glens
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Posts posted by glens
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1 hour ago, BEC said:
The higher the number in db, the lower the output of the midrange.
Because the number is negative...
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It doesn't really matter, does it? What happened to the extra/lost months when the calendar was corrected years ago? Surely they got missed at the time, but the "big picture" is what's important! You'll get them, and they'll be good.
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On 3/18/2020 at 9:31 PM, Edgar said:
Someone told me a long time ago that more heat is shed by the resistor leads than by the resistor body. If true, then the one longer lead on a stand-up resistor mount makes sense.
If true, yes. But I highly doubt it's true. Surely a stand-up resistor is some combination of layout tidiness and better body dissipation via air all around it. An IR image would certainly settle the question.
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I say for passive development, first Zobel the driver, then work on the C and L. Save time and effort.
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Agreed. The time required to "pick out" the difference is inversely proportional to the amount of difference. But once you've reached loops of several minutes you've substantially reached your goal. When the time gets very long your ability to discern goes out the window. Presumably the differences you're then comparing also include environmental and physiological influences which change throughout the day and especially from day to day. Don't forget that this particular individual above has claimed to discern driver time alignment within 1/8 inch, and the sweetening of the spectrum in certain ranges with the same value capacitors in either gain stages or at-speaker crossovers! Certainly A/Bing bypass caps in a crossover will be a test he can pass with flying colors. I want to see it happen! It would be as awe-inspiring as watching a person juggle running chainsaws while riding a unicycle blindfolded.
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Yeah. Excuses why no difference can be heard in A/B for some of this stuff are legion, and mostly ought to be used as punch lines for really geeky jokes.
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15 hours ago, Dave A said:
Combining a 10uf and 15uf gave me half the esr of either cap separately and half that of the 25uf on it's own.
So now you'll need an extra 1/2 ohm on the resistor you need anyway to knock down the level of the driver?
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1 hour ago, codewritinfool said:
it takes hours or perhaps overnight to "form", and so changes are not instantly noticeable
Yeah, sure, that's the reason no change can be discerned in an A/B...
And "un"forming is instantaneous?
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Haha! That's a real-life kick drum, not what ends up being mastered into a modern recording.
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0 - 4 ohms, 25 Watt, at the tail toward the driver. 'Adjust to taste'
If you've got a suitable-enough variable, use that to determine what "tastes" good, then measure and replace with the real thing.
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So put a resistor in line before any other elements, like in the Jube schematic: to taste. Try the range given in that Jube schematic. Was it something like 2 - 4 ohms?
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You just reminded me of the time the truck showed up from the lumber yard delivering the 3/4 t & g panels for the floor of the full room above a new large garage. The 6'-something 250 lb. kid from the yard pulls in, hops up onto the truck, grabs two sheets like they were nothing, and pokes the end up through to me. I grabbed ahold, gave a tug, and says no thanks. I gotta go one at a time...
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I'm sure he'd meant the two were swapped, and that that's what he did.
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4 hours ago, Chris A said:
I've always been a bit puzzled by this part: digitization wasn't mentioned by the OP. This is not a consideration worthy of discussion because there is no audible effect of this. I don't mention it because of that.
Well, there certainly can be audible effect, depending on the implementation in any case, but specifically so in the minds of some in every case. It doesn't need iteration that the pre-disposed mind is a huge factor in things audio. (There is one occasional participant at this site who specifically comes to mind regarding that!) This OP, our "luddite," does at least occasionally feed his Belles some digital, but his first-mentioned source is a hopped-up record player...
What's the sample rate and word size used in your current DSP gear?
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4 hours ago, Chris A said:
- the back-EMF/EMI of woofers affecting the other drivers/horns due to much higher moving mass (even horn loaded),
- time misalignment of the drivers/horns, and
- the loss of amplifier damping of the woofers and other drivers due to the added reactance of the passive crossover circuits removing the amplifier's control from direct coupling to the drivers
To the OP:
Item #1 in the quote is the only thing you'll gain by full-range bi-amping through your passive crossovers (unless, perhaps, you need the extra amplifier headroom which will marginally become available). This is why I said it's "very incremental" above.
Repeating myself again, it'll cost you next to nothing to try while you mull it over about going active.
Another factor I believe I noted was that your source is predominantly analog. You did mention some digital equipment so you must not be totally averse to it, but you'll definitely be going digital (and back) to do actives right.
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There's benefit from feeding the low and high crossover inputs separately, with separate amps (and I'd guessed that was your intention), it's just that it's very incremental as compared to going with active crossovers. It would cost you next to nothing to try. My guess is once you get the gains set properly you might notice an improvement. Maybe. And you'll just leave it that way anyway until you need that second amp for something else.
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7 hours ago, Alexander said:
Just curios. How would we determent (calculate) the resistor/polyswitch values one would use to add to an existing tweeter circuit? Say you were to be building an a or aa xo using a k77 from scratch? But I would rather know how to calculate the values rather than be given them for the above example.
I don't think it's rocket science. Size the polyswitch to your needs, and the resistor is there to maintain a circuit (when the switch opens) after the crossover elements solely for the safety of the amplifier (assuming the driver hasn't blown).
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10 hours ago, Don Richard said:
Running two amps through the passive crossover is known as "fool's biamping". It's far better to split the signal before the amps, preferably with a digital loudspeaker processor.
I agree active crossover has the best chance of getting the most/best out of the speakers, but we still don't know what was had in mind in that regard with the original question.
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I don't know about the brads, but the strength of a joint shouldn't be provided by just the solder. I've always had great success in situations like that above by folding the end of the lead back and crimping the wire with it prior to soldering. That is a tidy assembly shown above.
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Oh, I'd still give it a shot. After all, it mightn't be quite the definition of insanity yet to do so. (you know, doing the same thing over and over expecting a different result - just one more time...)
Stagger the cuts, abrade or melt (or dissolve) the coating, twist, solder, and wrap a splint into the splice might restore them.
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I guess the question which needs to be asked is the biamping going full-range through the crossovers or after low-level splitting?
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A Zippo might bare up some copper, but I've never had any luck with that stuff.
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I don't think density and resonance necessarily scale the same, inversely or otherwise. There's more at play.
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The Forte review was merely a re-typed version of the scanned Stereophile from days gone by. Don't know about the others. Had been nice to see attribution. Perhaps there is but my ad-blocks remove it?
RP-8000F and Denon PMA-60 Class-D Amp
in 2-Channel Home Audio
Posted
I read the first linked-to thread in that link immediately above and was very surprised to see so many folks having their ac routers set up with the same SSID for both bands. Why would anyone even do that, much less blame the endpoint devices for getting confused about it?