4410 crossover in a L80T (GI)

[dub]

Hi!

My project is to implement a 4410 network into an existing JBL L80T GI speaker.

There is only two questions left:

Do I get it right, that I can use the existing crossover layout adjusting to the 4410 values?
Polarities should be equal, right?

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Second question:

Which L-pad replacing resistor values would you recommend to pad down mid and high frequencies?
I will not be using adjustable pads.

The 80T network is using 3.9 / 20 ohms where the 4410a uses 1.2 / 10 ohms for the midrange. Same question for the high frequencies...

Thanks,

Marc

[BMWCCA]

I have two pairs of L80Ts, both modified with L80T3 crossovers as well as Gordon's recommendation for lengthening the port tube and packing additional insulation in the top.

Is it possible the GI version already has T3 crossovers?

What changes are you hoping to achieve?

Check this thread (there are many others): http://www.audioheritage.org/vbulletin/showthread.php?31044-L100t-Crossover-Image

[dub]

My crossover is somewhere in between. It has a 13.5 mfd cap for the midrange.

Everybody seems to like the 4410 sound, whereas there are different opinions about t vs t3.

I am looking for a clearer, more transparent midrange which is one of the reasons why I intend not to pad it down too much.

Any suggestions for the resistance values to replace the l-pads with?

[Robh3606]

Any suggestions for the resistance values to replace the l-pads with?

Hello dub

Build with the L-Pads adjust to your preferred sound then measure across the legs and put in resistors of the same value or just leave them be.

Rob:)

[dub]

This would certainly be a good idea.

Unfortunately I do not have those l-pads...

I am fully aware of L-pad calculators, just not too confident about the actual effective sensitivity values

[Robh3606]

Unfortunately I do not have those l-pads..

Just purchase them they are an easy find.


https://www.parts-express.com/cat/speaker-l-pads/306


Rob:)

[SEAWOLF97]

does the difference in box volume affect this ?

[Robh3606]

Hello Seawolf

It could change the low end a bit depending on how different the boxes are tuned but the crossover won't be affected.

Rob:)

[dub]

Hi Rob (and others ),

I would like to thank you for your advice and the link provided.

I will be receiving my order tomorrow with an assortment of resistors and will proceed with these fixed ones.

Could somebody please just confirm if two values are correct:

- may I assume 4 ohms as nominal impedance for the standard mid and high frequency drivers?

- is the sensitivity of 94db for the mid and 92db for the high frequency driver correct to function as a reference for calculation? The 4410 manual states these values.

Marc

[dub]

Trying to ask in a different way: What impedance (ohms) do the original l-pads of the 4410 have?

Merry Christmas everyone!

[Robh3606]

8 ohms

Rob:)

[dub]

Thank you very much, Rob. That helps me a lot.

Now the high frequency section of the schematic is easy to copy.

Since I don't have those pads I just want to avoid having to perform trial and error more often than necessary...

Now for the 104h-2: Technically it looks as if I just have to add a given wiper (serial) position of the 58450 L-pad (let's assume the 0 db setting) to the preceding fixed 1.2 ohms in the schematic.
And then parallel the result of 20 ohms with the paralell reading of the pad. (see schematic below which is identical to the 4410)

The frequency curve in the 4410 manual shows the 0 db setting to be flat. Is that what most people use?
Could be a little too hot, right?

Marc

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