You don't need big resistors for the FT17.
Let's say your tweeter magically crosses over very steeply at 15kHz. With your 4 watt amp running flat out on pink noise 25% of the power is there: 1 watt. Of that watt half will be dissipated in the tweeter, the other half is in the resistor. The resistor will only be dissipating 0.5 watts of energy in the worst possible case.
Use Wavepad or similar to analyse the frequency content of a segment of your favourite music, see just how much area under the curve (power) there is. Anything remotely resembling music would have that resistor dissipating less than 100mW.
You need larger resistors for 85dB/W speakers of course, even with the 3dB attenuation of the resistor it's still 95.5 dB/W, that's a tenth of the power!
Just trying to save you a few bucks.
Let's say your tweeter magically crosses over very steeply at 15kHz. With your 4 watt amp running flat out on pink noise 25% of the power is there: 1 watt. Of that watt half will be dissipated in the tweeter, the other half is in the resistor. The resistor will only be dissipating 0.5 watts of energy in the worst possible case.
Use Wavepad or similar to analyse the frequency content of a segment of your favourite music, see just how much area under the curve (power) there is. Anything remotely resembling music would have that resistor dissipating less than 100mW.
You need larger resistors for 85dB/W speakers of course, even with the 3dB attenuation of the resistor it's still 95.5 dB/W, that's a tenth of the power!
Just trying to save you a few bucks.
I'm in a very similar boat. Last week I had some really weird things happening around 10k at high volume when I was trying out an EL34 push-pull tube amp. There was an impedance notch around 10kHz to do with my crossover that my SS amp didn't even notice.
I threw the 10k 12dB crossover away and used 8 ohms in series with 0.57uF in series with the tweeter. I was using FE207E which runs out of puff at 12-14kHz, your FE166 looks like it goes well in the top end so try 0.47 or even 0.33uF.
If you go back to an SS amp you'll find you'll need to change it again.
That HF impedance rise in the fostex FE drivers is actually a very good thing in this situation.
After trying out the tube amp I'm going to buy one. A High damping factor squashes the life out of this style of speaker.
I threw the 10k 12dB crossover away and used 8 ohms in series with 0.57uF in series with the tweeter. I was using FE207E which runs out of puff at 12-14kHz, your FE166 looks like it goes well in the top end so try 0.47 or even 0.33uF.
If you go back to an SS amp you'll find you'll need to change it again.
That HF impedance rise in the fostex FE drivers is actually a very good thing in this situation.
After trying out the tube amp I'm going to buy one. A High damping factor squashes the life out of this style of speaker.
Big thanks to Dave at Planet-10 and Scott for the phase plugs.
Arrived Saturday morning, fitted them Sat afternoon.
1st impression - the looks
Make a mundane looking driver (I hated the hole in the middle of the dust cap) look very very cool.
2nd Impression - the sound
Had a search round the post's and have now convinced my self I'm not going mad!
Removes the treble hissines, but once its gone its hard to compare it to anything. I had a couple of tracks that realy showed
the problem up, trouble was I could,nt remember what track they were, and couldn't find them cos the problem had gone. This change is quite subtle, I realy noticed it quite near to the speaker and off axis, the trble is much cleaner and more focused.
BASS, I thought I had gone mad at first, cos there was so much more (apparent) bass.
I was expecting a subtle change, it wasn't, its a shock, I spent a long Sat night listening and trying to work out why the major change, had to have a drink to steady my mind!
and if anyone hasn't fitted phase plugs, do it.
Arrived Saturday morning, fitted them Sat afternoon.
1st impression - the looks
Make a mundane looking driver (I hated the hole in the middle of the dust cap) look very very cool.
2nd Impression - the sound
Had a search round the post's and have now convinced my self I'm not going mad!
Removes the treble hissines, but once its gone its hard to compare it to anything. I had a couple of tracks that realy showed
the problem up, trouble was I could,nt remember what track they were, and couldn't find them cos the problem had gone. This change is quite subtle, I realy noticed it quite near to the speaker and off axis, the trble is much cleaner and more focused.
BASS, I thought I had gone mad at first, cos there was so much more (apparent) bass.
I was expecting a subtle change, it wasn't, its a shock, I spent a long Sat night listening and trying to work out why the major change, had to have a drink to steady my mind!
and if anyone hasn't fitted phase plugs, do it.
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