30-50 ohm resister in series with JBL 2446

[David Ketley]

I'm sure I've read somewhere that a 30-50 ohm resister in series with the JBL 2446 takes the distortion at 7000 higher can anyone enlighten me on this?

Dave

[ivica]

I'm sure I've read somewhere that a 30-50 ohm resister in series with the JBL 2446 takes the distortion at 7000 higher can anyone enlighten me on this?

Dave

Hi Dave,

I think that so large resistor "in-series" with 2446 would not be the best solution if You want to reduce its output level.
Usually one "in-series' and one "in-parallel" would be better solution. Values depends on the 'reduction level' You want to get.
In the first quest You can use that the 2446 impedance is about 12~16 Ohms....

reagrds
ivica

[martin2395]

Also, I've been told not to use a single resistor but at least 2 or 3 paralelled and then put these in series.

[pos]

When putting such a high value resistors in series you are basically leaning toward current drive mode.
This can reduce distortion, especially with woofers, but will also change the frequency response of the driver, so beware...

[David Ketley]

I'm sure I've read somewhere that a 30-50 ohm resister in series with the JBL 2446 takes the distortion at 7000 higher can anyone enlighten me on this?

Dave

I see its already been well covered here http://www.audioheritage.org/vbullet...hp/t-7027.html

Dave

[pos]

So you meant a parallel resistor, not a series one.

[David Ketley]

So you meant a parallel resistor, not a series one.

I had only a very brief note of a series resistor being used but this discussion clears up a lot of my questions.

Dave

[Ian Mackenzie]

Pos is right.

Nelson Pass has written an article on this topic for the Amplifiers that have this property..

The modification to the response will be more significant than a reduction in distortion as an audible change.

At the low frequency end it will effect the crossover characteristic where you are using a passive crossover network.


What type of diaphragm are you using?

Since that very old thread there have been advances in both diaphragm and horn design.

If you have access to a RTA it will help validate any modifications.

Back to the point I am aware of resistive shunting of drivers.

Basically a driver is an electro mechanical motor that is not resistive but can be also inductive. By swamping the impedance with a low value resister the driver becomes largely a resister by characteristic. This is good for the driver and good for the network looking at the driver. The overall impedance would still need to be a suitable load for the amplifier

Assuming a loss in sensitivity is not a problem there are advantages.

I would also have a read of the crossover design paper on the PI loudspeaker site

[David Ketley]

Pos is right.

Nelson Pass has written an article on this topic for the Amplifiers that have this property..

The modification to the response will be more significant than a reduction in distortion as an audible change.

At the low frequency end it will effect the crossover characteristic where you are using a passive crossover network.


What type of diaphragm are you using?

Since that very old thread there have been advances in both diaphragm and horn design.

If you have access to a RTA it will help validate any modifications.

Back to the point I am aware of resistive shunting of drivers.

Basically a driver is an electro mechanical motor that is not resistive but can be also inductive. By swamping the impedance with a low value resister the driver becomes largely a resister by characteristic. This is good for the driver and good for the network looking at the driver. The overall impedance would still need to be a suitable load for the amplifier

Assuming a loss in sensitivity is not a problem there are advantages.

I would also have a read of the crossover design paper on the PI loudspeaker site

Thanks Ian,
Im using the Jbl 2446 with the JBL diaphragms not Beryllium yet that is a cost I will have to defer for a while. Its the fact that in the region I want to cross to the JBL 2405 8000hz I gather there are issues with the response there. Im using three way active with a Marchand crossover then a cap or high pass filter to the 2405s, but wondered what resisters in series or parallel would do to the upper response of the 2446?
Does a L pad have the same sort of affect on the frequency response and distortion after all these are series parallel resisters? I run Musical Fidelity amplifiers.