This is one of four I purchased on eBay. As far as I can tell, units like these were manufactured as early as 1956 and I’m guessing all of mine are considerably newer. The DC resistance measures 6.5 ohms and the impedance is 8 ohms. The others all have very similar DC resistance ( 6 to 7 ohms) and are 8 ohm impedance. If you look closely around the edge, you’ll see a Philips head screw and three dark red circles. The red circles are the highly coveted JBL wax seals. If you can find an 075 with all four seals in place I understand they become considerably more collectable. All of mine sound great, and I’m using two at the present time.
One thing I’m not good at is determining the proper value of conponents for a crossover network. I do know that inserting a capacitor in series between an amplifier and a speaker will reduce the level of low frequencies reaching the speaker. With that in mind, I have decided to use a value of 2 microfarads, non electrolytic, 250 volts for a crossover capacitor. The 075’s sit atop and are connected to a pair of older Pioneer CS-63 speaker systems. By the way, I replaced The stock Pioneer 15-inch woofers with Electro-Voice DL-15’s. These are rated at 400 watts and have 2.5 inch voice coils. By now, some of you may be cringing, but I think these speakers sound and work quite well. I’m sure no damaging low frequency energy is getting to the 075’s. My amplifier has less than 30 watts per channel and I always use a compressor ( Alesis NanoCompressor ) between my source signal and amplifier to prevent any peak level from getting to the speakers. I sense after listening to alot of different sounds and especially cat hissing that my crossover is well above the suggested frequency of 2.5 kilohertz. From what I’ve read online, alot of audiophiles prefer a higher crossover on these tweeters for a “sweeter” sound. Please listen and enjoy “Hissing Very Loud” on this site. I think you just might know by now what speakers I connected when that recording was made.
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Follow-up comment rss or Leave a TrackbackNice 075s, I found a JBL Apollo C51 with the 075s and the D120 woofer and I am quite impressed with the sound.
I’m a long time Negativland listener ever since a Big 10-8 place, wish I still had the poster. 🙁
Thanks for sharing your sounds on the web and for keeping life interesting in the land of the big repression, USA.
Thank you for noticing and commenting. There will be more hi fi stuff to come and maybe an experiment where I use a JBL 075 or 2402H as a microphone!
I just now noticed Mr. Raven that you referred to the woofer as a D120. I have never heard of that model. I am familiar with the JBL D130 15 inch speaker and the D123 12 inch speaker both having a shiny metal dust cap. I also think these models were considered full range but usually they are treated as woofers. I just looked at Ebay while writing this and there does appear to be a 12 inch model D120, but it looks like it was meant to be used mainly as a musical instrument speaker in Fender guitar amplifiers.
Actually it’s a D130, my bad, anyway as a two way with the 075 in an easy to make vented box it has a very full and dynamic sound. I will be curious to read your mic reviews.
Are you guys getting into reworking the new Chinese condenser Neuman knockoff mics.
Keep up the good work, really enjoyed the 180-Gs acapella covers of your work.
As of May 5, 2010 I have in fact demonstrated how a JBL tweeter performs as a microphone. It is a model 2402H-05. This unit is unusual in the fact that it has a model 2405H diaphragm rather than the standard 2402H diaphragm. This tweeter has a slightly smoother higher frequency response than a regular 2402H. Go to http://www.negativland.com/dumb/blog/?p=2016 to hear and see me testing this speaker.
Would it work in this configuration?
http://thereifixedit.files.wordpress.com/2010/12/699e0bd2-2f75-4349-bfc0-6deb11fdfe3b.jpg
I just now looked at your picture (sorry I’m so slow). You could add one of these types speakers to the existing speaker of that unit provided that a non polarized capacitor of about 2.2 microfarads (10 to 50 volts rating) or lower is installed in series on the positive (red) side. The capacitor will block low frequencies which could damage the diaphragm in the tweeter.
Mr. Raven (from October 2nd 2009), Sorry about my ignorance on JBL speakers. I know now there is a model D120 as well as D123, both 12 inch drivers. Thanks to eBay for making me a little less ignorant!