| could you make a transformerless short ribbon work with a series Xover - Click HERE for Original Thread |
| Puggie |
Ok, sorry about the long title and lack of pictures.
I'm looking at building a pair of short ribbon tweets, one set will be 1" long super tweets to go with some wide range horns that lack a little from about 15kHz up (I'm thinking along the lines of the townshend Maximum audio supertweets), and the other pair will be more conventional 3" ribbon tweets.
I was thinking could you run a ribbon without a transformer in a variant of a series Xover?
sorry no pics but I'll try and explain
ribbon in series with the midbass driver, the total impedance is about the same as the midbass driver (4ohm) then put an inductor in parallel with the ribbon and a cap between the top of the ribbon and the inductor so the inductor is now in parallel with the cap/ribbon comination.
the amp would see the impedance of the midbass, the ribbon would have the bass blocked by the cap and the inductor would take these low frequencies to the midbass. The whole unit will have about the same impedance as the midbass driver so no prob for the amp, and the ribbon will be free of any transformer.
would this work, am I oversimplifying things? |
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| LineSource |
Hi Puggie,
Most ribbons are very delicate and will stretch or tear if driven with low frequency power. For this reason, a steep 4th to 8th order crossover is frequently used. A high order passive network will have several inductors which can be wound with thin high resistance wire to help create an amplifier safe impedance. You will probably need a simulation program, or at least SPICE, to design this lossy network. |
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| Puggie |
4th or 8th order!!!
I was thinking 2nd or 3rd order (electrical) slopes. But it is acceptable to use low dia wire to increase resistance and not use a transformer for ribbon tweets. |
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| tinitus |
above 10khz it should be possible to use a series resistor of 2 - 3 ohm - a Vifa or ScSp "ringradiator" is about 3 ohm
At very high crossover frequency it should be sufficient with low order slopes
I am working on something similar
But you have to consider how efficient you want it to be - a series resistor will take away some of it - but actually I think you dont need very high efficiency at these high frequencies
Your ideas about using a series crossover are interesting, but a 3-way series crossover - I wouldnt, and I wouldnt even consider a 3-way
Make your 3" ribbon about 1/2" wide - will do the trick alone |
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