My home cinema (1 Viewer)

[andySu]

Microphone modified SPL db meter project.


I found a small plastic throw a way pen that I can house the microphone inside the top of the pen with some glue or filler to harder around the microphone and feed the wires down though the pen. Then I can handle the microphone for multiplex placement in the room.

 

[Dr Griffin]

Presently, it looks like the only JBL speakers that are THX certified for home theater are the JBL Synthesis line, and they are pricey!

http://www.jblsynthesis.com/

 

[Dr Griffin]

What do you know about the JBL 8320 Surround Speaker from the Pro line? They are a little big for HT at 16 inches high but I found them for $249 apiece. High sensitivity and power handling for $249!

http://www.jblpro.com/www/products/cinema-market/surround-systems/8320

 

[andySu]

What I know is a speaker is a speaker its the crossover that makes the speaker.

Plenty JBL bookshelf surrounds show up on ebay everyday.
8330
8333
8340
8320

Oh list runs on and on and there was another type model around 1980's.

Popular model seems to be 8330. Hundreds of thousands of them around.

if you think you can fit them in your room as fitting in mine if I had 20 of them would be so easy.

That 8320 model is about same power handling as control 1, it has higher sensitivity 91, lower frequency response and its THX approved. Pair in a box will cost hundreds.

The little JBL control 1, have been used in professional cinema installs at Empire Liecester Square Empire 1, and Odoen screens 4 and 5 down town during the 1990s and held up to Apocalypse Now, evening show 35mm Dolby Stereo A-type and we all know that film is LOUD! There was x4 control 1 black, fitted to the ceiling on those little metal brackets.

 

[andySu]

Microphone multiplex project update.

Found some bell wire and stripped it down for equal length so I can move it about the room over a few meters.

Soldered up the mics and fitted them inside the plastic pens.

I'll finish the rest later on and wire up to the SPL db metre and see how it goes?

 

[andySu]

Microphone project tests now running to see how good it is? So far so good. But still early days.

Panasonic WM-61A Datasheet of microphone

http://www.usefulcomponents.com/.../wm_61a_datasheet.pdf

With microphones placed close to the each of bass mid driver and HF horn to balance the LF and HF by looking at the pink noise C weighting.

 

[Dr Griffin]

I can't access the link for the mic. What prompted this project? Did the built in mic fail, or are the other mics of higher quality?

 

[andySu]

The mic is super fine. I can wire up a few microphones and use output on metre to preamp for RTA and place 2 mics at each

LF HF driver compare SPL db or frequency response or place each mic at LCR LF HF and do the manual EQ a lot faster as well as place them near each LCR or surrounds and subs.

Need a third microphone and many more or make cheap multiplexer.

 

[andySu]

Microphones placed around the side and overhead surrounds. I haven't yet done the below surround? I'll get around to that in short while.

 

[andySu]

More testing around early night morning hours.

Checking the frequency response and its not half bad if I had an extra 12 or more cheap 1/3 EQ to address the small nit picks.

Microphone placed under the seat and above aimed downwards at a selected seat.

I've been thinking for some while to using the X-over on the CP45 for side overhead and rear wall by carefully blending the 500Hz or 800Hz with the whole speaker so the HF outputs to the speaker but I'd have gain adjustment to lower it or rise it to suit the room. The rear surround on the processor doesn't support crossover. But its just an idea.

Frequency of the overhead and this is just a fast example as you can toggle move the microphone around and the pink noise freq waves up and down.

Microphone is aimed off axis here and I can do on and off and upside turned around even inside out if wanted to.

It wasn't easy at first to fit this underneath but I soon found a way.

Below surround

Microphone aimed downwards while Dolby CP45 outputs pink noise.

 

[Dr Griffin]

Do you bi-wire any of your speakers? This would be great for Eq-ing a bi-wired speaker for better matching. Of course, you'd have to have an abundance of equalizers in an HT setup, but would be interesting for a stereo setup.

 

[andySu]

Do you bi-wire any of your speakers? This would be great for Eq-ing a bi-wired speaker for better matching. Of course, you'd have to have an abundance of equalizers in an HT setup, but would be interesting for a stereo setup.

The stage LCR runs though the Lucasfilm Ltd THX Sound System, crossover/monitor.

Like any common AVR that can run mono / stereo / 5.1 7.1
I can select all that on the CP500 to SDDS or on Onkyo I can swap and mix channels around on the SDDS if I wanted to do that. If I wanted to I can play the centre for mono and mix blend the rest of the HF to the left and right or play all three as mono for mono films so it fills the area up front or play mono all around or stereo.

 

[andySu]

The DOLBY STEREO A-type trailer sounds great with the overhead surrounds just like it was at UCI 25 years ago.

I can select side wall surrounds or switch to overhead and have the at 0.04-5scond Our Feature Presentation music passing overhead.

Waterfall with microphone near to overhead surround while playing the trailer.

Direct waterfall monitored on THX sound system.

 

[Dr Griffin]

Yeah, Ive been meaning to ask you how you laid your hands on the THX monitor, they weren't ever really for sale were they? Don't tell me - Ebay!

 

[andySu]

pm, sent.

 

[andySu]

ALIEN ice cream THX approved last night.

 

[andySu]

More testing with the microphones yesterday.

Spaced them out about 8" apart to see what I can see on the RTA it was somewhat different than a single microphone. I have another project idea I'd like to try but even on the cheap with these each around £2.95 the cost can easily equal a modest good one for under £100.00 so I might go for slowly a few steps at time.

Bed sheet screen is mounted above.

 

[Dr Griffin]

You need to get that spandex screen up nice and tight!

 

[andySu]

You need to get that spandex screen up nice and tight!

I could have brought the wood many times over that doesn't cost much.

The hinge idea so I can latch the screen up at the ceiling is neat idea. I'd like x2 more JBL control 12SR cheaply or maybe some other older JBL pa small box speakers that I have been looking at or keeping look out for? Then build the barrier wall around the speakers fit the screen. I'm not in hurry or rush, like most are. I can wait. Is not going to grow legs and run away...

I'd have to remove the light and tap off of it to use flush finished lights in the ceiling or use LED multi around the room for low power efficiency.

 

[Dr Griffin]

I like the swinging screen idea, but I still wouldn't be able to keep the plasma up behind it due to LCR speakers. So I will probably go with the screen wall, built out about 3 feet from the front wall, with speakers in a baffle of some sort - to be determined later. The hinged screen looks like a good idea for your setup.