[SamL]

Just wonder anyone here use their power amp to drive a subwoofer and how they control the phase, crossover frequency cut off, delay, bass boot and etc.


Sam

[SamL]

Just found an interesting product from BK Electronic in UK.
http://www.bkelec.com/Diy/sbp.htm

Pretty reasonable price. However, the phase control look like a on/off option 0 or 180D and nothing in between. Which may be a problem for some system.
Hay Hugh, will we be seeing a 200W amp kit in the future? Will you sell just one channel?

Sam

[JohnR]

Off the top of my head, you can get a kit which will do these kinds of things from marchand. I believe Jaycar even has something in a kit, which would get you started - ?

[SamL]

John,
Is this what you refering to?

Stock Code: KA1814
https://secure2.vivid-design.com.au/jaycar/productView.asp?ID=KA1814&CATID=25&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=xxxxxxxxxx&Keyword2=xxxxxxxxxx&pageNumber=&priceMin=&priceMax=&SUBCATID=557

For the price, I will give it a go.

Thanks,
Sam

[AKSA]

Hi Sam,

Thinking of a 200W AKSA.  Done most of the work, but not yet!!

Cheers,

Hugh

[JohnR]

Sam, that looks like the one. It doesn't have phase control by the looks of it, but since it has an inverted output you could at least do 0/180 degrees. As you say, for the price it's worth a go and you could at least learn something from it

[PSP]

I'm using a single-channel 100w AKSA to drive a VMPS New Original Sub (efficiency approx 90db).  My crossover is a Marchand XM-9.  

You can feed the signal from your preamp into the XM-9, run the summed low pass output to the sub amp and the high pass output to the main power amp (55w AKSA in my case)... I did that and was not happy with the sound from my mains... a certain edgyness and tizzle to the sound.  What I've ended up doing is running my mains full range (i.e., the XM-9 is not in the main signal path), and using the XM-9 / sub combination to simply fill in the bottom from 40Hz on down.

Preliminary messing around has suggested to me that the mains might sound better if their bass response is curtailed a bit (when the mains play 50 Hz, doppler effects can lead to distortion when the speaker also playing higher frequencies).  Currently, I have plugged a port on each of my main speaks (definite improvement in low midrange clarity); in the next month or so I will try a series cap on the input to the main AKSA amps to roll off the bass at somewhere between 50-100Hz) and fill in the remaining bass with the sub.

The 100w AKSA works very well as a sub amp.  The only modifications were:
- a 1uf RTX input cap vs. the stock input cap
- I doubled the PS caps, this seemed to add some "punch" to the low bass
- I used an inrush-limiting thermistor (because of the 2X power supply caps) to avoid possible stress on the PS diodes

Good luck,
Peter

[SamL]

Thanks for sharing

- a 1uf RTX input cap vs. the stock input cap

That will the C1 on Aksa100 right?
However, I am not sure if aksa100 will be able to drive my Lambda SB10 which is only 86db in a sealed box. A 200w will be good. Anyway, I am thinkning of using my Plinius Sa100 in bridge mode to drive it until I get a sub amp or some sort.

This of course is after I finish building my aksa100n.

Thanks,
Sam

[andyr]

.  What I've ended up doing is running my mains full range (i.e., the XM-9 is not in the main signal ...

Peter, hi.  Yes, I have heard that gently rolling off the main speakers with a series cap (ideally before the amp driving those speakers) is a good thing to do.  You use 43Kohm as the res figure to calculate the cap for your preferred -3dB rolloff point.

Regards,

Andy

[AKSA]

Sam,

I endorse Peter and Andy's comments.

A 100W AKSA on an 85dB/watt/meter speaker produces embarassing amounts of volume;  you really don't need 200W unless you live in a basketball stadium........

Cheers,

Hugh

[andyr]

A 100W AKSA on an 85dB/watt/meter speaker produces embarassing amounts of volume;  you really don't need 200W unless you live in a basketball stadium........

Cheers,

Hugh

C'mon, Hugh, hasn't your daughter taught you that visceral, gut-impacting base is wot ya MUST have   ??  And that needs a minimum of 200w!!

How else does the Sunfire 1000w active sub-woofer sell!!

Regards,

Andy

[SamL]

Ops!   Recheck my figure and the lambda SB10 is actually only 82.7db, plus seal box is 3db less efficient as vented.

Sam

[AKSA]

OK Sam,

You do have an inefficient speaker driver there, no doubt......

So the question is - how loud do you like your bass?  If very loud, to make the floor shake, then 200W is the go.  If you like natural levels, found in real life, then maybe the 100W is still adequate.  

The other issue is movie effects.  If you enjoy car chases, and lots of Spiderman stunts, then you likely need a little more power.

BUT, subjectives are very important here;  you need to be comfortable with your choice.

Cheers,

Hugh

[JohnR]

plus seal box is 3db less efficient as vented.

Um... that doesn't sound right, you don't lose efficiency that way by going for sealed.

I'd give it a go with 100W, or you could bridge a stereo amp (assuming that you have an 8 ohm driver) -- there's your 200W.

[EchiDna]

go with horn loaded subs! more efficiency for your dollar   try LABhorns, DIY, 116db efficient you can get away with the AKSA 55 and still go deaf should you want too....

http://home.comcast.net/~labhorn/

[SamL]

plus seal box is 3db less efficient as vented.

Um... that doesn't sound right, you don't lose efficiency that way by going for sealed.

I'd give it a go with 100W, or you could bridge a stereo amp (assuming that you have an 8 ohm driver) -- there's your 200W.

Sorry I should word it as - vented are generally 3db louder due to the port gain. And mine is a 4ohm driver.