Adding a rear-firing tweeter

[Nuuk]

What is the correct wiring when adding a rear firing tweeter.

I currently have a tweeter with just a single 0.47 uFd cap as crossover. I want to add a rear firing tweeter but what is the correct way to wire it in?

Is this correct?

 

[Rudolf]

Above is for bipole operation. If you want a dipole, you should invert the rear tweeter connections. Which of both is "correct" can not be decided without further information about your system and room situation.

Rudolf

 

[picowallspeaker]

0u47 F is very little ...
It should start to cut frequencies under 20 KHz for an 8Ω tweeter

It might be good for the rear tw, surely ..but for the front REAL one ?

 

[Nuuk]

Above is for bipole operation. If you want a dipole, you should invert the rear tweeter connections. Which of both is "correct" can not be decided without further information about your system and room situation.

Rudolf

Sorry Rudolf, I should have said that this is for an open baffle speaker with the full-range drivers being (modified for OB use) Goodmans 201's.

So I guess that I should wire for dipole rather than bipole.

 

[Nuuk]

0u47 F is very little ...
It should start to cut frequencies under 20 KHz for an 8Ω tweeter

It might be good for the rear tw, surely ..but for the front REAL one ?

They are actually Supertweeters (Realistic 40-1310) and I have also been confused that they have so much audible output with just a 0.47 cap.

 

[picowallspeaker]

If it's audible it's not a supertweeter

 

[Nuuk]

If it's audible it's not a supertweeter

They are if you're a bat!

 

[tinitus]

Sorry Rudolf, I should have said that this is for an open baffle speaker
so I guess that I should wire for dipole rather than bipole.

probably
just be aware that you introduce other phase errors as well
tho a super tweeter sounds easy, it really isn't
and it can really make you pull your hair out
once you have heard it, you want it so bad because it just sounds so bloddy good
and yet you still can't make it work good enough to let it say in the system
now I have warned you

 

[Rudolf]

Sorry Rudolf, I should have said that this is for an open baffle speaker with the full-range drivers being (modified for OB use) Goodmans 201's.
So I guess that I should wire for dipole rather than bipole.

You should try both versions. I don't know where the tweeters come in, but at say >4 kHz the difference between bi- and dipole becomes moot anyway. You may want to attenuate the rear tweeter somewhat depending on the character of the front wall reflection. But - as Tinitus mentioned - it is always a good idea to have it in the first place

Rudolf

 

[Nuuk]

Thanks guys. I was aware of the problems with using dipole tweeters. But isn't it the same with nearly all hi-fi - there's is usually a compromise somewhere!

I can certainly cobble in some attenuation but first I must decide on which tweeters to use for the rear.

 

[tinitus]

..... first I must decide on which tweeters to use for the rear.

small paper cone or a poly cone variant
cheap, and good

 

[Rudolf]

... but first I must decide on which tweeters to use for the rear.

Any of the Dayton ND20s? I prefer wide dispersion domes against Tinitus' narrow dispersion cones.

 

[Nuuk]

If I follow the advice from you two - I will land up with a second pair of speakers!

Seriously though, thanks for the pointers.

 

[tinitus]

you could also try it the omni way

 

[Rudolf]

I believe it depends much on the individual situation whether a wide or narrow dispersion will be better. So if you haven't tried both you can't be sure.

 

[Cal Weldon]

I would use the same tweeter as the front.

 

[Nuuk]

I would use the same tweeter as the front.

That's what I've always read too Carl. But I'm not sure how easy it is to find another pair of the Realistics.

 

[Cal Weldon]

Sorry, I misread. I thought you had the Realistics for the rear. Those are a Fostex unit if memory serves so...

Fostex Super Tweeters

Who's Carl?

 

[Nuuk]

Sorry, I misread. I thought you had the Realistics for the rear. Those are a Fostex unit if memory serves so...

Fostex Super Tweeters

Who's Carl?

My apologies Cal - trying to post too fast as usual.

Yes, I'm currently looking on Ebay. I was lucky with mine paying 20 UK pounds on Ebay a few years back. They are a copy of the Fostex, and mine have 'made in Japan' stamped on the rear.

 

[Cal Weldon]

I don't think they are a copy, I think they are rebranded 'Realistic'. Foster makes them. They are the Japanese company that makes Fostex. Nowadays they may outsource the manufacturing but back when yours were built, they were made in Japan. Radio Shack started selling them in the late 70's IIRC.