[AmpDesigner333]

Given that this is false what follows does not have univesal application....

Dave,

I don't understand why you disagree.  The ideal amplifier is a variable voltage source, and the ideal variable voltage source has zero output impedance.

Also, you state power supply current as the culprit of load impedance minimums, but this is an over simplification. The output stage is in between the power supply and the load.  So is the speaker wire.  Connectors too, but since you think damping factor isn't important....

Here's an easy experiment you can do to examine the effect of output impedance driving a speaker....  Run a simulation with an ideal voltage source through a resistor into a speaker load model. The parameters of the speaker model can be simple (let's say, a two way system).  Run plots of the response across the source resistor.  Step this resistor value using a range equivalent to a damping factor of 1 to 1000, log. Check out the "loss" across this resistor!

Keep in mind many speakers use drivers that have a HUGE impedance spike at resonance, typically 30-100Hz, which is where (freq wise) manufacturers typically measuring damping factor.  This happens to be where it matters the least.  Typical amps the start losing control of the speaker as the frequency rises, ironically as the speaker's impedance goes lower.  Many well respected high end speakers go below 2 ohms, for example.  So, that leads me to another question....

Have you ever heard a Cherry Amp?  Specifically our newer models, like Maraschino or MEGAschino?  These are good examples of what amps with high wideband damping factor, low distortion, DC coupling (no bass phase shift), high bandwidth, and low noise can sound like.  Plus, we take it through additional steps to optimize for sonics.  This is why Cherry Amps don't suffer from the "dry" sound of other Class-D designs or the "sloppy" sound of tube amps.  Those are bold claims, yes, but I'm not alone in my opinion here.  Take a look at reviews on our Circle.  The proof is in the pudding.

When it comes to damping factor, there's no reason for wanting it lower.  Well, maybe if your selling amps with poor damping factor.

I want you to know that I do appreciate your use of math and science.  That is refreshing, and even if we don't agree on some narrow issues, we both believe in engineering.

-Tommy

[planet10]

=I don't understand why you disagree.  The ideal amplifier is a variable voltage source, and the ideal variable voltage source has zero output impedance.

Many of the speakers we design do not like to be driven by low output impedance amplifiers. So we have direct counterexamples that disprove your assumption of what an ideal amplifier is.

An example (in fact, almost all of the Fostex FE series want to be driven by a high output impedance amplifier):

you state power supply current as the culprit of load impedance minimums

It is certainly the biggest reason.

Here's an easy experiment you can do to examine the effect of output impedance driving a speaker....  Run a simulation with an ideal voltage source through a resistor into a speaker load model.

How about a real world version of that where one puts a resistor in series with the speaker. With the appropriate speaker the bass improves.

(let's say, a two way system)

Let’s say a 1-way speaker.

Have you ever heard a Cherry Amp?

You asked that question already and i said no. And with so many amplifiers to try, and the more you show your ignorance of this subject the lower your amp’s get on the list.

...amps with high wideband damping factor, low distortion, DC coupling (no bass phase shift), high bandwidth, and low noise...

We like most of those, but high damping factor is very speaker dependent (with the right speaker, a current amp can provide the best performance), and one has to ask how you are quantifying low distortion. It is well understood that THD is meaningless.

Cherry Amps don't suffer from the "dry" sound of other Class-D designs or the "sloppy" sound of tube amps.

I interpret “dry”as lean, which is often caused by overdamping a speaker, and there is as much variation in quality of tube ams as there are in SS amps. Many of today’s tube amps are just clones of vinatge amps with all their same problems, and Single Ended amps with their highish output impedance want to be used with an speaker that likes that (like the Fostex mentioned)

Those are bold claims, yes, but I'm not alone in my opinion here.

It only takes one counterexample to show that your opinion is out-to-lunch. A speaker & an amplifier need to be considered as a system. There are speakers that will like your amps, and there are speakers that they will not work well with. My bet is that all the positive reviews are people using the amps with speakers that like them (in which case they may sound spectacular).

When it comes to damping factor, there's no reason for wanting it lower.

Except when you have a speaker that likes a high output impedance amplifier.

dave

[AmpDesigner333]

Many of the speakers we design do not like to be driven by low output impedance amplifiers. So we have direct counterexamples that disprove your assumption of what an ideal amplifier is.

An example (in fact, almost all of the Fostex FE series want to be driven by a high output impedance amplifier):



It is certainly the biggest reason.

How about a read world version of that where one puts a resistor in series with the speaker. With the appropriate speaker the bass improves.

Let’s say a 1-way speaker.

You asked that question already and i said no. And with so many amplifiers to try, and the more you show your ignorance of this subject the lower your amp’s get on the list.

We like most of those, but high damping factor is very speaker dependent (with the right speaker, a current amp can provide the best performance), and one has to ask how you are quantifying low distortion. It is well understood that THD is meaningless.

I interpret “dry”as lean, which is often caused by overdamping a speaker, and there is as much variation in quality of tube ams as there are in SS amps. Many of today’s tube amps are just clones of vinatge amps with all their same problems, and Single Ended amps with their highish output impedance want to be used with an speaker that likes that (like the FOstex mentioned)

It only takes one counterexample to show that your opinion is out-to-lunch. A speaker & an amplifier need to be considered as a system. There are speakers that will like your amps, and there are speakers that they will not work well with. My bet is that all the positive reviews are people using the amps with speakers that like them (in which case they may sound spectacular).
 

Except when you have a speaker that likes a high output impedance amplifier.

dave

Dave,

I suspect that the speakers you show would have difficulty reproducing realistic (live level) SPL.  Do you use subwoofers with these?  I'd be worried about popping that little cone onto the floor.     No idea how good it sounds at low SPL, but everything gets easier when you're only trying to reproduce a "miniature version" of a musical performance.  This is not to say that a system is only good if it can "play loud".  I do like the idea of no crossover, but I remember a similar system at 2016 RMAF that came with tons of hype and the sound of a table radio.

We like to make systems where you feel like you're listening to a band, not a stereo system.

Yes, I asked the question about listening to Cherry Amps more than once ---- for a reason.  Think about it.

Please proofread your comments.  Misspellings and grammatical errors sometimes change the meaning.  I suggest you re-read your comments to see what I'm talking about, like "read world" where it appears you meant "real world".  The quality of one's communication means a lot.

I prefer the term "nostalgia audio" over "vintage audio".  There have been many improvements in audio technology over the years.  Going back is typically just that.  Nothing personal.

Thanks for contributing to my thread, but I'd appreciate a less insulting tone moving forward.  Let's keep it classy.  Also, this is supposed to be a fun hobby.  Animosity is not a good spice to add to the broth.

Back to damping factor....  If your speaker "likes" series resistance, why don't they just build that into the speaker?  Of course, this means you can get away with poor damping factor, but why kludge the amplifier to fix a speaker problem?  Damping factor is not the only thing about our amps that sets them apart.  The amp as an isolated element shouldn't be handicapped to accommodate the speaker.  Our philosophy is that the amp should do the best job it can to be as close to an ideal amplifier as possible without compromising it's ability to deliver a fluid, musical experience.  This also allows bringing new life to old speakers!

-Tommy O

[planet10]

Assertions that are not true need to be challenged — like yours that an ideal amplifier has zero output impedance. There are for instance arguments that suggest an amplifier with a very high output impedance (a current amp) is best. But there is no best in hifi, far too many compromises need to be made for that to be possible.

Every loudspeaker has a series of compromises. A good FR speaker does things that no multiway can achieve. For some this is seductive. All the ones i deal with are diy because good commercial ones are few on the ground and often very pricey.

dave

[AmpDesigner333]

Assertions that are not true need to be challenged — like yours that an ideal amplifier has zero output impedance. There are for instance arguments that suggest an amplifier with a very high output impedance (a current amp) is best. But there is no best in hifi, far too many compromises need to be made for that to be possible.

Every loudspeaker has a series of compromises. A good FR speaker does things that no multiway can achieve. For some this is seductive. All the ones i deal with are diy because good commercial ones are few on the ground and often very pricey.

dave

Are you familiar with the work of Stewart Hegeman?

[planet10]

Yes.

dave

[AmpDesigner333]

Yes.

dave

So you know about his famous "straight wire with gain" stance?

[planet10]

Yes.

dave

[AmpDesigner333]

Yes.

dave

Dave,

Do you agree with Stewart Hegeman?  If you do, you agree with the "ideal voltage source".  This doesn't mean anything bad.  If you don't need an ideal amplifier for your particular speakers, or something even close, there's no harm in that either.  Thanks again.

-Tommy O

[planet10]

I dodn’t think that that says  “ideal voltage source”. A speaker is a current device. Using the impedance of the loudspeaker as the resistor in an I/V converter is fraught with problems. Amplifiers as volatge sources  made it conveinient for loudspeaker makers to move into a corner of the possible design space.

dave

[AmpDesigner333]

Just revisited this thread after a long time.  There are many pseudo-science and even anti-science claims made by fancy cable makers.  Stuff about skin effect, which is not significant at audio frequencies, polarizing shields, which is just silly, and other similar junk (like various metals, etc.).

When it comes to designing electronics, or electromechanical devices, it takes education AND experience. Each is not a substitute for the other, no matter the magnitude.

Regarding speaker cables:
1. Shielding isn’t necessary because the impedances are so low.
2. The lower resistance, the more damping factor is preserved.

Regarding amplifiers, the ideal voltage amplifier (as 99.99% of audio amps) has voltage gain and no output impedance, regardless of frequency, amplitude, or load.  This is fact, and not debatable.  If you’re an electrical engineer, this is something you were taught early in school, as soon as the core courses were out of the way, and simply second nature as a practicing engineer, if you are fortunate enough to be one.  Some engineers get the degree and never wind up doing any actual engineering.

Now, we have speaker cables available, although we don’t push them or try to make any significant margin on them.  They are designed for easy use (physically flexible) and LOW RESISTANCE!  Our current top-of the-line model is the MEGA Snake, a 9-gauge equivalent cable!  Here’s a photo....





Fact is, there are many companies, and individuals, that make up problems so they can “solve them”.  This stuff comes from marketing, not engineering.