My PANASONIC RX-A5 ** Project Kumonga

The official name for the blaster will be the DISCO KUMONGA AKA CLUSTER-BUMP


I have a minty RX-A5 from the bay & the decks need light service but work. The radio & Line in etc. are perfect & the tuner light is nice & brite, like new, really so I wanted to mod it to have all 8 woofers. The A5 normally has 2 woofers & 2 passive radiators, per cabinet, for a total of 4 each. The radiators are really just paper cone woofers that have the cones & dust-caps & suspensions but without the voice-coil or magnet attached. They are not a good solution & the entire unit together sounds quite good in the low mid to high range but bass is sorely lacking again, like the CFS-88S which drove me to again address that issue as much as possible.

Hence Kumonga is growing into the 8 woofered beast...


The idea is to get some extremely efficient 4.5" speakers that have decent punch & replace all 8 cans with the woofers. Acoustic research has established that arrays of speakers working together to reproduce frequencies are much louder per watt than a large single woofer by about 6db which would be equal to a 4 fold increase in amp power.....

Pictures & video coming soon as I assemble the beast...

BAM!!!

Well, since I'm going for higher SPL's & also better bass I searched hi & lo for some decent but cheap buyouts that might be on ebay & sure enough I managed to buy 2 lots of 4 woofers each for about 28 bucks per lot, plus bulk shipping which actually took only a week to arrive anyway. The total shot was about 129 CDN to my door, taxes in.....

BAM!!!

Check out the magnets on these cans....they are HEAVY!!



I bought 8 in total & they have a 3.0 OHM DC resistance & are rated for 4 OHMS nominal impedance. They are Boston Acoustics array woofers & quite efficient....

Here you can see a 4 woofer array I plan to use for each cabinet.



I will run each quad in a combination series/parallel setup to maintain it's 4-OHM impedance & run that woofer set again in parallel with the tweeter & it's crossover. Since the crossover is a 12db slope applied only to the tweeter, the added woofers will not affect the tweeter's output & the amp will see a normal load compared to the original.

The difference will be the added woofers will couple together & create a much more efficient use of wattage & a significant increase in acoustic output per watt. Hopefully it will sound better too...



So let's take a look at what is in there now, what a joke compared to the arsenal I'm going to cram into those boxes....



More to come......

This project should only take a day or so, to complete. The hardest part is cutting & fitting deadmat gaskets to the speaker cutouts....



Cpl

Awesome upgrade - love it!!!!!!!!!!!!! That thing is going to sound nuts! That factory setup is pretty weak looking.

You're just upgrading the factory parts that were designed by the company accountants!

I'm looking forward to your demo vid!

James...

Thanx JJ--70-10...been waiting to do this for about 2 months while I scraped up the coin & searched for the right deal.....I really lucked out....well so far, I've installed 4 of the woofers to one of the cabinets 7 here's some pics while I finish up the project. I'm going to wire up these cans & test & then do the 2nd cabinet tomorrow...

Enjoy:












Ready to wire & assemble......


Cpl

Now that looks much beefier - if it sounded ok with those puny old speakers, it should sound awesome with twice as many upgraded speakers.

There is obviously plenty of room inside those cabinets.

Must add to the weight though.

James..

OMG - the bass will be so powerful . Is amp have power for all those speakers?

goodman said:

OMG - the bass will be so powerful . Is amp have power for all those speakers?

Click to expand...

We'll find out, won't we These woofers are no joke & are very well made as I can see without even hearing them yet....The panny should have enough power to drive them adequately & the added woofers will dramatically boost the acoustic output vs the original setup.....probably by at least 10db which equates to twice the volume to our ears because our hearing works in a logarithmic manner...

Finally as a last secret weapon, each woofer is rated at around the 94-96db per 1watt/meter which means, watt for watt they are much more efficient & put out more decibels per watt on top of the coupling effect....

I'm really hoping to transform the A5 into an A2 contender worthy of the NATIONAL PANASONIC branding. Another CONION killah!!

Cpl

jimmyjimmy19702010 said:

Now that looks much beefier - if it sounded ok with those puny old speakers, it should sound awesome with twice as many upgraded speakers.

There is obviously plenty of room inside those cabinets.

Must add to the weight though.

James..

Click to expand...

Yup!! Lots of space & even high quality blanket insulation for the backwave damper so we're in business...

Weight will be 15 lbs per cabinet & the magnets line up dead-center so the standing balance will be perfect, no tipping either...

Cpl

Interesting project - do like the idea - looking forward to the results.

Well..first cabinet wired up with a series/parallel circuit for the woofers & that array is then wired again in parallel with the tweeters & capped with a brand new 4.7uF poly-film cap, same as before....

I've wired up the first speaker to my Yamaha Surround & it does pound out the bass....even with basic BASS & TREBLE controls & no other adjustments, the acoustic output is good & balanced....actually a bit bassy due to the coupling in the midbass/mid regions but that is what I wanted....

Now it's time to wire up the 2nd cabinet which should take about 1/2 an hour or so...I may also install M90 Tweeters if I feel they need to be beefed up. I'm betting the 6 OHM JVC's will boost the SPL's by quite a bit, due to their efficiency...

If the cabinet could sustain so much air pressure & vibration the speakers can theoretically handle about 200w RMS collectively but that would sound pretty crappy in such a tight plastic box. The cabs are very rigid tho & would benefit from some good deadmat treatment & maybe a bit more insulation to break up standing waves...

Stay tuned...

Cpl

Holy sweet mother of god!

Well, back to report on some updates....overall VERY pleased with the sound when combined with the console unit & its 5 band EQ...

Here's some pics of the progress...



As you can see here 2 woofers make a series circuit & then are part of 2 circuits in parallel....


Here is the blaster all finished up & blastin' away for the video shoot....





Stay tuned for the vids to come...

Cpl

IT CRANKS!!! DISCO KUMONGA is ALIVE!!! It climbs out from under the reefs & caves of JAPAN & devours the cities man has created in his impotency against nature....AHHHHHH!!!

Listen to this JAZZ session & take note of the decent bass & clarity, especially the organ notes & flute......
https://www.youtube.com/watch?v=QKku347RE9s


It's a very good listening test if you use good headphones or speakers, not cheap laptop or desktop stuff. I am quite happy with both fidelity & stereo clarity or imaging as some would describe it...I'm also uploading a good Electro-808 track, classic of the early 80's so stay tuned...

Chronic OUT!

Wow, it even sounds great on my IPhone! So how would you sum up how the sound now compares with the original setup?

How the cabinet manage 4 speakers driving the voice coil in the same direction??

Cheers.

Good job!

jimmyjimmy19702010 said:

Wow, it even sounds great on my IPhone! So how would you sum up how the sound now compares with the original setup?

Click to expand...

Thanx guys!! Compared to the old setup, the sound is much better & it gets really LOUD, almost A2 loud & the tweeters blend very well with the new woofers while the poly-film cap is very smooth as you can hear. Plenty of BASS & TREBLE which wasn't the case with the old woofers & passives...I will play around with some deadmat & poly-fill to reduce the standing waves & improve the cabinets...

The only downside is it weighs 48lbs without batteries......

I'll do some tests with some thumpin' dubstep & tune it as I go...

Stay tuned....

Cpl

test with some real nice tracks, like:

Loose Ends - Feel the Vibe
Mantronix - Bassline
Mantronix - Needle to the Groove

Nice sound in your speakers indeed.

Cheers.