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Hi
I do know, what the different impedance tabs on the transformers of my triode-amp mean, and I do know, that the "lower" the output-tab, the more current the amp is able to deliver to the speaker.Still, there is on question left unanswered for me: what is the difference, when I choose the 2 ohm, 4 ohm or 8 ohm Tab for an 8 ohm speaker? Or in other words: what are the pros and cons to choose or deliberately NOT choose the exact match of impedances between the transformer output and the loudspeakers nominal impedance? What kind of effects could the different "matches" provide electrically and sonically?
Follow Ups:
It's a complicated issue. The impedance curve of any speaker is not constant with a large abberation at resonance, not to mention a passive crossover with insertion loss or gain and the damn wire problems. You just have to try different taps with your speakers and your cables and see what best suits you. I would reduce the cable run as much as possible. I use 1 foot and my amp is at the speaker. Start low. Ray Hughes
Well, the taps numbers are about as meaningful as "use third gear for 35mph" kind of statements.The right answer is - it all depends on what you are trying to do.
The very idea of calling taps "X Ohms" is silly from the very beginning. It gives you the perception that this is correct speaker impedance... and it ain't.
Usually it simply corresponds to the point of maximum power. And in most cases matching speaker impedance to the tap one is simply not the best combination.
Some amps are designed with the Pmax point being lower than the "tap impedance", meaning you are getting better drive at the expense of maximum power. And that is often a good tradeoff.
Without going too deeply into this big subject, I personally always recommend that you try all taps, and see which one produces the result you like most. If your amp is designed well, you will not damage it by doing this.
Generally speaking, when using lower number taps you get more control and drive, with higher - you get more open sound. So often people use this as a built-in room correction tool.
Thanks for your answer!Currently, I do drive my Magnepan 1.6 QR off the 2 ohm tab, simply because Maggies are said to need current rather than voltage - and that's what I learned in this forum, that a 2 ohm tab for a 4 ohm loudspeaker can deliver more current (let's just skip the "naming-discussion" for a second...)
Now, with the possible buy of a ZERO autoformer ahead, I am confronted with this subject anew: I could let any "tab" of the output transformer "see" any load, that the ZEROs are capable of "producing". I think, with my Magnepan I could go from 4 to 16 ohm "visible load" and connect these loads to any of the three output tabs. Just consider the possible combinations - I'd get crazy in testing them all out.
So I was trying to find out beforehand, if there are some sort of rules about matching those two different "impedance values" (again, skip the naming-error...).
Maybe, this explanation will help you to give me some more advice?
well if you want a Rule of Thumb so that you can sleep at nite knowing you have hooked them up *correctly* and not bother with fine-tuning your system, then the speaker impedance should be equal or lower than that specified at a tube amplifier's output tap. See the conundrum?
I agree,
a 6 ohm speaker should be connected
to the 4 ohm tap not the 8 ohm tap.
The lower the Zo the better for a
linear drive (aka voltage source).
Depends on what you would like to improve in your system.If it is control, then go lower, But if you need more power, then probably go to the one "matched".
It usually helps to know at what point the max output happens for that particular model.
VictorI agree, more knowledge is always good.
I have heard tube amps with lots of power
but no control on the bass.
I have heard heard tube amps with extended highs
that were very harsh and irratating(usually pentode).
I even heard tube amps that didn't handle
the crossover frequencies well.
It's all in the design and implementation -
amplifier and speaker system.But Joerg has Maggies and they definitely
prefer the lower impedance taps.
(ie they NEED current/control)As far as matched vs lower imp taps -
If you have enough volume with the 2 ohm taps
(with Maggies) then stay there.
Adding a zero will only introduce another
componant/source for distortion/
potential problem into the circuit.
The difference between 2 ohm and 3 ohm
is minimal and not worth the extra money.
The difference between 3 and 4
is another story with Maggies.
If you have enough volume
with the 2 ohm tap then
all is well IMO, FWIW.
Huh? I thought the safe rule of thumb was to , for example have a 6ohm speaker it should be hooked to the 4ohm tap, not what you are explaining in having a 6ohm speak hooked to the 8ohm tap of amp?, I have never heard it the opposite way until now, please clarify Ron Oehlert... thanks
I assumed a triode with various output taps was a tube amp, so I gave him the Tube rule of thumb. For a transistor amp the rule is reversed; speaker impedance should be equal or higher than that specified at amp output. The riddle is that he found 2 ohms to yield the best result.
My quad 12ls (6ohm) sound much better to me on my 8 ohm taps vs 4. Everything sounds better, from bass slam all the way up!
-rob,,, YOU ARE 100% RIGHT!!!! I tried my 8ohm tap, unfortunatly I could not do this before because I literally had to drill new holes in the back of the amp and Add binding posts(which after this post started I did it last night), which worked out perfectly, now I have access to both 4 & 8, and I thought it already sounded really good, but I picked up the 35 to 50hz range that was missing on the 4 ohm tap and the distortion is much lower as well as I am getting much Higher volume output at the same level from without turning it up!! Digital sounds much Smoother and fuller, the 4 ohm tap is now useless to me on this amp, but at least it is there...
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