Hi,
Almost. The 57uF will resonate with both drivers voice coil inductances which can be fun, so you need to place a snubber/zobel across each driver to make it appear resistive.
I used this trick in the 80's with Schulze KSP215 (East German Full Range drivers made for Studio monitoring) to allow more power handling and loudness, withpot loosing this "single-driver" sound.
Ciao T
Almost. The 57uF will resonate with both drivers voice coil inductances which can be fun, so you need to place a snubber/zobel across each driver to make it appear resistive.
I used this trick in the 80's with Schulze KSP215 (East German Full Range drivers made for Studio monitoring) to allow more power handling and loudness, withpot loosing this "single-driver" sound.
Ciao T
Hi,
With the drivers I used then (~ 25 Years ago) they where essential.
If your drivers have very low voice coil inductance (by virtue of having a copper cap over the pole piece) you may be able to do without.
Yes, plus the Zobel must be sized to oppose the Voice coil inductance, which as we know also varies somewhat excursion... If the manufacturer supplies reliable spec's for Le (Voicecoil Inductance) there are on-line calculators for the job...
Ciao T
With the drivers I used then (~ 25 Years ago) they where essential.
If your drivers have very low voice coil inductance (by virtue of having a copper cap over the pole piece) you may be able to do without.
Yes, plus the Zobel must be sized to oppose the Voice coil inductance, which as we know also varies somewhat excursion... If the manufacturer supplies reliable spec's for Le (Voicecoil Inductance) there are on-line calculators for the job...
Ciao T
Great, thanks very much.
The drivers are MarkAudio/CSS/Planet 10 EL70s, with a reported Le of 0.256 mH.
For anyone finding this thread, here's the most to-the-point article on Zobel circuits I found: TA Speaker Topics - Neutralizing L(e) with a Zobel
The drivers are MarkAudio/CSS/Planet 10 EL70s, with a reported Le of 0.256 mH.
For anyone finding this thread, here's the most to-the-point article on Zobel circuits I found: TA Speaker Topics - Neutralizing L(e) with a Zobel
Hi,
With 56uF this would give a resonance at 1.3KHz... So Zobel needed I think.
In addition, there is an important piece to note. Shunting one driver at MF/HF does not provide anything like baffle step correction, due the drivers being in series all that happens is that we slowly "belnd over" to single driver operation at higher frequencies.
So any baffle step correction still needs a series LR circuit in series with the Speakers!
What the Cap across the second driver does is to create a system that has greater LF power handling/displacement/SPL than a single driver, but at high frequencies acts as pure single driver system, with non of the comb filtering etc associated with multi-driver systems.
Ciao T
With 56uF this would give a resonance at 1.3KHz... So Zobel needed I think.
In addition, there is an important piece to note. Shunting one driver at MF/HF does not provide anything like baffle step correction, due the drivers being in series all that happens is that we slowly "belnd over" to single driver operation at higher frequencies.
So any baffle step correction still needs a series LR circuit in series with the Speakers!
What the Cap across the second driver does is to create a system that has greater LF power handling/displacement/SPL than a single driver, but at high frequencies acts as pure single driver system, with non of the comb filtering etc associated with multi-driver systems.
Ciao T
The impedance curve is one i actually measured... LMS use a log vertical scale which was inconvienient. My kit will measure a higher Fs...
dave
I think he's refering to what we discussed here: http://www.diyaudio.com/forums/css/149694-el70s-have-arrived.html starting at the bottom of the page. You corrected the data sheet, but Bob never did upload the correct sheet to the site.
This is the proper sheet: http://homepage.mac.com/planet10/CSS/EL70/CSS-EL70-data-080909.pdf
This is the proper sheet: http://homepage.mac.com/planet10/CSS/EL70/CSS-EL70-data-080909.pdf
Can bsc be addressed by moving the second driver to the rear or side? And what would be the sonic advantage (if any) to having both drivers forward firing?
Exactly what I'm trying to achieve.
I got one speaker finished last night. I've been listening to single drivers in TL boxes for a few months, so I have a very good idea of what these speakers sound like. So far I don't think I'm very happy with the effect the Zobel has on the sound. It seems like it takes too much off the top. Pus I'm only using a 4.7 uF cap, instead of the 10-15 uF the various Zobel calculators I've found recommend. I'm going to continue trying different values for the Zobel and LPF caps to see if I find something I like, but I may end up pulling the Zobel altogether. It just might be unnecessary for these drivers in particular.
Hi,
No. You do not change the energy radiated in the room, you merely make the radiation pattern at mid and high frequencies more complex.
More predictable dispersion, the possibility to use driver spacing to create better (narrower) vertical dispersion.
Ciao T
No. You do not change the energy radiated in the room, you merely make the radiation pattern at mid and high frequencies more complex.
More predictable dispersion, the possibility to use driver spacing to create better (narrower) vertical dispersion.
Ciao T
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