B'ASS Current Amplifier

[AlainGr]

Here is the plot of the Tannoy System 15 DMT II...

[PeterSt]

Was that rephrasing ?

[AlainGr]

Ha ha ! I feel lazy

Nevermind Peter It was just a question related with the compatibility between current, impedance and what would result of them. I am not sure myself that my sentence makes sense.

When I will be able, I will certainly order a B'ass with a VC, but I will ahve to ask questions about the # of amplifiers...

Regards,

Alain

[PeterSt]

Last time :

Would such a situation be put more in evidence with a B'ass ?

Can you make English of that ?
Hey, I am serious. Please be so too.

[AlainGr]

Ok. Since there are impedance variations depending on the frequency and these variations can make an amplifier pass from X watts to Y watts very rapidly, can this be a positive or a negative... ? Will the B'ass increase this behavior ?

Alain

[PeterSt]

Ah, now I understand.

Ok, first back to your (first) assertion that it would be bad of the amplifier changing its power so fast;

First off, this change in Wattage is the same as change in current (you can well say it is the same thing). So, draw more current means consume more Watts.
Now it is exactly what I am saying that should happen or otherwise nothing of it works to begin with. Point of course is that you are told that this is a bad thing. Now :

That impedance response of your speaker does not look spectacularly wrong to me. I think it can be much worse. But what is "worse". So in the end it is dead-normal for a speaker to behave like that and it is only that it is never a good thing. So means exist (cables) that take out the effect as much as possible.

If someone has told you that *because* you have a fast amplifier, it is a bad thing that it follows the current need so quickly and with that sort of pulls over itself ... I can imagine something with that. So remedy : let it be and miss out on those more diffficult frequencies ?
I don't think it should work like that. I'd rather think that your amp is okay with it and that it is all meant to work like that.
It would be quite easy to think (from some other perspective) that when the amp delivers more power that fraction of a second, that it is boosting into the speaker all the time with this. But this is not how it is supposed to work;
There's a voltage to sustain and this is for all the frequencies while the amp does not really know about the freqencies. It just tries to put up the voltage and sustain that. The speaker kind of shortcuts it with the lower resistances, which are in certain frequencies. Those "parts" of the whole just draw more now ? It is per se not so that because 2K needs more "power" that 100Hz also receives that more power. It is exactly the other way around (and my story about buffer behaviour instead of current amplification). It is taken where needed.

One thing remains and this is the amplifier pulling itself over (so to speak). So yes, it would be fairly difficult tuning of the amp, if it continuously changes its power. Say that it would be the 180 degree opposite of what I try to achieve in a PC (most stable behaviour). So from that perspective I can agree.

And most I do is reasoning - not knowing !
Regards and thanks,
Peter

[AlainGr]

Thanks Peter.

It should be a good thing since I do not "hear" this happening. All that was said from that person was about the graphic I showed with the speakers I own. But he did not hear them in real life.

And I can obviously imagine that it should be good in the results.

Regards,

Alain

[PeterSt]

Hmm ... I see that I forgot to answer the question (since I finally understood it );

It is hard to tell whether the B'ASS may contribute to such behaviour (as a negative). I don't see how. It may count for itself (see previous post and the poweramp pulling over itself) but I don't really see how to test that. Anyway, that is a different story.
So emphasizing what the poweramp does on its outputs as a response to the impedance changes of its load (the speaker) ... no ... I don't see the B'ASS doing that.
The poweramp may behave differently though, because what was not taken in for "firm frequency", now does. So it must be capable better and assumed this is no problem, it will draw current in a different fashion, itself.
But this is all a different story and quite complicated to follow (all).

Peter

[acg]

Peter,

I was told by someone that judging by the frequency response plot of my main speakers (from my sig) and the consequent change in impedance (depending on the frequency), my power amp (also in my sig) would switch very quickly from 200 (under 8 ohms) to 400 watts per channel (under 4 ohms) - back and forth, mutilating the sound.

Alain, perhaps that is true, but in reality there are not many amplifiers about that are able to double power when impedance halves, and I do not know whether yours can do this or not.  Those amplifiers that properly "double-down" to low impedances have huge power supplies that most people don't want to pay for!

Speakers are generically voltage driven for normal impedances...the higher the impedance the more voltage and less current is required.  When the impedance drops more current and less voltage is required.  Is the amplifier capable of providing enough current for low impedance?  Well that depends on the electrical characteristics of the speaker and amplifier in unison.  I think there is a lot to be said about current driven loudspeakers, but that is a whole other subject not really applicable to this conversation.

Peter, thank-you for your writings following my earlier question.  To my way of thinking the B'Ass would impact the input stage of the amplifier (signal integrity as you describe) rather than the output stage (where the power for the loudspeaker is produced) but you seem to be talking about the speaker load being integral to the effect of the B'ass.  In my example, with zero-feedback single ended triodes and the associated transformer de-coupled speakers the speaker load is not really "seen" at the input of the amplifier (of course the speakers are not absolutely-totally de-coupled, but I would suggest that they are much more de-coupled than for most solid state amplifiers especially those with global feedback).  What the B'Ass would "see" in my situation is the variable impedance of the Passive Line Level Crossovers at the inputs to my amplifiers, not the speaker load as you talk about, so I still have a niggle about what the B'Ass will achieve other than providing enough drive for a highly variable amplifier input impedance, but I guess there is only one way to find out, to put a B'ass in there and see.

Regards,

Anthony

[AlainGr]

Hi Anthony,

It is obvious that my knowledge is so thin about the matter that I never really got worried about this, unless I would have heard something odd with this amplifier. The good thing is that I have another power amp that I could compare with the one I mostly use and there were not much differences I could really hear. On the contrary I had the feeling that the cheaper of them was a little "rougher" than the Spectral Audio.

I learned something new with the factor impedance, voltage and current - I will keep that in mind

And as for the B'ass effects, my thoughts are the same as yours in your conclusion: the only way to see and feel what will happen, well... Is to get one But it is also a matter of trust in Peter and that has not been lacking for many years, even if I am late in upgrading my NOS1...

Regards,

Alain

[PeterSt]

Peter, thank-you for your writings following my earlier question.  To my way of thinking the B'Ass would impact the input stage of the amplifier (signal integrity as you describe) rather than the output stage (where the power for the loudspeaker is produced) but you seem to be talking about the speaker load being integral to the effect of the B'ass.

Hmm ... With my poor (and too long-winded) English that must have sneaked in somewhere. Anyway, I thought this would say it all :

So emphasizing what the poweramp does on its outputs as a response to the impedance changes of its load (the speaker) ... no ... I don't see the B'ASS doing that.

Also mind my usage of emphasizing in whatever person but not the first. So "I" am not the one emphasizing (or not) - the B'ASS can't do that (is what I'm saying here).
So we talk about the same.

Something else is (and that may have fooled you) that the more firmness of the signal will travel through the poweramp and has its effects there. Theoretically it must be faster now, or deliver current faster just because more requirement is there. This all could be (!) obvious. But then I gave the example for the speaker (driver) which should be able to follow and this was just an example, because everybody understands that.
So with the example of the speaker driver, the poweramp must be able to do the same (which is much less visible to most).

DAC (is as is) -> B'ASS (= more powerful) -> Poweramp (must be more powerful as a derivative of faster) -> Speaker (must be faster).

Anyway I am sure we talk about the same and hopefully others can follow (me) as well.

Regards,
Peter

[acg]

Ok, yes, we are on the same page then...I must have misinterpreted something.  Phwew!

[Bigear]

Hi Peter,
 
not 100% sure what is mend with "more powerfull bass".
You mean faster / more controlled and deeper? Could this affect the sound balance in your setup ending up being to bassy?

If so, would you be able to select the amount of B'ASS stages used in parallel in the new device you propose?

Also I'm a bit worried that my tube amplifier (more voltage amplification)  might behave different from your solid state gainclone's (current amplication?) on adding a B'ASS stage?

- Quint

[PeterSt]

Hi Quint,

Could this affect the sound balance in your setup ending up being to bassy?

Explicitly not because everything is amplified equally. Well, more equally than equal because what has been underwhelmed is now equally "put out".
Read back on the frequencies requiring more current and how that (also) tears down the lot.

not 100% sure what is mend with "more powerfull bass".

And I am not 100% sure where I said that. Haha. Doing a search on the last two pages I only can come up with this :

by now I start to wonder how an open baffle speaker (it still is that ) is even capable of producing such powerful bass

... which is nothing about "more powerful bass".
But if you really like to know what is going on :
Of course it is a more powerful bass, but then everything is more powerful. If I make that "more effortless", maybe it is clear better ?

might behave different from your solid state gainclone's (current amplication?)

I don't know how that would be "current amplification" !

Also I'm a bit worried

Somehow it is difficult to see / bring across that it is just an extension of the DAC ... and that there's nothing special about it (see previous posts from e.g. yesterday) ?
How much current can your mains (one outlet) supply ? Say it is 25A @ 230V. Does this bother your poor 72W light bulb ?
The 25W one ? The 5W ?
It does not matter. The lightbulb consumes what it needs, and as long as the current required is there, it will lit. A dim 5W for the 5W bulb and a more bright 75W for the 75W'er.
The 5W consumes 5/230 = 0.022A and 75W consumes 75/230 = 0.320A.

But now what if the current is not available ? Say that there is 0.02A available only ...

The 5W bulb : 230 x 0.02 = 4.6W. It is not as bright as intended.
The 75W bulb = 230 x 0.02 = ... 4.6W. It behaves even poorer than a 5W bulb.

While this is light, audio comes in "bursts". So supposed that an audio signal is intended of 75W but only 4.6W is available, then all is clipped to the 4.6W signal and the sound will be totally flat (and disturbed, but alas).

The above can not 100% represent reality but it gives the idea;
If the 4.6W can be extended to e.g. 30W, then all will be more powerful - not only the bass. All we could perhaps say is that when no high freuqencies are present, there's more power available for the bass.
The total power is utilized for all the frequencies at the same time.

Ever back I tried to sort out how much Watts "music" as such requires, but this is quite undoable and also not linear. Regarding this, think again about a loudspeaker driver. Say a woofer which can do 1000Hz.
When a bass signal is there at 500Hz then that part is working. Now we superimpose 700 Hz on that and you can tell me whether this is from the ground up (as if the 500Hz were nog there yet), whether it is on top of the 500Hz (so with the same SPL the 700Hz much make the same excursion on top of what 500Hz already is doing) or that it is something else. One thing : only one amplifier takes care of the both and when it does not have sufficient power (is current !!)  it can not do all - all equally bad, the 500 better than the 700 or the other way around. Or something else of course.

Regarding this, again think about the interlink length and current math : How was that ? for 20KHz only ? or was it for a 1000 different frequencies at the same time ?
So I say that the math for that could be as difficult (undoable) as it is for the power music requires.
So let's be on some safe side with it, and know that your light bulb of 75W will also be litting with 200A "pushing" behind it.

Clear a little ?

Best regards,
Peter

[Bigear]

Hi Peter,

thanks for explaining. A sound which is "more effortless" is what I am looking for...

Cheers, Quint