My SONY CFS-88S ** Project 2 OHM stable

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Cpl-Chronic

Cpl-Chronic

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Hey all, :-D

Anyone who has owned a SONY CFS-88S knows it is a HUGE beast with 8" woofers, great GIANT VU meters, a really good tuner & exceptional finish overall. The speakers detach & are connected through it's hinged brackets to the amp when hooked to the main unit or you can use the speaker wires & spread them out away from the main unit.

The only real drawbacks to the blaster are it's weak Hitachi HAF1392 amp, extremely stiff woofers & overbright tweeters. This gave the unit a very bright mid-range & high end while mid-bass & warmth were non-existent. I installed some modern woofers & tweeters to improve the sound but the modern woofers I installed were 8 OHM & only pulling out about 3-4 watts @ absolute maximum output.

The sound was much more balanced & warm but bass response was still a bit weak due to the lack of power.

So, since I know these chips can handle 2 OHM loads, as proven over & over with the Sharp 777Z, I decided to try my luck with 8" 2 OHM speakers to see if I can wring out a few more watts from this sexy beast..searching, searching & searching, I finally got some Sanyo MX-920 Woofers from Nikon Foo that were 2 OHM, 20 watt rated to try....

Stay tuned, pics coming soon....

Chronic
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Here is a pic of the woofers I installed previously. They are a good low cost 8" woofer but their 8 OHM impedance was a poor match the hitachi AMP IC's since the chips were designed with a 3.2 to 4 ohm load in mind...

Also, they barely fit in the enclosure & I had to create a hole in the back of each cabinet to properly vent the center pole of the drivers.

4qgah2.jpg
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Finally, Nikon Foo had some MX-920 woofers for sale on ePay & the pics of them looked pretty minty so I tried my luck since they had a 2OHM impedance & decent wattage range. Just what I've been looking for since I finished the DISCO Kamacuras....


Both drivers are optically & physically in good shape, no tears, blemishes or issues I can see. While testing one of the drivers is a bit weak when pushing the bass but overall, both drivers perform well without issues...
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Stay Tuned...
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
ThanX. I may try the Prosonic next. It also uses the same IC for the 2 channel amp of the 9962 AKA Goldstar, AKA Poor Man's M90...

If I could get it to 10w per side, the Prosonic would sound pretty good too.

Chronic
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
jimmyjimmy19702010 said:
The 8 inch drivers I used in my last DIY build would have been perfect - they look very similar to your ones except mine were 4 ohm (92dB sensitivity) - they are screamers!! - you can get them in either 4 or 8 ohm.
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Interesting...too bad they aren't 2 OHM. How much wattage do you need to drive them with some decent bass? Any idea?

Uh, my goal was to find some decent boombox speakers that were 2 OHM to wring out 10w per ch. but still have some decent bass & warmth....The 88s has the same HAF1392's as the 777Z so I wanted to see if the 88s was up to the 2 OHM challenge so I could get some BASS & volume out of this massive looking blaster.

I think I vastly improved it's plyability considering the tiny cabinets...

Chronic
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Thanx BBL48! :-)

UPDATE: The old set of woofers had a bit more midbass detail but these cans do make a noticable difference in dynamic range & clean volume to my ears so I call it a win overall...the tweeters sound more balanced with the woofers too. Before the tweeters were more pronounced & a bit too strong in the upper mids..
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Well, back to the drawing board....the Sanyo 2 OHM woofers were good & I would have kept them but the right woofer had a rubbing coil from day 1 & didn't last the extended listening tests. It started shorting out so I had to revert back to the massive woofers I had installed previously. As you can tell in the video below, it sounds very good with the previous set of woofers, warmer but not as loud as the Sanyos....

https://www.youtube.com/watch?v=pZCePjf0UDw&feature=youtu.be

Cpl
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Ok, listened to a few more songs & decided that the upper midrange suffers a hole, muting the upper octaves of voices, instruments etc. while the tweeters sounded too pronounced & unconnected to the rest of the sound spectrum...will try 3.3uF & 4.7uF caps to correct it...

Stay tuned...

Cpl
 
Cpl-Chronic

Cpl-Chronic

Member (SA)
Yeah, double checking the math & 6 OHMS inline with 2.2uF caps cuts it off at 12Khz, above the 10Khz treble point of most blasters. 3.3uF will drop the cutoff to 8Khz, just about right, creating a 6db drop @ 4Khz & 12db drop @ 2Khz....

That should sound pretty good with normal Bass & Treble settings...

Stay tuned...
 
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