BillFitzmaurice.info

Hello everyone

Currently in the middle of constructing two DR250s, to run on top of two almost finished T60s, so starting to think about amp choices for the 250s.

As we hope to be running a preamp with inbuilt 3-way active crossover, we were planning to bi-amp the HF drivers and woofers. I’m wondering if anyone has any recommendations for amps for this, one to run one Deltalite II 2510 per channel, and one to run two ASD-1001s per channel.

Now I've read from the plans that the power rating of the driver is not particularly useful, and that output capacity in this situation is determined by the xmax, but I am not sure how to calculate the displacement limit in volts from the xmax (which in the case of the 2510 is 4.2mm). Would anybody be able to help me out there?

As far as the tweeters are concerned (8ohms 50W) would a crown macro-tech 600 (210 watts/channel @ 8ohms) be a suitable choice to run 4 (2 in each cab) comfortably? I’m assuming there are no displacement issues with tweeters…

cheers!

monekh wrote: would a crown macro-tech 600 (210 watts/channel @ 8ohms) be a suitable choice to run 4 (2 in each cab) comfortably?

That's way more than enough, but why a macro-tech for what looks like a small system? If this is a mobile system - save your back and go with a lighter amp for the horns....If it's an install that's staying put, then keep the macro-tech.

Bruce Weldy wrote:

monekh wrote: would a crown macro-tech 600 (210 watts/channel @ 8ohms) be a suitable choice to run 4 (2 in each cab) comfortably?

That's way more than enough, but why a macro-tech for what looks like a small system? If this is a mobile system - save your back and go with a lighter amp for the horns....If it's an install that's staying put, then keep the macro-tech.

+1
You'll probably never send more than 10-20w to all those HF drivers combined.
You could probably get a few tiny 20w Class D amps and run those for your highs...
Or you could also, y'know, stick to the plans and run passive crossovers.
Then, the Macro tech could power the whole speaker, and you'd be a-ok.

thanks Bruce and Ryan, useful advice. yes I had a feeling the MA600 might be overkill. I guess we intend to keep expanding the system as we go, so would rather use something that had the potential to carry more drivers. Drawn towards crown because they're fairly easy to pick up in the UK for a decent price and seem to be reliable and universally respected... I wouldn't know a good 20W class D from a terrible one!

As regards voltage at displacement limit with the Deltalite 2510, does anyone have any clues?

As regards voltage at displacement limit with the Deltalite 2510, does anyone have any clues?

Sure, set the limit to 40V.
That's what the driver can handle, but it is likely you will hear distortion from the DR250's before you hit that point.
If you're driving the DR250's to the point of distortion, you need more cabs or turn down.

Other things you need to do to biamp:

For CD's:
The 2 x CD's must be wired in series and a 250V 20uf Cap in series before the CD's.
Crossover frequency is set to 2K with an 18dB LR slope (IIRC) for CD's.

Amp power:
with the 2 x ASD1001's in series, they will handle 40V max/16ohms, so 100W per channel.

Assuming you want to biamp for time alignment the other things you need to know:
Driver horn length is 2 feet.
CD horn length is 3 3/4 inches.