1st order/ Azurahorn

discussion of magnetic volume control design for both line and speaker levels.

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gregoh
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Joined: Sat Feb 28, 2015 3:21 am

1st order/ Azurahorn

Post by gregoh »

Hey Dave
Some time ago I purchased your nickel autoformers for my Gary Dahl Speaker build. I Experimented with Gary's posted crossovers, also JMLC's 3rd order BW and presently (flashback to Bruce Edgar)I am using the following. GPA 416 (8ohm) 2nd order 800 HZ with an AH 425/ Radian 745 (16ohm)neo BR / 1st order HP. I'm using a 2.2 Silver/ oil Mundorf with a 39 shunt resistor and a 16ohm resistor in parallel with the compression driver and -17db tap.
Would you model my HP at 1000HZ 1st order so I have some more accurate data on the shunt resistor and cap. (suggestion appreciated)

I use only low powered SET's , 45 ,300B and 845's.With the type of music I prefer and mostly vinyl I'm enjoying the 1st order . The autoformers allowing for a very small High quality cap is a big plus.


Thanks
Greg
dave slagle
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Post by dave slagle »

Hey,

I think this is what you asked for. It looks like you are just over 6dB down at 1K which seems a bit drastic which leads me to look at the value of your shunt resistor. In the second sim I swept the shunt resistor for 20, 40 and 80 ohms so you can see the effect. Since the 17dB of attenuation is a voltage stepdown of just over 7, it has an impedance stepup of 50 which makes the driver appear as 200 ohms in parallel with the shunt resistor for the load value that the 2.2u cap works against. If you parallel 39 and 200 you get 33 ohms which based on a 2.2u cap nets you clost yo what you are seeing.
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gregoh
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1st order/ Azurahorn

Post by gregoh »

Thanks

After experimenting with resistors and amps all day I decided on a 16ohm Mills shunt and 16 swamping resistor on the compression driver sounded good.

Based on your experience would the system benefit from your custom resistors in these locations ?


FYI
I know Gary is using his PP300B and recently added Eq . However , I'm satisfied, for a second, with my 845 SET and a 2nd order LP and 1st HP . My Welborne 300B's have a lush mid but lack the top end and tight bass of the 845. Maybe a better 300B or if my 45 had a dozen watts --- Oh well back to " Lake Street Dive"

Thanks again
Greg
dave slagle
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Post by dave slagle »

16 ohms seems a bit small for the crossover combo you mentioned but if it sounds good....

Since this position dissipates a bit of power, I would keep away from the copper resistors since they do shift value a bit with temperature.

dave
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oltng
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Joined: Fri Mar 25, 2016 10:44 pm

Gary Dahl’s speakers

Post by oltng »

Greg, big congrats on building Gary Dahl’s speakers!
Last edited by oltng on Fri Apr 15, 2016 5:09 am, edited 2 times in total.
gregoh
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Post by gregoh »

OTLNG
I am unable to receive pm's until I have 5 posts

My system is like Gary's with the exception of the low end . I use multiple Rythmik servo sub's under 60 Hz

Greg
gregoh
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Post by gregoh »

oltng
I've built dozen's of 2 ways using 12 or 15 in mid bass drivers with all kinds of horn profiles. IMO after years of this madness it's about total system synergy and to a degree personal preference. I prefer the 1.4 Beryllium CD and the tone of the Altec driven by my Line Magnetic 518, 845 amp. This 845 has the best bass of any SET i've tried. I've attempted various tweeter's firing them up/ back / front and decided to live with the horn alone. Synergy--The front end ,at the moment, is a VPI Classic / Lyra Delos/Manley Chinook . The preamps are the Slagel auto former, K@K extreme, and Monarchy NM24( NM24 also DAC when playing digital). I'm considering upgrading my vinyl front end and working on an ultrasonic cleaner. Your question on horns and very low level listing ? I would sit in my living room and listen to my Yamaha NS 1000's but thats another story.

Greg
oltng
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Joined: Fri Mar 25, 2016 10:44 pm

Post by oltng »

dave slagle wrote:16 ohms seems a bit small for the crossover combo you mentioned but if it sounds good....

Since this position dissipates a bit of power, I would keep away from the copper resistors since they do shift value a bit with temperature.

dave
dave, Please see my pm
Greg
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