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In Reply to: RE: Magnepan LRS posted by pictureguy on February 21, 2021 at 11:07:36
A bridged amp can seldom be used with a low impedance speaker. It is usually an either\or kind of thing.
"low impedance" meaning less than 4 ohms? I don't know how to characterize the combined M/T portion of the Tympani IV-A. IIRC their ribbon tweeters alone are 3 ohms. Before buying the Brystons I presently use, I had zero difficulty driving the entire speaker, M/T plus their bass panels using the bridged Adcom GFA-555 (original release, assembled in NJ). Back in the day, ~25 years ago I admittedly was a loudness freak. Nothing bothered the bridged Adcoms, the Tympani, me, or caused blown fuses, not even the (original) CD release of Telarc's 1812 cannons. (Before using IV-As I had Tympani 1Cs and I did set one GFA-555 on fire going up with a flame and smoke, appropriately by the 1812 cannons, however my loudness days are long gone, but something in me misses them. OTOH I have always enjoyed listening to Beethoven's chamber music and continue to do so.)
"IotaVX stack in Bridge mode. 50W (8Ω, 2 channels), 100W (8Ω, 1 channel bridged)100W (4Ω, 2 channels), 180W (4Ω, 1 channel bridged)"
You might want to find the Telarc of 'Wellingtons Victory'.......a piece originally scored for some kind of machine somebody was building.
But the Telarc recording has LOTS of what may be 12 pounders and even more musket fire......
Too much is never enough
True with RARE exception.
the complaints I'm aware of deal with quality of sound which is apparently lacking in a bridged amp.
From what I've seen, Especially with certain listeners, they vastly over estimate how much power they need.
Even my very Low sensitivty panels probably don't use more than 4 or 5 continueous with 10x peaks even when I'm trying to annoy the neighbors. I could probably be happy with my Aspirational amp, the Pass Labs.....XA30.5 which has nearly 6db headroom against the rating.
It cracks me up when somebody had 95db sensitive speakers and 'needs' 600 watts. Makes little or no sense, especially from a 'system' viewpoint.
Too much is never enough
"... It cracks me up when somebody had 95db sensitive speakers and 'needs' 600 watts. Makes little or no sense, especially from a 'system' viewpoint. ..."
FWIW, when you take 10dB off the top for FIR filters, that 600wpc amp becomes a 60wpc amp or conversely that 95dB efficient speaker becomes 85dB efficient.
Another point to consider is running the amp within its comfort/lowest noise zone. Amps are not linear in their noise/power/frequency profiles.
Not to mention needing to change amps every time you change speakers, so speaking from a system and longevity prospective, it does make sense.
How did FIR filters get into this?
My panels are low 80s sensitive and I just was looking at Klipsch speakers which THEY call 99db sensitive but Stereophile calls > 96db.....Magnpan makes some claim but at 2 watts / 2.83v not the 4 ohm requirement for same 1 watt.
You lost me with the filter thing.....Though I'm used to the 10db / 10x calculation. If my panels were 10db LOWER in sensitivity OR my amps 10db lower in output? I'd be running nearly at redline when turned 'up' on a weekend afternoon...
And I've seen plenty of power / distortion curves @stereophile. Starts at some low level at miniscule power than slopes lower until hitting a null than more sharply upward to amp power limit....Call it 1%, just for the sake of discussion. That may play into 'needed' power for a given speaker in some way.
But it would also seem that distortion is either inaudible or of vanishingly Low audibility run below amp clipping, IF you agree 1% is a reasonable upper limit.
Link to the MiniDSP 'mini' article on FIR vs IIR Filters. All done or CAN be done in the digital domain which starts me asking more questions.
Too much is never enough
"... How did FIR filters get into this? ..."
Digital speaker and room correction is not uncommon (DEQX has been around for 2 decades) and PC audio has embraced it for quite a while.
I started with Klipsch, 101dB/1 watt/1 meter before going to Maggies. Had to buy stronger amps.
Started with 1.6's, then went to 3.6's. Had to buy stronger amps, AGAIN, then to 20.1's.
If you are familiar with making digital speaker and room correction filters, you will know many use the "cuts-only" method to avoid clipping. The cuts-only method can easily exceed 10dB attenuation to do speaker and room correction. That means your output is 10dB lower (unless you have special premamp hardware to compensate for this and drive your amp(s) accordingly, read: certain pro-gear with more than 4V output).
Thanks for explanation. I was worried for a second until you went for the 'DIRAC solution....
I'm not doing any form of speaker correction.
If you want to REALLY get an eye / ear full? Go to Emotiva Lounge and find the DIRAC thread which is not up to OVER 150 pages. Have a bottle of Aspirin handy!
I did metrology for a living for years. And can assure anyone that the devil in DIRAC and similar sytems is repeataility of measurments. Doing it a different way than you did today is a recipe for confusion and disaster. Those on the DIRAC thread on EMO webiste are really in a state.
For example? Some settings of LFE would appear to apply a 10db BOOST to those frequencies. Some people are hung-up on what I'd consider (for music) massive SubWoofer Overkill.
I get it going from 101db speakers to something in mid / low 80s. Makes PERFECT sense. I have 1.6s and find a PAIR of Parasound A23 suit me fine.....One per speaker but NOT yet an active crossover. So while I am passively biamping, i do NOT get the full and potential 3db benefit were I o go full ACTIVE.
Without all the electronic aids I could EASILY see needing more than 10x the power when going from highly sensitive KLIPSCH to Maggies!
Too much is never enough
I started with an old DEQX unit, still have it. I have ARC DRC in my Anthem Statement D2V Pre/Pro but never liked what it did so completely disabled it.
DIRAC has a PC software version that I have not tried, nor their embedded versions.
MarcL uses DIRAC for full blown home theater to good effect. I have seen his REW plots and his D50 clarity ratings are exemplary.
I have tried the Audiolense XO demo, but can't get consistent delay measurements with it on my PC. If I am going to use something for time and phase alignments, I need it to create consistent repeatable results.
I am using REW and RePhase. I get much better consistency/repeatable measurements with REW. I am also experimenting with REW on Realtime Linux to see if handles timing latencies better than Windows (with respect to measurements and playback).
emailtim, what version of Linux you running, I'm using Mint Cinnamon 17.3 and 19.2 Thanks
I am testing Debian (10) Buster with the latest 5.9 buster-backports vanilla and realtime kernels on an Intel Atom D525 and i7-3770K.
Kernel 5.10 hasn't been back-ported yet debian-buster.
I am also using the RedHat "tuned-adm" profile package, lightweight display manager and XFCE4 desktop, JRMC 26 and REW via ALSA direct to hardware.
Here are some of the latencies I have measured using cyclictest during 2 channel playback (X-axis is in microseconds).
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