Dayton ND90 4 ohm ..2 questions

[bill poster]

Hi,
Am I right in thinking if I use x2 of these per cab I will get 8 ohms?

Also would anyone recommend a super tweeter with these? They fall off rapidly after 10 khz but no serious breakup so I'm thinking I can leave the daytons crossover free?


thanks

[Taterworks]

Re: Dayton ND90 4 ohm ..2 questions

Resistances in series: R = r + r + r...

Resistances in parallel: R = 1/[(1/r) + (1/r) + (1/r)...]

For equivalent resistances, the parallel expression above simplifies to R = r/n where n is the number of equal resistors.

If you wire the 4-ohm ND90s in series then you'll get R = 4 + 4 = 8 ohms. If you wire them in parallel then you'll get R = (4/2) = 2 ohms.

Two drivers wired in series will have the same voltage sensitivity as a single driver because even though you are doubling the radiating area, you are also doubling the resistance (more voltage needed to produce the same power). Two drivers wired in parallel will have double the cone area of a single driver (+3 dB over a single driver) and half the resistance for double the current from a constant voltage, which doubles the electrical power (+3 dB over a single driver), which adds together to a +6dB increase. dipole, bipole, cardioid, and end-fired configurations get more complex because they involve phase differences and driver polar radiation in the calculation.

[critofur]

Re: Dayton ND90 4 ohm ..2 questions

Hi,
Am I right in thinking if I use x2 of these per cab I will get 8 ohms?

Also would anyone recommend a super tweeter with these? They fall off rapidly after 10 khz but no serious breakup so I'm thinking I can leave the daytons crossover free?


thanks

I think they actually go almost up to 20Khz flat, I got some I could measure, don't have a baffle cut for 'em though.

If you have a tweeter, you'll still need a crossover at least to protect the tweeter, and probably need something to help w/phase alignment, maybe BSC?

[critofur]

Re: Dayton ND90 4 ohm ..2 questions

Huh - guess they don't go out to 20 - friend of mine had some and I thought he said they did, oh well - I slapped one in a cardboard box and measured it for you:

[bill poster]

Re: Dayton ND90 4 ohm ..2 questions

Thanks very much guys- and for measuring the unit- thats really useful. I wd protect the tweet yes, want to leave the main units crossover free. These units are great value but with tweets it pushes price into jordan jxr6 territory. Hopefully a sub could compensate for no baffle step circuit?

[bill poster]

Re: Dayton ND90 4 ohm ..2 questions

another thought... like with some cone tweeters, wd adding a face plate with slight flare help boost frquencies above 8 khz?

Don't know about flare diameter to frequency etc

[critofur]

Re: Dayton ND90 4 ohm ..2 questions

...These units are great value but with tweets it pushes price into jordan jxr6 territory.

How much is the Jordan? What tweeter are you talking about? One of the best tweeters for this would be this one: Dayton ND20FB-4 Rear-Mount 3/4" Neodymium Dome Tweeter (sorry I didn't point out the DOTD yesterday they had it for $5)

Hopefully a sub could compensate for no baffle step circuit?

Hmm, not in the normal sense of how people typically have subs setup, but it would be possible - the sub would have to be near the speakers, either a pair of subs in stereo, or, one in between with the driver facing towards you - it would be complicated and probably wouldn't work well because we're talking about frequencies above a few hundred Hz - look at the average level from ~150 - ~700 Hz and compare to the avererage level from ~900 Hz - ~6.5 KHz - you either want to boost the lower range or lower the upper range.

another thought... like with some cone tweeters, wd adding a face plate with slight flare help boost frquencies above 8 khz?

"Waveguides", horns, different baffle shapes, etc. will boost the LOWER frequencies of the tweeter, the higher the frequency the more directional the driver is and the less horns and such will affect the output - particularly with regards to boosting...

[bill poster]

Re: Dayton ND90 4 ohm ..2 questions

very disheartening.. lol But thanks. Maybe I'd better stick to the little Jordans.