As far as I know, the BBC and a few UK manufacturers were the only ones using EQ back then. In the USA, it was all "Not Invented Here". My work at Audionics in the mid-Seventies were some of the first American speakers to use EQ and notch filters, but that was nothing new in the UK. It probably helped I'd been reading "Wireless World" back in Hong Kong in the Sixties, and was familiar with the writing of D.E.L. Shorter of the BBC.
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Back in the days of the old green Altec amplifiers you would probably be lucky to have seen a Longevin EQ, not much else was around that far back. Boy those were the days. matching transformers and tube amps.
My father is in the south end of Fort White. He works at O'leno state park. I lived there for awhile. Nice area.
Not sure they have. I followed some published designs to find that they did not work well for me at all. The crossovers I ended up using had to be designed from scratch.
Active is much easier and faster to get right. So a lot of people will tell you how much better it is than passive. It ain't necessarily so. A proper passive crossover can be just as good, maybe better. It's just takes more skill - or luck.
It might sound a little weird, but passive is partly a matter of "feel", of knowing where the driver wants to go. Some drivers don't respond well to equalization; they measure just fine, but sound worse than the non-equalized version. Sometimes it's a region of high IM distortion, sometimes narrowband resonances, sometimes it's just plain bad sound in a certain portion of the spectrum. EQ certainly doesn't fix everything; it all depends on the driver. Some are better choices than others.
Just to keep things interesting, driver vendors like to make subtle changes to drivers that might or might not be measurable, but are frequently audible. A revision to the crossover might offset the change, but it might not. That's when you're just SOL (a technical term widely used in the industry).
Just to keep things interesting, driver vendors like to make subtle changes to drivers that might or might not be measurable, but are frequently audible. A revision to the crossover might offset the change, but it might not. That's when you're just SOL (a technical term widely used in the industry).
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A theory on this is that while you can eq away a peak in the response curve, the eq will not remove any harmonics that hits the peak, and thus sticks out like a sore thumb...
Johan-Kr
Fenalaar,
You hit the nail on the head there. That is what is so often missed by those who think they can electrically solve a resonance problem in a device. Even cutting a sharp hole in the program material doesn't mean that a harmonic above or below that frequency won't mechanically excite the resonance you've cut from the frequency response. Sympathetic vibrations at double or half the frequency can do just that with their own harmonics. This phenomena is so overlooked or discounted but the physical functions of the device are hard to overcome by simple EQ means.
You hit the nail on the head there. That is what is so often missed by those who think they can electrically solve a resonance problem in a device. Even cutting a sharp hole in the program material doesn't mean that a harmonic above or below that frequency won't mechanically excite the resonance you've cut from the frequency response. Sympathetic vibrations at double or half the frequency can do just that with their own harmonics. This phenomena is so overlooked or discounted but the physical functions of the device are hard to overcome by simple EQ means.
The idea is to choose horn and driver combinations that are linear and have little resonance in their bandwith. A good horn system should only need contouring to bring the upper midrange down to the upper treble. It's been that way for decades. If the out of band is garbage use steep crossovers, notch filters or do the right thing and choose a better driver. I see there are many people here using the digital EQ and wonder how they deal with listening to their records? Maybe they should take their EQ house curve and add a reverse RIAA curve to enjoy LP's LOL
🙂 More than one way to skin a cat
That might be fun - do it in the tape loop of the preamp? Still need to load the cartridge properly - adjustable RIAA 😱
Yep/
The idea is to come into your soundcard A/D with linear gain after the cartridge. Apply the RIAA as a FIR or IIR filter. It can be done very precisely that way. And if needed, the response of the cartridge can easily be corrected by DSP. It's fun to play with.
The idea is to come into your soundcard A/D with linear gain after the cartridge. Apply the RIAA as a FIR or IIR filter. It can be done very precisely that way. And if needed, the response of the cartridge can easily be corrected by DSP. It's fun to play with.
Sounds interesting Pano. I've been thinking how to add a phono input to my active speakers without getting crazy, no blowtorches allowed!
i have an altec amplifier 1268 that came with the matching input transformers. no autoformers; transistor output. might be a dual mono design. good sounding amp. use it to audition new 'used' speakers. if they sound good with it, they sound good period.
probably part of the 'problem' with the a7 was using a crown dc300 amplifier. wrong amp for this type of speaker. would magnify the shrillness and harshness.
ok, so you'd have to test each iteration of a crossover with a microphone and o-scope.
yes, nice area. just north of it in the lake city area.
there might be some xover mods in the altec heritage archive.
Doesn't make sense to me. If I EQ a band by -2 db, doesn't matter where it originated, it's down by 2 db.
tnargs,
No that is not completely true. Yes you can cut the program material but that does not guarantee that the device won't still have a problem at that frequency if it is a mechanical resonant problem with the device. Sympathetic frequencies can still excite that mechanical resonance. It will not need source frequency to excite that resonance.
No that is not completely true. Yes you can cut the program material but that does not guarantee that the device won't still have a problem at that frequency if it is a mechanical resonant problem with the device. Sympathetic frequencies can still excite that mechanical resonance. It will not need source frequency to excite that resonance.
Two
If you have a second order harmonic, the source frequency will be an octave lower, and is not affected by the eq. If it is a third order harmnic, the source is two octaves lower.
Johan-Kr
The eq only works on the electrical signal.
If you have a second order harmonic, the source frequency will be an octave lower, and is not affected by the eq. If it is a third order harmnic, the source is two octaves lower.
Johan-Kr
Could be, yes. I haven't looked. I HIGHLY recommend measuring, simulating and then building. Crossovers can make or break a speaker. I do NOT trust generic crossovers. Published crossovers for anything other than the exact drivers and cabinet are also suspect in my mind. Been burned too many times. 🙁
So anyone have an improved xo to go with the 808-8A Altec driver mounted on an 811 horn? I've never messed with these speakers, they are vintage since new, my father purchase them for me when I was still in high school. I never could get myself to change them even though I knew they could use it, I've just left them alone and built other speakers that I didn't worry about doing what I wanted. The cabinets are still beautiful and look like they came out of the showroom. Got them at the old Pacific Stereo in Santa Monica, brings back memories. If I change them I would just bi-pass the original xo and leave then unmolested. Someday someone else will want them in original condition. They have the 411-8A bass drivers in a sealed enclosure. I haven't used them in forever, they just sit there looking pretty. And yes the surrounds are in great shape, I know they work, I checked them a few months ago.