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Crossover Network Help Please!

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photoman2

Member
I have a pair of Advent AS2's and would like to make a change to the network that would yield more power to the tweeter.. I have a backyard knowledge of crossovers networks.. For those who can help but don't know this speaker Advent the off brand *now* Name of the newer Advent SA2's I will describe them and then network. They are a floor standing 2 way system with two 6 1/2 woofers and one soft dome liquid cooed tweeter.
The crossover network works well and is well thought out, sound is nice and smooth.. My goal is just to let a bit more power to the soft dome and not change it's crossover point..
Ok back to the network.. It has dual binding posts and component wise it has two chocks one larger wire wound and one smaller ion core wire wound, it also has two caps one large and one smaller with two resisters wire wound in a ceramic oblong square.. One looks to measure 5.4 ohms and the other 1.2 ohms.. I'm not sure that this matters as I think I have to short out one with a pice of wire to boost the power to the tweeter.. The speakers are rated at 200 Watts continuous power and think it's rated so high do to the resisters in the network on the most part.. They would more then likely never see more then 100 clean watts.. Can someone help me out with the info I have provided? Thanks! George
 
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I pulled the network out and took a few pictures of it will be a few days before I get to uploading to the computer.. I'll post it if that will help.. Thanks! George
 
I didn't hear you say anything about a resistor is series with the tweeter. If there is no resistor, you are out of luck,

Changing the caps will alter the xover frequency.

You best bet is to use an EQ to boost the HF in your amp.

Regards,
Jerry
 
Jerry
Thanks for your help and input.. I know I could even just tun up my treble control but with so many years of much better speakers I just can't push myself to do that.. I have been into EQ's * had many* over the years and I found myself always fiddling with it to the point of fault and losing my music enjoyment.. These Speakers are darn good for the money with a excellent built box and I think well worth a little tweaking of the network.. I have no interest in changing out a cap for a different value as I don't want to change it's crossover frequency.. I do have two ceramic wire wound resistors that look to be in series going to the tweeter so they have less out put* IMO* and if I was to eliminate one this would bring up the SLP to the tweeter without significant change in cross over frequency I believe.. This is my goal! I still cannot find the time to draw a schematic. Dose this sound logical?George
 
Yep, sounds reasonable.

Just remember, George, any significant resistance change will also impact the xover frequency.

We must remember that the xover frequency is that frequency were both drivers are putting out 50% of the sound. When you increase the sound output of the tweeter with respect to the low frequency drivers, you are lowering the xover frequency.

Your speaker manufacturer took all of this into account and designed the xover network to achieve the flatest overall frequency response.

If you want to maintain that terrific flat response of the Advents, gain some emphasis in the high frequencies and NOT mess with EQ's, you might try passive bi-amping.

This way you have two independent amps powering each half of the speaker. Via the volume controls on these amps, you can balance the sound to your taste based upon the music source (CD's, vinyl, FM, etc.).

Hope this helps ...

Regards,
Jerry

PS: This is what I do with my AR's and I love the sound and ... the control I get.
 
Jerry,
Thanks! Good thinking..I do have dual binding posts.. I never used bi-amping before! I do have another 100watt X2 amp hanging around here not in use.. Will my main amp control my Bi-amp speakers amp once I get it balanced out?How would the hookup go?
The Advednts I'm taking about are the new ones Now made in China not the good old one of years ago. I don't think much testing was done I bet most all of it was built on a computer and they called it good.. These are ported speakers with dual 6 1/2 woofers and they used fiberglass for insulation.. I have not see that here in the USA in 20+ years.. So I'm thinking that there are some design floors in there attempt at marketing the speakers.. George
 
photoman2 said:
Jerry,
Thanks! Good thinking..I do have dual binding posts.. I never used bi-amping before! I do have another 100watt X2 amp hanging around here not in use.. Will my main amp control my Bi-amp speakers amp once I get it balanced out?How would the hookup go?
Click to expand...

The easiest way to hook up a passive bi-amp, is to select one amp as your main. The main then controls the source. Hook audio cables between the tape out on the main to the tape in on the secondary.

Now you have two independent volume controls; one for each half of the speaker. This is what you want as the balance of lows to highs varies greatly by music source. (Vinyl for example, usually has greatly emphasized high frequencies.)

Hook your main to either the low or high frequency posts on the speakers. Usually you have the more powerful amp driving the woofers. YOU MUST REMOVE THE STRAPS ON THE SPEAKERS THAT JUMPERS BOTH HALVES OF THE SPEAKERS TOGETHER. Then hook your secondary amp to the remaining posts on the speakers.

Once connected, set the volume controls on both amps at minimum and then turn everything on. Slowly increase the volume control of the main and you should hear music from both speakers, but just from half of each speaker. Turn the main down and slowly increase the volume on the secondary and you should hear music from the other half of both speakers.

Now bring the main up and balance to your taste.

Good luck!!

Jerry
 
Zilch,
Here is the info you requested, I hope you can make out my Hand drawn schematic!! I also took a few pictures that had been taken in a way so you can read the board from front to back.. *Please Note* That the 10w 1RJ resistor measures 1.4 ohm, and the 10w12RJ measures 4.2 ohms this is with the resistors still in circuit on the board.. I hope you have a recommendation on elimination of one of them or replacing one with a different value.. Thanks for your help!! George
hand2crossovervh0.jpg

Shot at 2008-02-03
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Shot with MAXXUM 5D at 2008-02-03
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Shot with MAXXUM 5D at 2008-02-03
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Shot with MAXXUM 5D at 2008-02-03
TRY this link.. If you can't see the pictures here. Best I can do.. http://www.flickr.com/photos/23431649@N05/



For some reason I can't post host the pictures any chance you can send me your e mail in a PM and I'll send them to ya.. I can try sending them to ya in a PM too.. Thanks again..
 
Jerry,
Thanks for the detailed info on the hookup.. I will give it a try if I can find a space to run the extra amp.. Wife is not so hot on the idea of more audio junk in the living room.. The only place I can set things up! I'll check out both ways of tweaking then setup one way or the other.. Thanks Again!! I'll post and let you know what I did and how i made out..
 
It's a three-pole filter on the tweeter, and the two resistors comprise an L-Pad.

Either shorting the 1-Ohm or removing the 12-Ohm will give you more drive to the tweeter.

Doing both will boost it 2.5 dB, assuming a 4-Ohm tweeter. That's 78% more power to it.... :scratch2:
 
Zilch,

I'm not to good *as you can tell* at reading the circuit especially the two resistor L-pad one.. I'm not sure how the cap,coil, and resistor works together.. I'm guessing that the cap is the X over frequency that it uses as cut off to the tweeter and this is achieved by the use of the coil and the 1 ohm resistor.. The other resistor 12ohm * measures 4.2 in the circuit for some reason* is used to change the load so the tweeter See's less power.. I know this is way oversimplified for you but I'm trying to understand it to make my best choice.. I'm not sure what the 1 role the 1 ohm resistor plays in the circuit, help me understand it if you can.. If your estimate is correct 78% is far to much.. I'm thinking more like 25%.. so would replacing the 12ohm resistor get me close to that with say a 6 ohm one? Also why does the 12 ohm resistor measure 4.2 again in the circuit? This is a dual binding post feed for possible Bi- wiring. I think this makes it harder for me to read. Somehow that 10 uf cap, 1 ohm resistor and the 0.235 mH choke only plays a part in the tweeter circuit when the bars are on the binding posts. IMO they are not in use when Bi wiring is.. Is this correct? Thanks! George
 
Zilch,
Thanks for the great link! Lots of good reading there for sure. It will help!
On your attachment Looking that the circuit it looks like they use both the + and -. One side has the 12 ohm resistor this is the - side and the + side incorporates the 1 ohm resistor and the 0.235mH choke and the 10uf cap.. Does this make sense to you? George
 
You'll have to figure it from here. I've done what I can from your pics and drawing.

You can see why the 12-Ohm resistor measures differently in the circuit.

Removing it and measuring won't tell you any more than what it says on it.

If you want different attenuation, Elliot tells you how to calculate the L-pad. R1 gets smaller, and R2 larger, for more drive to the tweeter.... :yes:
 
Thank you for your help. Looks like i have some reading to do and at least one stop at Radio Shack for some parts and figure what I have to do to get the output up about 25%.. George
 
I think Zilch has got it. Though it appears that the tweeter is wire in reverse polarity. That's an interesting note but not significant.

Simply press a hot soldering iron to the solder trace on one end of the 12RJ resistor, when the solder melts, pull that end free and tape it up to prevent an accidental short. That should increase the volume on the tweeter.

If that works and you want more, you could short the 1Rj resistor, and that should give you everything that is potentially available.

Best to do one speaker at a time so you can compare them side-by-side.

I really don't think shifting the crossover point will help at all.
 
Bluewizard,
Thanks! I'll give that try! Strange about the revere polarity on the tweeter! Would it add any SLP or brightness if I got the polarity right on the tweeter's by reversing the wires? George
 
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