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Re: 4 way Frankenstein high efficiency speakers

Posted: Tue Aug 17, 2021 2:16 pm
by valvesRus
Daniel Quinn wrote: Tue Aug 17, 2021 1:29 pm As far as speakers bass is concerned. Size is everything.
I'd not necessarily agree with that DQ.

Size + proper implementation more like.

When I first heard Nick Gorhams open baffle speakers with the Eminence Beta 15 bass driver I was mightily impressed, and that led me onto my own journey with open baffle speakers.

I currently use 18" Beyma drivers (SM118/N) but I need to experiment with low pass bass filters and 50W chip amps to get the best from them. I have got the parts to hand to do the job but the enthusiasm is lacking.

Re: 4 way Frankenstein high efficiency speakers

Posted: Tue Aug 17, 2021 6:59 pm
by Lindsayt
Daniel Quinn wrote: Tue Aug 17, 2021 1:29 pm As far as speakers bass is concerned. Size is everything.
That's a sort of yes and no.

There's no doubt that there's a huge difference in the bass between every 5" woofer (at that size it's actually a squawker being asked to do bass duties) and every 18"+ woofer that I've heard.

On the other hand, the 2 x 12" woofers in my Bozak Symphonies start rolling off at 40hz - in a semi infinite baffle enclosure. A single Bozak woofer would probably start rolling off at about 45hz.
If I were to put a 12" Altec 414-8C in the same cabinet, according to these 2 sites:
http://alteclansingunofficial.nlenet.ne ... Small.html
https://www.diyaudioandvideo.com/Calcul ... Enclosure/
The Altec would start rolling off at over 100hz, and therefore give me crappy LS3/5a type bass extension.

I did think about getting 2 x 12" Bozak woofers per channel and putting them in a semi-infinite baffle box for this project. And that's a route that I might still go down.

But for now I fancy experimenting with 18" to 24" woofers to fill in below the 414's.

What's mildly annoying is that I naively thought that by getting an 18" to 24" woofer I could get a combination of high efficiency, bass extension down to 28hz, as well as good bass quality, as well as relatively simple cabinets. So far I've not come across any such woofers...

Re: 4 way Frankenstein high efficiency speakers

Posted: Tue Aug 17, 2021 11:20 pm
by Docfoster
As far as bass is concerned, and in my very limited experience, size matters a lot up to 12 inches and then there's diminishing returns through 15 and 18 inches.
Also as driver size increases I have found that cabinet rigidity / bracing becomes more of an issue; so its not a free lunch. Whether that's due to the cabinet becoming inevitably larger physically, or the bass energy being greater, or both, I have no idea. (But hence my using braced 18mm MDF and lining the cab with bitumen and concrete for my bass cab (12 inch driver).)

Re: 4 way Frankenstein high efficiency speakers

Posted: Tue Aug 17, 2021 11:25 pm
by Docfoster
BTW re measurements...
It's weird, as I'm sure will come to as surprise on this 'ere bored...
These are they for my system's bass...first is measured with the mic where my ears are, the second is where my hand rests on the arm of the sofa...so only about a 50cm difference in position.
Exactly the same sweep.

Image

Image

Edit: be reassured measurements of these kind play no part in my design process, things are tuned by ear… I just find it academically interesting to measure things post-facto.

Re: 4 way Frankenstein high efficiency speakers

Posted: Mon Aug 30, 2021 9:55 am
by SteveS57
Hi lindsay, nice to see you starting this project, I know you don't live too far from me, if you want to visit me.
your more than welcome.

Or anything you want to ask just say

Cheers

Re: 4 way Frankenstein high efficiency speakers

Posted: Mon Aug 30, 2021 12:58 pm
by Geoff.R.G
Docfoster wrote: Tue Aug 17, 2021 11:25 pm BTW re measurements...
It's weird, as I'm sure will come to as surprise on this 'ere bored...
These are they for my system's bass...first is measured with the mic where my ears are, the second is where my hand rests on the arm of the sofa...so only about a 50cm difference in position.
Exactly the same sweep.

Image

Image

Edit: be reassured measurements of these kind play no part in my design process, things are tuned by ear… I just find it academically interesting to measure things post-facto.
If nothing else the graphs demonstrate the futility of designing for flat response in an anechoic chamber.

Re: 4 way Frankenstein high efficiency speakers

Posted: Fri Sep 03, 2021 12:08 pm
by Docfoster
Geoff.R.G wrote: Mon Aug 30, 2021 12:58 pm
Docfoster wrote: Tue Aug 17, 2021 11:25 pm BTW re measurements...
It's weird, as I'm sure will come to as surprise on this 'ere bored...
These are they for my system's bass...first is measured with the mic where my ears are, the second is where my hand rests on the arm of the sofa...so only about a 50cm difference in position.
Exactly the same sweep.

Image

Image

Edit: be reassured measurements of these kind play no part in my design process, things are tuned by ear… I just find it academically interesting to measure things post-facto.
If nothing else the graphs demonstrate the futility of designing for flat response in an anechoic chamber.
Quite.
I’d be interested to see how anechoic chamber measurements for various speakers compare with those same speakers’ measurements in a “typical living room”.
I wonder if there’s a typical EQ effect that a “typical living room” has?

I happened to be decorating my living room last week. Took everything out. All the soft furnishings, rugs, blinds, curtains, hifi etc.,…
When I’d finished the painting I set up the hifi first. Thought it would be interesting to hear what it sounded like in a naked room (the opposite of an anechoic chamber I suppose).
It sounded unspeakably awful. So bad in fact, that I feared I might have broken something when moving the hifi around.
Thankfully when the room was back together, things sounded back to normal. But, I was reminded of what a crucial component of the overall sound that enters one’s ears is the “listening environment”.
And I think that’s why building, or at least tweaking, one’s own speakers in one’s own room is such a rewarding experience.

Re: 4 way Frankenstein high efficiency speakers

Posted: Sat Sep 04, 2021 12:40 am
by Lindsayt
SteveS57 wrote: Mon Aug 30, 2021 9:55 am Hi lindsay, nice to see you starting this project, I know you don't live too far from me, if you want to visit me.
your more than welcome.

Or anything you want to ask just say

Cheers
It's a very slow burning project. One that I started over a year ago. And may well take a year or two or three before I get something that I will play music through.

Do you know of any woofers that will extend down to 40hz before hitting the -3db figure in a sealed box / semi infinite baffle and that would be 96 or more dbs efficient?

Also, looking ahead to the crossovers. Any recommendations on capacitors, inductors, resistors to use? Something that will sound decent but isn't stupid money.


...And yes Docfoster, when I've listened to music in rooms I've been decorating it has sounded very echoey. Sticking all the furniture and clutter back in makes a significant sonic difference.

Re: 4 way Frankenstein high efficiency speakers

Posted: Sun Sep 05, 2021 12:32 pm
by Docfoster
Lindsayt wrote: Sat Sep 04, 2021 12:40 am
SteveS57 wrote: Mon Aug 30, 2021 9:55 am Hi lindsay, nice to see you starting this project, I know you don't live too far from me, if you want to visit me.
your more than welcome.

Or anything you want to ask just say

Cheers
It's a very slow burning project. One that I started over a year ago. And may well take a year or two or three before I get something that I will play music through.

Do you know of any woofers that will extend down to 40hz before hitting the -3db figure in a sealed box / semi infinite baffle and that would be 96 or more dbs efficient?

Also, looking ahead to the crossovers. Any recommendations on capacitors, inductors, resistors to use? Something that will sound decent but isn't stupid money.


...And yes Docfoster, when I've listened to music in rooms I've been decorating it has sounded very echoey. Sticking all the furniture and clutter back in makes a significant sonic difference.
Indeed. Although I think the points I wanted to make, and which I was insufficiently clear about, were more general than that: That each listening environment probably has its own EQ and sonic signature (reverb, etc.,...) and; that home demoing / tweaking / DIY is the route most likely to arrive at kit that will suit one's tastes.
As an aside, my system did sound echoey, but it was worse than that. It was all midrange! (Possibly because those were the frequencies that echoed most.)

On the subject of capacitors I usually use Monacor (they make great drivers too) or Mundorf. I tend to source them from https://willys-hifi.com/ , simply because I find that online shop convenient, efficient and friendly. There may be cheaper alternatives.

I'm not sure about a driver that meets your requirements. When building my current bass cabinet my initial ambition was for a sealed cab, but I could not find a dual voice coil driver that could get down low enough in a sealed cabinet (like you, I wanted to achieve 40Hz, but for me, having a single DVC bass driver was more non-negotiable than having a sealed cabinet.) It may be that there's more chance of sourcing a driver that meets your frequency requirements in a sealed box if you're looking at more usual single coil drivers.

Finally, I agree that introducing any design feature (e.g. a port) does introduce the possibility of that feature being done badly. I have heard many ported speakers that sound terrible, probably because of a badly / lazily / cheaply designed port (some seem to be simply a drilled hole). But in larger cabinets with large bass drivers in which the port is not being asked to do all the heavy lifting, I'm unsure that ports are necessary bad.
I am a lover of sealed cabinets (NVA cube 1, Goodmans Goodwood and Magister, various old JPWs and my own sealed designs) but I am pretty pleased with the sound of my current DIY main speakers and the bass cabinet (all have rear-firing ports (that I like to think I took a lot of time to get right...I am in no way a physics expert but there are lots of free online tools that can help with designing a port that meets the symbiotic requirements of driver and cabinet.))
If one can avoid a port, then all things being equal, it's best to. Why introduce a design feature that one doesn't need? So, if you can find a driver that meets your requirements in a sealed box then you should definitely go for it. But, if you can't, then I'd be confident that with the size of driver and cabinet you are implying, a well designed port would be a perfectly acceptable contribution to achieving the bass you want.

Re: 4 way Frankenstein high efficiency speakers

Posted: Sun Sep 05, 2021 1:23 pm
by Lindsayt
The link to Willys is useful. As well as the Monacor or Mundorf recomendation.

When the time comes I'll be getting my head round the different types of crossover components. EG do bipolar capacitors have large mood swings? :obscene-hanged: