Transform STK404-130S + board

[themaquise]

Hy guys,

I'm new in electronic and this thread would be quite unusuable
I just bought a Sony Active Subwoofer SA-WMSP85. The amp is STK404-130S. It works perfectly but I don't have a receiver nor do I have the $ to buy one so currently I only have bass.
Here i the active subwoofer:

Here is the amp/circuit board:

Here is the STK amp datasheet: http://pdf.datasheetcatalog.com/data...wlpx9ha3wy.pdf

So my question is where can I plug/weld and a high frequency speakers or how can I modify the amp/board circuit to also provide high frequencies output?

I can provide any additional information if needed.

Thanks.

Cheers.

[J M Fahey]

What kind of program will you listen to?

To be more precise, which will be your Music source?

[themaquise]

What kind of program will you listen to?

To be more precise, which will be your Music source?

Currently the sound source is simply a smartphone and it is quite loud as it is an active subwoofer but still I only have bass. I wondered if there's an amplifier within yhe subwoofer maybe there could be a way to use it to get the amplified sound - high frequency speakers before all the high frequencies gets filtered out.

[Jazz P Bass]

Here are the specs:
Continuous RMS power output
(6 ohms, 20 – 250 Hz)
SA-WMSP85 100 W
Reproduction frequency range
28Hz – 200 Hz
High frequency cut-off frequency
150 Hz
Here is the schematic: SA-WMSP75_WMSP85.pdf

From the looks of it the preamp coupling capacitors seem to be doing all of the frequency cutoff.

Full SM: Sony--SA-WMSP75--service--ID11377.pdf

[J M Fahey]

In principle you may bypass the heavy lowpass filtering at the input and have a flat poweramp.

Problem is the speaker, muddy as h*ll, ZERO mids and highs.

Best is to build a small, simple mid/highs cabinet, say a 6" woofer/mids and a Tweeter, so it plays the "Music" and the subwoofer the deep lows.

Youīll need to drill the SW cabinet to add a connector for the external satellite speaker, and add a simple (2 capacitor) crossover for the mid and high units.

To save on build time, you can slightly mod a small "pawnshop find" cabinet similar to what I suggest.

In theory you might cut 2 larger holes in the SW cabinet and add tghe couple speakers there, but woofer backpressure will damage the midrange unit, so best is to have it separated.

[themaquise]

Thank you Jazz P Bass, those schematics have help a lot!

[themaquise]

In principle you may bypass the heavy lowpass filtering at the input and have a flat poweramp.

Problem is the speaker, muddy as h*ll, ZERO mids and highs.

Best is to build a small, simple mid/highs cabinet, say a 6" woofer/mids and a Tweeter, so it plays the "Music" and the subwoofer the deep lows.

Youīll need to drill the SW cabinet to add a connector for the external satellite speaker, and add a simple (2 capacitor) crossover for the mid and high units.

To save on build time, you can slightly mod a small "pawnshop find" cabinet similar to what I suggest.

In theory you might cut 2 larger holes in the SW cabinet and add tghe couple speakers there, but woofer backpressure will damage the midrange unit, so best is to have it separated.

Thanks Juan,

I will go with your solution.
Based on the schematic given by Jazz P Bass, where could be welded the audio output from the subwoofer to the seperate cabinet?
I have 2 of these satellite speakers which will be used for this project:


Concerning the seperate cabinet, will it have its own power source, amp etc. Could you please indicate/provide a tutorial (coud be an online tut.) to build one?
A simple amp from 2 or 3 transistors for the mid and high end should be ok as I have kept aside few transistors from a non working woofer:


Thanks.

[J M Fahey]

OK.

2 options:

1) the Full Mon ty one: get a cheap EBay mono/stereo amplifier to drive the satellites, make a split box to connect Smartphone to Stereo/Mono amplifier which in due time powers the satellites (even 10W + 10W will be ample for Home use) and active subwoofer to give them power/"oomph"

Itīs just a small plastic or mints box with and input jack (from phone) and 3 output jacks: Left, Right and Sub + 2 mixing resistoras, 1k or 2k2 is fine.

2) Plan B: Iīll upload the corrected schematic so STK module becomes full range, then goes into a simple crossover which you mount on subwoofer inside .
Its woofer output goes to internal speaker, its high frequency one goes to 2 connectors mounted on subwoofer side or back wall and then to satellites.

I suggest wiring them in series, so combined satellite impedance is higher and single STK module can drive both them and woofer.

Any data/info on satellites? At least impedance.

Almost forgot, system will be Mono (we have a grand total of *one* power amp but thatīs not a big deal.

[themaquise]

OK.

2 options:

1) the Full Mon ty one: get a cheap EBay mono/stereo amplifier to drive the satellites, make a split box to connect Smartphone to Stereo/Mono amplifier which in due time powers the satellites (even 10W + 10W will be ample for Home use) and active subwoofer to give them power/"oomph"

Itīs just a small plastic or mints box with and input jack (from phone) and 3 output jacks: Left, Right and Sub + 2 mixing resistoras, 1k or 2k2 is fine.

2) Plan B: Iīll upload the corrected schematic so STK module becomes full range, then goes into a simple crossover which you mount on subwoofer inside .
Its woofer output goes to internal speaker, its high frequency one goes to 2 connectors mounted on subwoofer side or back wall and then to satellites.

I suggest wiring them in series, so combined satellite impedance is higher and single STK module can drive both them and woofer.

Any data/info on satellites? At least impedance.

Almost forgot, system will be Mono (we have a grand total of *one* power amp but thatīs not a big deal.

Thanks Juan,
I've thought about it and I'll go with plan B.
Once I have your schematic I'll have to remove/short circuit the appropriate indicated resitor, capacitor, etc. I have a spare volume treeble, bass volume control which also be used if it is going to be full range.
The impedance of the satellite speakers is 6ohm.

Thanks.

[themaquise]

Hi Juan,
Sorry, forget the spare treeble, bass, volume control as these will be handled by the equalizer from the audio source (poweramp Android - Samsung S7).
Will then only need help to modify the board (remove capacitors, resistors...) to make the amp amplify all ranges without filtering out the mid and high ranges.
And also the subwoofer speaker will not be used but I'll use the two sony speakers below:

They already have built in crossovers for the built in tweeters.
Thanks.

[J M Fahey]

Ok.
A tree fell and physically cut my phone line so no p'hone or Internet, now **crawling** using my sloooowww phone so minimizing data transfer but when normal will upload a couple drawings.

So you will not use the subwoofer?

Will you enclose the plate amp in its own new enclosure or leave it in the original one?

[themaquise]

I forgot to mention, the active subwoofer amp will be moved to another smaller encloser and the subwoofer speaker will not be used but will use the 2 Sony speakers as indicated above.
I've already started working on the encloser...
And thank you for your time in helping me out with this