Oh, all right I'll do that, thanks. Am I correct in my assumption about the impedance consideration?
The answer will be no. The input impedance is governed by the
value of the pot used to adjust the relative levels in parallel with the
100K of the input buffer.
If you use a 100K pot, then at midpoint you would see 25K in series with
the input of the Jfet buffer and this would inhibit the high frequency response.
Better to let 600 ohms drive 10K.
😎
value of the pot used to adjust the relative levels in parallel with the
100K of the input buffer.
If you use a 100K pot, then at midpoint you would see 25K in series with
the input of the Jfet buffer and this would inhibit the high frequency response.
Better to let 600 ohms drive 10K.
😎
Thanks Nelson. I took another look at the specs for the EAR 868, and they state not that it has an output impedance of 600 ohms, but that it puts out 5 volts into a 600 ohm load. EAR's Tim de Paravicini does a fair amount of work in the recording studio field, where I take it that 600 ohm figure is a standard. It doesn't seem like the specs would be given that way if the pre-amp couldn't drive a 600 ohm load, so 10k should be no problem. I'll just get me a revised B4 and give 'er a shot. Thanks again, the B4 looks like a beaut!
Yeah, EAR doesn't provide much technical info on their products, and my feeble memory latched onto that 600 ohm figure. But it's for the other side of the equation!
I have a few questions about the B4, this is probably the best place for them even though this is an old thread.
I have one (Thanks Mark at Reno HiFi), and am using it to cross a 2-way with an Altec 416 and a Heil AMT. Right now the Heil sounds best with a 1st order passive, but that may be because I haven't found the sweet spot on the B4 for it yet.
2A3 SET amp on the Heils, PPP EL34 on the Altecs.
1. On the 416 1000Hz @ 24db - What's the difference Sallen Key vs. Linkwitz Riley? I have all the DIPs the same (4 sets each channel).
2. On the Hi Pass, is the S-K vs L-R set by the setting on the Low Pass, or is there only one default type for the Hi Pass?
I have tried to mimic my passive but just doesn't sound quite right.
I also tried 1000Hz 24db on the Altecs and 1000Hz 24db on the Heils, and again not quite right.
(btw: Replacing a pro XO with the B4 only on the Altecs yields much improvement)
TIA
I have one (Thanks Mark at Reno HiFi), and am using it to cross a 2-way with an Altec 416 and a Heil AMT. Right now the Heil sounds best with a 1st order passive, but that may be because I haven't found the sweet spot on the B4 for it yet.
2A3 SET amp on the Heils, PPP EL34 on the Altecs.
1. On the 416 1000Hz @ 24db - What's the difference Sallen Key vs. Linkwitz Riley? I have all the DIPs the same (4 sets each channel).
2. On the Hi Pass, is the S-K vs L-R set by the setting on the Low Pass, or is there only one default type for the Hi Pass?
I have tried to mimic my passive but just doesn't sound quite right.
I also tried 1000Hz 24db on the Altecs and 1000Hz 24db on the Heils, and again not quite right.
(btw: Replacing a pro XO with the B4 only on the Altecs yields much improvement)
TIA
Back in January NP announced on the FW website that the B4 was to be discontinued. I'm wondering if there are any plans for a replacement?
There is a replacement for DIYers whose artwork is done and it is intended
for sale in the store here at DIYaudio.
for sale in the store here at DIYaudio.
I'm very pleased with my First Watt B4 crossover. In conjunction with DSP, my speakers have zero passive components now.
This is going to be a terrific DIY project for those that want to try an active crossover.
This is going to be a terrific DIY project for those that want to try an active crossover.
Nelson
Will the new crossover be as flexible as the B4; 4 poles per filter, attenuation to equalise gain, etc?
Will the new crossover be as flexible as the B4; 4 poles per filter, attenuation to equalise gain, etc?
It will use pots to adjust filters instead of switches. For a given set of
capacitors I am planning 4:1 frequency ranges.
I expect there will be several versions, since the artwork is modular and
easy to modify.
capacitors I am planning 4:1 frequency ranges.
I expect there will be several versions, since the artwork is modular and
easy to modify.
It would be very nice to have a location to solder in a fixed resistor rather than the pot.
Graeme
Graeme
I am revising the artwork after evaluating the prototype art, and as a
concept you could have one in a couple weeks. I think it will take the
DIYaudio store a little longer to put the offer together after they decide
what level of kit they want to offer and how the metalwork will be
handled.
concept you could have one in a couple weeks. I think it will take the
DIYaudio store a little longer to put the offer together after they decide
what level of kit they want to offer and how the metalwork will be
handled.