Harrison Labs FMOD

Discussion in 'Amps [BG]' started by blastjv, Feb 3, 2011.


  1. blastjv

    blastjv Supporting Member

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    Philly Area
    Hey,

    I've done some research both here and elsewhere on the Interwebs, and it seems to me that overall people have either:

    1 - Tried these and liked them

    or

    2 - Not tried these, and based on theory (often people who know what they're talking about and using apparently very sound theory) dismissed them as either useless or a crapshoot at best.


    What I'd like to know is - Has anyone who as actually TRIED these as a part of their bass rig found any problems with them? Did they not work as you hoped? Did they have any negative effect on your tone or other performance issues?


    They're cheap, so I figure I'll probably just buy 'em and see for myself, but thought I'd solicit some input before doing so...

    FWIW, I plan to buy a pair of the 20Hz FMOD High Pass Crossovers ( http://www.parts-express.com/pe/showdetl.cfm?Partnumber=266-246 )and link them together to get a 40Hz HPF at 24db per octave. I plan to put them between the Preamp Out/Poweramp In on my SVT-VR. I may also experiment with the Attenuators they sell to see how it effect my gain.


    What say you???


    Thanks,

    -JV
  2. billfitzmaurice

    billfitzmaurice

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    Owner, Bill Fitzmaurice Loudspeaker Design
    That's not how cascaded filters work. Do a search, read the thread on high pass filtering.
  3. blastjv

    blastjv Supporting Member

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  4. billfitzmaurice

    billfitzmaurice

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    Owner, Bill Fitzmaurice Loudspeaker Design
  5. Boostedrex

    Boostedrex

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    Lincoln, CA
    I haven't used these in pro audio, but have seen them used in home and mobile audio. They're little better than crap. They tend to induce a LOT of noise and don't even work very well either from measurements I took off the amp using an O-scope. I wouldn't waste your money. Just my .02.
  6. blastjv

    blastjv Supporting Member

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    Well, I tried it anyway since others reported good results. (no disrespect meant, fella's... ;) )

    With one of the 20Hz HPF's I noticed almost no change in sound (maybe no noticable change in sound at all), but I did notice a very noticable reduction in the amount of cone movement. I was also able to boost the bass slightly more than I usually do without farting.

    I tried linking two of them together with a 3db attenuator in between. It was not the Harrison Labs attenuator, if that matters. It didn't sound right, weak and slightly distorted, so I removed the attenuator.

    I tried linking just the two HPF's together and notice a slight rolloff of the low frequencies, and maybe a slight reduction in volume (might have just been the rolloff of the lows, though it was very slight). I increase the volume just a touch and increased the bass just a touch and was very happy with my sound. It seemed to clean it up a bit, and though just throwing the HPF in there with no changes to the amps controls seemed to give a very slight reduction in volume and low end, I was able to boost both more than I normally can before things get a little too overdriven and farty, so the end result is more of what I love. The cones moved even less. They still visibly move when I'm hitting big low notes, but MUCH less than without the filters.

    So far so good...that's how I'll leave it for next rehearsal and see how that goes...


    -JV
  7. blastjv

    blastjv Supporting Member

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    Rehearsal on Monday showed that running the two FMODs in series was killing my low end. Everyone noticed. (sounded great last week playing by myself...I thought...) So, I removed it and returned my amp to its previous settings to finish rehearsal. I'll try next week with just the one FMOD and see how that works. If not, I'm back where I started...

    -JV
  8. bongomania

    bongomania Gold Supporting Member

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    owner, OVNIFX and OVNILabs
    I know you've already moved past asking for input, but I have posted on my experiences with them before--and believe it or not, what I posted matches your description. You get "enough" rolloff with two of the filters cascaded, but it drops your overall levels significantly; and depending on how you set your gain and EQ, it can also gut the lows you wanted to keep.

    What you really want is the [sfx] Thumpinator.
  9. blastjv

    blastjv Supporting Member

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    I'm never done looking for input. I appreciate everyone's advice. I do want a Thumpinator, but had to give the cheap 'solution' (maybe not a solution at all) a shot first.

    Thanks,

    -JV
  10. Passinwind

    Passinwind Charlie Escher Supporting Member

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    Here's another suggestion. Or if you want to take it up a notch, this in something like this:

    [​IMG]

    I still think the ESP filter is probably the best, most cost effective one if you're comfy with DIY builds though. I'll post a thread on that when I get around to building one. ;)

    Edit: Have you looked at fdeck's little box?
  11. greenboy

    greenboy

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    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Looking nice, Charlie. If you are ready to show a picture you must be getting closer to some deets.
  12. Passinwind

    Passinwind Charlie Escher Supporting Member

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    Just have to build up the power supply and it'll be done. I'll post a dedicated thread early next week, most likely.

    Just want to opine: none of these things should be really be necessary if you're buying an integrated bass amp. They should already be built in as a matter of course IMHO. I sure wouldn't buy another bass head without one...
  13. greenboy

    greenboy

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    The more graphed responses seen (or rig combinations played), the more obvious it is that most companies haven't had a meaningful approach to high pass filtering up to now. Some have baked-in voicing approaches that supply a vestigal rolloff... which is kind of like using a little finger as an opposable thumb ; }

    Others have ridiculous boosted low end baked in that make the ones with 3 dB rolloff per octave starting at 125 hz seem like they are doing something special.

    I too would not buy an integrated head that didn't have something better than what most have had up to now. What seems to somewhat protect speakers with a lot of them is the poor power delivery they exhibit once the demands get poured on.
  14. blastjv

    blastjv Supporting Member

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    I tried it with just the one FMOD last night at rehearsal, and it sounded a lot better than the 2 of them in series did, but still lost that certain 'something'.

    I'm calling it. They don't work for me in the way I had hoped to use them (despite the sound advice I was given ahead of time that they wouldn't...)


    -JV
  15. dhomer

    dhomer

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    Owner, Gigmaster Soundworks, Auth. greenboy designs builder, MI
    I have an FMOD-Sub in my preamp effects loop. Just use one side of it, and I set it @35Hz. It does what I want it to, which is keep the speakers from jumping wildly when I touch the strings. When I put that in, I was running an 18 w/an f3@28 Hz. Effectively cured subsonic run amok. I just like the tightness of the sound, so even though I'm not running that rig anymore the device stays connected.
  16. blastjv

    blastjv Supporting Member

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    I can't say they don't work, and I'm not saying they're garbage, just that they didn't end up working for me with my gear for the tone I wanted. I actually think your positive comments about them in other threads were one of the reasons I had tried them anyway, but it took something from my sound that I missed when it was gone, so for me it turns out they're a no-go...

    -JV
  17. blastjv

    blastjv Supporting Member

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    Actually.....I tried just the one again, and I think I'm going to keep one of them installed as part of my rig. 2 of them together was a failure, but A/B'ing just one against nothing, there was almost no difference in tone. It changed VERY slightly, and think it was just a very slight loss in volume, which was easily compensated for with the...volume knob(s)...

    -John

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