Speaker matching

[hebaton]

I am wondering if there is a way to compensate for different efficiency/sensitivity between speakers.
Could you put a 97 db/1W/1M with a 100 db/1W/1m together and have a resistor before 100db one ?
If so, how would the value of the resistor be measured ?

THanks to any one who can either answer or point me to a source where I can find such info!

[Stevem]

The peak sensitivity rating of any speaker takes place at a certain given frequency, not across the whole frequency spectrum.

For example your 97 DB rated driver might have that SPL level at 2K and the 100 DB rated drive might have hit its peak 3.5k.

As I hope you can see there is no way to use just a resistor to do what your looking to achieve, and besides there is problem that I have ever come across with two different SPL rated drivers.

You main concern should be how well they play together tone wise to fit your notion of what sounds good.

[hebaton]

I hear you, yet whaen hi fi audio speakers are designed, I am sure drivers of varying sensitivities are used to build 2 or 3 way spealer system. So I would think some sort of "balancing " is happening in the CRossover system ?

[TUBEDUDE]

Your talking about the crossover network to send different frequency bands to different drivers. So the bass doesn't kill the tweeter. If you are using 2 12's that's not the.case.
If you are trying to separate the frequency bands, then yes, as you seperate the signals you can pad down the woofer or tweeter for better balance.between the two.

[hebaton]

Yes, but all the drivers in those speakers have different efficiency for their target frequency range, they still have to ba matched so that all frequesncies reach the listener at the appropriate amplitude

[LOUDthud]

If needed, a tweeter of midrange will have an attenuator (volume control) on the back of the speaker cabinet. For guitar speakers, simply use a resistor in series with the loudest speaker. Something in the range of 8 to 20 Ohms with a power rating about half the speaker's power rating. It will get hot.

[hebaton]

If needed, a tweeter of midrange will have an attenuator (volume control) on the back of the speaker cabinet. For guitar speakers, simply use a resistor in series with the loudest speaker. Something in the range of 8 to 20 Ohms with a power rating about half the speaker's power rating. It will get hot.

that was my thinking. Do you know of a way to calculate the optimal value of the resistor ?

[LOUDthud]

Assuming an 8 Ohm speaker, 3.4 Ohms in series would give a 3dB reduction, 8 Ohms would give a 6dB reduction. The most reduction will be between 200Hz to 800Hz, bass and treble not as much reduction.

If the speakers are 16 Ohm, you have the option to run one from an 8 Ohm tap and the other from the 4 Ohm tap.

Weber used to sell an impedance matching transformer (didn't see it last time I looked) that could be used to reduce Voltage going to the louder speaker.

[hebaton]

Assuming an 8 Ohm speaker, 3.4 Ohms in series would give a 3dB reduction, 8 Ohms would give a 6dB reduction. The most reduction will be between 200Hz to 800Hz, bass and treble not as much reduction.

If the speakers are 16 Ohm, you have the option to run one from an 8 Ohm tap and the other from the 4 Ohm tap.

Weber used to sell an impedance matching transformer (didn't see it last time I looked) that could be used to reduce Voltage going to the louder speaker.

Great, so assuming one 97 db efficient speaker you want to match with a 100db eficient speaker, Using the Weber impedance matching box running the 8ohm 100db speaker on ath boxe's 4 ohm setting while runnimg the 87 db directly out of the amps 8ohm tap would be a fairly good solution here ? or is this the 16ohm setting ????

[LOUDthud]

Again, you haven't said what impedance the speakers are or the amps intended load impedance.

If your amp has an wants a 4 Ohm load, I would connect the Weber Z matching transformer's 8 Ohm tap to the amp. Then connect the 8 Ohm 97dB speaker to the amp and the 100dB speaker to the Z matcher's 4 Ohm tap. The amp will see a 5.33 Ohm load.

Note: Voltage wise, when you select an impedance tap that is half the impedance, the Voltage is 0.707 times less. That's 3dB. On the typical 16-8-4 transformer, the 4 Ohm tap is the center tap. Do the math(s). Voltage = SQUARE ROOT ( Power * Resistance ). Calculate the Voltage for 50W @ 16 Ohm, 50W @ 8 Ohm, 50W @ 4 Ohm.

[hebaton]

THe amp has 4, 8 and 16 ohms taps. THe speakers both 8 ohms
My head is spinning a bit.

THe Zmatcher has 1 in two outs ( parallel ) The amp ha two outs ( parallel ) and an impedance switch,
So zmatcher set to present 16 ohms to one out with the 100db speaker and the 97 db to the other amp out directly
amp on 4 ohms

1/ (1/8 + 1/16 ) = 5.3

Correct ?

[pdf64]

I am wondering if there is a way to compensate for different efficiency/sensitivity between speakers.
Could you put a 97 db/1W/1M with a 100 db/1W/1m together and have a resistor before 100db one ?
If so, how would the value of the resistor be measured ?

THanks to any one who can either answer or point me to a source where I can find such info!

Have you tried both the speakers together and noticed a problem, eg one drowning out the other?

Or is this just a problem you're assuming would occur, based on the speaker model data?

[LOUDthud]

THe Zmatcher has 1 in two outs ( parallel ) The amp ha two outs ( parallel ) and an impedance switch,
So zmatcher set to present 16 ohms to one out with the 100db speaker and the 97 db to the other amp out directly
amp on 4 ohms

I was thinking about the naked transformer, not the one in a box with the jacks and switches added.
Looking at the picture https://www.tedweber.com/?s=z+matcher I would set the amp switch to 8 Ohm and the Speaker switch to 4 Ohms.

1/ (1/8 + 1/16 ) = 5.3 Correct ?

Yes, I don't see many people using that formula. If you're clever, you can work it backwards. What resistor do you need in parallel with a 5.3 Ohm load to make it 4 Ohms ? 1/ (1/4 - 1/5.3) = 16.3 (round off error because 5.3 should be 5.3333333). The 1/X key gets a lot of work on my calculator.

[hebaton]

I am wondering if there is a way to compensate for different efficiency/sensitivity between speakers.
Could you put a 97 db/1W/1M with a 100 db/1W/1m together and have a resistor before 100db one ?
If so, how would the value of the resistor be measured ?

THanks to any one who can either answer or point me to a source where I can find such info!

Have you tried both the speakers together and noticed a problem, eg one drowning out the other?

Or is this just a problem you're assuming would occur, based on the speaker model data?

THe question is because I am wanting to try a mix of speakers but trying to anticipate problems. But I know 3 db is quite an imprtant difference, it can represent double the percieved loudness.

[Phil_S]

While I can see there is a potential problem, you may be overthinking this...looking for a solution in search of a problem. See if you can impedance match to the transformer and give it a try. Either you like the result or you don't. If you don't, you can think about the next step.