audio-talk

I think Ali that most of us would be interesting to see/ hear what he has achieved.
On the other hand theres a massive difference making speakers that work well in your living room, then placing them in a large room with 30 or more expert pairs of ears!
I'm sure they sound good though

They have moved on since I heard them, but yes very good, the bass has to be heard to be believed.

did some faffing with those 12" drivers i found in the back of the wardrobe. just wired them in parallel and propped them up. no crossover, just whatever they got fed

12" drivers lash up by anthony cresswell, on Flickr

they appear to be el cheapo qtx drivers that have been doped with something, probably bison kit as they came from richard dunn. not long before he died he was toying with ideas for some speakers and was experimenting with cheap big drivers to see if it was worth pursuing. what the ts prameters are is anyones guess. efficiency will be down abit on the 93 quoted. probably more like 88 - 90 ish now i reckon with the extra cone weight. supposedly the basic driver has a 45hz to 6k range. i doubt that..... the bison kit doping will probably have lowered the resonant frequency a bit though

interestingly, the 15-300tc is down to about the same at about 70hz ish. Wasn't expecting much, it was for a laugh, but they give a subtle extra kick at the bottom end, more extension, and a little more presence in the lower midrange. they do nice things. no honking. worth more investigation.

im thinking a very small u shaped baffle initially so they stand up and can be put somewhere alongside the speakers, and some sort of inductor on them to cut them off at about 100hz. dont really want to cut holes in the cabs

i shall need to reinstall the spectrum analyser app i had and burn some pink noise or a sweep to a cd to see what they are doing though

quite promising, wonder how much the 15 inch versions are

Interesting Ant. And that is without extending the response into the lowest octaves...

My experience with baffle less use of woofers is that they really don't develop a realistic body and weight unless you are doing something like Vic's deployment where each of the drivers dynamically load the other. If doing a baffle for the beastie try to ensure it seals to the floor and if the side wings extend back more than about 8 inches (20cm) taper the side profile a bit so it doesn't reinforce the same frequencies all the way up its height (like a U-baffle does)...

Have fun!

James

Or use a bit of DSP.

spent a few hours making a proper job of a stand for the drivers out of a bit of scrap bbp
decided i didn't want any baffle gain at all, i wanted just the driver or as close as. so the baffle its on is only 12 3/4" square

12" driver lash up by anthony cresswell, on Flickr

also put some actual speaker cable on it instead of the bell wire i dug out.

12" driver lash up by anthony cresswell, on Flickr

its getting a bit of gain from the rear due to the close proximity of the speaker front, but that's it.
they are keeping up with the 15s no problem, its intriguing because it shouldn't work but it does.....
need some measurements

Got some paul simon on now rather than massive attack, prodigy, faithless, and others ive had on for the past few hours.
It seems to be filling in the bottom of kickdrums, bottom of bass guitars ect. Theres a bit of a peak at about 50hz as expected, no crossover
Ive kept turning the volume down for some reason

As is, everything ive put seems to be richer sounding

ok some measurement.
bear in mind this is a phone app, the phone is a Samsung galaxy note 9, so an ageing high end model with a good mic in it, but not measurement quality. but perfectly acceptable for broad strokes.
this is using pink noise

this is the speakers as is without the bass helpers

Without by anthony cresswell, on Flickr

ignore the big weird looking 2k ish peak, that's the key sound on the phone when recording starts.

this is with the bass helpers

With by anthony cresswell, on Flickr

interesting.
it doesn't seem to be doing very much after about 100hz as it is with no crossover or baffle, which is what i was after.
the measurement was taken from where I sit, not a 1m or anything scientific, and there is a big footstool in the way too. Its response is broadly the same after about 300hz or so

Dqs issue with his speakers has spurred me revisit this. These drivers are the ones i got off richard dunn.
In parallel with the 15" driver they filled in the hole around the resonant frequency of the 15" driver.

Since then i got a behringer ecm8000 mic, a behringer interface, and have rew on the laptop so i could actually measure it properly. Got them this time last year and havent used them.

I think these drivers are the same as the ones dq had in his speakers, so i need to make sure they work

To be continued

Hmm also remembered that the speaker itself has the aperiodic vent in it that wouldnt have been there in those measurements so im curious to see what they are actually doing now
Need to learn to use rew

There not the ones I’ve got. The magnet is bigger and the paper as no ridges on it.

I’m due to take them apart tommorrow I report back .

just bought 3 sheets of BB....ouch!! didn't see that coming.

big surprise, the hardwood is cheaper than the softwood. Not sure what the hardwood is but its 13 plies.

ed wrote: ↑Mon Apr 25, 2022 7:25 pm just bought 3 sheets of BB....ouch!! didn't see that coming.

big surprise, the hardwood is cheaper than the softwood. Not sure what the hardwood is but its 13 plies.

I wanted some wood for a non hi-fi project, but when I saw (pun intended) what the local DIY store were charging the project was cancelled.

I got a brand new piece of kitchen worktop ( 2.2 metre offcut) for nowt on the local freecycle.

Would cost about £60 normally.

Sheet material prices have gone barmy recently. Not on everything though, chipboard is about the same, mdf seems to be a little dearer but not alot. Ply is blummin redunculous though. Bbp seems to be like gold dust from the suppliers i ususally use and costs accordingly. I wanted some 25mm bbp to make a new top plate for the xerxes, there was a sharp intake of breath and a large sigh....
Thats been put on hold for now......