Recs for the passive portion of an active/passive biamp setup

[whtboy]

hi,

i'm considering biamping my cornwalls. i've got an adcom gfa-545 ii lined up for the low end and am still looking for an amp to drive the upper half. i'll be using a P09 active crossover from red elliot to split the preamp signal into separate 20-600Hz and 600-20kHz signals (filtered at 24db/octave).

the bass signals will go into the adcom, which will drive the woofers directly.

the high end will go into a separate amp, which will then drive the tweeters/squawkers with a passive 2-way network.

do i need to do anything special for the passive network here, or will a traditional 2nd order filter work well?

something like this - http://www.colomar.com/Shavano/spk12db2.gif

thanks!

-jacob

[whtboy]

or could i even use a simple 1st order network to avoid the high end phase issues that come up with 2nd order networks?

if i use a 2nd order network would it be worthwhile to put in a phase selector switch in so i can flip the tweeter leads back and forth without opening the cabinet?

i'm hesitant to use a 3rd order network because i've read 3rd & higher orders become exponentially more sensitive to variations in the values of the components, and i currently don't have a CL meter to measure caps & coils.

-jacob

[whtboy]

or if teac a-l700p's can be had for $100 a piece, would it make more sense to build a 3-way active crossover and use all 6 of the teac's channels to tri-amp it, completely avoiding the pitfalls of passive networks altogether?

[whtboy]

hmm.... maybe this will drive the top end =)

http://www.6moons.com/audioreviews/sonicimpact2/t2.html

[whtboy]

god i love being an impulse buyer! one of these babies should be hooked up in my living room later this week.

jeff, i think it's getting close to that time when we should do an a/b/c test between my crap yamaha receiver, your crown + preamp and my new t-amp =)

[djk]

Tripath says the 2024 can put out 9W clean at 4 ohms, 5W at 8 ohms, and I would guess 3W into the 16 ohm Cornwall midrange.

The amp has 0dB of headroom due to the desing of the power supply, at least a 3.5W 2A3 amp has about 6dB of headroom before it totally conks out.

The new one still looks like it has low quality electrolytics in the signal path, such is progress?

[whtboy]

oh well, if it doesn't work out i can always use it for a low power system at work =)

[whtboy]

Tripath says the 2024 can put out 9W clean at 4 ohms, 5W at 8 ohms, and I would guess 3W into the 16 ohm Cornwall midrange.

The amp has 0dB of headroom due to the desing of the power supply, at least a 3.5W 2A3 amp has about 6dB of headroom before it totally conks out.

The new one still looks like it has low quality electrolytics in the signal path, such is progress?

can you elaborate on why it has 0dB headroom and what "desing of the power supply" means? also, what is a 2A3 amp?

thanks

[djk]

Any amplifier with a fully regulated power supply has 0dB of headroom by design

A typical amplifier with an unregulated supply will have about 3dB of headroom for transients.

A flea-powered tube amp like a 2A3 with 3.5W will have lots of 2nd harmonic distortion when driven into clipping, and may sound louder than an amp with 6dB more power and a regulated supply.

The Tripath is not the best amp for horns, the IM distortion goes up about 10dB at 1W with respect to the THD at full power.

[whtboy]

what is im distortion and how is it different from total harmonic distortion?

[PrestonTom]

Whtboy,

I am a bit confused about your goal here.

The Adcom amp is a pretty good amp (plenty of headroom, capable of providing current for difficult loads, fairly clean sound, etc). The Klipsch speakers are not a difficult load (efficient, impedance does not drop to a very low level).

What sort of improvements are you looking to find. I am afraid that you are going to be adding some distortion to your system, as DJK as also suggested.

Good Luck,

-Tom

[whtboy]

Yes, the t-amp may be a bad choice for running the top end. My goal in biamping is two-fold:

- to get a steeper slope between the mid & woofer to minimize the boomy sound of voices that bleed over into the woofer's signal

- to improve the bass control by eliminating any inductors between the amp and the woofers voicecoil

I've also read people have reported better clarity with each amplifier channel only reproducing a subset of the frequency response.

I'm not sure how much of a difference this will make, but I'm willing to go this route to find out.

-jacob

[IB Slammin]

Yes, the t-amp may be a bad choice for running the top end. My goal in biamping is two-fold:

- to get a steeper slope between the mid & woofer to minimize the boomy sound of voices that bleed over into the woofer's signal

- to improve the bass control by eliminating any inductors between the amp and the woofers voicecoil

I've also read people have reported better clarity with each amplifier channel only reproducing a subset of the frequency response.

I'm not sure how much of a difference this will make, but I'm willing to go this route to find out.

-jacob

Weddo, (sp?)

Consider the source. ( an aggressive CW mod-er) As I understand your goal, a nice ES or high order passive filter and a better mid horn/driver would fit the bill. There are warm, tube-like SS amps out there to be had for fair $$. Put a nice little JMA tube preamp in front and you got it. I am considering bi-tri amp, but for a different reason.

Regards,

Terry

[whtboy]

I hooked up my new Super T Amp last night and had a listen. I was very surprised. The sound was at least as good as my Yamaha receiver at normal listening levels, and I couldn't hear any audible distortion or clipping at SPL levels I could stand. SPL at the half marker was more than I could comfortably listen to for more than 15 seconds at a time.

I did notice that on some tracks the stereo image wasn't as well-defined at high levels, but I'm not sure if the same thing happens with my Yamaha. Having a speaker/amp switchbox would be really convenient for situations like this.