In Reply to: Re: Need Math help posted by Wayne Parham on August 01, 2002 at 00:18:04:
Wayne,
Thanks for the info, it is exactly what I needed. I was not sure that a conversion from 8 ohm circuit to a 16 ohm circuit would double the values, but I wanted to be sure.
Now I know this may sound stupid, but since the R1 and R2 resistor components form a voltage divider, why do you list for 1.6khz/12 db the values of 25 ohm and 16 ohm, but for the 800hz/12db the values are 20 ohm and 14 ohm. I'm sorry to not catch the reasons why, but I thought a voltage divider would be dependent upon resistance, not frequency.
One last question for you, Parts Express has discontinued some popular resistor values (10 watt variety). I was buying qty's of 10 or 20 count of 30 ohm and 15 ohm and they are out or discontinued. Those values, especially the 30 ohm combine to make 30 ohm/15 ohm/10 ohm and 7.5 ohm. I bought the 33 ohm on the last buy. I can use my 8 ohm 20 watt resistors(in series) to make a 16 ohm(40watt) R2 on most of my projects, or use the 33 ohm (10 watt) resistors(in parallel) for 16.5 ohm(20 watt). I am running Marantz 2215B (15 watts/chnl)for my main power to the speakers. I will be building a 4 Pi-pro soon with my 8 ohm 2226H's which I will go 40 watts on att/comp circuit. My question is how much lee-way is there if I need a 14 ohm value (for R2) and I use 16.5 ohm (33 X 2 parallel). I am guessing that there is more room for error on R1 than R2, am I close in that thinking????
By the way, my Marantz receiver with only 15 watts per channel using the 4 Pi-pro (2226J/2418/2373 in 3677 cabinets) put out 108db at my couch in my 12' X 16' Living room and I am not pushing it hard at all. The 4 Pi-pro rocks, I had to put the Carver(250w/chnl) away because I was worried about permanent hearing loss. The Marantz receivers from the early 70's can power the 4 Pi's decently usually staying in low wattage (close to class "A" to a couple of watts) and put up a great sound stage. Thanks for taking over for JBL since they no longer cater to the consumer crowd with great monitors anymore, These are the JBL monitors of the 90's and the new millenium. Thanks, Ron
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