pretty.
  9. svenyonson


    Jun 16, 2009
    Boulder, CO
    Good question. I don't push it hard like an electric player might, but I was prepared to vent the fan to the outside. I stuck a meat thermometer in the line out extension jack on the back of the cabinet. Beginning of gig: 77 degrees. End of 2 hour gig: 79 degrees. If it ever turns out to be a problem, I'll vent it.
    Lance Bunyon likes this.
  10. svenyonson


    Jun 16, 2009
    Boulder, CO
    I can't explain why, but it has TONS of low end, sounds really good. There is enough overhead with 200 watts that I don't need to care about efficiency. I went with the LF as that is what I played through using my friends polytone. I've also read that the non LF is very midrangey, which I don't want with my upright. I know it has less excursion than the LF. Maybe because the driver favors the low part of the spectrum and the cabinet inhibits it because of its size, that maybe it balances out. I may try a non-LF someday, but so far, I really like the tone.
  11. svenyonson


    Jun 16, 2009
    Boulder, CO
    I guess I don't really care about performance, i.e. efficiency or power, I just need tone that I like. I need very low volume. If I need more, I go through the house with a DI. The dimensions are just about exactly the same as a MiniBrute III, which has a 15", and I like the sound of it. (But LOVE the sound of this amp). One other consideration: I drive a Mini Cooper, and I need to fit my upright bass, my amp, and my sweetie. And I do. Barely, but I do.
    Stumbo and Lance Bunyon like this.
  12. agedhorse

    agedhorse Supporting Member Commercial User

    Feb 12, 2006
    Davis, CA (USA)
    Development Engineer-Mesa, Product Support-Genz Benz
    Ummm, ok.
  13. Al Kraft

    Al Kraft Supporting Member

    May 2, 2016
    Northern Virginia
    You had your design engineer hat on and didn't see that one coming did you? :)
    Seanto and staccatogrowl like this.
  14. svenyonson


    Jun 16, 2009
    Boulder, CO
    Is this Bob Ross from Denver, luthier? If so, the bridge you made for me is working out great - thanks!
  15. Chef

    Chef Moderator Staff Member Supporting Member

    May 23, 2004
    Columbia MO
    Staff Reviewer; Bass Gear Magazine
    Did you want this moved to the double bass side?
    I can move it if you do.
    I have no problem with it being here tho.

    Neat project.
  16. svenyonson


    Jun 16, 2009
    Boulder, CO
    Sure, that makes sense.
  17. Bob_Ross

    Bob_Ross Supporting Member

    Dec 29, 2012
    Sadly, not the same Bob Ross. (I say "sadly" because I'd rather live in Denver than where I am now!)
  18. svenyonson


    Jun 16, 2009
    Boulder, CO

    Thanks all for you comments, critiques and suggestions - I decided it was worth $200 to know if the non-LF is a better choice for this cabinet. And, yes it is. More mid/highs - although now I have to dial down the treble to reduce the sound you get just by sliding your fingers on the strings. But overall much nicer, and at volume you need more high end to cut through. So, I'll sell the LF, and take a small hit in the name of better sound.
    Chef likes this.

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