tonal differences of running your amp 8 or 16 ohm...

If you're saying you mismatched impedance, then I think there can be a tonal difference. If you're matching impedance, I think any tonal difference between 8 and 16 would be very subtle.

 

Indeed,

I have been running my stock 8 ohm Rivera into a series wired 2x12 16 ohm cab, dramatic diff with this mismatch.

It opened the amp up tonally

Additionaly, rewired a marshall 1960a 4x12 from parallel-series to series-parallel both at 16ohms and powered by an SLX and there is even a difference there although more subtle than a mismatch.

In each example above, a change was introduced unlike running an 8ohm cab from a 8ohm tap or a 16 ohm cab from a 16ohm cab. If there is any difference with this, its only due to peculiarities in the OT windings.

 

Nope, you are not hearing things. Wait, actually you are hearing things, like a real difference.

A one-step mismatch (4 ohm to 8, 8 to 4, or your case 16 vs 8) will alter the tone in tube amps since it "loads" the transformers differently, thus affecting your output tone. Whether one likes the mismatch is up to him. Caution, though: while most amps' transformers can tolerate said mis-match, other amps may be less friendly to a one-way mismatch (like 8 -> 16 is ok, but 8 -> 4 is not ok), while with other amps you risk killing the tranny with any mismatch (I've heard to never mismatch vintage Marshalls). So check with the maker, or ask here from owners.

Edward

 

If I understand your question, what you did was disconnect one of the two speakers in your 2x12, and adjust the impedance setting on the amp to match the new 16 ohm impedance. Is that correct?

Well, running your amp into only one of the speakers of your 2x12 is giving that one speaker twice the power load. The speaker is going to respond differently with twice the power going into it. In fact it may be near the upper limit of its power handling and compressing and otherwise coloring the tone - thereby sounding "better".

If you didn't adjust your amp to match the new 16 ohm impedance, then you've got an impedance mismatch in addition to more power going to the speaker. Note that in a mismatch situation, the speaker wouldn't be getting twice the power of the 2x12 situation, because the amp would be operating at less than optimum efficiency. So you'd be getting less than twice the power into the one speaker, but that one speaker is still handling significantly more power than it is in the 2x12.

 

I've noticed in his books Geral Webber (Kendrick amps) reccomends running the amps at their highest impedance setting, with propper load, as you are using the full OT and not a tap off it.

 

Some say no way,others say yes. Ive heard a difference(amp dependant) running matched between 8 and 16.

Also amp dependant.

Didnt hear much of a difference with my Rivera Chubster when I tried a couple 16 ohm speakers. Im surprised I didnt sell it but a couple of months ago I switched to JJ6V6's and that finally made the difference. Ive been digging the amp since. Ironically I matched the impedance mismatch caused by running the 6V6's by using a 16 ohm speaker! lol! Bob

 

I run my Clubman with two speakers at 16 ohms, I think it sounds better.

I read once that the higher impedence is easier on the tubes because it is further from a dead short then 0 ohms. Don't know if this is BS or not but it seems feasible.

 

I played a gig awhile back, accidentally running out of a 4 ohm output rather than the 8 ohm into a 1x12 8 ohm. I knew something sounded muffled, but it wasn't until we were breaking down after the gig that I realize what I had done. Fortunately it caused no transformer damage.

 

I should have said ohms. The way I heard it explained is teh closer to zero the more it is like the door is open wider. Thus the tubes tend to run hotter because the load is like, "hey send me more, I can take it." From what I read at higher ohms there is a more resistive effect which tends to keep the tubes in check (basically buffeting them somewhat) I don't know if this is hogwash but it seems possible. I do know that 0 ohms would be a dead short a result in blown fuses and such.

 

Yes 0 ohms would be a problem in an amp. It would put out the max current with no where to go. Essentially like stepping on the end of a garden hose. After a while the water (or current) builds up with no outlet the hose blows.

 

After all of this talk about mismatching, I think I'm going to play it safe and get a Weber Z-Balance for my Super. No sense in screwing up my amp or not hearing the speakers with the correct load after all of the money being spent on this makeover.

 

I would not put anything in between the amp and cab unless it was a good attenuator. I had a Z-Matcher for about a week. Took out the punch and sweetness.

 

I think this is one of the big factors in why I think a vintage Marshall sounds the best running at 16 ohms into a Marshall 16 ohm 4x12. It's also why I've never really liked using a Marshall with a 2x12 which are usually 8 ohm cabs. It just sounds best to me at 16 ohms.

While the tone difference may be subtle, the feel of the amp is much more noticeable. Of course, I believe I read somewhere that Eric Johnson likes running his Marshalls at 8 ohms so what do I know.

 

I struggled with this very same issue a few months ago. I've got a Frankenstein blonde Bassman that came from the factory with a blonde Twin output tranny, which essentially makes it run at 8 ohms. I play it through a matching 8ohm blonde cab that I loaded with a pair of Scumnicos and it sounds heavenly. Then out of curiosity, I played the Bassman through my 16 ohm Marshall 4x12 cab with greenbacks. I noticed that playing into a higher impedance mismatch made the amp lose it's punch and dynamics and also resulted in a noticeable drop in volume. I didn't like it so I only play into 8 ohm cabs now. Different strokes...

 

A speaker's load should match the output tranny ...that's the moral of the story. A vintage Marshall sounds good at 16ohms because that is what it was designed and voiced for; nothing magic or beneficial running at an impedance greater than what the amp was designed for. If it does not match, a "one-step" mismatch between tranny and spkr is generally tolerable for most modern trannies ...BUT check your manual/factory as this is not a rule as much as a generality.

Edward