Series wired speakers=bad bass sound. Why?

Discussion in 'Amps and Cabs [BG]' started by Rockin John, Aug 1, 2001.

  1. This has been stated quite a few times on TB.

    Is there any proper, scientific reasoning behind this theory or is it just a kinda a bass player's tale?

    I can't really believe it can be correct but, as usual, I'm very willing to be corrected.


  2. MikeyD


    Sep 9, 2000
    Yeah - this would my question, too. I saw Psycho post this recently in another thread. I could see having a problem if the two speakers (or sets of speakers) were of different size or parameters, but let's assume they are identical. I'd like to know the physical reasoning behind the claim that they wouldn't sound good wired in series rather than parallel. As far as I've seen, there are lots of cabinets out there whose drivers are wired series-parallel, at least.

    The only other thing I can think of is that if one driver's coil or lead burns open, the whole set goes silent, whereas in parallel, this wouldn't happen.

    - Mike
  3. It's kaka for solid state amps, and reality for tube amps. :D

    Tube amplifiers REQUIRE a correct impedance match with the load. They have taps to change the output impedance accordingly. Solid state amplifiers only have a minimum load requirement (2 or 4 ohms) and anything higher just cuts down on the power transfer. It has nothing to do with tone.

    The Damping Factor is the ratio of load impedance to output impedance. If anything, wiring speakers in series INCREASES the damping factor, which is the amount of control the amp has over cone motion. Transients (slaps) are better controlled with a higher damping factor.

    Parallel wiring increases the efficiency but does not increase the power handling capability of the speaker. This is because it cuts the impedance in half, allowing for 2x more power transfer.

    Series wiring does not increase the efficiency, but does increase power handling capability due to the increased impedance.
  4. Luis Fabara

    Luis Fabara

    Aug 13, 2000
    Ecuador (South America)
    Audio Pro - Ecuador
    As MikeyD stated, if the drivers are identical, it should work fine.
    The only backdraw is that if one blows, good-bye sound.

    Now, if the drivers are different, its a whole different story.
    Impedances on drivers are nominal impedances, but each driver reacts different to the frequencies it is reproducing.
    Some have higher impedances at high frequencies or vice versa.
    So if you sum two different drivers they will react in strange ways killing the sound in some areas. Attenuating some frequencies and boosting others. Thus an unbalance in the sound.

    Now in the case of the 4x15 with 2 Isobaric 15" (Psycho´s reply), there is a thing.
    To be Isobaric they have to be OUT-OF-PHASE with each other so they can reproduce a sound.
    So it would have a pair in Parallel (Front Drivers)
    And another pair in Parallel with the others but Reverse parallel between them.

    Now, do that with a complete set of series wired speakers. I dont think its difficult, but the results could be disastrous in terms of sound, I believe.

    Series is not bad. It is good as long the drivers/cabs are the same.
  5. Hi guys.

    Yes. Thanks. I'm well familiar with the techy stuff. But non-techy bassists seem occasionally obcessed with the idea that their sound - their tonal quality -will be adversly affected by series connected speakers. It seems to have nothing to do with with technical aspects. Its purely and simply a percieved degrading of tone, 'sound' or however else described.

    I can't see this theory being correct. As Mickey said, everything else being equal.

    Perhaps if there's a bassist out there who holds this opinion, I'd be glad to hear an opinion.




    To keep our wonderful Moderators sweet, gents, I'm going to open another speaker thread. If you fancy responding.....

  6. steinbergerxp2

    steinbergerxp2 Guest

    Jul 11, 2001

    I'm no authority, but I have a friend who is pretty good at this and his explanation was that in a series wired cabinet, only the last driver in the chain (nearest the amp) actually received any damping value from the output stage of the amp. Overall, tube amps have rather poor damping characteristics as compared to solid-state amps, because the output transformer decouples the load.

    As to tube amps (I don't go there personally) but he has quite a collection of MusicMan, Marshall, and Ampeg gear and said that the output impedance varies pretty widely, regardless of what they labelled the transformer taps; it's not uncommon to see anything in the 4-24 ohms range labelled as 4-16 on the amp.
  7. Damping factor, by definition is the ratio of amplifier output impedance to load impedance. It is impossible for the closest device in the chain to be the only device being controlled by the amplifier damping circuitry. If this was the case, then this would be the ONLY device being driven by the amplifier. The amplifier damping circuity controls the back EMF generated by the speaker(s) that continue in motion after the signal is removed. Every speaker seeing amplifier power will also see amplifier damping.

    Can't speak to tube amps. However, the damping factor is either published (referenced to 8 ohms) or can be easily calculated. If the manufacturer publishes the output impedance of the amp (SS only) you can divide it by the speaker load to get the damping factor. I.E. 800 ohm output impedance divided by an 8 ohm load is a damping factor of 100. Most sources indicate a DF of >= 100 is desirable. Under 100 is considered poor.

    Tube amps have taps that match the output transformer impedance to that of the load. A tube guy will have to speak to the DF here... not my area.
  8. lo-end


    Jun 15, 2001
    from now on I'll be calling slaps transients. :D

    "hey how do you like the sound of funk-transient bass?"

    "nice transienting there, Flea."

    "wow, was that a quadruple-transient?"

    and so on.
  9. Not necessarily. Examine the impedance curve from any ported box, and you will notice a very definite pattern. Impedance is lowest at the box tuning frequency, rises at Foh, declines again, then rises steadily from the inductive effect of the voice coil combined with increasing frequency.

    The massive power required to produce bass frequencies has nothing to do with impedance, it has to do with speaker efficiency at coupling a small cone to the air. The opposite is a bass horn that effectively operates as a transformer to couple the high impedance of the cone to the low impedance of the air at a very high efficiency. Bass horns require very little power to achieve very high outputs.

    Damping factor is defined as the ratio of amplifier output impedance to load impedance. When the load impedance rises, whether from power compression or a higher DC resistance, the damping factor increases. By definition.
  10. Psycho, you're not making a very strong case. The stuff you say about differences between tube amps and ss amps simply shows you know a lot about tubes, but very little about ss. This sounds harsh, but you really should stick to your field of expertise. You don't see me saying anything about tube amps. Why? Because I know very little about that. I'm writing the TB FAQ right now, that's why I don't visit that often lately, but the tubes section is still blank. In time, would you...?

    Back to the topic.

    I can imagine, due to a-symmetrical cabinet design (i.e. one speaker closer to the port) a slight resonance difference in the high-mid range, but for low frequencies the cab dimensions are totally unimportant.

    Electrical current flows with the speed of light (or close to it) so phase problems simply don't exist. The fact that electrons move with only microns per second, doesn't affect the speed of the current.

    What might be of infuence is specifications tolerance spreading of the individual speakers. Good brand speaker don't suffer from this. Maybe when they're 20 years old.

    Would you be able to A/B test two identical cabs, one wired series and the other parallel? Connected to the proper output taps of course.

    Would the sound of a tube amp change if you pick another transformer tap? Could this be it? I'm beginning to believe so, since you (by my knowledge) only play tube amps.
  11. I can flamed at work, and get paid for it.

    End of discussion. You can rant to the wind.
  12. Gentlemen please......

    The idea of this thread was for me to learn a bit more about speakers.

    A slanging match between a few guys wasn't the plan. It really hasn't helped me with what was a genuine if perhaps naive enquiry.

    It seems this animosity might be a spill-over from a previous encounter? Either way, if it's possible to cool the thing a bit.....? So we can all get @ the good technical and subjective advice that's somewhere in the replies.


  13. Bruce Lindfield

    Bruce Lindfield Unprofessional TalkBass Contributor Gold Supporting Member

    I've seen loads of slanging matches like this - often with the some of the same participants! ;)

    My experience of these disagreements over the years has lead me to believe that there is nothing "objective" you can say in this field - possibly beyond the weight and dimensions of the gear in question!

    Everything else is purely subjective and one person's "warm and full-sounding" is another's "muddy and indistinct" !!

    I decided that the only way to buy amps is to go and listen to them - talking only generates arguments or slanging matches.

    Buy what sounds good to you - ignore all the specs etc. ;)