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Post by leonski on Sept 5, 2021 0:34:05 GMT -5
Mr. Deleted
I am SO glad you provided the impedance curve for your speakers. But you missed an additional bit which is VERY important.
Above the impedance curve line is the PHASE data. That's the line in TEAL BLUE.
And at the impedance minima? Phase appears to be very 'benign' at about Zero to maybe Negative 15 degrees. This is a 'no problem'
zone and any competent amp should handle this without heartburn.
Problems occur when you have an impedance DIP to a very low level AND a very high phase angle....either positive or negative. One of which
will be capacitive the other inductive. Don't ask me which!
The phase dip at about 60hz is associated with a reasonable impedance, so no worries.
And donh, above is both right and wrong. while you'd HOPE a bridged amp would be 2x the power at 8 ohms.....4ohms to the amp, that ain't always the case. I had the older (now) ROTEL RB1070.
They called it I think 135x2 at 8 ohms. And I think (IIRC) It was about 360 bridged. That would imply 180x2 @ 4ohms......But OH was this amp a stinker. Simply incapable of driving my low sensitivity panels properly.
And back to Deleted? Crossovers are certianly NOT brick walls so lots of overlap. 24db / octave I'd surmise has the LEAST such overlap and 6db / octave the most. If you knew the crossover frequency and slope, I'd think with some
Log/Log graph paper you coudl APPROXIMATE what it'd look like......At least electrically. Add driver 'natural' rolloff, which us consumers generally don't have access to..
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Post by donh50 on Sept 6, 2021 10:12:30 GMT -5
Positive phase is inductive, negative phase is capacitive.
The word "should" is important in my post on bridging. Theoretically an amp should quadruple power when bridged; in practice 2x to 3x is more typical due to other limitations like power supply, thermal management, etc.
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Post by routlaw on Sept 6, 2021 10:54:39 GMT -5
FWIW in the conversation I have been running the DR-1's on my Genesis 6.1 speakers for over a year and a half now, the the DR-3 on my Genesis center and surrounds for the same period. While these speakers do not measure well due to impedance dips below 2 ohms the reviews of them were a different matter altogether. These amps driving these speakers do not sound the least bit harsh IMO, and others who have heard the system concur. The amps never get hot and in fact are barely warm no matter how hard they are driven. Attaching a quote below from the Sound and Vision review.
Hope this helps.
"While the measurements of the Genesis 6.1 and G6.1c are not the most impressive we've seen, the results of SS's listening tests command attention. For a discussion of the pros and cons of listening vs. measurements, I can do no better than direct the reader to John Atkinson's "As We See It" editorial in the January 2004 issue of our sister publication, Stereophile, which crossed my desk just as I was writing this.
My main concern with both of these speakers is their difficult impedance—the lowest I can recall ever measuring for SGHT. Only an amplifier comfortable with driving loads down to 2ohms—and even slightly lower—need apply. This system will be extremely sensitive to the electronics in front of it, not only because it is inherently revealing, but also because it challenges the amp's power-delivery capabilities. This is relieved only slightly by the fact that the G6.1's bass is handled by its onboard subwoofer, thus relieving the amp of the power-sapping bass chores in the left and right channels—and perhaps the center as well, if you designate the G6.1c as Small in setup.—Thomas J. Norton"
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Post by leonski on Sept 6, 2021 17:21:57 GMT -5
Positive phase is inductive, negative phase is capacitive. The word "should" is important in my post on bridging. Theoretically an amp should quadruple power when bridged; in practice 2x to 3x is more typical due to other limitations like power supply, thermal management, etc. That pesky Theory and Practice are ALWAYS butting heads. I'll probably not remember positive from negative phase, but glad SOMEBODY knows! |
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Post by leonski on Sept 6, 2021 17:25:58 GMT -5
FWIW in the conversation I have been running the DR-1's on my Genesis 6.1 speakers for over a year and a half now, the the DR-3 on my Genesis center and surrounds for the same period. While these speakers do not measure well due to impedance dips below 2 ohms the reviews of them were a different matter altogether. These amps driving these speakers do not sound the least bit harsh IMO, and others who have heard the system concur. The amps never get hot and in fact are barely warm no matter how hard they are driven. Attaching a quote below from the Sound and Vision review. Hope this helps. "While the measurements of the Genesis 6.1 and G6.1c are not the most impressive we've seen, the results of SS's listening tests command attention. For a discussion of the pros and cons of listening vs. measurements, I can do no better than direct the reader to John Atkinson's "As We See It" editorial in the January 2004 issue of our sister publication, Stereophile, which crossed my desk just as I was writing this. My main concern with both of these speakers is their difficult impedance—the lowest I can recall ever measuring for SGHT. Only an amplifier comfortable with driving loads down to 2ohms—and even slightly lower—need apply. This system will be extremely sensitive to the electronics in front of it, not only because it is inherently revealing, but also because it challenges the amp's power-delivery capabilities. This is relieved only slightly by the fact that the G6.1's bass is handled by its onboard subwoofer, thus relieving the amp of the power-sapping bass chores in the left and right channels—and perhaps the center as well, if you designate the G6.1c as Small in setup.—Thomas J. Norton" I'd need to see the measured data. Your quote from the reviewer does not mention frequency at which the minima occurs OR the phase data of the speaker at that frequency. If by CHANCE the speaker were very close to pure resistive at 2 ohms AND at 5hhz or higher? Yawn. But that same 2 ohms at 50hz with 45degree phase angle is another matter altogether. And would be quite a job for all but the best amps. Here is stereophile measured data from the 5.2 model. This is a MONSTER for most amps and demands some very good electrical performance. If the 6.1 follows this pattern, AND the DR-1s can take it? 'More Power To You'.....is the expression..... www.stereophile.com/content/genesis-advanced-technologies-52-loudspeaker-measurements |
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Post by routlaw on Sept 6, 2021 18:04:52 GMT -5
leonski they did quote the frequency where the impedance dip was but don't remember and you're right it was not in the text I quoted. However if you are curious enough just google the 6.1 for reviews and it should pop right up. They posted graphs of the measured results too. I just didn't want to dig too deep into this technically but rather to state the DR series of amps from my perspective have no trouble with low impedance loads. Thanks
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Post by DavidR on Sept 6, 2021 18:49:29 GMT -5
 What amp is game? |
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Post by donh50 on Sept 6, 2021 22:24:48 GMT -5
Just post the graph for an original Apogee Scintilla...
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Post by leonski on Sept 6, 2021 22:43:33 GMT -5
Just post the graph for an original Apogee Scintilla... The ONE OHM version may be the worst speaker ever.....in that regard. FEW amps could handle it. One good amp was an earlier KRELL....one of the KSA series? I have no idea of the phase data for that particular speaker... Here is a link to the Audiograph system. It is used to measure amplifiers and uses various resistive loads in combination with both inductive AND capacitive loads to 60 degrees. This will characterize an amplifer into these loads which are increasingly normal.....except, perhaps in the HT space where amps are notoriously feeble AND speakers undemanding. www.audiograph.se/wp-content/uploads/2018/10/PowerCube_12p_brochure_complete.pdfI've had discussions with people about a speaker Dummy Load to be used for amplifier testing and get NOWHERE. Too much BS and vested interest in selling 'power' based on a resistive load...which has little to do with a real speaker. Everyone selling amps seems to support the 'difficult speaker' myth. Some ARE and some AREN'T. The downside? Good performance in this measurable is NO guarantee of good sound, while it could be argued that a POOR result means a speaker / amp combo WILL have problems. Especially at higher levels. |
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Post by DavidR on Sept 7, 2021 9:27:28 GMT -5
Just post the graph for an original Apogee Scintilla... Here it is  |
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Post by leonski on Sept 7, 2021 15:52:05 GMT -5
Horrible Mesured Results. Just AWFUL. The only Possible good news in that mess? The highest phase angle is near a higher (what a laugh) impedance
at around 4khz. Other than that?
When I bought my Magnpans in the 70s......I was at a buddy' house. He and his brother were VERY good at this stuff and built some of their own gear.
Including a modified SOTA TT. They demo'd the Maggies which I bought. I was Gobsmacked. But they hooked up a pair of what may have been
Electrostats to thier amplifier. When they pressed 'go' the amp emitted a small 'chirp' and that was IT. Better luck next time.
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Post by donh50 on Sept 7, 2021 16:55:30 GMT -5
ESLs tend to have very low impedance at high frequency (e.g. the latest Martin Logan 15A is ~0.5 ohms at 20 kHz) and, while required power is usually very low, if the amp is not stable it will oscillate itself into oblivion very quickly.
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Post by leonski on Sept 7, 2021 17:11:12 GMT -5
ESLs tend to have very low impedance at high frequency (e.g. the latest Martin Logan 15A is ~0.5 ohms at 20 kHz) and, while required power is usually very low, if the amp is not stable it will oscillate itself into oblivion very quickly. ESLs ALSO tend to capactive at those higher freuquencies......And yes, for sure, the low power requirement helps a LOT.... |
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Post by leonski on Nov 5, 2021 13:57:02 GMT -5
But the CJ5 in bridged mode can only handle an 8 ohm load. Says so right on the back of the amp. So 4 ohm speakers are out. Most likely it doubles. And all this time I thought a CJ5 was a Jeep model. I addressed this bro in my response. I'm inquiring w/ Tekton at the moment as to whether the internal speakers can be rewired utilizing the same speakers for 8 ohm cabinets. This will ultimately decide my upgrade path. Mind you the Tektons are actually 2.3 ohms at around 100hz. At that point I'm speculating that there's a hand off from 2 12" subs to 4 7" drivers..... All of which are 4 ohm speakers in each 21 driver cabinet. You may find that it is not the impedance that is the main drive behind the differences in sound. But rather the PHASE at frequencies where the impedance is lowest. I can't read the graphic you posted, but if You Can? Good on 'ya. If the phase is 45degrees or higher at anything below maybe 3 ohms? Amp is apparently not happy..... |
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