Klipsch forte iii

[StingRay]

I’m not against measurements, I just find it annoying when people purport to give advice when they have no practical experience of the kit in question.

Yes, it’s gets very boring. Many people have found measurements don’t give them the best sound. Practical experience is important.

 

[George 47]

Thanks for the input Ric.  I'll read the article.  It will be difficult for me to audition at home for any speaker purchase.

Jimmy,

Good to have another members from the USA. I reviewed the Klipsch Forte III here;



And I drove the speakers with a solid state amplifier, but they worked much better with a Unison Research S6 valve amplifier. Klipsch speakers, particularly those with the new MUMPS shaped horns, work really well with valves and I suspect that the Prima Luna amplifiers will 'work' really well. I found it sounded better facing straight forward or with a small amount of toe-in. 

Basically, if you want to hear the excitement and fun in music, with a real live sound, then Klipsch are for you. However, if you want to sit there and admire the sound and stroke your chin at the accurate frequency response, ultra low distortion and study the graphs, then maybe not. 

I would not be too perturbed by the difficulty in driving these speakers. They will run your amplifier at a much lower power output for LOUD music and have less distortion. But remember, Enjoy The Music, which is not an academic exercise.

 

[tuga]

By ‘go well’ I mean the combination of PrimaLuna/Klipsch sounds good according to all the reports I’ve read. Additionaly, the amp doesn’t have technical issues with the speaker load in practice, as you think it might from your ‘theory’.

The theory is not mine. It's physics, and the combined response will be as expected.

Whether someone will like it or not will depend on that person's taste. Which is why I wrote "Are you able to try before buying?", because @JimFin said he had a valve amplifier and I know that many have high-ish output impedance. Prima Lunas have very high output impedance.

For example, here you see what happens to the theoretically flat response of the Prologue One when driving the Kantor dummy load - the combined response looks a lot like the speaker load because the amplifier has very low "damping factor":

Prima Luna Prologue One, 8 ohm tap, frequency response at 2.83V into (from top to bottom at 2kHz): simulated loudspeaker load, 8 ohms, 4 ohms, 2 ohms (2dB/vertical div., right channel dashed).

https://www.stereophile.com/content/prima-luna-prologue-one-integrated-amplifier-measurements

And here is what the modified Kantor dummy load looks like:

Modified Kantor speaker simulator, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

https://www.stereophile.com/content/real-life-measurements-page-2

 

[tuga]

I would not be too perturbed by the difficulty in driving these speakers. They will run your amplifier at a much lower power output for LOUD music and have less distortion. But remember, Enjoy The Music, which is not an academic exercise.

You are missing the point here, which is that the combination of a Prima Luna with the Fortes will result in a messed up response, regardless of how you feel about how that sounds.

All I said is that this would happen and that it would be wise for @JimFin to listen before diving. Were he to use an amplifier with low output impedance (audiophiles might prefer a high "damping factor") then the issue would not take place.

The fact that would not be too perturbed by the difficulty in driving these speakers only attests to your lack of knowledge.

 

[tuga]

Yes, it’s gets very boring. Many people have found measurements don’t give them the best sound. Practical experience is important.

There's no doubt about that. I only raised an issue that is real, but may or may not matter or sound bad to the person who asked the question.

In fact I said that practical experience would be very important in this instance.

 

[George 47]

The fact that would not be too perturbed by the difficulty in driving these speakers only attests to your lack of knowledge.

Ric, My knowledge is good and I know how the amp and speakers will interact, thank you. The S6 has a similar output impedance and the phase angle is not dissimilar. No problem in driving these speakers to very loud levels without too much alteration of the frequency response. A bit of real experience is far better than a bucket-load of theory.

And as you quoted the Stereophile review here is Ken Micallef's views using his Shindo SET valves (with a worse output impedance) : Good friend and hi-fi guru Steve Cohen visited not long after the Klipsch/Shindo pairing was in place, and we sat and listened in silence to this mighty system: Good sound, good friends, and good music make for joyful living.

His views and mine are not unique. Both of us used the speakers for the purpose which they were made, to play music.

 

[tuga]

Ric, My knowledge is good and I know how the amp and speakers will interact, thank you. The S6 has a similar output impedance and the phase angle is not dissimilar. No problem in driving these speakers to very loud levels without too much alteration of the frequency response. A bit of real experience is far better than a bucket-load of theory.

And as you quoted the Stereophile review here is Ken Micallef's views using his Shindo SET valves (with a worse output impedance) : Good friend and hi-fi guru Steve Cohen visited not long after the Klipsch/Shindo pairing was in place, and we sat and listened in silence to this mighty system: Good sound, good friends, and good music make for joyful living.

His views and mine are not unique. Both of us used the speakers for the purpose which they were made, to play music.

So you know about impedance interaction. Would you say that the theory doesn't matter if we were discussing cartridge loads? Compatibility between a pream and a power amplifier? And you know that there wasn't "too much alteration of the frequency response" because you measured the response? And how much is "not too much"?

The "it's all about the music" cliché is but a lame justification or excuse. I can enjoy an amazing listening experience playing music in the car or on my old iMac's internal speakers.

People like what they like. Reviewers praise.

 

[rabski]

The "it's all about the music" cliché is but a lame justification or excuse.

No. It really, really isn't.

 

[garn63]

Saw what was coming earlier...and refrained from posting. It was some ones "problem" with their "taste" & that they don't know the "facts".  Sometimes it's just not very nice...and indeed usually happens when the thread is quiet. 

* Its  & cowardly.

 

[tuga]

No. It really, really isn't.

If it weren't we'd all be listening to the same system and good sound would be universal.

 

[tuga]

This issue has been discussed many times before:

Looking at the impedance curve of the XT8F (I expect that of the XT6F to be similar) I would be careful (even avoid) partnering it with valve amplifiers, particularly ones with high output impedance such as Line Magnetic or Prima Luna models; it's likely that the combined sound will be somewhat to very "bright".

In any case, do try before buying.

Impedance interaction:

Questions of Impedance Interaction

Heavy Load: How Loudspeakers Torture Amplifiers

Real-Life Measurements

.

See the wiggly black line in the frequency response below (coloured graph)?

That's the effect of the modded Kantor speaker load (black & white graph) on the combined response, which follows the speaker's impedance trace.



The output impedance varied slightly with frequency and load impedance, but was approximately one-quarter the nominal value of each output-transformer tap: 3.8 ohms (16 ohm tap), 2 ohms (8 ohm tap), and 1.1 ohms (4 ohm tap).

These impedances are relatively low for a single-ended-triode amplifier. As a result, the modification of the LM-518IA's frequency response due to the Ohm's law interaction between this impedance and that of our standard simulated loudspeaker remained within limits of ±0.8dB (4 ohm tap), ±1.2dB (8 ohm tap; fig.1, gray trace), and ±2.1dB (16 ohm tap). The traces in fig.1 were taken with the volume control set to its maximum—note the excellent channel matching, which was preserved at lower settings of the control.

https://www.stereophile.com/content/line-magnetic-audio-lm-518ia-integrated-amplifier-measurements

.

This is from the XT8F:



https://hometheaterhifi.com/reviews/speaker/floor-standing/tannoy-revolution-xt-8f-floor-standing-speakers-review/

Even @rabski agrees:

Yup, and sensitivity is only part of speaker matching. The drop to a couple of ohms would be fine with almost any valve amp. The rise to 40 ohms and above is a very different matter. Not the end of the world, but with a lot of valve amps, that's an excellent way to get a really uneven frequency response. Mind you, that'd be 'interesting' with some sooid state as well. It's definitely not what Id' call a benign impedance curve.

 

[StingRay]

There's no doubt about that. I only raised an issue that is real, but may or may not matter or sound bad to the person who asked the question.

In fact I said that practical experience would be very important in this instance.

So why are you dismissing George’s experience and telling him he lacks knowledge?

 

[tuga]

So why are you dismissing George’s experience and telling him he lacks knowledge?

His experience is personal. You and I may agree with his perceived impression or not. It is a matter of taste. And making this a rule is plain wrong/misleading.

He may like the result but the effect of impedance interaction with high output-impedance amplifiers is an undeniable fact and will be audible (I would expect to most descriminating people) and may not please others as it does him. So he either lacks knowledge or prefers to ignore the facts.

But I still don't understand all the animosity when all I did was to point out that the impedance interaction would be an issue and that I would recommend extra care when listening.

Or I do; some people like the result and get upset if one points out that such combination will impact the tonal balance in a negative way.

 

[StingRay]

His experience is personal. You and I may agree with his perceived impression or not. It is a matter of taste. And making this a rule is plain wrong/misleading.

He may like the result but the effect of impedance interaction with high output-impedance amplifiers is an undeniable fact and will be audible (I would expect to most descriminating people) and may not please others as it does him. So he either lacks knowledge or prefers to ignore the facts.

But I still don't understand all the animosity when all I did was to point out that the impedance interaction would be an issue and that I would recommend extra care when listening.

Or I do; some people like the result and get upset if one points out that such combination will impact the tonal balance in a negative way.

But have you heard them?

Im not saying he is right because I have not heard them. You seem to be contracting yourself.

 Seems many users are not having issues.

 

[tuga]

But have you heard them?

Im not saying he is right because I have not heard them. You seem to be contracting yourself.

 Seems many users are not having issues.

Any users matching low "damping-factor" amps with these speakers will have "issues" (messed up frequency response).

But they may actually enjoy that, or might not be able to identify those issues. But the issues are real and audible.

That is why I told the person asking the question:

Are you able to try before buying? They're not the easiest of speakers to drive:

https://www.stereophile.com/content/klipsch-forte-iii-loudspeaker-measurements

.

Edit: I see you own a Prima Luna so definitely not the best of matches.

I didn't tell he wouldn't like the sound, or that it would sound bad to him. I didn't tell him it wasn't worth listening either.

(even if, personally, I wouldn't find it worth listening)

 

[StingRay]

Any users matching low "damping-factor" amps with these speakers will have "issues" (messed up frequency response).

But they may actually enjoy that, or might not be able to identify those issues. But the issues are real and audible.

That is why I told the person asking the question:

I didn't tell he wouldn't like the sound, or that it would sound bad to him. I didn't tell him it wasn't worth listening either.

(even if, personally, I wouldn't find it worth listening)

But others have heard them and not found an issues, so you dismiss them as not knowing what they are talking about. 
 

What amp do you suggest would be the most suitable?

 

[tuga]

But others have heard them and not found an issues, so you dismiss them as not knowing what they are talking about.

Most people assess sound according to whether or not they like the result. And many audiophiles and reviewers are unable to identify shortcomings and/or to judge them in a neutral manner (not biased by their own preference/taste).

In this video (made at the RMAF2015 show) you can see an Audio Precision engineer testing the audiophile audience's capability to hear distortion; only a few raise their hand when the level is low.

What amp do you suggest would be the most suitable?

Any amp with low output impedance would be suitable. Perhaps one with low power considering that the speaker is highly sensitive.

That doesn't mean it would sound better to you.

 

[StingRay]

I looked on the Klispsch forum and several people are extremely happy with the Forte 3s and the PrimaLuna Evo 400.

Others are running them on low power tube amps with good results. 
Is it not the result that matters and how much you enjoy the music?

 

[rdale]

I looked on the Klispsch forum and several people are extremely happy with the Forte 3s and the PrimaLuna Evo 400.

Others are running them on low power tube amps with good results. 
Is not the result that matters and how much you enjoy the music?

I even found a discussion on the Klipsch forum about whether damping factor matters:

https://community.klipsch.com/index.php?/topic/200570-does-damping-factor-matter/
 

At the end someone pastes an old newspaper article by Paul Klipsch in 1956, which starts:

”Speaker systems employing adequate acoustic loading do not need additional damping in the amplifier..”

 

[George 47]

His experience is personal. You and I may agree with his perceived impression or not. It is a matter of taste. And making this a rule is plain wrong/misleading.

He may like the result but the effect of impedance interaction with high output-impedance amplifiers is an undeniable fact and will be audible (I would expect to most descriminating people) and may not please others as it does him. So he either lacks knowledge or prefers to ignore the facts.

But I still don't understand all the animosity when all I did was to point out that the impedance interaction would be an issue and that I would recommend extra care when listening.

Or I do; some people like the result and get upset if one points out that such combination will impact the tonal balance in a negative way.

I was going to leave this alone before it goes into the same circles as before (Bartok) or ends up in insults. The OP has got your and my views, and as an intelligent individual I am sure he can arrive at his own conclusion. If he needs more assistance, I am sure he can ask.

Can I assure you, I have the knowledge and experience of the theory to know about speaker/amplifier interactions? Yes, I have read about those interactions and I am aware of the work reported by Benjamin, Atkinson, Howard and the Kef engineer comments on Class A, A/b and D amplifiers. 

I am not ignoring anything, but we listen to complete systems and the interactions can be complex. Focusing on one interaction that does make a difference, and putting someone off from using his valve amplifier, and steering him towards a SS transistor amplifier (with a much lower EPDR) without ever listening, may be doing him a disservice.

Obviously, listening to the two together would be ideal but may not be possible.