Increasing HF attenuation on S3100 MKII network

[kelossus]

I'd like to increase the attenuation on the HF section of my current speakers. These speakers have a rotary switch on the back with 3 separate positions, -1db , flat and +1db. A rather useless amount of attentuation. I would like to increase attenuation to at least -3db and -6db. Does anyone with passive crossover knowledge know which parts I need to change and to roughly what values?

[Robh3606]

How are you running them?? Simple way would be to passive bi-amp them and attenuate the HF amp using the sensitivity control on the HF amp. Providing they use jumpers you could remove and separate the LF HF inputs.

Modifying the passive network will not be easy you are changing both the resistors and the HF bypass cap values. You would have to work out the values changes in LEAP or equivalent as an example.

You might be able to work it out using a dummy load without measurements but measurements would be preferred.

Rob

[Ian Mackenzie]

If you put a fixed pad on the horn with 6.2 ohm resistance in series and in parallel with the horn compression driver it will help. But you will need to experiment. My is to use a variable 8 ohm L pad. Once you have the right setting swap out the L pad with fixed resistors.

[Robh3606]

If you put a fixed pad on the horn with 6.2 ohm resistance in series and in parallel with the horn compression driver it will help. But you will need to experiment. My is to use a variable 8 ohm L pad. Once you have the right setting swap out the L pad with fixed resistors.

You talking a pad before the input connectors? That 0db looks like a 62? Strange?

Rob

[Ian Mackenzie]

It’s on the driver not the input of the horn network. We use it as a simple pad for biamping. It’s 6.2R in series with the driver and a 6.2R resistance in parallel with the actual driver.

Based on an average 10 ohm driver impedance this is a consistent impedance for the network

Calculation
For driver impedance of 10R (1/x) = 0.1 in parallel with 6.2R (1/x) => 0.16

Then 0.26 (1/x ) = 3.84 R,

Then add 6.2 R + 3.84 R = 10 ohms.

Greg had been using this pad for years on compression drivers.

It’s a starting point in the absence of real measurements in this situation.

I may pop down and check it out.

To be clear this is a fixed constant impedance attenuation. Place it on the driver after the network. Before the network will not work.

[Robh3606]

Based on an average 10 ohm driver impedance this is a consistent impedance for the network

Hello Ian

Hey heads up. Looking at the 3100 Mk 2 it uses the 8 ohm version. Apparently there are an H and J versions.

DCR is 3.2 ohms

Rob

[Ian Mackenzie]

You talking a pad before the input connectors? That 0db looks like a 62? Strange?

Rob

It 1.00 am over there.

Yes you right. I think the schematic has a mistake in it. Not the first time unfortunately. Between that and the BS JBL marketing it’s no wonder there are a few disagreements….Lol. I stumped my little toe this morning so l am a bit slow.

*Hey, Check out the feedback from Greg on the Array 1400 in the imaging thread. I’m gona build a poor man’s diy Array…Lol.

[Mr. Widget]

I'd like to increase the attenuation on the HF section of my current speakers. These speakers have a rotary switch on the back with 3 separate positions, -1db , flat and +1db. A rather useless amount of attentuation. I would like to increase attenuation to at least -3db and -6db. Does anyone with passive crossover knowledge know which parts I need to change and to roughly what values?

Do the right thing... through a DSP in the system and you can fix a lot of other issues too.

Analog and passive have their place, but this is 2024 and adding a little contemporary tech in there is really the right answer.


Widget

[grumpy]

dumb thought... Treble knob?

[Robh3606]

dumb thought... Treble knob?

LOL! You mean from when you had preamps with tone controls with selectable shelving, MM/MC phono stages, Cartridge loading., a stereo/mono switch and so on as SOP?

Most preamps this day leave a lot to be desired.

No not a dumb thought!

Rob

[toddalin]

If you put a resistor BEFORE the first element of a 2nd+ order crossover, you reduce the volume but you don't change the slope. I actually demonstrated this on the other forum.

That said, you could try to put a resistor BEFORE the Red terminal that goes to the horn section of the crossover. A resistor in this position goes a long way so you would use a low value (couple ohms or less) that could carry the wattage.

https://audiokarma.org/forums/index....etwork.926881/

[kelossus]

If you put a resistor BEFORE the first element of a 2nd+ order crossover, you reduce the volume but you don't change the slope. I actually demonstrated this on the other forum. That said, you could try to put a resistor BEFORE the Red terminal that goes to the horn section of the crossover. A resistor in this position goes a long way so you would use a low value (couple ohms or less) that could carry the wattage. https://audiokarma.org/forums/index....etwork.926881/

This is how I am running them now. With 5.1 ohm 10 watt resistor in series with the red terminal of the HF section. I've given the speakers a good flogging and the resistor doesn't seem to get hot.

[Ian Mackenzie]

Hi Earl and Todd,

For the benefit of others it would be cool if you can collaborate together on illustrating the effects of these sort of network modifications with some simulations (voltage drives) and practical implementation with FR measurements.

In this situation Kelossus had a particular need to modify the tonal balance of the S3100mk2 for his preference in line with the 43XX series. The modification outlined here is not a cure but is an easy diy tweak until the owner decides on something more sophisticated such as a line level response tile with bass boost and treble cut or other EQ.

In other circumstances a fix L pad to replace a variable Lpad might be desired. But how does the owner go about this?

I am sure others would find this interesting.