A couple of things to be aware of when testing and comparing gear

Discussion in 'Amps and Cabs [BG]' started by Freight Train, May 22, 2012.

  1. Freight Train

    Freight Train Earth-based Alternative Scientist, Sex Researcher

    Feb 25, 2012
    Dallas, Texas
    Just to qualify myself, I've been a bassist for around 47 years, and a recording and mastering engineer for over 38 years. Obviously (or hopefully) there's a lot I've learned, and I'd like to share some things with my bass playing bro's that'll maybe help in gear choices and uses.

    First, regarding trying cabs in the music store. Most people don't realize that bass cabinets are not only good bass reproducers, they are also excellent bass absorbers at the resonant frequency of the cab if they are not being used. So if you're playing a rig in a room full of bass cabinets, you're getting a pretty big suck-out in the critical 40 - 60Hz. range. Ever wonder why the cab miraculously seems to have more bottom end when you get it home? That's why. The only way to prevent this from happening is to short the unused cabs. Not the amps, that'll let the smoke out and they'll never be the same, but the speakers themselves. I learned this in an esoteric hi-fi store I worked at in the early 70's. For the speaker demonstration room, the tech built a speaker switcher that would short the terminals of the unused speakers as you switched around. But he had a main relay switch where you could un-short everything, and by flipping the shorting circuit on and off it sounded like you were adding a bass roll-off to speakers you were listening to, which essentially you were. Not much you can do about this in the store - you can't take in a bunch of 1/4" shorting plugs and go around shorting cabs - but just be aware that the cab you're testing is probably going to have considerable more butt than what you're hearing in the demo room if there's a bunch of cabs sitting around.

    The second bit regards how easily our ears can be fooled by doing quick A/B comparisons. Just the nature of the human ear/brain mechanism, when given two sounds to choose from, and they are played immediately one after the other, we will almost always choose the sound that is either louder or has more bottom end, even though it may not be the best sound at all. Again, I learned this from my hi-fi days. Most receivers of that day, and probably still, had a 'loudness contour' button, which was designed to be engaged when you listened at lower volumes. Human hearing is less sensitive to lows and highs at lower volumes, so the loudness contour boosted lows quite a bit, and highs some, to compensate for this. (If you want the gory details on this, google 'Fletcher-Munson Curve'.) But of course 90% of users kept the loudness button on all the time, because they would switch it on and off while listening to music, and when they would immediately hear the music with and without the bass boost, it sounded wimpy without. We always stressed to our clients to try to use very little or no eq, and to leave the loudness off unless listening at low levels. To prove the point, we'd have them switch the loudness button on and off while listening to music and choose which they liked best, and they would always choose the sound with loudness on. Then we would sit them in the listening position and tell them we'd play two sounds, which do you like? We'd play them music with the loudness on, then silence for about 30 seconds, and then play the same music with loudness off (or vice-versa, didn't matter which was played first). I'm not exaggerating, 100% of the time they chose the sound with no loudness contour as the better sound. And this is over several years, not a week.

    So here's the point, whenever you are comparing two sounds, don't immediately switch between the two. Listen to one sound, then off for at least 15 seconds, and then listen to the other sound. The silence is like audio sorbet cleansing your aural palette. This applies to almost any fx you're auditioning, but is especially important when you're making eq decisions. Don't immediately switch eq on and off. Listen to it without the eq, then silence for a while, then with the eq. You may be surprised that you change your mind on some decisions you made by quickly A/B'ing between the two. Remember that volume will fool you as much as bass boost, so it's important to get volumes adjusted so the two sounds you're comparing are at equal perceived levels.

    Another instance where this is important is in selecting pickup positions. I know a lot of players don't even consider using the single coil position if they have the choice because by immediately switching back and forth you're going to like the positions with more bottom end almost every time. But just pick the bass up and set it to single coil and start playing and see if, rather than being bass shy, it instead has plenty of bottom but has a push in the upper-mids that the other positions don't have.

    Anyway, hope this wasn't just totally boring and that some may find use for it. If it is helpful let me know and I'll post some other stuff now and again. If not, carry on as you were.
  2. Versatek6

    Versatek6 Fretless is like Trombone

    Oct 7, 2008
    Twin Cities, MN
    That is something new regarding cabinets. Does using a grounding plug make the magnet "live," for lack of a better term, and cause it to act like a brake on sympathetic cone movement?
  3. I've never thought of it like that....


    Thanks for posting this! :D
  4. Andyman001

    Andyman001 moderation must be taken with a grain of salt

    Feb 11, 2010
    S/E Idaho
    Good stuff
  5. Philonius

    Philonius Supporting Member

    Mar 22, 2009
    2k W of the Duwamsh
    More please.
  6. arai

    arai Inactive

    Jul 16, 2007
    Great read, thanks for taking the time to post it
  7. smcgov

    smcgov Supporting Member

    Mar 12, 2010
    Northshore Mass
    this topic makes me horny, what speakers were you selling back then?

    I used to LOVE going to hifi stores.
  8. Bean639

    Bean639 Supporting Member

    Aug 18, 2010
    Richmond, Va

    I can already tell that it will take me years to process this. :D
  9. Staccato

    Staccato Low End Advocate Supporting Member

    Aug 14, 2009
    Great thread...people also need to be realistic, and accept that every piece of gear for what it has (by design) to offer the user. For demo: take the amp off the shelf, and set it on the floor. Example: 'baffled speaker shelving' used by GC will not deliver the sound like your carpet/rug, concrete, or hardwood on your floor at home. No way!

    Always worth mentioning:
    Shoppers often buy a piece of gear, and suddenly give it poor marks because a characteristic or part is not included in the design.
  10. murphy

    murphy Supporting Member

    May 5, 2004
    great stuff.
    thanks for sharing and certainly food for thought.
  11. billfitzmaurice

    billfitzmaurice Commercial User

    Sep 15, 2004
    New Hampshire
    Owner, Bill Fitzmaurice Loudspeaker Design
    It doesn't make the magnet 'live', it gives the coil a load, albeit a short circuit, in effect operating as a generator. That forces the cone to 'work' if it moves, so it doesn't move as easily as it would with no load. It used to be recommended that cabs and even raw drivers be shorted when shipped, to prevent potential coil damage, but I haven't seen it done for many years.

    The bass suckout effect from having unused speakers in the room is very real. For that reason speaker testing is never done with unused speakers in the same room. If the testing is done outdoors unused speakers aren't even in the vicinity of the tested speaker.
  12. Lo-E


    Dec 19, 2009
    Brooklyn, NY
    Thanks for posting! Very interesting stuff. The first paragraph alone is worth the price of admission!
  13. Thank you for posting - I feel like my head/mind is bigger and my ears more "sensitive" right now...
  14. Russell L

    Russell L

    Mar 5, 2011
    Cayce, SC
    Thanks, Freight Train. I think your post should be a Sticky (mods, ya'll listening?).

    I have run into the thing about extra speakers in the room, at home mostly. Bill filled me in, at the time, as to what was happening. I had always thought that maybe the extra ones would make the sound better, but it just shows how counter-intuitive some this audio stuff can be. I'll have to try shorting them out. First time I've heard of that. I have noticed how puny some cabs sound in a store, though, sure 'nuff.

    And I agree, A/B'ing doesn't seem to help much when choosing a sound. That silent space in between is important. Why, I've even come back to a setting after hours of not playing and had a reveletion about that particular sound, different than the impression I originally had of it.

    Again, thanks, pal.
  15. blowinblue

    blowinblue Kind of not blue. Supporting Member

    Nov 29, 2006
    SoCal USA
    My wife is not going to be happy. Instead of having all my bass cabs in my music room, they will now be spread out to different locations in our house. "Sorry Babe, that's the only way they can achieve their sonic potential."

    M. M. :)
  16. Freight Train

    Freight Train Earth-based Alternative Scientist, Sex Researcher

    Feb 25, 2012
    Dallas, Texas
    Thanks Russell and everyone else with the positive comments. I have always been about sharing knowledge, because when I started I had professional people around me who were willing to answer all of my stupid questions twice and explain to me what they were doing and why. Some people hoard their little techniques like they're precious gems or something for no one else to see, but believe me nothing is new under the sun. Everything's been done, you don't know some big secret of the universe that nobody else knows. Share it and help make everyone's music better.
    I haven't hawked my mastering room since I've been on TB because that's not what I'm here for, and it whips my ass when guys use this strictly to promote their gig. But I have a blog that has a lot of info about music production and hi-fi related stuff. So I'm not trying to sell anything, it's an info blog, just saying you guys may find some good stuff there. www.desmastering.blogspot.com
  17. Freight Train

    Freight Train Earth-based Alternative Scientist, Sex Researcher

    Feb 25, 2012
    Dallas, Texas
    Our main lines were B&W, Klipsch, Boston Acoustics and ADS. But we also carried the Sony Esprit Series, which is the most esoteric thing Sony's ever done in hi-fi. A $25k stereo system in 1975 - that was no joke, son. The speakers had four square flat drivers that were honeycomb aluminum or some super light weight metal covered with I don't know what material, so they were extremely low mass.
  18. will33


    May 22, 2006
    Yep. A speaker is a transducer, so is a microphone, they're just working in opposite ways at opposite ends of the chain. Shorting them puts a "load" on the coil when it tries to move making it harder to move, thus turning the cab into more of a room boundry and less of a bass canceller.

    You can hook the speaker leads up to an amp, sing into the cone, and it will make sound. Search "subkick microphone" for more on that.

    Good info from the OP. The ear/brain system does funny things with sound perception, both real and imagined.
  19. Freight Train

    Freight Train Earth-based Alternative Scientist, Sex Researcher

    Feb 25, 2012
    Dallas, Texas
    Forgot to mention an important detail - how to short extra cabs in your practice room if you want to see if it makes a difference. I was just talking about that like it should be obvious, but some may not understand. All you would have to do is take a speaker cable with 1/4" on one end and bare wires on the other, plug the 1/4" into the cab and twist the bare ends together. If you want to be fancy, take a 1/4" plug and solder a short jumper between the + and ground lugs, and that's a proper shorting plug.
  20. I think this is along the same reasoning for strings too.

    I find that when I put new or different strings on, the change is pretty dramatic - unless I wait to judge them for a day or so.

    First impressions are that I dislike the new strings.

    The time-out of 24 hours is a good way to actually hear how good they are, separated from the old strings.

    In any case - great information. Now I've gotta make shorting jacks for all my unused cabs.
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