604B & 605A/B crossovers

[jmarkwart]

Hi All,
Some months ago I reported here on a recent 604B crossover design I undertook. At that time I had no schematic to share. I now have one for the 604B as well as the 605A&B at http://home.earthlink.net/~jmarkwart/
Jeff

[frankmalz]

ALL I CAN SAY :

TRY THIS SCHEMATIC its very good and musical!!

I use it with my 605A.

Thank you Jeff


frank

[soundoff88]

Jeff,
Any idea if this crossover design will work with other 604 versions (C, D & E)?

Thanks,
Dj

[billfort]

You forgot the G soundoff. I?d love to try Jeff?s design but I know a B reconed as an E would be significantly different than my 8ohm G?s.

[soundoff88]

Hi Billfort,
I didn't forget. :-) I only asked if it can be applied to the drivers that I have.

DJ

[jmarkwart]

DJ,

As I mentioned in the original thread on this subject, I only measured and modeled 16 ohm 604Bs fitted with 25hz 604E LF cones. I haven't had the opportunity to measure and model the other 16 ohm 604 types (C thru E), but this filter should correct for the horizontal voice coil spacing/phase shift that is common to all these alnico motor 604s.

I also mentioned that I didn't use any HF compensation circuits for the 604B compression driver/horn combo as its output was pretty smooth above 2kHz. The C thru E share the later horn design, and they may need some specific compensation added to get acceptably smooth HF output. The B horn also showed a nasty dip at 1100Hz (-10/12dB), and the 3rd order HP slope limits its effect on the combined drivers' output. The C thru E horn may not need as steep a slope here.

So will the filter work on the C thru E? Sure, it just won't be optimized for the changes Altec eventually made to the horn and compression driver circuit. If you build it, you may want to substitute a 16 ohm L pad for the shelving circuit in the schematic to give yourself some additional HF attenuation capability the C thru E might require.

Jeff

[soundoff88]

Jeff,
Thanks for sharing the info on your xover design. I was trying to get some confirmation from you on the applicability of the design to other versions. May be I'll play with the design in the near future.

Regards,
DJ

[zelgall]

Jeff, great post, I'm getting my 604's out of the box they've been sitting in for 6 months. I noticed that you're using hovland caps, what brand of coils did you use? I looked at the usual suspects and couldn't find the same resistance values for the coils. Is it necessary to get exactly the same inductance and resistance to achieve the same results or is the inductance and a close resistance value O.K.? Thanks, Kyle.

[jmarkwart]

Kyle,
In the notes section of both schematics I list the inductors as Solo CFAC, which is the Solo brand of copper foil air core type inductor. I heard they may be out of production. Alpha Core and Jantzen make copper foil air cores that are similar to the Solos. Try Percy Audio or Parts Express for availability.
You can use values that are close to mine and get results that are close to mine, however, inductance variations will effect the crossover point of the filter and the combined response of the drivers; DCR increases will lower speaker sensitivity and affect driver Q. They are both important. I hold series inductor DCR to less than 1/10 of driver DCR, and less than 1/20 of the driver's load impedance at the crossover frequency to minimize these effects. CFACs allow this to be done easily, plus they vary more linearly with voltage and do not saturate on peaks like some iron, laminate or ferrite core inductors. If you follow these rules-of-thumb with whatever type of inductor you use it should have a minimal adverse effect on the driver.
Jeff

[zelgall]

OK so I'm blind. I didn't see the Solo brand. I did look for inductors with your resistances on a variety of sites and I think I'd better go with the Solo'd or recalculate. Thanks, Kyle.