New 2-channel DIY speaker project

gatemplin

I have started a new DIY project with a lot of help from my friend Jon Hancock. This is the new project diary I will use to document the progress. There aren't many DIYers here, but maybe I can change that.


The new project is a full range 2-way design using a Seas tweeter and the Adire Audio Extremis midwoofer.

The Seas 27TDFC tweeter is a great performer for this application and is popular in high end audio designs. They are used by Joseph Audio and Reference 3A to name a couple.

Here is the Seas:



The Extremis6.8 is a high tech midwoofer. It uses a dual gap motor (XBL^2)with a copper shielded pole piece. It has massive excusion and low distortion down low compared to the Scan Speak 8545. Here is the Xmax video:

Here is the Extremis:

michael_w

Cool... where are you getting your parts from?

gatemplin

Originally posted by michael_w
Cool... where are you getting your parts from?

Thanks,

The Adire Audio Extremis6.8s are available from www.creativesound.ca

I'm buying the Seas and crossover parts from www.Solen.ca

gatemplin

The speaker design goal is flat frequency response, huge bandwidth, ultra low distortion and great off-axis response. The transient response will also be excellent.

The tradeoffs to achieve these goals are efficiency, size, cost, and max output.
They are going to be around 80 dB efficient.

The most important part of the design is the brain, the crossover. Jon is going to design this one using an 8th order Linkwitz-Riley design, modified with Cauer elliptic filters. Jon has been designing speakers for about 30 years. He is a published designer and a member of the Audio Engineering Society. I'm really lucky that he has been helping out with this hobby. He is an EE, but does this for fun.

The crossover point is going to be very low. Probably 1kHz even. The Seas can handle that because attenuation is so high in this design.

gatemplin

My version of the project will be an EBS box. 37L tuned to about 29 Hz. The anechoic F3 is 28 Hz according to Unibox. The in room F3 should be closer to 22 Hz.

gatemplin

Here is a AutoCAD drawing of the box I am building. I am using a 3" flared port about 15" long which is why the cabinet is so deep. The box is made from MDF, butcher block and birch ply wood in varying thicknesses from .75" to 1.25".

Edit: CAD drawing in next post.

gatemplin

EBS box.

michael_w

Looks like an interesting project. Kinda makes me want to get more into diy ... but I have a lot of learning to do before I start.

gatemplin

Originally posted by michael_w
Kinda makes me want to get more into diy ... but I have a lot of learning to do before I start.

That's why I started this thread. I hope to spread the disease.

The best way to get into DIY is to build a kit or copy a plan. I did a few of those to start. It builds your confidence and you learn a lot. And you are guaranteed good results.

There are tons of great sites and books. The Loudspeaker Design Cookbook by Vance Dickason is considered the DIY bible.

PM me if you want recommendations for kits, websites, books etc.

michael_w

I'll do some more reading then get back to you on that one. I'm contemplating a sub but I'm not sure just yet.

gatemplin

This is probably the final crossover for the project. 8th order at 1.2 kHz. Jon just finished it.

It's a Linkwitz Riley based design with Cauer-elliptic filters modifying the transistion bands to achieve about 8th order attenuation.

Here is the crossover schematic:



Here is the frequency response. There are room interactions and not much smoothing. We're not selling them so there is no need to make it look pretty.



I am so glad Jon is helping me out with the crossover design. I tried getting these drivers flat but could figure it out.

He did a great job and I cant wait to build and listen to them. The roll offs at the top and bottom are irrelevant. These are flat from 30 to 20k anechoic.

gatemplin

Here is the off axis response graph by Jon.



Very flat through the crossover, me likey.

I'm ordering the parts tomorrow and finishing the cabinets. Trying to get these ready for a DIY meet Saturday.

BlueMDPicker

Fascinating, to say the least! I'll be watching as your concept comes to fruition (and wishing I had the knowledge, plus the facilities, to undertake such a wonderful project.)

Mike

gatemplin

Thanks Mike,

Most of the knowledge and work is from my friend Jon. I help out as much as I can. This has been a great learning experience for me.

Here is the front baffle layou designed in Baffle Diffraction Simulator by Jon, I drew it in AutoCAD. I'll be cutting up the baffles and making the tweeter housing tonight. Hopefully paint tomorrow, then crossover work Thursday and Friday.

Toxis

Originally posted by gatemplin
There are tons of great sites and books. The Loudspeaker Design Cookbook by Vance Dickason is considered the DIY bible.

I have this book and all I'm going to say is... wow. I haven't even got that far through it but I'm learning way more than I thought I would being this far into it.

I've been wanting to try some DIY speakers but I don't have the tools or facilities to build the enclosure. Plus, the part that I'm VERY green about would be the crossover network. That makes me go all crosseyed. Hopefully when I buy a house next year, I'll have the area to do something like this and by then, I'll have the knowledge to feel comfortable with a task like so.

gatemplin

I placed my order for the crossover parts today. I am using all Solen Perfect Lay 14 gauge air core inductors except for one. And all Solen Fast Caps polypropylene capacitors. Hopefully they will ship tomorrow so I can have them for the weekend DIY meeting.

If anyone is thinking of building this project figure between 600-700 US for the parts including wood. Not cheap, but this is a good design. Many months of work went into this. If you like to build things, and when you consider the performance, these things are bargains.

This is a new animation from Adire of the motor in the Extremis6.8

http://www.adireaudio.com/images/X_68_Motor_Animation.jpg

gatemplin

I finished the speakers last night and brough them to a DIY meeting today.

I think they sound amazing. It is really nice to finally hear something that I (and Jon) worked so hard on.

They were powered by a DIY SS pre amp and a Bryston 3B power amp.

gatemplin

Here is a pic of the front setup. The crossovers are on the floor. They weren't going to fit inside, not even close.

gatemplin

This is a pic of the left speaker and a better look at the 8th order LR crossover.

gatemplin

Here is a pic of the DIY crew. That's me on the far left.

gatemplin

Here is Dave's instant crossover prototyping rig with the horns in the back.

BlueMDPicker

Very nice work! I guess you could hide the crossovers in the stands?

dorokusai

Outstanding!

gatemplin

Thanks guys,

I think I will incorporate the crossovers into the stands somehow. I have to figure out what size the cabinets will be first. No hurry though.

Here is a pic of the RCA field coil horn. Pretty cool I think. VERY efficient. Powered with a gain clone.

gatemplin

Here is proof that the RCAs go loud. Thats me with Chris plugging his ears in the background with the music at about 105 to 110 dB. It was painful.

gatemplin

Here is a pic of Fred's speakers. These looked and sounded beautiful. The woodwork was incredible, I'm very jealous. Raven ribbon and Seas Excel midrange.

michael_w

They look great gatemplin.... didn't expect the crossovers to be so massive but it'd be pretty original to have them built into the stands or something. Kind of like a tower bookshelf speaker.

I think I will pop by the library sometime soon and pick up that Loudspeaker Design Cookbook while I have some free time to read because of Spring Break..... WOOT. I told my boss I was "going away" and wouldn't be able to work at all during spring break . I need a break from doing 25-30 hour weeks at work and going to school so maybe this will be it .

gatemplin

Thanks again for the compliments guys.

I really can't articulate how much I like these speakers. I didn't realize speakers could sound this real.

BlueMDPicker

I think we need a speaker swap program!

Put me first on the list, please.

Graham, what do you use to drive your new creations? Did the finished project end up in the 80 db efficiency range as you anticipated?

Mike

gatemplin

Originally posted by BlueMDPicker
I think we need a speaker swap program!

Put me first on the list, please.

Graham, what do you use to drive your new creations? Did the finished project end up in the 80 db efficiency range as you anticipated?

Mike

Thanks Mike.

I use a Sansui AU999 integrated from 1970. The outputs are modified from the one in the pic to take banana plugs instead.



The efficiency is quite low, but they do go plenty loud. 80 dB is not as bad as it sounds. We use almost full baffle step compensation, which makes the speakers sound very warm and full even at low volumes. I listen at least 3 dB quieter with these speakers because they are so clear. I have played these on a 50w Harman receiver and it did a fine job aswell.

gatemplin

Here is a pic of the back of the speakers. You can see I added a 3" flared port instead of the old 2".