First Watt for 112 and 109 db speakers

[noviygera]

Hi,

I am in the process of moving from a digital crossover to a passive one for my mid and high horns. Even though both speakers are made by one company, Funktion-One, the tweeter horn is 112db/watt (12 ohms)and the mid is 109db efficient(16 ohms). One option is to use one good amp and pad down the tweeter, other option to use separate amplifiers with very similar sound signature for tweeter and mid but with different gain, to eliminate the padding.

I am thinking about giving the First Watt amps a try (currently using Jeff Rowland and Arcam amps). My goal is to preserve the class A sound of Rowland and possibly even improve on it and have consistency in sound.

Any of the two above options seem advantageous? Other good solutions I should consider?

Thanks,
Herman

 

[westend]

Biamping/triamping does it for me so two amps would be a good thing.
An easier path would be to design a crossover network with Lpads or fixed resistors to deal with any level difference.

 

[Nelson Pass]

I would try an F3 with a passive crossover for the mid/top.

😎

 

[noviygera]

Thank you. For the F3 amplifier, would a series crossover with high impedance work better? 28 ohm vs. 7 ohm load if wired in parallel ?

Herman

 

[Nelson Pass]

A parallel crossover will easier to work with, I think. You might just want to
pad the tweeter with a 16 ohm L pad (you can replace it with fixed values
later if you want), and cobble together the appropriate passive. The F3
should be happy 8 to 16 ohms.

😎

 

[noviygera]

Mr. Pass,

What would be your opinion on J2 vs F3 vs F2 in terms of background noise on very eff high horn with one capacitor as the high pass?

Herman

 

[Zen Mod]

that's easy - just compare their noise figures

pdfs are on FIRST WATT HOME

or like this :

http://www.firstwatt.com/pdf/prod_j2_man.pdf

http://www.firstwatt.com/pdf/prod_f3_man.pdf

http://www.firstwatt.com/pdf/prod_f2_man.pdf

 

[woody]

Using a single capacitor for a compression driver isn't a good idea. Take this example
you have a 8 ohm driver that has a 32 ohm impedience peak at 500hz and you are going to cross it over at 2000 hz with a single capacitor. So by 500hz it should be
down 15db but because of that 32 ohm impedience peak it will only be down about 4db. This was off the top of my head and my math is realy bad but this gives you a
rough idea and your power handeling is also much less with a 6db/oct crossover.

 

[Roscoe Primrose]

If you're using a compression driver in a home environment, and you're pushing it hard enough that you need to worry about power handling, your ears will burn out long before the diaphragm....

Roscoe

 

[noviygera]

>> So by 500hz it should be down 15db but because of that 32 ohm impedience peak it will only be down about 4db.

One of the reasons why I was considering using line level passive filter instead of the speaker level. Will it work with Pass Labs F3 amp - single cap for a first order high pass? How do I calculate the value of the filter cap?

 

[AndrewT]

Yes, combine the speaker level passive filter (DC protection) with the passive line level filter and the passive tweeter roll-off for an 18dB/oct filter/crossover.

Alternatively add an active, either single pole or two pole, filter with a suitable Q to compensate for two of the passive Qs and eliminate the third passive to get a 24dB/oct filter. In this case I would eliminate the natural tweeter roll off from the filtering by moving all the other filters up by an octave or two.

 

[tiefbassuebertr]

Very good thread; my prefered solution here is a combination from a passive and an active crossover without additional op amp resp. line amp stages (path lenght of audio signal must be as short as possible, particullary for mid-low horns with very high efficiency) - go to post #342 about
http://www.diyaudio.com/forums/pass-labs/153832-pass-delite-amp-baf-35.html
and to post #101 about
http://www.diyaudio.com/forums/pass-labs/166784-pictures-your-diy-pass-amplifier-11.html
and the thread
http://www.diyaudio.com/forums/pass...itional-op-amp-ultimate-sounding-phl1230.html

 

[AndrewT]

.............an active crossover without additional op amp resp. ..........

Explain.