First Time Speaker Builder Questions about the Usher 8945a

[Schnur67]

I am designing a pair of floorstanding speakers that will implement a 7" Usher 8945a woofer and 1" Vifa XT25BG60-04 tweeter each. This pairing seems to be well documented and most people seem to recommend a crossover at 2,250 Hz, but Parts Express only seems to carry 2-way Dayton crossovers at 2,000 and 2,500 Hz. Would crossing it at 2,000 Hz be optimum? I don't plan on building crossovers myself.
Also, I have searched the internet for days, but cannot seem to find the optimum placement of a port for my woofer in this type of build. Why do some speakers have them at the bottom, away from the woofer, while others will have them right next to the woofer? I was planning on putting it right under the woofer so that way the enclosure it is in can be what I calculated it to be (around 0.5 cu. ft not included the woofer or port). If it was placed on the bottom, the enclosure it is in would be huge. I want the port to be front facing.
Thank you to whoever replies. I have been designing these speakers for a while now and am finishing up before building.

[wintermute]

Hi Schnur67. I've moved your post to multi way.

You will more than likely receive a lot of responses as to why you should not go down the route of using an off the shelf crossover. Having been there and done that, I will agree with them

I'd advise reading this thread Introduction to designing crossovers without measurement It will give you a better understanding of what is involved, and why off the shelf crossovers generally won't cut it.

Tony.

[Schnur67]

Thank you. I will do a lot of research and see what I can find.

[jgv]

I'm working on a project using a similar woofer (SS8545) and the same tweeter, I'm crossing them at about 2800Hz with great results.

[Schnur67]

The speakers look great so far. I am surprised that the woofers can handle a frequency that high. The response graphs had a dip at about 2,250Hz for the Usher woofers, but if they sound good, then that is great.
I am going to try to design my own crossovers now, so hopefully that turns out right. I followed the instructions on the beginner's guide to designing crossovers that can be found on this forum which was helpful. There doesn't seem to be any end-all method of designing them though, which makes me nervous. I may end up changing my crossover frequency because it is designed at 2,000Hz right now.

[Lojzek]

Hi Schnurr67 !

Originally Posted by Schnur67

I am designing a pair of floorstanding speakers that will implement a 7" Usher 8945a woofer and 1" Vifa XT25BG60-04 tweeter each. This pairing seems to be well documented and most people seem to recommend a crossover at 2,250 Hz, butParts Express only seems to carry 2-way Dayton crossovers at 2,000 and 2,500 Hz.

The Usher woofer looks really exciting and there is nothing wrong with your choice of drivers, although I have to say that there is practically no chance you will get them to perform great using Dayton off the shelf crossover. Going this route, you are likely to end up being very disappointed with your project regardless of using good quality parts. If I were you, I’d use crossover parts published in similar projects and interchange with others somewhat different in value and take time to evaluate.

Originally Posted by Schnur67

Would crossing it at 2,000 Hz be optimum? I don't plan on building crossovers myself.

Personally, I would cross these at about 3 kHz. This way the safety margin of risking to cook the voice coil of the tweeter would be increased and the distortion performance should be better.

Originally Posted by Schnur67

Also, I have searched the internet for days, but cannot seem to find the optimum placement of a port for my woofer in this type of build. Why do some speakers have them at the bottom, away from the woofer, while others will have them right next to the woofer?

My best guess, the reason for placing a port at the bottom might be trying to boost the port sound pressure using floor reflections. I prefer placing it near the woofer because it gives me less headache while trying to record the output.

Originally Posted by Schnur67

I was planning on putting it right under the woofer so that way the enclosure it is in can be what I calculated it to be (around 0.5 cu. ft not included the woofer or port). If it was placed on the bottom, the enclosure it is in would be huge. I want the port to be front facing.

Possible solutions to determine the inner box volume for reflex ported box are based on:

1. TS parameters provided by the manufacturer, Vb=15 liters, F3=50Hz
2. TS parameters published by Zaph Audio, Vb=25 liters, F3=40 Hz

Which are more accurate, remains uncertain. The best way would be to measure it yourself, but it seems this is not an option for you. I would go with Zaph parameters.

Originally Posted by Schnur67

I Thank you to whoever replies. I have been designing these speakers for a while now and am finishing up before building.

You’re welcome.

[garrettba03]

I can say I have the xt25tg30 (single magnet version) crossed at 3k in towers with peerless 830883 sealed dedicated mid and two scan 8535 as bass drivers and the tweeters sound remarkably clean in that system! 130 rms/channel amp and 88db sensitivity=loud

I also have lots of speakers lying around including 8945a, ss8535, 830883, sb15s, and I can tell you the 8945a sounded pretty good with the xt25 when we were "playing" around with them. if not more than about 80 watts rms amp...id prolly be tempted to try for 2.3-2.5k crossover properly designed but thats just what I would do.

How big is the listening room? Amp?

I personally prefer 2way crossed 2-2.5k. Im thinking maybe power response issues high up I tend to get a smaller sweet spot...but I cant be sure just makes sense to me.