Re: Re: 4435 choke values
Thanks for answer Giskard.
What i found out with BB6 is that the lower DCR gives me the possibility to tune the 4435 a little bit lower.
I came to a duct of 180 to 200mm (instead of 133mm)
This yield in a tuning frequency of appr. 24 Hz and 3 dB more output below 20 Hz. I should try this when the cabs are finished.
What do you think?
Quote:
Originally posted by Giskard
The really nice thing about the 4430 and 4435 is that you can biamp them and use a 6 dB/octave passive line level high pass instead of the 6 dB/octave active high pass in a 5234 or 5235. ;) You can fine tune it with precision resistors if needed. It will work in conjunction with the series 20.0 uF capacitor (which should also be of the highest quality) to provide the necessary 12 dB/octave attenuation.
This I do not understand. What do you mean with "6 dB/octave passive line level high pass instead of the 6 dB/octave active high pass in a 5234 or 5235"?
Re: Re: Re: 4435 choke values
Quote:
Originally posted by Guido
This I do not understand. What do you mean with "6 dB/octave passive line level high pass instead of the 6 dB/octave active high pass in a 5234 or 5235"?
The 52-5130 card for the 5234/5235 and 4430/4435 has a 6 dB/octave active high pass. One can use a line level passive high pass instead. They are considerably "cleaner". Decide what amplifier you are going to use for the high pass and then figure out the capacitor value to place between the preamp and power amp to obtain the same voltage drive as the stock 52-5130 high pass. The input impedance of the high pass amplifier can be augmented with a parallel precision resistor. Just keep the value of the precision resistor as high as possible to minimize insertion loss.
Look at a BX63A schematic to see the simplest way to make your own 6 dB/octave passive line level high pass. I think it makes the 4430/4435 sound as good as it possibly can in bi-amp mode, especially if you also replace the 20.0 uF series capacitor (and 2.0 or 2.5 uF EQ capacitor) in the stock network with something like a Hovland.
Passive Line Level; Yep, a whole lot cleaner .
Hi Guido / Giskard
Quote:
One can use a line level passive high pass instead. They are considerably "cleaner".
I can sure vouch for what Giskard stated above regarding "Passive Line Level HiPasses". Early this winter I moved the hipass for my biamped setup to a "balanced" passive inline line-level hipass . I don't use any "load" resistors in this circuit - just two surplus polystyrene capacitors per channel ( or actually, 4 once I DC-biased the network ) . This is certainly the fastest ( and cheapest ) way to uncover and draw upon the "resolution well" . My circuit , being inherently "sloppy" doesn't achieve a 6 db slope until octaves down into the "stop-band". The slope is really more like 4 db an octave below the choosen point. This "first" pole of my 2-pole approach is also set to be about an octave below the desired Fc .
My circuits second pole ( inline with the horn driver ) is from a "shunted" inductor that's @ 1/2 the book value ( or about an octave above the desired Fc . This combo actually represents a "flipped" approach to obtaining a 2-pole LR transform . This inductor is "hidden" from what the amp "sees" by the 8 ohm resistor within the RC network ( for 8 ohm drivers ) . This "very necessary" and critical resistor prevents the amplifier from seeing a frequency dependant short-circuit .
The sharp "eyed" will notice that this portion of the circuit lacks "DC" blocking caps between the amplifier and horn drivers . This is true. And, therefore, this approach is a dangerous setup for those with amplifiers of marginal stability ( or a full comprehension of all the ramifications ) .
The net results, sound really , really good .
<. Earl K
Re: Passive Line Level; Yep, a whole lot cleaner .
Sounds cool Earl!
Biased eh? :)