Custom 8x15 bass cabinet

[bootsy666]

[quote name='M@23' timestamp='1429352295' post='2750661']
How much amplifier will you need to power this thing? Will it work with a standard 500w class D job?
[/quote]
I willbe running this with a marshall vba400, x8 KT88's.

[bootsy666]

[quote name='Jecklin' timestamp='1429352913' post='2750669']
@bootsy666 I LOVE the look of the burnt wood on your bass and guitar cabs! (I'm a big fan of raw wood cabs anyway)

Your back line would look amazing in less conventional venues as well. Ie where an audience can really see the stuff making the noise.

Have you got some other gig dates lined up?

Not a judgement on anyone at all - but I'd hazard most commenting here have no comprehension of the sonic context your band operate in.
I'm lucky enough to have seen Sunn(0))) at the underworld 11years ago, having gone with friends but knowing nothing about the music. It certainly changed my perception of amplified distorted bass
They weren't using much of the PA system
[/quote]
One of my favourite bands!!! And in a great venue too.

[Beer of the Bass]

I can sort of see where both Bootsy and Bill F. are coming from here. I guess some adjustment of expectation is required for a musical genre where speakers with wildly uneven frequency response, running past their Xmax and distorting, over a background of port-chuffing noise would be considered a desirable sound and it's going to seem downright ridiculous to someone who has spent decades designing these properties out of their speakers.
But on the other hand, walking into a dimly lit room with a band making that kind of sound through a huge array of weirdly cobbled together equipment can have its own particular impact.
Though if you put it together and find it's not quite doing what you wanted, Alex's advice on porting would probably be a good avenue to investigate.

[Number6]

I hope it works and i hope you take it to the Underworld because i want to come along and see it in the flesh in all it's Demonic glory.....

[bootsy666]

I really only wanted advice on venting the speakers, mostly for heat exchange. I was thrown a bit of coarse by all this, I've gone back to my original plan and TF speakers. I like the sound of them, I've tried them in a pair of matamp 2x15's.
I've made 8 ports of 2 inches each, one for each speaker, if this ends up being too much then I will block some off?

[SubsonicSimpleton]

I don't think anyone is hating - if you like the sound of the celestion TF speakers in the Matamp cab that's great, but if you put the same speaker drivers into a cab with a different internal volume and porting arrangment then they won't sound the same as they did in the matamp cab you liked.

Regardless of what you want to acheive sonically, the laws of physics affect all speaker cabs in the same way - it might be a bit of a shock to the system to unveil your design and receive criticism, but considering how far you are downtuning, surely the low frequency response of the cab is important?

[3below]

[quote name='bootsy666' timestamp='1429350869' post='2750638']
.....I did do my homework before starting, and decided against the modern designs that computer programs claim are the best, instead I went with the same idea as the early sunn cabs that have been very successful.
[/quote]

[quote name='bootsy666' timestamp='1429367323' post='2750848']
I've made 8 ports of 2 inches each, one for each speaker, if this ends up being too much then I will block some off?
[/quote]

I suspect some classic cabinets would probably be sub-optimal when subjected to computer aided design - I am particularly thinking of the Acoustic 360 that I once owned.

Blocking off is a good pragmatic solution. If you find you need larger ports they can always be put in the back of the cabinet.

[bootsy666]

[quote name='3below' timestamp='1429369264' post='2750872']




I suspect some classic cabinets would probably be sub-optimal when subjected to computer aided design - I am particularly thinking of the Acoustic 360 that I once owned.

Blocking off is a good pragmatic solution. If you find you need larger ports they can always be put in the back of the cabinet.
[/quote]
Thanks, I'm going with 4 ports and blocking the other 4 to start with, if need be I can just unblock tye other 4.

[alexclaber]

Bootsy, a few simple things to bear in mind. When you make a cab smaller per driver then you lose true lows (sub 100Hz) and gain a small amount of upper bass (100-200Hz). Because your cab doesn't have much volume behind each 15" it won't get a lot out of each in the real low but you'll get plenty of output in the 100Hz+ region. Bear in mind that if you're downtuning to A your lowest fundamental is 27.5Hz, first overtone 55Hz, second overtone 82.5Hz etc.

However, because your cab has eight drivers working in unison and the total size is large, you'll still get a lot of output in the sub 100Hz region - you might need to back off the 100-400Hz region with your EQ so your low-mids don't overwhelm your true lows because otherwise you may end up sounding just like a big guitar rather than proper doom bass.

Regarding the ports, if I were you I'd plug them. They're too small to work without making chuffing noises once you're cranking and the more you plug, the worse that will be.

[bootsy666]

[quote name='SubsonicSimpleton' timestamp='1429368716' post='2750866']
I don't think anyone is hating - if you like the sound of the celestion TF speakers in the Matamp cab that's great, but if you put the same speaker drivers into a cab with a different internal volume and porting arrangment then they won't sound the same as they did in the matamp cab you liked.

Regardless of what you want to acheive sonically, the laws of physics affect all speaker cabs in the same way - it might be a bit of a shock to the system to unveil your design and receive criticism, but considering how far you are downtuning, surely the low frequency response of the cab is important?
[/quote]
I did ask a question about mixing high and low frequency speakers in the v shape of the baffles, but I was just mocked rather than given an answer.
It would have been nice to have had an answer to that question tho.

[bootsy666]

[quote name='alexclaber' timestamp='1429370143' post='2750885']
Bootsy, a few simple things to bear in mind. When you make a cab smaller per driver then you lose true lows (sub 100Hz) and gain a small amount of upper bass (100-200Hz). Because your cab doesn't have much volume behind each 15" it won't get a lot out of each in the real low but you'll get plenty of output in the 100Hz+ region. Bear in mind that if you're downtuning to A your lowest fundamental is 27.5Hz, first overtone 55Hz, second overtone 82.5Hz etc.

However, because your cab has eight drivers working in unison and the total size is large, you'll still get a lot of output in the sub 100Hz region - you might need to back off the 100-400Hz region with your EQ so your low-mids don't overwhelm your true lows because otherwise you may end up sounding just like a big guitar rather than proper doom bass.

Regarding the ports, if I were you I'd plug them. They're too small to work without making chuffing noises once you're cranking and the more you plug, the worse that will be.
[/quote]
This is the kind of stuff I need to hear! That's very helpful man. Celestion have to me that the speakers need venting for heat exchange?
Is it an option to block all front ports and install lagers ports in the rear? I used a cab with rear porting once but didn't like the sound of it.

[skankdelvar]

Frankly, I think a mere VBA might be a bit of an anti-climax. Perhaps Mr Bootsy666 might have a word with John Chambers and see if he'll build another one of his 1000w valve amps.

[alexclaber]

You're only using a 400W amp with them and the drivers will each handle 250W thermally - so 2000W total. Heat definitely isn't an issue, whatever Celestion say!

You can definitely rear port them but you need to get the size/lengths right or you'll end up tuned too high which will kill off your deepest lows. As soon as you make the holes bigger you have to add length to keep the tuning frequency the same.

[Billy Apple]

[quote name='skankdelvar' timestamp='1429371608' post='2750911']
Frankly, I think a mere VBA might be a bit of an anti-climax. Perhaps Mr Bootsy666 might have a word with John Chambers and see if he'll build another one of his 1000w valve amps.


[/quote]

Ah, the Bilborough Startler!

[bootsy666]

There's an old amp tech who lives near me who's built a few 1000watt tube amps in the past, I might ask him to do me one.
I think the vba will be fine, what's the equivalent of 400watts valve compared to solid state?

[skankdelvar]

[quote name='bootsy666' timestamp='1429372474' post='2750926']
what's the equivalent of 400watts valve compared to solid state?
[/quote]

More. Just more. Of everything.

Actually, I agree the VBA will be fine. Just that a handmade, Savile Row Gentleman's rig should [i]probably[/i] include a suitably excessive head. Preferably about six foot wide with a strobing faceplate and a Martin-Baker ejector seat.

[JTUK]

[quote name='3below' timestamp='1429369264' post='2750872']
I suspect some classic cabinets would probably be sub-optimal when subjected to computer aided design - I am particularly thinking of the Acoustic 360 that I once owned.
.................
[/quote]

The 360 is a 40 plus year old cab and even back then I don't recall them being usable without a 412 linked up..?
Certainly the one I had in the late 80's needed something like that.

[Bassman Steve]

Yeah, so did Jaco - oh wait, no he didn't.

[bootsy666]

[quote name='skankdelvar' timestamp='1429373794' post='2750937']


More. Just more. Of everything.

Actually, I agree the VBA will be fine. Just that a handmade, Savile Row Gentleman's rig should [i]probably[/i] include a suitably excessive head. Preferably about six foot wide with a strobing faceplate and a Martin-Baker ejector seat.
[/quote]
Someone told me once that a 200 watt valve amp was the equivalent of a 1000watt solid state. If that's true then the vba could handle a 2000 watt cab, that's one of the reasons for making the cab 2000watts.
I currently have a quad of 6550A valves in it, but u also have a set of brand new sovtec KT88 Russian valves sat in my garage waiting to be used. I wanted to hear the 6550's with this cab before changing them tho.

[JTUK]

[quote name='Bassman Steve' timestamp='1429374410' post='2750944']
Yeah, so did Jaco - oh wait, no he didn't.
[/quote]

Or Vega, but you have to know how they approach getting a sound...but you don't see them in use today
for a reason... and 99.9% of bass players aren't a Vega or Pastorios either.

[alexclaber]

[quote name='bootsy666' timestamp='1429375182' post='2750945']
Someone told me once that a 200 watt valve amp was the equivalent of a 1000watt solid state. If that's true then the vba could handle a 2000 watt cab, that's one of the reasons for making the cab 2000watts.[/quote]

It doesn't really work like that, it's pretty much the reverse - the bigger the cab, the easier a time the amp has. Think of it like the amp is trying to push air, and the more speakers, the easier it is to push air because each speaker doesn't have to work as hard.

A 400W valve amp has the same power output as a good 400W solidstate amp but because they overdrive nicer you can get a few more dB out before it sounds nasty. If you run a load of fuzz and compression before either amp then there's not much in it at all.

There will always be something cool about big valve amps and huge cabs though - a bit like big block V8 cars. Nothing logical but does that matter?

[3below]

[quote name='JTUK' timestamp='1429374085' post='2750942']
The 360 is a 40 plus year old cab and even back then I don't recall them being usable without a 412 linked up..?
Certainly the one I had in the late 80's needed something like that.
[/quote]

Seemed OK to me at the time, then again I was 18/19 and what seemed ok to me in the very late 70s would not now. Have just done some Google and found / remembered the cab was a 361. Quite popular at the time [url="http://www.bassplayer.com/amps/1166/full-circle-360-degrees-of-the-acoustic-360/26984"]http://www.bassplaye...ustic-360/26984[/url] it seems. I saw Ricky Cool circa 1977 - bass player was using one and I just thought - yep got to have one.

Edited April 18, 2015 by 3below

[planer]

This is turning into an epic build thread :-)

I can't wait to see and, given our apparent proximity, probably hear the finished beast!

Good on you for building something wild, it's a corker.

Edited April 18, 2015 by planer

[JTUK]

[quote name='3below' timestamp='1429386126' post='2751051']
Seemed OK to me at the time, then again I was 18/19 and what seemed ok to me in the very late 70s would not now. Have just done some Google and found / remembered the cab was a 361. Quite popular at the time [url="http://www.bassplayer.com/amps/1166/full-circle-360-degrees-of-the-acoustic-360/26984"]http://www.bassplaye...ustic-360/26984[/url] it seems. I saw Ricky Cool circa 1977 - bass player was using one and I just thought - yep got to have one.
[/quote]

I had one for the same reason...it pushed out a lot of bass that just wasn't anywhere typical at the time...
But you learn from those sort of moments..or you hope you do.

[bootsy666]

Besides technical stuff, I've brought some good quality black leatherette, I used the same stuff to wrap my vba400 in and it came out quite nice.
I did plan on using it on the front baffles only before the speakers go in, but I'm having second thoughts now.
I guess I could always remove it if it doesn't look right.