My Latest Speakers

[angsuman]

Hello all, I've finally finished my set of speakers. This was my attempt to go all out. Before this project i've only built a few cheaper designs.

Firstly I have to add felt to the sides of the drivers for diffraction effects. (I'm router impaired and can't flush mount for my life).
The design is a 3-way using the dayton RS225, RS52 dome midrange, and the vifa xt19 tweeter. I have made no measurements yet but will soon once my microphone capsules arrive. It sounds great, but a bit different. Some recordings sound horrible through it while others are amazing. The treble is a tad bright for my tastes. There is just something minor wrong somewhere that I have to pinpoint in the crossover. Perhaps i should wait till measurements before making any judgements. Anyways i'm pretty satisfied with the project. Any comments, criticisms appreciated.

[angsuman]

Here's the predicted response. This response doesn't take into account baffle step so until I have measured responses I have no idea how much more the midrange and tweeter need to be attenuated.

[polkymon]

I was interested in the Dayton dome for my next project and would like to hear your opinion of it. Seems like it would be ideal for a midsized bookshelf w/o dealing with backwaves and/or taking up volume for woofer.

[angsuman]

Yea the dayton dome seems to have good measurements. According to zaph and Mark K. One of the reasons why i got it. Also its very cheap at $30. Its convenient too since you don't need a rear chamber. I put everything in a 1 cu ft. MTM cabinet from partsexpress since my woodworking skills suck. The midrange sounds really nice. I can't really describe it as anything other than just neutral. You can cross the mid relatively low around 500hz but it depends on how much output you need.

[Shaun]

Hi

The design is a 3-way using the dayton RS225, RS52 dome midrange, and the vifa xt19 tweeter.

I am building a 3- or 3.5-way too. I considered the XT19 (my current first choice), but have to make do with what I have, which is the RS D28 shielded tweeter. My other drivers are RS52 and 2x Extremis 6.8.

You can cross the mid relatively low around 500hz but it depends on how much output you need.

I'm glad to hear that one can use the RS52 so low down. My intention is to cross at 800Hz. I listened to it without a crossover, and it's amazing how high up it extends to.

[owdi]

Don't be surprised to find huge deviations from your predicted response once you measure them. I've built two 2-way's so far, and in both cases made mistakes that were only clear when measured.

It appears the crossover point for your dome midrange is in the right place where you will not need a BFC circuit. Instead, you will probably have to pad down the midrange dome and tweeter to achieve a good tonal balance.

Dan

[angsuman]

Yes that dome midrange is very nice. I have a few concerns about my speakers. I haven't yet gotten around to any measurements or felt treatments.

1. Anyone that has done what i'm trying to do which is put a layer of felt around the drivers to make it flush, does this work just as well or better than having it flush mounted in the first place?

2. My design has series resistors before the crossover...how exactly do resistor power handling ratings work. For example if i have a 10 watt resistor what does that rating mean exactly, how much power can it really handle?

[Shaun]

I don't have any experience with felt as a means of reducing diffraction effects. I usually model the speaker using the Baffle Diffraction Simulator, and make my driver placement based on this analysis. I would suggest that you first measure your speaker on- and off-axis to see just how much diffraction is taking place.

I suspect, though, that if you don't flush-mount the drivers, the discontinuity where the driver edge meets the felt will cause early diffraction. This will likely cause the upper frequencies to have a ragged response. But it's just a guess...

Another method of reducing diffraction (with drivers surface mounted as in your case) is to make a grille from solid wood/MDF/hardboard about the same thickness as the driver flanges. The speaker cutouts are just slightly larger than the outer edge of the drivers. This will be the equivalent of flush mounting. In some cases I've seen the inner edges of these grilles bevelled or curved where the driver flange thickness was smaller than the grille thickness.

[Salas]

1. Felt is good, flush is better.

2. A 10W resistor can dissipate just that. 10W safely for some time. Lets say we are using a 2 Ohm 10W resistor feeding an 8 Ohm 20W (true RMS) tweeter above 3kHz. The crossover is going to feed about 17W for HF when running flat out a 100W amp with music. 2/8 of that is going to be dissipated by the resistor. I.e. peanuts.

[demon2091tb]

Is there any possibility that i could get you to post up your xover desin.

I'm considering a RS225, RS52, x design soon and would like a good place to start with the overall xover points and such. What are your respective xover points and slopes with the passive in that, and how do you avoid beaming using a dome midrange in the home. (i'm using one in my car)