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Amps with built-in / baked-in HPF

Discussion in 'Amps and Cabs [BG]' started by CyberSnyder, Oct 11, 2019.


  1. CyberSnyder

    CyberSnyder Gold Supporting Member

    Jun 19, 2003
    Maryland
    I Endorse Alien Audio Basses
    .
     
    Last edited: Oct 12, 2019
    chupacerveza and jnewmark like this.
  2. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    IIRC @Stumbo has already done this?
     
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  3. CyberSnyder

    CyberSnyder Gold Supporting Member

    Jun 19, 2003
    Maryland
    I Endorse Alien Audio Basses
    Oh, my bad. I didn't find anything in a search. I'll look again.
     
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  4. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    I asked for this in the mega HPF-LPF thread. Someone replied that Stumbo did this, but I couldn't find it. If it is there somewhere, it should be at the beginning of the thread. Anyways, The Subway amps, the Genz Benz Shuttle series, and the Genzler amps have an HPF on board. Fender BXR 300, also.
     
    Last edited: Oct 11, 2019
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  5. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    I'm not sure, which is why I pinged him. [​IMG] [​IMG]
     
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  6. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    Seems like it would a good topic for Stumbo's Wiki too.
     
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  7. ddnidd1

    ddnidd1 Supporting Member

    Check out the newer Mesa amps.
     
  8. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    It would also be helpful if the whole " cascading " effect that Agedhorse alluded to in a previous thread, could be dummied down so the rest of us non tech guys could understand it more readily. In another thread, I said that I tried an Fdeck HPF with a Shuttle head just for grins. I could not hear much difference set at the minimum setting, but as soon as I turned the Freq knob up, the whole bottom end disappeared.
     
  9. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    That's a very good question. Many if not most amps already have at least a first order HPF response going on, since just a simple coupling cap at the input leads to a 6db/octave rolloff slope. And there are often more coupling caps as you go through the internal signal chain. When I was designing the HPF for my DIY amps I spent a lot of time looking at that bigger picture, which gets pretty complicated pretty quickly, at least for this tech not engineer type. And in my case I typically have the HPFs placed after the Aux inputs, which have their own composite responses going on.

    I'll sort through some of my Spice models from those projects and see I can find something that might make sense to anyone else, and that doesn't give away my humble but hard won IP. I was unsure enough about it all that I made the HPF section modular so I could try inserting it in various spots in the signal chain. Truth is, I liked how it worked in the very first iteration enough that I've never gotten around to rewiring it in the other half a dozen or so ways I could.[​IMG]
     
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  10. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    Thanks, very cool. It might be wishful thinking though. You would have to know the specs on the built in one, and also the specs on the outboard one, and then have a way to calculate how the two would effect each other's function. Might not be a problem getting the info on a say, Fdeck HPF, but good luck finding it on a Fender BXR 300 ! ;)
     
  11. Passinwind

    Passinwind I know nothing. Commercial User

    Dec 3, 2003
    Columbia River Gorge, WA.
    Owner/Designer &Toaster Tech Passinwind Electronics
    You already know my take: measure it yourself. I do model commercial pieces off schematics from my library occasionally, but in my case I think it would be kind of bad form to post those results on TB unless the manufacturers are down with it. And my own builds are pretty quirky, to say the least!
     
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  12. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    Understood.
     
    Passinwind likes this.
  13. There's an amp I haven't heard about in a long time. Is your BXR a combo or just the head? I remember the combo definitely had attenuation down low.
    But I think it worked by keying the low frequencies to really fast compressor on the circuit. It was in the circuit even with the "Comp" switch off...

    The amp could get loud, but you could never "pop" it (or get it loud via a TR-Style drum machine)

    Saw a lot of those amps lose their graphic EQs in a drunken stupor on stage. It didn't take much to snap those little things right off.

     
  14. jnewmark

    jnewmark Just wanna play the groove. Supporting Member

    Aug 31, 2006
    Stax 1966
    Third St. Cigar Records staff musician.
    TB'er Jim Chjones has or had one.
     
  15. JeroB666

    JeroB666

    Dec 22, 2012
    Canada
    Bergantino Forte HP has one
     
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  16. Al T.

    Al T. Supporting Member

    Sep 24, 2006
    Richmond, VA.
    Acoustic Image Clarus SL has an adjustable HPF. It works very well.
     
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  17. Amano

    Amano

    May 5, 2015
    Planet earth
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  18. Lonnybass

    Lonnybass

    Jul 19, 2000
    San Diego
    Endorsing Artist: Pedulla Basses
    Crest Proline w/ DSP has one.
     
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  19. arbiterusa

    arbiterusa

    Sep 24, 2015
    San Diego, CA
    The GK MB series has one at 30Hz. Even the old SWR amps have them but at 15Hz, they are of dubious utility.
     
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  20. Mesa Subway D800 has it preset at 30hz I believe - not adjustable like on the D800+ and WD800
     
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