3 way driver compatibility check: first time speaker builder

[fishish1]

Good morning all,

I'm an engineering student who is a first time speaker builder and am seeking some more experienced builders opinions on the quality and choice of the drivers I have selected. Im trying to do this once and do it right and although im only going to be using hand calcs and possibly some freeware am hoping to end up with a pair of 3-ways that will at least knock the panties off some girls at parties.

The drivers I've selected are as follows:

Tweeter: seas prestige 29tff
Mid: dayton audio rs52an-8
Woofer: dc380-8

Im thinking that a big box will lower the spl of the woofer and the bandpass region will create a db gain in the midrange leveling out the spls mostly but ill account for this more once I get to the crossover calcs.

Thanks for any advice,
Brian

[fishish1]

All I think im looking for is just a double check by someone on frequency range and spls and possibly what the effect of using a 6 ohm tweeter is... just to clarify

[weltersys]

Originally Posted by fishish1

All I think im looking for is just a double check by someone on frequency range and spls and possibly what the effect of using a 6 ohm tweeter is... just to clarify

Brian,

Specific questions might help.

A 6 ohm tweeter is only nominally 6 ohms, the actual impedance of any speaker varies with frequency.

This makes building a crossover for speakers that actually works well very difficult, since the speakers do not behave much like a simple 6 (or whatever) ohm resistive load.

Read the crossover design sticky in this forum, it will help you.

Introduction to designing crossovers without measurement

One basic rule: the Fs of the mid and high drivers should be at least an octave below the acoustic crossover points.

[AllenB]

Originally Posted by fishish1

Im thinking that a big box will lower the spl of the woofer

Yes, but not in the passband. This is therefore not a reasonable approach to the SPL mismatch. In my opinion the mismatch is relatively insignificant anyway. Furthermore, it is not unreasonable to want the low end to take on a slight rise.... then there will be baffle related tuning opportunities.

and the bandpass region will create a db gain in the midrange

Using the crossover for gain in a bandpass section is not usually encouraged, besides, with a varying complex impedance the result would need discrete calculation versus frequency. You may be better starting with a target response.

[jerome69]

15"+2"+"1 not an obvious choice, a difficult challenge for a beginner. woofer + mid have a nasty peak on the end.

similar project :
Parts Express DIY Project

[AllenB]

That image helps put it into perspective. A small dome mid matches the directivity of a 15 below the fs of the mid. There seems to be the potential for a 'boom-tizz' system.

[Loren42]

Using that woofer I would recommend looking at this link:

Dr. Mark Says Blog Archive Three way speaker using Dayton DC380-8_Eminemce Alpha 6 and Hi-Vi Research RT 2H-A

The mid and the tweeter are available at Parts Express.

A better combination would be the Audax PR170M midrange and a Morel tweeter such as the MDT-37. The MDT-37 is going to be very tight on the SPL, but will work. This will require changes to the crossover.

The Seas, while a very good tweeter does not, in my opinion, have enough SPL to match the woofer.

As a general set of rules, you want the mid and the tweeter to have a higher SPL than the woofer. You can pad these down easily enough.

Second, the mid range needs to have sufficient diameter for the audio passband that it is designed to operate in. 2" is out of the question here. You can learn more at:

Lenard Audio Institute - Education - Professional Live Sound.

Lastly, a 3-way system is a very hard system for the first time builder to do. 3-ways are much, much more complex from an engineering standpoint than a 2-way.

I am not saying you can't do it, but you will be spending a lot more engineering time than you ever imagined (by orders of magnitudes) getting a good design.

As an engineering student you need to make sure you have enough time to spend on your studies. If you take on a 3-way design from scratch you may find you have no time at all for the girls in the first place.

An alternative would be to build a kit from Madisound or a preexisting design. You will be better assured that you will have a system that meets your goals, within budget, and in a timely manner.

[sreten]

Hi,

Some links below, but I severely recommend building :

Zaph|Audio - ZDT3.5
or
HTGuide Forum - Dayton RS WMTW Center & TMWW Mains
or
https://sites.google.com/site/undefinition/tarkus


Stay the hell away from crossover calculators, utter garbage,
and guaranteed for a 3-way to get it all completely wrong.

rgds, sreten.

undefinition (see FAQs)
Zaph|Audio
FRD Consortium tools guide
RJB Audio Projects
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

[Luke]

Hi Sreten,

have you heard the Tarkus? It seems to be around 86db efficiency I think but he claims it goes very loud. It looks like a good project but I was hoping my next project would be 93db efficiency.

[sreten]

Originally Posted by Luke

Hi Sreten,

have you heard the Tarkus? It seems to be around 86db efficiency I think but he claims it goes very loud.
It looks like a good project but I was hoping my next project would be 93db efficiency.

Hi,

No I've not heard them, but they seem like they would work well.
(Main point is that they are designed properly, like the other two.)

The SLS bass driver has a 24mm long coil with an 8mm gap giving
+/- 8mm throw - real subwoofer territory performance, they will
go very loud and low cleanly when fed lots of juice.

Why do you want 93dB efficiency ? Only good reason is a low powered
amplifier. The combination means you'd need huge boxes for decent
bass extension and bass levels, no better than the above, likely worse.

rgds, sreten.