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Modifying RX-CT980 has made a portable HI-FI

RX-CT980 Panasonic Modifying Bi-Amp hi-fi speackers bass pots tweeters 3-way Customization

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#1 Reelcassette

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Posted 30 November 2019 - 03:15 AM

A Hardwood bracing, Layer of adhesive thin pwc foam,

Cotton and Layer of thick natural Wool +

Discreet  Tweeters  were installed

behind bass reflex ports into my RX-CT980 speakers

Tape compartments covers were removed

 

Capacitors for twitters are installed as well

4.4 PDS Bi-AMP System 

became  4.6 (4 Amps / 6 Speakers - standard on other PLATINUM series models )

 

THIS Bi-AMP MACHINE WITH 3-WAY SPEAKERS SOUNDS AMAZING NOW !

 

Happy listening !

Check out those nice Reel Cassette Tapes here :

https://sites.google...elcassettetapes

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#2 Reli

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Posted 30 November 2019 - 01:05 PM

Interesting, so the new tweeter is suspended above the bass port?

Seems like its sound would be directionally limited, since it must pass through that port.

But very creative, nevertheless.

 

Good idea for the wood bracing. You can also use Dynamat or Rockmat.

It was silly of Panasonic to use cheap plastic walls for a system with that much power and bass.



#3 Reelcassette

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Posted 30 November 2019 - 02:23 PM

Yes, Sir! Tweeters are suspended on distance equal to diameter 

of bass port.
It doesn't affect their work, because high freq.never

intersect with spheric low freq.

They just go thru the bass ports like beams .

 

And yes - plastic is incredibly thin on these speakers.

Vibration was insane and that was killing

the entire idea of BI-Amp system..

So now there no vibrations  at ALL and 

that's very decent and serious portable sound !

i'm very proud of this machine , to be honest ,

because the hardwood bracing was extremely hard to do ..

Now those speakers  walls  are hard  just like a rock which significantly 

increased the quality of sound and brought it  to HI-FI  standards! 



P.S. Those Reel Cassettes made by me as well.

I'm the only person in the world who makes 

Metal Reels Cassettes  with Radially Polished Aluminum Reels.



#4 jimmyjimmy19702010

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Posted 30 November 2019 - 03:19 PM

So with the extra bracing, new tweeters, extra wiring and sound deadening material inside the cabinets and thus a large reduction of the internal cabinet volume, how have you not altered the cabinet port tuning frequency?

BTW, I’ve never seen/heard a 680 with cabinets that exhibited ‘vibrations that were insane’.

It’s true that the DT680/CT980 could benefit with the inclusion of proper dedicated tweeters. Unfortunately, you have wired your new tweeters to the amp circuits that power the drivers so they’re only being fed low end frequencies!?
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#5 Reelcassette

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Posted 30 November 2019 - 03:36 PM

 That picture was taken when trying to connect  tweeters with low freq.circuit .

to see what would happen)

Of course they are wired with original  tweeters!

I just don't have any other pics.

 

Bracing parts don't take any significant space.

 

ALL of them have identical drivers and Amps.

SOME OF THEM ARE  4.6 PDS 
and i've installed tweeters according to official Panasonic

diagram from maintenance manual.



#6 Reli

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Posted 30 November 2019 - 03:42 PM

BTW, I’ve never seen/heard a 680 with cabinets that exhibited ‘vibrations that were insane’.
 

 

 

They might not "vibrate with insanity", but I can guarantee those plastic walls color the sound a bit.  Every time I've added Dynamat to the walls of a plastic 3-piece, the bass deepened because the crappy mid-bass "coloring" was reduced by the Dynamat.



#7 jimmyjimmy19702010

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Posted 30 November 2019 - 03:46 PM

That picture was taken when trying to connect tweeters with low freq.circuit .
to see what would happen)
Of course they are wired with original tweeters!
I just don't have any other pics.

Ok, but some people with no electronics or speaker building knowledge will see your mod with pics including obvious wiring errors and try to replicate it. Panasonic did a very good job with the 980/680 models. I’d advise people not to mess with the speaker system.

BTW, I’ve never seen/heard a 680 with cabinets that exhibited ‘vibrations that were insane’.



They might not "vibrate with insanity", but I can guarantee those plastic walls color the sound a bit. Every time I've added Dynamat to the walls of a plastic 3-piece, the bass deepened because the crappy mid-bass was reduced by the Dynamat.
Yes, adding internal bracing and sound deadening material would reduce vibrations but you cannot add extra material to the speaker cabinets of a tuned bass reflex system without altering the tuned frequency (will possibly kill the bass). I would have thought most people here would know this. :-)

#8 Reli

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Posted 30 November 2019 - 03:48 PM

If you're talking about the frequency of the bass port, this assumes the manufacturer even bothered to tune/size it properly in the first place.  Maybe a good brand like Panasonic did, but I doubt most did.



#9 jimmyjimmy19702010

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Posted 30 November 2019 - 03:51 PM

If you're talking about the frequency of the bass port, this assumes the manufacturer even bothered to tune/size it properly in the first place. Maybe a good brand like Panasonic did, but I doubt most did.

The 680/980 heavily rely on their tuned cabinets to produce bass. Just for fun, try removing the rubber plug around the cabinet wiring and listen to the bass almost completely disappear from the soundtrack! Hold you hands over the ports and all you’ll hear is mid bass coming from the drivers - no deep bass.

So yes, Panasonic did bother to tune the speaker cabinets. Did you think that deep bass was coming from those relatively small drivers? No, the deep bass is coming from the ports so filling the cabinets with all of that crap WILL alter the tuned frequency. :-)

#10 Reelcassette

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Posted 30 November 2019 - 04:02 PM

Bracing parts don't take any significant space.

 

ALL of them have identical drivers and Amps.

SOME OF THEM ARE  4.6 PDS 
and i've installed tweeters according to official Panasonic

diagram from maintenance manual.

 

Bracing parts don't take any significant space.

 

ALL of them have identical drivers and Amps.

SOME OF THEM ARE  4.6 PDS 
and i've installed tweeters according to official Panasonic

diagram from maintenance manual.



#11 jimmyjimmy19702010

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Posted 30 November 2019 - 04:05 PM

Bracing parts don't take any significant space.

ALL of them have identical drivers and Amps.
SOME OF THEM ARE 4.6 PDS
and i've installed tweeters according to official Panasonic
diagram from maintenance manual.

Bracing parts don't take any significant space.

ALL of them have identical drivers and Amps.
SOME OF THEM ARE 4.6 PDS
and i've installed tweeters according to official Panasonic
diagram from maintenance manual.

It’s not the bracing, it’s the sound deadening that’s taking up internal volume. You’ve almost completely filled them up!!

Adding a tweeter on another part of the front panel would be a good idea but the only space is above the port so you’d have to loose the Panasonic badge.

As you may be aware, high frequencies are very directional. It’s never ideal to install a tweeter that sits deep inside a cabinet (through a small bass port) as the sound coming from it will only be heard when you’re directly in front of the bass port. Sitting even slightly off axis will result in a big reduction in audible tweeter output!

The fitting of internal bracing and sound deadening is entirely suitable for a sealed cabinet system like the Panasonic RX-C45 (done this mod) but leave the existing factory bass reflex setups alone.

Hey, I love modding and I can see you’ve put a lot of work into this mod. I just can’t help pointing out the issues that other people will run into if they copy you. :-)

#12 Reelcassette

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Posted 01 December 2019 - 06:12 AM

Check my earlier modifying of RX 900

http://boomboxery.co...ass-from-40-hz/





Also tagged with one or more of these keywords: RX-CT980, Panasonic, Modifying, Bi-Amp, hi-fi, speackers, bass pots, tweeters, 3-way, Customization