Speaker Attenuation...

jakelm

Attenuating an entire speaker?


Stacked speakers in certain applications can sound very good, but in my situation, one pair of speakers is slightly louder than the other. Which way is best to attenuate that pair? An inline resistor? What is the best way to attenuate an entire speaker, without, hurting the speaker's characteristics?




Jake

jakelm

To give alittle more info, I have combined my 4's and my 7's as mains. My 4's are a few feet above and to the side of the 7's, but are alittle louder than the 7's. Being they are alittle more efficient. Ther are connected in paralell wireing. This is a test, only a test. Please dont taze me for mixing my 4's with my 7's.:eek::D

jakelm

Where is Ben when you need him...:D















ittty bittty bumpy....

jakelm

The 4's are 8ohms. By adding an 8ohm resistor at the + post, the reciever should see a 16ohm speaker and lower the volume for that speaker. I wish there was a calculation for this. And if this process would effect both speakers or just the one I hooked the resistor to. I need about a 3dB drop.

jakelm

No ideas from anyone??...Ok....

unc2701

It's a simple 2 resistor circuit, see here for calculator:
http://www.mhsoft.nl/spk_calc.asp#att

ben62670

I would go for a single in-line resistor on the negative side of the more efficient speakers. This may have adverse effects on your high pass, but would have less effect on total output of your speakers. Also I recommend staying away from the dual resistor attenuation as it just bleeds of power to ground. Extra heat, and work for amp. I had a bookmark to a site that had the calculations for ohms to db, but I think 1 ohm drops one db. You can test with one of your 2.7ohms that you pulled when you upgraded your XO.... if you kept it. Try stacking your speakers with the tweeters close to each other, and then further away. You may have lobing issues with the higher frequencies. The best solution would be use just one pair of speakers:D

Ben

jakelm

On the negative side?

I was reading about adding a resistor, and read the same effect as what Ben said. resistor heating up and most of the wattage going to the reistor. The 2.7 ohm resistor is only 5 watt, will that be large enough to handle high output from reciever? Will the in-line resistor affect the less efficient speaker?

I am very familliar with attenuating one particular driver at a time, but never tested an entire speaker.

Help me out here,. Attenuating a driver in a xover, the resistor is placed on the +tive side of the board. Ben why am I placing the resistor on the -tive side of the speaker?

The 7's are 6ohms, the 4's are 8ohms. Total is about 3.5ohms. Adding a 2.7ohm resistor would bring the total to 6.2 ohms, which is a safe ohm for the H/K. But, being the H/K is reading 6.2ohms now, the total output is less with the resistor in place.

jakelm

ben62670 wrote: »

I would go for a single in-line resistor on the negative side of the more efficient speakers. This may have adverse effects on your high pass, but would have less effect on total output of your speakers.

I want less effect on high and low pass and more effect on total output. Make it alittle more quiet.

Also I recommend staying away from the dual resistor attenuation as it just bleeds of power to ground. Extra heat, and work for amp.

Ok, dual resistor?

I had a bookmark to a site that had the calculations for ohms to db, but I think 1 ohm drops one db. You can test with one of your 2.7ohms that you pulled when you upgraded your XO.... if you kept it.

Will use the 2.7ohm, if its big enough, its only a 5watt

Try stacking your speakers with the tweeters close to each other, and then further away. You may have lobing issues with the higher frequencies. The best solution would be use just one pair of speakers:D

Ben

They are very close to each other.

There has to be a way to intergrate 2 speakers on a single channel.

Thanks for all you guys help.

Systems

ben62670 wrote: »

This may have adverse effects on your high pass, but would have less effect on total output of your speakers.

Adding a series resistor will give some attenuation ,but it will also affect the Q of the woofer more than anything,so the quality of the bass response might change.

The best solution would be use just one pair of speakers:D

+1

If you must do it I would try and find a 20 watt resistor.

jakelm

Well what parts do manufacturs use when building an attenuator switch/turn knob for outside use? Or light dimming...etc

That type doesnt seem to effect the speaker dynamics.

Systems

jakelm wrote: »

Well what parts do manufacturs use when building an attenuator switch/turn knob for outside use?

Usually high wattage L pads.Also there are some transformer based attenuators that are very good for this purpose as well.

That type doesnt seem to effect the speaker dynamics.

Depends on how much resistance is added.The larger the value added in series, the more woofer damping is affected.

unc2701

Please note that an L-pad is just a variable form of the 2 resistor circuit that I linked above...

The transformer based attenuation is generally the best- any volume lost is turned into current, but they've got issues, too- you need transformers that have good coverage of the audio frequencies for one thing. IIRC the niles wallplates use transformers:
http://cgi.ebay.com/NILES-VCS-100R-high-Power-Stereo-Volume-Control-A-V_W0QQitemZ180205966704QQihZ008QQcategoryZ15065QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

ben62670

To add resistance on the negative side the currant flows from hot to ground. IF you do a currant test on the positive side of the cable more energy travel through it than on the negative side. Energy is spent in the voice coil, and lost as heat. If you didn't loose energy you could hook up 81 speakers in series, and parallel, and they all would get the same voltage. Why burn up energy before it gets to the voice coil via a resistor. I am not saying that this will be the perfect solution. It may throw the XO off enough to barely notice it, or you may not even notice it at all with 2 sets of speakers.

Systems

unc2701 wrote: »

Please note that an L-pad is just a variable form of the 2 resistor circuit that I linked above...

The transformer based attenuation is generally the best- any volume lost is turned into current, but they've got issues, too- you need transformers that have good coverage of the audio frequencies for one thing. IIRC the niles wallplates use transformers:
http://cgi.ebay.com/NILES-VCS-100R-high-Power-Stereo-Volume-Control-A-V_W0QQitemZ180205966704QQihZ008QQcategoryZ15065QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

And both methods are meant for things like outdoor speaks and multi room, not hi fidelity.

Systems

ben62670 wrote: »

To add resistance on the negative side the currant flows from hot to ground.

Its an AC signal so it should'nt matter which polarity the resistor is connected to.

unc2701

ben62670 wrote: »

To add resistance on the negative side the currant flows from hot to ground. IF you do a currant test on the positive side of the cable more energy travel through it than on the negative side. Energy is spent in the voice coil, and lost as heat. If you didn't loose energy you could hook up 81 speakers in series, and parallel, and they all would get the same voltage. Why burn up energy before it gets to the voice coil via a resistor. I am not saying that this will be the perfect solution. It may throw the XO off enough to barely notice it, or you may not even notice it at all with 2 sets of speakers.

How about with a non-common ground amp?

GV#27 wrote: »

And both methods are meant for things like outdoor speaks and multi room, not hi fidelity.

Totally agree there, but they're probably the cheapest solutions that won't totally screw with your load and/or Q.

jakelm

Thanks guys, great info here. I didnt know that it would effect the overall sound quality of the speaker. I thought a resistor would just add ohms and lower dB's. But I'm glad I asked first.

The L pad is what I was thinking, just couldnt spit it out.

These processes that were are talking about, only effects the speaker that the reisistor is hooked to , right. These processes will not, in any way, change the sound quality of the other speaker?

ben62670

You can put a resistor on the positive side of the speaker, and it will not have an adverse effect on the SQ. It just limits power to the speaker. You just need a larger value non inductive resistor to limit currant to the speaker.

unc2701

ben62670 wrote: »

You can put a resistor on the positive side of the speaker, and it will not have an adverse effect on the SQ. It just limits power to the speaker. You just need a larger value non inductive resistor to limit currant to the speaker.

Dude- the power flows BOTH directions. For half the signal, the red terminal will have a negative charge. That's the point GV#27 and I were trying to make. It doesn't matter which side the resistor is on.

jakelm

Will it effect all speakers on that channel, or just that speaker?

jakelm

Just alittle update. I installed Mills 3.5ohm resistors, in series with the 4's. My HK did not like that at all. I had to reset the HK because, for some reason, the L/R channels kicked off. I then installed the resistors on the -tive side, but there was no change.

I do not recommend, for reasons unknown, an istall of a resistor for attenuation.

zingo

Ya, for whatever reason, it sounds like your HK didn't like ther resistance and the protection kicked on. Bummer, but nice try. I thought it was a good idea...

Face

Maybe your HK is trying to tell you something.

jakelm

Face wrote: »

Maybe your HK is trying to tell you something.

It tells me **** all the time, but I dont listen. I put my foot down and say "just do it and dont give me no lip":mad:

I like the fullness the 2 stacked mids give me, Its the tweets are the slight problem. The tweet on the 4's are a tad more eficient. Nothing I cant live with.

My next step is to encrease the ohm's on the xover for the tweets on the 4's.

jakelm

zingo wrote: »

Ya, for whatever reason, it sounds like your HK didn't like ther resistance and the protection kicked on. Bummer, but nice try. I thought it was a good idea...

???? Resistance actually rose higher adding a resistor in series. I am 6ohm for 7's and 8ohm for 4's, Give about 3.5 ohms. With a 3.5 resistor in series with the 4, it should be closer to 4ohms. HK shouldnt have a problem with that. Unless the resistor is taking up too much voltage and confusing the HK, with different volume levels.

8ohm 4's become a 11.5ohm load, in paralell with the 6ohm 7's, 4ohm total.

jakelm

Or I could find 2 Peerless tweets and mod the 4's for them.



^^^ Thats my best option^^^






yes yes yes..I know, My best option is to remove the 4's from the channels:rolleyes:


..but damnit...I dont want to...:p:p.

ShinAce

Attenuation by means of resistors between the amp and crossover will not affect the crossover frequency. This will affect the Q of the speaker amp combo.

The ideal attenuator has 2 resistors, one in series, the other in parallel.

Try the speaker plus attenuation without the second pair as quick elimination test.

edit: Just to confirm, Q is damping and adding resistance will increase it.

jakelm

ShinAce wrote: »

Attenuation by means of resistors between the amp and crossover will not affect the crossover frequency. This will affect the Q of the speaker amp combo.

The ideal attenuator has 2 resistors, one in series, the other in parallel.

Try the speaker plus attenuation without the second pair as quick elimination test.

Like an L pad. I might try that too.

ShinAce

Precisely!

Make note for this to work perfectly, the driver impedance is assumed to be flat. If you do decide to make this a permanent solution, look at a Zobel network for the woofer.

Is this a 2-way or 3 -way speaker?

jakelm

ShinAce wrote: »

Precisely!

Make note for this to work perfectly, the driver impedance is assumed to be flat. If you do decide to make this a permanent solution, look at a Zobel network for the woofer.

Is this a 2-way or 3 -way speaker?

2 way, look at pics above.


I might get the L pads. Will check with parts express.