Bookshelf speaker crossovers

[Fee]

I am new to the crossover realm and was wondering how I would achieve running

Tang band 6.5 “ 50 watt rms , 4 ohm, 35-800hz
Dayton 4” 30 watt rms, 4 ohm, 80-20,000 hz
Hivi 1” dome tweeter 16 watt rms, 2,500-20,000 hz

I got this design off the web and was supposed to be running a lepai plate amp on back but they sound like garbage . So I figured I would try out some cross overs and run them directly to my Av

 

[eriksquires]

Hi Fee.



Well, you need to design a crossover.



A 3-way is twice as hard to do from scratch compared to a 2-way.



Why don't you consider purchasing a pre-designed kit instead? Lots of those from Madisound, Meniscus and in the Parts Express forums.



Best,


Erik

 

[Fee]

Hey Erik , I am familiar with all of those crossovers , but there are so many variations of handling. So what would you suggest with the set up I have?

 

[Fee]

Could I wire the mid and tweeter to archive a 8ohm loaf and run it as a 2 way?

 

[Douglas Blake]

Could I wire the mid and tweeter to archive a 8ohm loaf and run it as a 2 way?

Grab a copy of XSim ... this is a free crossover simulator that uses data files from Parts Express to assist you in crossover design and anlysis. Of course the simulation is not a final design, but it gets you pretty close.

 

[Fee]

Thanks Douglas

 

[morbo]

What is the design you built? Where you got it off the web might be a place to start looking for modifications or variants

 

[Fee]

Morbo I had all ready contacted the designer of it many days ago with no reply. There called the dinas. The lapai plate amp is a weird design and has you run the mid and tweeter out the box to the back of the plate. And the sub hooks up in the box like it should. Not a big fan of that design so scratching it and trying crossovers instead

 

[Drummer2005]

Toid's DIY Audioby 123ToidDinas – Do I need a Subwoofer Plans
The plans and crossover design are 20 dollars. YouTube
Here's the link from Joeandtell . Good luck. Glenn.

 

[wintermute]

It sounds to me like your have just connected everything to the plate amp without a crossover. As posted by drummer above, the designer sells the plans. considering the cost of the drivers, I think it would be well worth your while to spend the $20 on the original plans

Tony.

 

[Fee]

Winter I did get the plans and went to solder were they said and the plate amp fried twice, I talked to the reps at parts express and they said there shouldnt be any soldering on the amp itself . They said you would have to run the speaker wires out the back and hook them up to the speakers out . This just seems a mess of a design flaw to me . That’s why I rather just make or find cross overs and run it to my reciever .

 

[morbo]

Ah I see the design now. Yes as others have stated, you do need to build a crossover, not sure what it does as there's little detail provided on the site or in the videos that I can see, but it wouldn't be fair to evaluate without it. Even then, the little information provided seems to focus on 'how low they hit' and how 'fun' they are. This may be a design aimed at a different goal than you had in mind.

 

[Fee]

Morbo here is a link of what I have
https://toidsdiyaudio.com/?download...4997&key=32dc2806-daa7-45c7-8a53-08181bda9c7e

 

[wintermute]

Hmmm ok yes I see what you mean! It looks like the midrange is running full range (above whatever crossover frequency is set between the sub output and the full range output on the plate amp) and that the tweeter is only running at very high frequencies (proabably above 10Khz) I'd say it was originally designed as a two way and the tweeter was added in to fill in the top end a little bit.

You haven't mixed up the sub out and full range out have you?

Tony.

 

[Fee]

Wintermute no I have not, I think at this point I am going to order the plate amp AGAIN and try to put binding posts out and run it how parts express told me and see how that goes. If it sounds like garbage I am building some cross overs and trying a go with that. Learning is fun but spending money is not

 

[Drummer2005]

Make sure that you are connecting the sub and the tweeter in reverse polarity. Tony is right about the tweeter being added as top end filler. Glenn.

 

[Fee]

Drummer , yeah I get why he does reverse it . I am just dis pointed in the amp itself failing when I tried soldering the wires. Just seems easier to run a crossover and rock them that way

 

[Douglas Blake]

Hmmm ok yes I see what you mean! It looks like the midrange is running full range (above whatever crossover frequency is set between the sub output and the full range output on the plate amp) and that the tweeter is only running at very high frequencies (proabably above 10Khz) I'd say it was originally designed as a two way and the tweeter was added in to fill in the top end a little bit.

You haven't mixed up the sub out and full range out have you?

Tony.

Basically what they've done in the Dinas is to put a dedicated subwoofer into a box with a full range speaker, then add a tweeter to the top. They could have done so much better with an internal passive crossover.

As for the Lepai plate amp ... Meh... I've had half a dozen Lepai products die on me in the most unexpected ways so I don't buy them anymore.

 

[wintermute]

Fee perhaps you could let us know what aspect of the sound is bad. Looking at the tweeter and the midrange a rough guess as a starting point would be a proper crossover between the two drivers around the 3K mark, I was originally thinking 4K for that tweeter, but the dayton is starting to get a bit nasty above 3K.

My feeling is that the tweeter is being wasted being cut in at such a high frequency, and you are probably getting harshness from the dayton above 3Khz.

Also looking at the plate amps specs, the High pass filter is fixed at 100Hz 6db rolloff (which probably matches the dayton farily well, and the sub LP is 12 db /oct variable up to 150Hz so you could do some experimenting with the crossover frequency for the sub and the levels as well to try and balance the bass with the rest.

A measurement mic or an SPL meter would help a lot there.

There is one other aspect that you have some level of control over as well. The tweeter being external you can adjust the forward / backward position. This may allow you to time align with the mid driver. However for proper alignment it would need to be back behind the baffle and then you may start to get some undesirable diffraction effects, again a measurement microphone would be very useful for experimenting with this. With the current 0.68uF cap on it, it likely makes very little difference how you place the tweeter, but if you were to drop the crossover frequency, and have a low pass on the dayton then the position would start to become more critical.

Tony.

 

[Fee]

Winter Your probably rite on that. Just never have dived into cross overs at all and building of any speakers. This was a starting point for me to try out. I have carpentry background and was bored not being able to build up a chopper this season. I will look into getting some info and role that direction. Thank you