New speaker project [Archive] - The Art of Sound Forum

Dingdong

07-10-2011, 19:14

For some reason I bought these cabs on ebay the other day. Seemed like a good idea at the time.

http://i896.photobucket.com/albums/ac169/marktb/Speakers/IMG_0045.jpg

http://i896.photobucket.com/albums/ac169/marktb/Speakers/IMG_0043.jpg

They are not in bad nick. They seem to be solid cherry. Some of the joints are a bit diy, but they will do for my first go at building speakers.
This will be a long term project as funds allow.

I've got a whole bunch of ideas as to what drivers to go for.
The simplest being that I use the tweeters out of a spare pair of DM2's as I like the sound and add a mid and a big, f**k off, woofer in the side.

Any other ideas or suggestions are greatly welcomed. I've got a fair bit of learning to do.

Reid Malenfant

07-10-2011, 19:21

Are they a sealed box or is there a reflex port somewhere? Sealed will be easier imho as you'll have a wider choice of drivers which i believe may well be 12" for bass?

What are the precise internal dimensions? Just remember all that enclosure is for the bass unit ;)

Dingdong

07-10-2011, 19:33

Internally they are 20x35x87cm. There is a port at the top and a hole for the connections at the bottom. I have the ports and connections.

Reid Malenfant

07-10-2011, 19:39

60.9L with no drivers or port fitted... Bass driver will eat up a bit & so will a port.

What size is the cutout for the bass/mid? The bass driver on the side is only going to be good for up to a maximum of 150Hz or you'll have serious integration problems, even if you went active ;)

Dingdong

07-10-2011, 19:46

There is no baffle for the front. I'll have to make my own up.
I think active may be the way to go.

Reid Malenfant

07-10-2011, 19:47

Oh, while i think about it, what is the diameter of the port... You see i need to know how low that enclosure can be tuned & you need to leave at least one diameter of the port between the port itself & the back of the enclosure...

More is preferable :)

Reid Malenfant

07-10-2011, 19:51

There is no baffle for the front. I'll have to make my own up.
I think active may be the way to go.
Ah, so that hole could be utilised as a bunch of input connections & you could have a sealed box... Or is there another hole to be filled?

Just asking :eyebrows:

Dingdong

07-10-2011, 19:52

If you look at the 2nd photo. The port is the hole at the top. The id of the port that came with it is 65mm.

Reid Malenfant

07-10-2011, 20:00

65mm, cheers Mark.. Yes i now see where the inputs are located, in a rectangular slot... Way down low ;)

Dingdong

07-10-2011, 20:09

It should be possible to find the right mid that crosses over around 100hz and 3khz.
As for tweeters. It not necessary to use the Celestion HF1300 and Coles 4001's that I have now. It's just that I have some and I quite like the way they sound.

Reid Malenfant

07-10-2011, 20:21

Ok, with a 6.5cm diameter port you can tune down to about 23.5Hz in that enclosure, but using any normal 12" cone the port velocity will be too high & you'll get compression & distortion (chuffing) at high volume levels :(

I'm assuming a 55L enclosure due to volume loss of the bass driver, port & midrange enclosure needed.

Still work to be done though, so don't give up for an instant ;)

Dingdong

07-10-2011, 20:26

The alternative could be to go with a bigger 'ole or block it up. It's round the back so I wouldn't notice it.
My room is only 3x4m if that is any help.

Reid Malenfant

07-10-2011, 20:32

I have learn't that room size really doesn't matter ;) I happily reproduce 15Hz in a 4 x 4m room with no boom at all :cool: I'm sure Dave (synsei) will back that up, he was here hearing it & feeling it a few days ago :eyebrows:

Blocking it up would be one way of increasing your choices of driver, but don't give up yet ;) It's very early days & i'm the only poster so far :)

Dingdong

07-10-2011, 20:36

Once up and running they probably would need to be placed close(ish) to the wall. The cats like a good swing now and then.

Reid Malenfant

07-10-2011, 20:39

Once up and running they probably would need to be placed close(ish) to the wall.
So you need a low Q driver with a rolling off response so that room gain kind of equalises it...

Cats :eyebrows: They are fun...

Dingdong

07-10-2011, 20:51

Okay, I'll have a search round for one of them. I'd also need a mid that did from 100hz up to approx. 4-5khz as well wouldn't I?

Cats are less fun when you wake up to entrails left on the living room floor.

Reid Malenfant

07-10-2011, 20:54

Yes :) This might be the most important driver in certain respects, but if you are willing to go active between the bass & bass/mid then you open up lots of opportunities.

Dingdong

07-10-2011, 20:58

I've read the thread on what you did with the active crossover. Sounds interesting and makes things more flexible. Could it be set to crossover at 150,3k and 13khz for the 4 drivers or would a modern tweeter, such as the Vifa xt25 possibly the way to go?

Reid Malenfant

07-10-2011, 21:37

I used to use an active xover between the bass & lower mid & the lower mid & the rest of the drivers were fed by a standard Yamaha NS1000 crossover. I just needed to select a driver that'd match as much as possible the NS1000 bass so i split it four ways... Active below 110Hz & driven by another amp into the original Yam xover above 110Hz.

Not as easy at it sounds, but not impossible. It took time to find a driver that'd match as near as possible the reactance of the Yam 12" at the xover frequency of 500Hz & the sensitivity.

Dingdong

07-10-2011, 21:51

Wouldn't it be possible just to use the active crossover for all 3 or 4 drivers?

Reid Malenfant

07-10-2011, 22:07

Yes, but you'll need something like a Behringer DCX2496 to time align the drivers..

Luckily it'd do everything else to integrate a 3 way system... Gain, time delay, crossover rolloff & type etc...

Not perfect though, you see you need to feed it a stupendous voltage level level to make it use all the 24bits it's capable of using...Then you need to step it down to fit in with hifi amps...

Well i'm dieing at the quality of it non stepped up already, when i get this extra 25Db+ of input through modification & all the 24bits i guess i'll know what real linearity is :eyebrows: Right now it is better than any 16bit system...

Dingdong

07-10-2011, 22:18

Would the balanced out of my pre be too low? Then maybe balanced/unbalanced transformers on the i/ps of the power amps.

Reid Malenfant

07-10-2011, 22:28

Dingdong

07-10-2011, 22:53

Would it be possible to tweak the input and output analogue bits of the Behringer?

Ali Tait

08-10-2011, 12:47

You could perhaps use a pair of these Monocor ribbon tweeters Colin has used in his Edingdale speaker. I've not heard them with the ribbons yet, but Colin says they are very good, and I trust his ears. They are not expensive-

http://www.connect-audio.co.uk/proddetail.php?prod=MONRBT95

Ali Tait

08-10-2011, 12:51

No i don't think so, i'm using the balanced output of my ARC MP1 to feed the Behringer & the outputs are single ended. It's just that you are not using the Behringer to it's full 24bit capacity (due to the low input voltage) so linearity isn't as good as it could be.

If you increased the input it could make use of all 24bits on peaks & linearity would increase even if you attenuated the output ;)

It's what i'm planning to do...

Mark, have you tried turning the gain down on the Behringer and driving it with a higher level from the pre?

I've not thought about trying it myself and I'm not at home at the mo. If you haven't, have a go and see if it makes any improvement.

I would say it sounds pretty good as it is though.

Reid Malenfant

08-10-2011, 16:56

Would it be possible to tweak the input and output analogue bits of the Behringer?
Yes, & that's the plan ;)

Mark, have you tried turning the gain down on the Behringer and driving it with a higher level from the pre?

I've not thought about trying it myself and I'm not at home at the mo. If you haven't, have a go and see if it makes any improvement.

I would say it sounds pretty good as it is though.
Yes i'm in 100% agreement that it sounds good as it is :)

I can't get any more output from the pre other than turning the volume up further & i often hit 80/100, if there was some kind of gain control as well as the volume control then i'd be laughing. As it is i can reduce the gain, i just can't boost it :doh: