What causes speakers to sound 'boomy, not clear, muddy'?

Discussion in 'Speakers' started by bluesky, Mar 7, 2012.

  1. bluesky

    bluesky Addicted Member

    I have an extra spare pair of 1970 Sansui SP-2000 in the closet. I don't believe that they have ever been used or even taken out of the box, until I took them out and tried them last year. The cabinets are factory fresh in the original wrappings with all associated paperwork.

    1970 Sansui SP-2000.
    1 super tweet
    2 tweets
    2 mids (AlNiCo magnets)
    1- 12 inch woofer(AlNiCo magnet)

    The problem is that the speakers sound really boomy, undefined dull base response, not clear, or maybe the term is very muddy. To put it bluntly, they sound really bad. Like, there is something wrong! Big time.

    With that said would the problems be deteoriated caps (maybe from not ever being used), woofer problems (like voice coils), or something else like a corroded L-pad type dial pots?

    I do want to restore the speakers to spec, for fun and the basic education on speaker restoration, because the cabs are Mint, not even a fingerprint on em. And I like the sound of SP-2000s. I know there is better speakers out there but the SP-2000s are fine for me.

    Any information or advice, no matter how small, would be most welcolme.

    Thanks guys! :yes:

    The SP-2000s below are just a generic photo off of Yahoo Image.
    Last edited: Apr 25, 2013
  2. Copa1934

    Copa1934 My ears are bleeding Subscriber

    Start with some packing or stuffing the port. Many people have found filling the port or making it smaller helps tighten things up.
  3. spkrdtr

    spkrdtr spkrfixer Subscriber

    The first thing I would do is the toilet paper tube test to make sure every driver is putting out sound. I suspect some of yours may not be. If so, next tackle the pots with some de-oxit spray, then caps last.
  4. RayW

    RayW Parrothead with a badge Super Mod Subscriber

    Probably the 2 leading causes for that are Alnico magnets and the Sansui badge on the front.


    I would start with positioning. Get them away from walls/corners and off the floor. See what that does. After that, check for air leaks. Having a leaky box can futz with the tuning. After that, I'd check cabinet bracing. Weak side walls can add to the boom. Then I'd go with stuffing as Copa suggested.

    If you have a schematic of the XO we can see if there's reason for concern there. I'd recap it anyway but usually there isn't a cap in line with the woofer so it wouldn't affect boominess.
  5. bluesky

    bluesky Addicted Member

    Will do. But it's not really a port problem. It's the actual woofer sound, very bad, very dull, and boomy, like boom, boom, boom. Like that. I have another pair of SP-2000s that I am using that sound really good so I do know the speaker model very well.

    I was going to DioxiT the pots first. I remember a guy here on AK saying a long time ago to do that first and that may solve the problem, all the speakers will then fire up.

    1. What is a: " toilet paper tube test "? How do you do that. I will do it.
    2. Do you think it could be a bad woofers?

    Thanks guys. I really super appreciate it.
    Last edited: Mar 7, 2012
  6. bluesky

    bluesky Addicted Member

    I'll try taking the Sansui badge off. Think that would work??!! :D

    It's not positioning, it's definately the speakers, both of them. It 'readily apparent' as soon as they are energized, they are singing "I am broken".
    The speakers are ported, not acoustic suspension. The big port is like 2.5 inches or so.
    I'll check the bracing too but I'm sure the bracing is fine, but I will certainly check it.

    I don't have the schematic of the XO but I have drawn one up myself but haven't opened up the speakers yet to finish the drawing. I do know exactly what caps I need, and their values, from other AK Sansui members.
    Last edited: Mar 7, 2012
  7. whoaru99

    whoaru99 Part-time Iconoclast Subscriber

    Room issues and sub-optimal woofer/cabinet/port tuning are the most likely causes.
  8. spkrdtr

    spkrdtr spkrfixer Subscriber

    From your OP, it seems you have no highs. So, you need to find out if your mids and tweets are working. Take a toilet paper or paper towel tube and place it close to the driver your testing whilst playing music and listen for sound coming out of that driver your holding the tube up against. In particular, tweeters don't put out much sound so the tube test helps.
    Yes, you could simply have bad woofers as RawW pointed out.
  9. RayW

    RayW Parrothead with a badge Super Mod Subscriber


    There are actually higher pressures developed in a ported box than sealed. It seems counterintuitive but it's real. A leak in a ported box changes the tuning so dried gaskets or something like that can mess up the sound.

    Carl makes a good point about checking the HF drivers. Not having highs makes the lows sound bad. The toilet paper tube thing is basically a low cost, low tech stethoscope. It'll give you an idea of what's what with each driver. If the caps are degraded so that the HF drivers aren't driving it'll mess up the overall sound.
  10. Grainger49

    Grainger49 Old Fart Subscriber

    Of course the midrange might be poorly designed, too inefficient or damaged; this would give it a muddy sound.

    Often the bass is where the mud gets mixed. One part bass hump and one part early roll off of the midrange. You get a hole and a hump and it sounds pretty bad.

    In general I like to accuse the crossover. The speaker elements are usually pretty good but the crossover doesn't use the drivers in the right range, or roll off too steep/too slowly.
  11. puppet

    puppet Active Member

    Anybody know if the factory broke in the drivers first? I'd give them a couple weeks on a thread mill.
  12. PioneerGuy75

    PioneerGuy75 Certified Lurker

    I might add that too many drivers can cause muddiness and poor imaging...

    Read: KABUKI
  13. budgetaudio6

    budgetaudio6 Addicted Member

    if they have tone controls wiggle them alot. A good cleaning as others mentioned. And it kinda sounds like dried out caps from non use. But ive read that they tend to charge(for lack of a better term) up and allow sound through.

    Good luck with them.
  14. 1TUFSS

    1TUFSS Thread Killer

    Toilet paper tube's the way to go. A lot of big 70s speakers used crude crossovers which more often than not didn't even bother rolling off the higher frequencies on each driver, making it damn near impossible to pick a dud driver.

    Not only that, you could even have dead mids/tweeters and the woofer would still be producing these frequencies as best as it can...
  15. bluesky

    bluesky Addicted Member

    Thanks guys,

    I will try 'everything' you guys mentioned above. :yes: I really like the toilet paper roll for listening. Bet it works like a charm.

    The SP-2000 crossovers are not easy to recap because of the size of the new caps, being larger... but it can be done.

    Again, I really appreciate all your help. :thmbsp:
  16. FredC

    FredC Well-Known Member

    I've had the SP-2000's before. Even on a good day they don't sound that great. I sold mine for $75.
  17. menchi

    menchi Banned

    what causes speakers to sound crisp, muddy, etc? let's see.. here's a short list:

    1. room acoustics/treatment
    2. speaker positioning
    3. amplifier power/damping
    4. source material
    5. EQing
    6. speaker cabinet materials/design/quality
    7. (maybe) speaker decoupling (spikes vs flat on the floor)
    8. your aural perception.
  18. musichal

    musichal Addicted Member

    I guess you've already checked the surrounds on the woofers? Even boxed in a closet, time does its thing. So caps, too - but deoxit worth a shot. Remember you can have more than just one problem, so check those woofer surrounds.
  19. Altec Best

    Altec Best Well-Known Member

    +1 It all starts with the Cabinet IMHO.
  20. toxcrusadr

    toxcrusadr AK Subscriber Subscriber

    Hey guys, he's saying he's got another pair of the same speakers that don't sound the same at all. All this talk about bad crossover design and cabinet tuning and whatnot, is all well and good, but regardless of that, these speakers don't sound like the other pair.

    I second the driver operation > check pots > recap approach.

    Some crossovers also have caps in the bass section that are supposed to shunt midrange that gets through the inductor, and similarly in the midrange to shunt treble. Bad caps can make the thing sound crappy all over.

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