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Old 26th July 2015, 08:49 AM   #1
diyAudio Member
Join Date: Mar 2005
Location: Phoenix, Arizona USA
Default J2s with paralleled channels

My pair of J2s have been running perfectly since early-Nov., 2014, with the channels paralleled...
Paralleling channels of a J2.
...driving my 97dB-sensitive Serenity Acoustics Super-7s. This week I dragged my old Audio Physic Avanti IIIs out, connected the MR/treble to the mono'd J2s and the bass ends to a pair of plate amps.
Click the image to open in full size.

First and early conclusion was that the 60-Watts-into-4 J2s had, and still have almost a week later, plenty of power for the 87dB-(in)sensitive Avantis. Because the Avanti x-overs include no HP filters* for the MR drivers, I added a high-quality cap to the input jacks of the J2s to create a 190Hz filter, then changed it to a 130HZ and then an about-90Hz filter. As the input caps and the Avantis haven't operated for several years, they're still breaking in, but the system is sounding better and better. My golden-eared buddy, when I told him I was surprised the amps sounded as good as they did driving the power-hungry speakers, told me he thought the J2s were the best-sounding amps I've ever had in my system, and that includes a LOT of often-expensive amps.

I'm really pleased with the sounds of the new system and very happy I bought that pair of J2s.

More later.

August 15 update. The speakers still sound excellent, and I believe the amps are the best sounding I've ever heard.

* because I removed them

Last edited by jeffreybehr; 23rd September 2015 at 02:59 AM.
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Old 23rd September 2015, 03:08 AM   #2
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Join Date: Mar 2005
Location: Phoenix, Arizona USA
Default I've since improved the Avanti IIIs a bit

1. I replaced the LP choke driving the lower-MR driver with a 12g. version (v. the original 20g. version) to get a little more lower-MR energy from the system, and...
2. Replaced the already-wrong* 3rd-order HP filter for the tweeter with a single-order filter, that being a huge 6.8uF SoniCap Platinum (Teflon-film-and-tinfoil) cap.

Now we have a little more warmth and cleaner treble, and I'm even happier with them.

LOVE those J2 amps!

Click the image to open in full size.

* I had already replaced the hard-sounding ring-radiator tweeter with a B-G Neo-3 PDR mag-planar driver, which improved the quality of the treble substantially.
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Old 23rd September 2015, 04:17 AM   #3
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Very nice.
"If you leave this point unattached to some circuitry, an ideal constant current source will emit a small lightning bolt which will travel until it connects to something." Nelson Pass
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Old 23rd September 2015, 12:42 PM   #4
WalterW is offline WalterW  Netherlands
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Location: Utrecht
oh my, that's a real man cave, you got there !!
Pass F5, F5Tv3, ACA, Aleph J, DDDAC1794, DCB1, BA3-preamp, VFET CSX1, Pass F6
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Old 23rd September 2015, 06:17 PM   #5
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TYVM gentlemen.
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