Some thoughts on ASR and the reviews
I’ve briefly taken a look at some online reviews for budget Tekton speakers from ASR and Youtube. Both are based on Klippel quasi-anechoic measurements to achieve "in-room" simulations.
As an amateur speaker designer, and lover of graphs and data I have some thoughts. I mostly hope this helps the entire A’gon community get a little more perspective into how a speaker builder would think about the data.
Of course, I’ve only skimmed the data I’ve seen, I’m no expert, and have no eyes or ears on actual Tekton speakers. Please take this as purely an academic exercise based on limited and incomplete knowledge.
1. Speaker pricing.
One ASR review spends an amazing amount of time and effort analyzing the ~$800 US Tekton M-Lore. That price compares very favorably with a full Seas A26 kit from Madisound, around $1,700. I mean, not sure these inexpensive speakers deserve quite the nit-picking done here.
2. Measuring mid-woofers is hard.
The standard practice for analyzing speakers is called "quasi-anechoic." That is, we pretend to do so in a room free of reflections or boundaries. You do this with very close measurements (within 1/2") of the components, blended together. There are a couple of ways this can be incomplete though.
a - Midwoofers measure much worse this way than in a truly anechoic room. The 7" Scanspeak Revelators are good examples of this. The close mic response is deceptively bad but the 1m in-room measurements smooth out a lot of problems. If you took the close-mic measurements (as seen in the spec sheet) as correct you’d make the wrong crossover.
b - Baffle step - As popularized and researched by the late, great Jeff Bagby, the effects of the baffle on the output need to be included in any whole speaker/room simulation, which of course also means the speaker should have this built in when it is not a near-wall speaker. I don’t know enough about the Klippel simulation, but if this is not included you’ll get a bass-lite expereinced compared to real life. The effects of baffle compensation is to have more bass, but an overall lower sensitivity rating.
For both of those reasons, an actual in-room measurement is critical to assessing actual speaker behavior. We may not all have the same room, but this is a great way to see the actual mid-woofer response as well as the effects of any baffle step compensation.
Looking at the quasi anechoic measurements done by ASR and Erin it _seems_ that these speakers are not compensated, which may be OK if close-wall placement is expected.
In either event, you really want to see the actual in-room response, not just the simulated response before passing judgement. If I had to critique based strictly on the measurements and simulations, I’d 100% wonder if a better design wouldn’t be to trade sensitivity for more bass, and the in-room response would tell me that.
3. Crossover point and dispersion
One of the most important choices a speaker designer has is picking the -3 or -6 dB point for the high and low pass filters. A lot of things have to be balanced and traded off, including cost of crossover parts.
Both of the reviews, above, seem to imply a crossover point that is too high for a smooth transition from the woofer to the tweeters. No speaker can avoid rolling off the treble as you go off-axis, but the best at this do so very evenly. This gives the best off-axis performance and offers up great imaging and wide sweet spots. You’d think this was a budget speaker problem, but it is not. Look at reviews for B&W’s D series speakers, and many Focal models as examples of expensive, well received speakers that don’t excel at this.
Speakers which DO typically excel here include Revel and Magico. This is by no means a story that you should buy Revel because B&W sucks, at all. Buy what you like. I’m just pointing out that this limited dispersion problem is not at all unique to Tekton. And in fact many other Tekton speakers don’t suffer this particular set of challenges.
In the case of the M-Lore, the tweeter has really amazingly good dynamic range. If I was the designer I’d definitely want to ask if I could lower the crossover 1 kHz, which would give up a little power handling but improve the off-axis response. One big reason not to is crossover costs. I may have to add more parts to flatten the tweeter response well enough to extend it's useful range. In other words, a higher crossover point may hide tweeter deficiencies. Again, Tekton is NOT alone if they did this calculus.
I’ve probably made a lot of omissions here, but I hope this helps readers think about speaker performance and costs in a more complete manner. The listening tests always matter more than the measurements, so finding reviewers with trustworthy ears is really more important than taste-makers who let the tools, which may not be properly used, judge the experience.
Except that "basic engineering" says there should be a difference. Your background is not electrical engineering so you wouldn't understand.
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I think you measured using a single frequency at steady state response at one 1KHz. It might not reveal the affectiveness or deficiencess of the power plant. It is not even close to being adequate. A better test would be using a square wave input then look at how the output follows the input square wave with different load - using high current and low current load. This would be a more difficult test than steady state. Also make sure the partner amp that you’re using for the test is not the limiting factor. An outlaw amp probably is not really a good candidate. You probably need a better amp. I think the flaw of most of your testing is because they are done in the frequency domain.
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The input signal may be in time domain, but the analysis is done in frequency domain and the graph you show only shows steady state response. No transient information. But it’s in the transient that truely show the performance with different loads. You also need to test with different loads as well. May be at 2ohm, 4ohm to show the current capability of the amp. If the P12 does what PS audio said, I think you will see it in the transient response.
No the square wave will test for transient condition. It is like a step response to test how the amp can deliver the current. You can make the square wave period long enough so wait out any ringing or steady state settling time.
You don’t have to worry about that. A real world square wave will have finite rise and fall time. Music is not a sine wave or multiple of frequency sweep either but you use it for your testing.
As for measuring output impedance, what you did might not be adequate and I think you might have taken the short cut. In order to really test for it you have to: 1. Measure the PS12 output with no load. 2. Use a spectrum analyzer to measure the amplitude at several frequency since the output is not a pure sine wave. 3. Now connect the output to different load such as 2ohm, 4ohm, .... or more. 4. Then measure again the output spectrum again with the loads connected. The output amplitude now will be slightly lower due to the finite output impedance of the unit. 5. With those information, you can use a simple equation to calculate for the output impedance. That’s the only accurate way to measure. It’s a little bit more involvement and I am not sure you’re prepared or have the setup to do that.
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We are measuring output impedance. The spectrum analyzer measures the voltage amplitude for each frequency. Why do you need to introduce "time domain" here? If it is just DC voltage then you just need a Fluke voltage meter. But the output here comprises of multiple frequency that’s why you need a spectrum analyzer. Also I assume the load is mostly "real" and not "complex". If it is "complex" then it can be complicate as you need the phase as well. That is why I said this is not an easy test to do and you’re may not be prepared to perform it.
Then use a higher impedance load to reduce the current load. I was only using it as an example.
This is what the spec for the P12. You can use it to calculate how much current is appropriate. If the output is 120V then the max current is 1000VA/120V = 8.3A.
That is why I said it’s not simple test to measure and I don’t think you have a setup for it. You can reduce the wattage by using a square wave instead of a continuous output.
They all have to obey Ohm’s law. They all should have output impedance that can be measured. There is nothing special here except you’re dealing with very high voltage and current. That is why the test is not easy. You took the short cut.
That is just your conjecture. I don’t have data to back it up.
I am not saying you should use square wave to test for everything, but in this special case of testing a AC power regenerative, the square wave can tell you if the P12 does what is is supposed to do - that is delivering the current from a very low impedance source.
Then use a lower frequency for example 1KHz. Use just need to mimic a step response to see how the amp can produce a demand current. If you don’t like square wave, just use step response.
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Pass Lab second harmonic generator. Makes the sound more like tube. Some people like that. https://www.audioasylum.com/forums/amp/messages/24/244324.html |
