honest question: tone differences between 4, 8 and 16ohms

Discussion in 'Marshall Amps' started by Filipe Soares, Jan 21, 2020.

  1. Filipe Soares

    Filipe Soares Well-Known Member

    Joined:
    Mar 8, 2019
    Messages:
    820
    Likes Received:
    1,235
    I see a lot of people saying different impedance generates different tone in amps. like x ohms are tighter than y ohms. I know nothing about it (no sarcasm intended, I really know nothing about it), could you please explain to me what are the differences?

    Generally I have my cabs wired to 16ohms, but I could wire it to 4ohms easily.
     
    tce63 likes this.
  2. Rocky Mountain Way

    Rocky Mountain Way New Member

    Joined:
    Mar 22, 2015
    Messages:
    16
    Likes Received:
    8
    If you set your Amp to 8 ohms and plug a 16ohm cabinet, you will lose power/volume compared to an 8 ohm cab.

    Some people like Scott Henderson think a super lead sounds significantly better on 8 ohms using 2 cabs, I saw Jeff Beck with the same configuration (with one cab turned backwards, I could see the back of the cabinet) and I'm convinced he did that for tone.
     
    houseofrock and tce63 like this.
  3. marshallmellowed

    marshallmellowed Well-Known Member

    Joined:
    Jun 26, 2009
    Messages:
    3,351
    Likes Received:
    3,659
    There is a difference, and that would be hard to dispute. Which sounds or feels best is a personal preference. I can only speak to my experience, but I've found that an amp sounds more "immediate" when running into a 4 ohm load than the 16 ohm (could have that backward). You'll also get slightly more volume when running into a 4 ohm load, if that's what you're needing. There's also a noticeable difference, although subtle, running a slight mismatch (ie. 8 ohm amp setting into a 16 ohm cab...).
     
    Last edited: Jan 21, 2020
    Kinkless Tetrode likes this.
  4. Filipe Soares

    Filipe Soares Well-Known Member

    Joined:
    Mar 8, 2019
    Messages:
    820
    Likes Received:
    1,235
    the mismatch part I've tested several times. but the same cab, like and old 1960, that could run both in 4 and 16ohms, in the same amp, generating different (not judging here, yet) it's my doubt. I'll try that when I got home
     
    Mitchell Pearrow likes this.
  5. South Park

    South Park Well-Known Member

    Joined:
    Sep 14, 2019
    Messages:
    1,490
    Likes Received:
    1,118
    When you talking transformers you are trading off voltage for amps if you increase voltage you decrease amps but the watts are the same.if anything effects tone in the speaker it would be the difference in the power.
     
  6. Nik Henville

    Nik Henville Well-Known Member

    Joined:
    Jul 18, 2018
    Messages:
    1,228
    Likes Received:
    2,008
    Location:
    Eastern Seaboard, the nook-shotten isle of Albion
    An old and wise speaker guru once told me that the impedance affected the damping factor, all else being equal. But he also told me the differences were almost inaudible in the first place, and that moving the speaker a foot to the left or right, a foot further away from or nearer to the back wall, a foot higher or lower... all would have huge audio effects that would completely swamp any difference in sound due to impedance changes (assuming in and out matched etc...)

    He could have been wrong, I could be wrong, but playing is way more fun than pissing about with speakers.

    :hippie::pirate::uk:
     
    Geeze, guzzis3, Jethro Rocker and 7 others like this.
  7. marshallmellowed

    marshallmellowed Well-Known Member

    Joined:
    Jun 26, 2009
    Messages:
    3,351
    Likes Received:
    3,659
    Key word "subtle".
     
  8. Seanxk

    Seanxk Active Member

    Joined:
    May 14, 2018
    Messages:
    194
    Likes Received:
    127
    I feel that there could be a little bit more grunt at 4 ohms, but is it just slightly louder, all a bit hit n miss and not easy to measure.

    But as Nik mentions, cab placement is a greater variant, even take the casters off and get a little more tightness in the bass.
     
  9. mickeydg5

    mickeydg5 Well-Known Member VIP Member

    Joined:
    Sep 30, 2011
    Messages:
    23,712
    Likes Received:
    10,743
    Location:
    US of A
    Everything matters and every difference makes a difference, subtle but there.
    A lot of it has to do with P=V*I or P=R(I*I), damping differences as well as the characteristics of the voice coil and other materials.

    If specifications are provided for each impedance rating differences can be seen in the data.
     
    South Park likes this.
  10. South Park

    South Park Well-Known Member

    Joined:
    Sep 14, 2019
    Messages:
    1,490
    Likes Received:
    1,118
    I would like to know how much mili amps you get in 8 ohm setting off the amp vs a 16 ohms or is it the same . What sounds best amps or voltage
     
  11. Seanxk

    Seanxk Active Member

    Joined:
    May 14, 2018
    Messages:
    194
    Likes Received:
    127
    6 x Tungsol 6550 running into 2 ohms, mmm so very moving.
     
  12. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

    Joined:
    May 1, 2008
    Messages:
    4,952
    Likes Received:
    2,489
    I think that ohms selection and it's impact on tone, feel, response, etc., does sometimes play a factor, but I also think it varies from amp to amp. Below is an example of how it might matter in certain amps.

    From the 1959HW owner's manual regarding the output transformer:

    Tonal Note 3: In the vast majority of Marshall valve amplifiers it is a standard design trait that the negative feedback (a circuit that drops the output impedance and thus controls the damping factor of the powerstage) applied around the amplifier is taken from the 8 Ohm tap on the output transformer. Doing this sets the power-amp up for a certain amount of damping that is independent of where you have the amplifier's impedance selector set. This means that, regardless of whether you use a 16, 8 or 4 Ohm cabinet, the damping on the speakers is the same.

    This said, as is the case with quite a number of ‘Plexi’ era 100 Watt heads, the negative feedback on the
    original 1969 circuit we've used for this reissue is taken off the actual speaker output itself. This means that the lower the impedance setting, the lower the damping factor - and the lower the damping factor is, the more loose and more resonant the sound. Consequently, if you’re using a 4 x 12" cabinet loaded with
    16 Ohm speakers that offers 16 Ohm and 4 Ohm mono inputs (e.g.: the Marshall 1960A, 1960B, 1960AV or 1960BV cabinets), the 4 Ohm input will be more loose and more resonant on the low end, while the 16 Ohm input will be tighter and more controlled.

    Not surprisingly, of the ‘tonally significant’ variants mentioned in this manual, this one is probably the most
    significant.
     
  13. Filipe Soares

    Filipe Soares Well-Known Member

    Joined:
    Mar 8, 2019
    Messages:
    820
    Likes Received:
    1,235
    upload_2020-1-21_15-11-4.jpeg upload_2020-1-21_15-11-4.jpeg


    upload_2020-1-21_15-11-4.jpeg
    Great answer! thank you!
     
    MonstersOfTheMidway and tce63 like this.
  14. Matt_Krush

    Matt_Krush Well-Known Member

    Joined:
    Dec 14, 2015
    Messages:
    1,153
    Likes Received:
    893
    Location:
    Saginaw MI
    Changing impedance on both the head and cab from 16 to 4 ohm....I can't tell a difference (at least with my amps and their settings).

    Technically, if both impedances are still matched, there should be no difference as they still be operating at the same power curve.

    Now, perhaps, depending on the amp...changing impedance could result in a tonal difference because you are moving to or from the tap that the negative feedback portion of the circuit is taken. And depending on how much negative feedback the amp has...you could be changing that as now you have a parallel load to it.
     
  15. BftGibson

    BftGibson Well-Known Member

    Joined:
    May 28, 2018
    Messages:
    1,362
    Likes Received:
    3,402
    I did mess with 2 heads back n forth 4 to 16...

    noticed..Amp ran way hotter at 4..a lil deeper sounding..just a lil seemed lil less tight

    prefer 16...i guess that first cab ever hooked a marshall to was 16 & in my head..lol..must stay
     
    Mitchell Pearrow likes this.
  16. RickyLee

    RickyLee Well-Known Member VIP Member

    Joined:
    May 22, 2010
    Messages:
    9,726
    Likes Received:
    3,219
    Location:
    Riverside CA U.S.A.
    And then . . . . what about the output transformer windings themselves? As in, using the entire OT winding at one impedance setting vs less of the windings at another impedance setting? Does that change the bandwidth or frequency response?
     
  17. guzzis3

    guzzis3 Active Member

    Joined:
    Aug 24, 2019
    Messages:
    195
    Likes Received:
    223
    Location:
    Brisbane Australia
    Negative feeback is the work of the devil. :D
     
    MonstersOfTheMidway likes this.
  18. assquatch20

    assquatch20 Member

    Joined:
    Jan 19, 2019
    Messages:
    41
    Likes Received:
    50
    Location:
    Tennessee
    I opened this thread to give a less eloquent version of this answer.
     
  19. MonstersOfTheMidway

    MonstersOfTheMidway Well-Known Member

    Joined:
    May 1, 2008
    Messages:
    4,952
    Likes Received:
    2,489
    Your opinion and experience matter, so let it roll!
     
  20. Scumback Speakers

    Scumback Speakers Well-Known Member Sponsor

    Joined:
    Sep 16, 2016
    Messages:
    713
    Likes Received:
    956
    Location:
    Los Angeles, Ca
    As the impedance is lowered there is less resistance, and an increase in power. Not a whole bunch, but incremental increases as you go from 16-8-4. There is also a different feel, which is also circuit based, so there's no one "standard", so to speak. Of course, negative feedback values change as you change impedance, and the speakers are affected as well.

    Long story short, you'd need to have multiple speakers, in multiple ohm ratings, and multiple wiring schemes (series/parallel, parallel/series, etc) to get through all the possible scenarios that are unique to each amp circuit.

    Generally, though, the 16 ohm tap has more bass and vintage feel. The 8 ohm tap has slightly more mids, and a more aggressive feel (dual 4x12 stack setup with a Super Lead 100w). The 4 ohm tap I didn't play with, you're on your own for that sound.

    Keep in mind, all of these changes are "subtle". You'd need me, Dave Friedman, George Lynch and Roy Blankenship all in the same room to come up with this summary, which is what we did about 2009 or so when Dave wanted "to know". And George and Roy were there as interested observers with their ears and experience.

    In the final analysis, you need to make your own judgement based on your gear, cabs, speakers, etc. It comes down to how fine you want to hone your sound, and how much $$ you want to expend towards that effort.

    Just my .02, worth exactly what you paid for it...the last 45 seconds of your life reading this post.
     
    T.J. and Filipe Soares like this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice