|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
In Reply to: Re: Euphonic Compression posted by RandyB on November 13, 2002 at 16:32:56:
That glare is system. Not the drivers. 99% of all speakers with crossovers hide this anomalie. High efficiency designs convey it. It's either a tube or wire, possibly combinations. The speaker driver is far less capable of creating glare on it's own than an amplifier. Magnet wire is easily had at Radio Shack for $3.99 for 3 sizes. Long crystal and enamel coated it is the basic ingredient for experimentation.This is why Directly heated triodes work best with high efficency. Tube circuits, especially push pull and hybrids etc. are prone to emphasising this upper midrange/treble resonance. SET's with Direct Heating have no resistors and capacitors in output stages and instead use chokes and transformers to couple the signal, far better tonality is the result.
Try some of the smallest magnet wire in the ratshack 3 pack for speaker wire. It does help "damp" some of the ringing. But damping and filtering are working in the wrong direction ultimately. The actual source of the problem lies not in the speakers driver but in the system IMHO. If damping electrically is needed, plain wire, either as a transfer function from amp to speaker or as a component of the speaker in the form of coil or tranny works better than splitting the signal into smithreens with ceramic or semiconductor. Follow link for introduction to Direct Heating. TC
Follow Ups:
Hi, TC:Thanks for the info on magnet wire, I'll get some and check it out this week . ...
I'm using DHT's now, PX25 and 300B SET amps, along with a Technics 100 wpc AV receiver (to check compatibility with SS mid-fi amps), Hafler 9505 200 watt mosfet, Shearne Audio 100 wpc dual-mono amp, and I'm hearing similar glare on all of these on maybe 1-2% of loudest transient peaks on my prototype high-efficiency speakers. I don't hear glare on less efficient commercial speakers being used for comparisons, Aerial Acoustic 10T's, various Reynaud models, various Westlake models, Heybrook 2000 series. I also don't hear the glare on various Loth-X high-efficiency models, Ion 1, Ion 2, Ion 3, and Ion 4.
I don't hear any glare or harsh peaks on any of the woofers I'm using, i.e., Eminence Alpha 6, Alpha 8, Beta 8, Beta 8cx, Beta 10cx, PHL 1240, 2460, 3451, and 3020.
The HF units I am using are Peerless dome tweeter with 1" waveguid (forget which model), Eminence APT 50 phenolic compression driver, Morel HD 37, and Raven 1 and 2 ribbon tweeters. I'm using first order xo's on on all but the Ravens, which have 3rd order (to provide steep enough slope per operating specs).
If I don't crank up the volume quite as loud as my preferred level, I don't hear the glare, only when I crank it up to realistic SPL's so that the woofer output is at what I feel is realistic levels . . .
Could it be that the tweeters are just too efficient relative to the woofers, that I need to add an l-pad or resistive attenuation on the tweeters? I'm going to try out some zener diodes to limit the loudest transient peaks to see if this resolves the tweeter glare, I don't know what the effect will be on overall sound quality with the zeners, I've never used them before . . .
Best regards, rdb :-)
Might be zobel/notch filter time for your crossover strategy. TC
Hi, TC:Thanks for the Zobel / notch filter ideas . ..
When I started this project, I was just going to use a cap on the tweeter, let the woofers run full range . . .. design creep has added attenuating resistors on the tweeter, a coil on the woofers, 3rd order for the Ravens, possibly zener diodes, now I'm considering Zobel and notch filter . . . . Maybe I'll call the final design "Topsy", it just grew . . . . . .
Your still here? You reveal more of your project every post which is helpful since
I don't know you. :) I would have presumed the Zobel was all ready in place.
That would have been my second move. The first being SPL check for HF beaming
which is obvious at higher volumes. I know the Alpha 6 tends to have a rising response
and will beam around 4k. It also needs a Zobel to stabilize it.
A recessed dome has beaming written all over it. :).
I found this very annoying with near field listening. In my own design, I prefer the slot dispersion
like a Selenium 320 for near field, with a carefully calculated Zobel, will have smooth Hi
end no matter how loud it is. Then issues of electrical phasing and step baffle come next.
The people over at HI Efficiency Asylum and PI forum deal with this all the time. Maybe
post there since this is the rant forum so far :) Later, Art
Hi, Art:I have been posting on Hi-Efficiency forum in the beginning stages, now I'm down to the 2nd and 3d order design issues, the basic designs are completed and I'm refining things, so I thought I'd see what the Propeller Heads think about a few issues, to get a fresh take on things . ...
Euphonic compression is used by several tube amplifier manufacturers to produce a "retro" sound, I was interested in finding out if I could put in just a little compression to get a "fat" sound, with the added benefit of maintaining a flat frequency response between the woofer and tweeter on the 1-2% of the loudest transient peaks.
I didn't want to use Zobels in this project, since these loudspeakers are designed to be used with flea-powered tube amps (and ss up to 100 watt rms), and I want to minimize power loss in the crossover. I originally wanted to use just a cap on the tweeter, and let the woofers run full range, but high frequency cone breakup and too much overlap forced me to add a coil on the woofers . .. I'm concerned that if I add a Zobel, it will suck too much life out of the few watts available on the lowest-powered SET amps, like 2A3, 300B, PX25, for example.
Hello Randy, I found that the Zobel is very much needed in hi efficiency just to
stabilize the impedance so the x-over can operate properly. Its like taming the beast.
hi efficiency is the only way to go in my opinion but the raw drivers are a bit ruff and
need some tlc to integrate them with each other. The stabilized impedance I would see
as an advantage for low power set, because set seems vunerable to impedance shifts.
Just MHO. Others know more...
Hi, Art:Thanks for the info re Zobel benefits, I'll definitely include Zobel topologies in the iterative design process, see if it leaves enough "life" with flea-powered amps . .. and how it improves driver integration and overall presentation . ... could be a desirable trade-off, fer sher!
If anyone out there has used a Zobel with flea-powered amps, please let me know results, if this can be done without making things too "polite", and if so, best practices for implementation . ..
This post is made possible by the generous support of people like you and our sponsors: