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16 vs. 4 ohms Yes they sound different.

Discussion in 'Amps and Cabs' started by DC1, Feb 1, 2008.

  1. DC1

    DC1 Member

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    Ok, wanted to get to the bottom of this for myself.

    The gear:

    1969 HIWATT DR103 with 4, 8, and 16 ohm outputs.

    1994 Matchless closed-back 4x12, run detuned with 2 of their modified 8-ohm V30's in the top 2 holes and the bottom 2 holes empty.

    First I ran the 2 in series for a 16 ohm load and set the amp accordingly.

    then I ran them in parallel for 4 ohms and set the amp accordingly.

    Wow! Yes it sounds quite a bit different w/o changing any of the amp settings. The 4-ohm setup is clearer and brighter, more detail, more clarity. The 16ohm setup is warmer and less lively sounding, less dynamic, but still a good sound. You can get brighter by changing the tone controls, of course, but it is still different than the 4-ohm setup and not as clear.

    Both are good sounds. I like the 4-ohm setup better, but YMMV.

    If you run an amp with 2 speakers, you should try this. It's pretty eye-opening. I did not try any mismatches... Too hard to find those trannies!

    DC
     
  2. sickboy79

    sickboy79 Member

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    I've had the exact same experience with a 4x12. I rewired my mid 70s Marshall 1982A 4x12 w/G12H30s to 4 ohms to accomodate my Fender Bassman heads - but, I use it with all my amps. I find the 4 ohm setup to be a bit brighter, clearer, tigher, with more punch. 16 is warmer and sweeter. Both have their advantages - depending on the amp of course.
     
  3. Twangzilla

    Twangzilla Member

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    The question is: Were you hearing the difference between 4 ohms and 16 ohms or the difference between running speakers in series and parallel? Or a little of both?
     
  4. ROKY

    ROKY Member

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    I'm really enjoying the 4 ohm parallel load for the reasons the OP stated;
    just started this very recently.
     
  5. Squigglefunk

    Squigglefunk Senior Member

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    I like the sound of 2.6 ohm load
     
  6. DGDGBD

    DGDGBD Member

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    I've had the same experience with the parallel/4 ohm vs series/16 ohm settings. I have a jenkins 2x12 cab loaded with the weber BD/SB ceramic combo, 8-ohm speakers. The cab is set up with a switch to do either parallel or series wiring. The parallel setting with 4 ohm output of my amp sounds noticeable livelier, tighter; than the 16-ohm/series setting. I believe its more of a function of the speaker wiring rather than the output transformer setting.
     
  7. HEAVENandHELL

    HEAVENandHELL Member

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    I've come to greatly dislike the 4 ohm output on my Dual Rec. When running only my 8 ohm Mesa 4x12, the tone is fat with large low end. However, all amp settings being the same, if I connect my 8 ohm Mesa 1x12 and put both cabs into the Dual Rec's 4 ohm outputs, my tone seems to get very bright and loose a lot of the low end "balls" that it normally had.

    I just tried this Tuesday as the other guitarist and I wanted to each run a cabinet on both sides of the stage. I could definitely hear both of us better, but my tone was affected so much that I'm not doing that anymore!

    Gregg
     
  8. DC1

    DC1 Member

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    Darn good question...

    It does affect the sound to run through a voice coil and then to another speaker, as in series, and it should sound different to run more of the output transformer or less.

    I can't say which is more audible.

    DC
     
  9. Groovey Records

    Groovey Records Member

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    try this 16 ohm wiring series and parallel just throw in a couple more drivers you can do them the same, top and bottom with two different pairs or wire neg to positive diagonally in a cross x pattern. Those empty holes are tone suckers.

    [​IMG]
     
  10. pgissi

    pgissi Member

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    First, to really hear the difference do not alter your tone settings when a/b'ing the impedance. It may be an obvious point but some forget since what you want to hear is the increase/decrease of low/mid/highs etc.

    I have posted extensively on this topic and use a 16ohm series speaker config on my 8ohm rivera, a 100% mismatch

    At the stock 8ohms or 4ohms the tone is brighter (harsher for me) with less compression and more fizz if you will. At 16ohms that characteristic Fizz you hear on many marshalls and their clones like channel 1 on my R30 is dramatically reduced and for me, this improves the overall clarity, the amps voice speaks more clearly and solo dont get lost in fizz and chords sound more rich and full.

    Some describe the 4 ohm mismatch as having increased clarity due to the increased brightness but when driving at stage volumes, it can be too bright and harsh, test at stage levels to really know. Pushing any tube amp will render its and the speakers/cabs real response.

    For my R30, at 16ohms the overdrive also has a more complex timbre although it is slightly darker and creamy, versus brighter and raw which I can recover using pedals when I want that. I believe the OD is more aggressive throughout the whole freq range at 16ohms because the tranny is slightly more stressed due to the higher relfected impedance it sees in this mismatch at 16 ohm and the series wiring naturally works to empahsize more low end and mid via mutual branch inductance.

    With any imp mismatch the power is reduced by 1/3, allowing you to push the tone stack and gain controls harder which most tube amps love but I did find I had to dial out slightly more lows, no big deal.

    IMO this 16ohm output impedance for this particular amp took it from an average or slightly better than average mid priced low wattage amp with an ok tone to a more refined tone approaching the tone of some of its more expensive counterparts either production or boutique and the best part, the amp feels better.

    There was some compromise, less power and slight darker tone with less headroom overall but it was minimal and the most positive change, the amps tone cuts more than it ever even using a 2x12 closed back cab has and this 30 watt amp hangs with other high wattage types.

    When doing a mismatch-
    -do not exceed 100%
    -lower cab imp mismatch will work the tubes harder
    -higher cab imp mismatch will work the tranny harder

    I have employed this high cab imp mismatch trick to cream up other harsh amps that have the busy bees in the high end which IMO is a show stopper since it causes ear fatigue and masks the high end in general under the swarm.

    I would be cautious doing it with high wattage amps, the xtra heat generated by the reduced efficiency of the mismatch has to be dissipated and sunk and the chassis and tranny case is where this happens so if you must, use a fan on the back of the amp for amps over 40 watts run at higher levels.

    P.S. In addition to this I searched for the best tubes for this particular amp, it ended up being tung sol 12ax7's and winged c el34's. I also biased the amp slightly hotter, listening to settings ranging from 65 to 85% of max dissipation and settled on just over 70%

    And finally speakers, they fell into my lap, are not a brand you hear bandied about but just sound good for this amp, this setup, these tubes, this bias, my pedals and guitars, me. they are Carvin V12's, go figure

    The moral of the story, theorize, config, test, theorize, config, test to find YOUR tone

    Simply by asking yourself "what does the difference between 4, 8, 16ohm series sounds like" you have opened the door
     
  11. ChickenLover

    ChickenLover Member

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    This doesn't sound all that surprising. You just took half the power away from 4 speakers (in a big 4x12 cab) and gave it all to just one speaker (in a little 1x12 cab). I wouldn't necessarily blame the amp or it's 4 ohm outputs. But make sure both cabinets are in phase just to be sure (just do a battery test on 'em).
     
  12. DC1

    DC1 Member

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    Oh man, you could not be more wrong. I used that cabinet for 10 years with all 4 speakers in it. Taking 2 out, improved the tone 100%.

    Have you tried it? Do you know about detuning?

    DC

    ps, that diagram you posted will result in 8 ohms, not 16, assuming they are all 8-ohm speakers.
     
  13. shallbe

    shallbe Deputy Plankspanker Gold Supporting Member

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    I've done this as well.

    I find 4 ohms to be louder and more dynamic, adn 16 to have less volume, more compression and sweeter overall.
     
  14. pgissi

    pgissi Member

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    1st problem, you are running an unbalanced speaker config with a total 4ohm load but with the 1x12 @ 8 ohms and the drivers in the 8ohm 4x12 probably being 16ohms each and wired in series-parallel for the 8ohm total load. Yes this accomplishes a total 4ohm load but in the wrong way

    This is not outputting power equally to the drivers and in addition you could have an out of phase condition

    Also I am assuming your using both speaker outputs on the amp and although I dont know the dual rec, there may be some special speaker jack switching doing something your not aware of, you need to get a schematic or manual.

    Dont assume, know exactly whats going on with the jacking just to be certain when using more than 1 speaker jack.

    If you want to use this additional 1x12 as an extension, use the line out from your head to another tube amps power section or SS power amp to isloate the Dual Recs output all tube output stage

    This will preserve your original tone and spread the crunchy love
     
  15. 908SSP

    908SSP Supporting Member

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    Both can sound good neither is right or wrong just different I have both and like both.

    As far as 4 vs 16 I had a 90s Marshall cab with V30 and that weird junk patch panel so you could just pull the cord to switch from 4 to 16. and my amp at the time had 6 outlets a pair of each so in about 5 seconds you could pull the cord from the 4 and shove it in the 16. There was difference I preferred the 4 for a while then changed my mind and liked the 16. Again there is no right or wrong just what sounds better try it you might like it or don't you won't know or miss the difference. ;)
     
  16. DC1

    DC1 Member

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    In the case of detuning, (which is really a different thread) it is almost alarming the difference doing this makes. Really, profoundly different and I like it a lot better.

    As far as impedance goes. I said the two different wiring schema sound different, not that one was better, and that I like the 4 ohm sound better.

    DC
     
  17. Zero

    Zero Member

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    I heard 4 ohms as clearer and brighter as you said also, vs. 16. I always choose 16 myself.
     
  18. zoooombiex

    zoooombiex Member

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    +1 -- I played around with something similar a while back, but doing it this way won't allow you to separate the series/parallel issue with the impedance issue. to isolate impedance, you'd need the same speaker in 8 and 16 ohms. to isolate series/parallel, you'd probably need to find someone who makes a 4 ohm speaker - so you could compare the two 4 ohms in series to two 16 ohms in parallel (both 8 ohms). but then you'd never know if the speakers are actually identical...

    I had two different cabs with the same speakers (G12H30 & blue), one in parallel one in series (parallel = 8 ohms; series = 16 ohms). I wasn't trying to do any comparison - they were just for different heads. But I eventually noticed that the cabs sounded different even with the same amp when I was rewiring stuff. I thought maybe it was the cabs, so I re-wired the parallel cab into series. It had a pretty dramatic affect. All amps were matched to the impedance of the cabs throughout.

    What I heard was the parallel setting was a bit softer and had a more neutral tone. Going to series made the cab much more forward sounding - more focused in the upper mids, a little punchier. I prefer the series combination for those speakers now.

    I tried this with some other speakers and liked parallel (8 ohms) better (Tone tubby alnico's, ceramics, and mixed alnicos and ceramics). With those speakers it was too much upper mid punch, it took on a more percussive and less open sound.

    But again, all the series were at 16 ohm and parallel at 8 ohm, so that didn't isolate that change, though it was less dramatic than 16 v. 4 ohms.
     
  19. rooster

    rooster Member

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    If you think about it, the results make absolute sense. There is more inductance on the 16 ohm setting, as the coils are in series. They run off a higher impedance tap on the OT, so there are more winds on it, again more inductance. Seems to me that would smooth the brights out a bit. In the parallel setting, you'd be dropping the inductance on the speaker side, and dropping the number of turns on the OT, so the small differences in impedance would take on more exaggeration. I'm thinking that the tap on the OT has more to do with the sound than the speaker, but who knows for sure?

    I think it's up to the individual speakers, the individual OT, the individual tubes, and a whole lot of individualities.

    rooster.
     
  20. DC1

    DC1 Member

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    I wish. Problem is the speakers themselves are not identical. Different amounts of wire, and perhaps different gauges as well in the voice coil.

    We design large sound systems for a living. I can tell you that series wiring for woofers and mids in a bi-amped or tri-amped system, sounds lousy compared to parallel. Rather than series a bunch of speakers together and use a big power amp, we prefer to use more, and smaller amps and dedicate each amp channel to one or two cabinets. Sounds better, cleaner, clearer.

    This may not apply to guitar amps at all. The effect of series wiring may be musically useful in a guitar amp.

    Interesting stuff everybody!

    DC
     

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