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JohnA

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About JohnA

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    Resistance is Futile.

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    Chattavegas

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  1. JohnA

    Step in here smart guys

    So, your HORIZONTAL door stroke is 85.5"? You want the ball to drop 58" from the ceiling? Use 2 pulleys on one shaft and bolted to each other, side by side. Suspend shaft with pulleys from ceiling. The circumference of one pulley is 0.68 of the circumference of the other. Wrap string around large pulley and attach to top of garage door. Wrap string around small pulley and attach to weighted tennis ball. Hang ball over parking spot at windshield. Door goes up, string unwinds and lowers ball. Door goes down and winds string up, raising ball. Should not have sloppy slack hanging around.
  2. JohnA

    Stumbled upon a great deal.

    You need more subwoofers! 😁
  3. I have tried several NAS boxes. The cheaper ones are slow. Now I am using an old 250 GB HD in a Sabrent USB 3.0 box plugged into the back of my router. https://www.amazon.com/gp/product/B00AF22NTY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1 My Integra pulls MP3s off of it easily. It also collects my weekly backups. But nothing I do at home needs to be backed up, save pictures and bought music.
  4. JohnA

    Digital Phase speakers...

    They were impressive at first listen. But he used MDF (non-resonant) cut in various places and called them resonant "Acousta-reeds". They were arranged in a baffle arrangement leading to a port in large, for the woofer, sized cabinets. I thought they looked like transmission lines. Daryl is still around, but I'm not sure he is still building speakers. After listening a while I found them to be one note bass speakers. He even told me his speaker were more efficient in the bass than any other speaker. He tested the frequency response of my Heresies with my custom crossover.
  5. JohnA

    Cans for outdoor use

    For my noisiest "activities" I use plugs and muffs, too. These electronic muffs replace a similar set of Peltors. With both I am well protected (-30 - 33) but essentially deaf. Hopefully, the new ones will protect my ears and let me hear voices.
  6. JohnA

    Cans for outdoor use

    Perhaps this is what you are looking for? Howard Leight Impact Pro R-01902. Amplified muffs with an NRR of 30 dB, but limits amplified sound to 82 dB. They have an 1/8" stereo input and from a brief listen sound rather nice, with rolled off extreme highs and lows. https://www.walmart.com/ip/Howard-Leight-Impact-Pro-Electronic-Earmuff/27954606
  7. Compare this response of a Peavey FH-1 to the Volti above. Note roll-off at 80, sag at 180 and return at 2k. The FH-1 has corner reflectors, but is otherwise similar to a La Scala. The similarities are striking to me.
  8. JohnA

    KG1's with Yamaha RX-777

    It is so rare for any amplifier made in the last 40 years not to "match" any speaker made in the last 60 years that the question has little meaning. Yes, some amps/receivers sound better than others, especially when pushed, but for all but the strangest situations, everything "matches" I suggest you find a pair of KG2s with passive radiator. Be sure to give the passive a few inches of clearance to the walls. The same applies to the rear port of your RB-51s.
  9. JohnA

    New to me Klipshorns

    That depends on your CD player. Early ones did have a harshness, on everything. Can you compare the same LP to its CD version? You should give 24/192 DVD-Audio a listen.
  10. The design goal is efficiency. A horn does it by trapping an air column against the driver cone so that its movement is tightly coupled to the air to produce vibration in the air. That tight coupling allows for very small cone/diaphragm movement at a given loudness where the driver is very linear and mildly stressed reducing a myriad of distortions. The low frequency limit (cutoff, fc) of a horn is defined by its length. Compare the sound of the cheerleader's megaphone to one you make from a sheet of paper. It is only the length of the a La Scala bass horn that prevents it from playing 30 Hz loudly. The same woofer in a K-horn goes that low pretty well. Folding makes the bass horn occupy less space in a room. Were it to be unfolded and built with a single path, it would be 3 feet long (with a mouth that is actually too small), compare to a K-horn's ~7 foot long horn path.
  11. If you can't swing K-horns, La Scalas or Belles will be your next best choice. La Scalas use the same drivers and horns as K-horns. But with either you will need subwooferS to get the bottom octave the K-horn delivers.
  12. JohnA

    KG-4 cabinet upgrade

    I didn't know Polks need so much work. If you don't change the cabinet volume much (calculate it) braces won't hurt, but likely aren't needed. Covering the backs of the horns with Dynamat or rope caulk MAY help. If the speakers are over 30 years old they might benefit from new capacitors. A dull, recessed treble will be the symptom. The only speaker I've heard that in was a 40+ year old H-700. Do not add stuffing to a speaker that was designed without it. It changes the "apparent" volume by making the trapped air more springy.
  13. JohnA

    Impedance For A Newbie

    No, since the POWER is equal into both speakers, both will produce the same loudness if their sensitivity is equal. To get equal POWER the voltage and current will both change. If you attach 2 speakers of equal sensitivity to an amp, (let's use a receiver with a speaker A/B switch) and adjust the amp's output voltage to some number and then switch from the 4 ohm speaker to the 8 ohm speaker, the 8 ohm speaker will be 3 dB quieter. That's because the impedance of the 8 ohm speaker restricts current flow to 1/2, thus cutting power input to 1/2. Note, our experiment deliberately held VOLTAGE constant. We could also hold current constant, but would have to adjust voltage to do it. It takes twice the voltage to push 1 amp through 8 ohms as is does 4 ohms.
  14. JohnA

    Impedance For A Newbie

    Speaker sensitivity is not directly tied to impedance. Impedance is the resistance to current flow. Impedance is DC resistance + AC "resistance" (a simplification) Water makes a great analogy. Voltage is Pressure. Current is flow. Impedance/Resistance is nozzle size. More pressure increases flow through the same nozzle (restriction). Less restriction (Impedance) allows more flow (Current) at the same pressure (Voltage). Ohms law says Current = Voltage/Resistance. I=V/R (V=IxR) Power = Current x Voltage. P=IxV Substituting Ohms law gets P=(VxV)/R (or P=IxIxR) Two speaker have the same sensitivity at one watt (one of the rating standards), but one is 16 ohms and the other is 8. If the same voltage is applied, say 2.83V, the power into 8 ohms is P=(2.83x2.83)/8 = 1 watt. For the other one it is P=(2.83x2.83)/16 = 0.5 watts. Power = I^2xR. 1 watt = I^2 x 8. I^2 = 1 watt/8ohms. I = sqrt(1/8) = 0.354 amps Power = I^2xR. .5 watt = I^2 x 16. I^2 = .5 watt/16ohms. I = sqrt(.5/16) = 0.177 amps Half the amps and half the power into 16 ohms at the same voltage. . Lower impedance "allows" more current (and thus power) at the same voltage. It is linear, so half the impedance doubles the power. This is why car speaker are 4 ohms or less. Battery voltage is limited to ~13V, but it can surge 300 to 400 amps. This relationship is important because power amps want to be voltage sources (a source of voltage with unlimited current capacity). As you turn up the volume knob, you are really turning up the voltage applied to your speakers. So, what happens if you turn up the voltage to 20 volts? Assuming your amp is capable, Power = (20v x 20v)/8 ohms = 50 watts. At 4 ohms it would be 100 watts. However, there is no such thing as a Voltage Source. Nothing, especially power amps, are that linear. One prime reason is that current flow causes heat and heat causes resistance to increase. That heat must also be pulled away from the transistors to keep them from burning up, too. Removing heat takes relatively expensive large heat sinks or even fans. My sub amps are Acurus A250s, rated at 250 wpc into 8 ohms. They test at 300 watts into 8 ohms and 480 into 4 ohms. They are conservatively rated and still don't double their rated output into 4 ohms. Speaker impedance is never a flat curve, but varies wildly sometimes, but the enclosures and crossovers help control the loudness in spite of the variations and modern power amps tolerate that foolishness well, most of the time. One thing to watch in speaker ratings is way it is rated. Is it 1 watt at 1 meter? Or is it 2.83V at 1 meter? 2.83 V is 1 watt into 8 ohms, but it is 2 watts into 4 ohms. Doubling the power increases output 3 dB! FYI, 10x the power is 10 dB, or twice as loud to the ear. https://www.crownaudio.com/en/tools/calculators
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