What's in the box?

[supertzar]

Greetings from Finland. Forst poster here but I'd rather get straight to business. I've been playing the bass for the last 15 years and mostly never bothered to dive too deep in to the abyss that is the ultimate tone. I'm happy with the rig that I have when playing with and amp+cab or when playing straight to foh. Even the old 30w behringer practice combo I've been using for those 15 years at home (and even in some small acoustic gigs!) has served it's purpose well enough for me. But now I'm finally looking to upgrade the practice/small gig setup with a micro amp and a small cab. Currently looking at the elf or bam200. As I'm pretty happy with what I got so far, I'm planning to amuse myself with a diy cab build for this project. I have studied different options and I have pretty much set with eminemce basslite s2012 and their suggested ported ultralight build. The idea here would be to go under 10kg and I'm 99% confident my plans would work for this.

However, the real question isn't about the diy eminence 12" cab. When I was planning this, I got an option for pretty much free behringer bb410 cab and I thought this would be A LOT cheaper option and I think I might just get that and try to butcher it to a 2x10 cab as close to 10kg as possible. Probably pretty hard to go under 10kg but maybe a well braced thin plywood might be possible well under 15kg? The problem is that I can't find any information about the drivers used in this cab? Does anyone know if this information is available somewhere?

Edited June 23, 2020 by supertzar
Typo

[FinnDave]

Can't help with your cab question, but where in Finland are you? I lived in the Kouvola area for many years.

[Beer of the Bass]

Behringer drivers are likely to be proprietary with no specs published - one of the ways they keep costs down is by keeping as much of the manufacturing as possible in-house.

[supertzar]

27 minutes ago, FinnDave said:

Can't help with your cab question, but where in Finland are you? I lived in the Kouvola area for many years.

Around South-West and Turku.

10 minutes ago, Beer of the Bass said:

Behringer drivers are likely to be proprietary with no specs published - one of the ways they keep costs down is by keeping as much of the manufacturing as possible in-house.

Yeah I think this too. I found out that they are "bugera drivers specially designed for this cab"... Just had my fingers crossed someone might have something useful. Is there any way to measure or estimate it? For this kind of project (and if using behringer) I fully understand that it would not be super fullrange facemelting hifi, but I would still like to know if I could extract something better than it is now. I'm assuming that there's quite a lot more to it than just roughly halving the internal volume of the whole 4x10? I think the porting would be a nightmare without proper way to measure the tuning of the cab.

[FinnDave]

3 minutes ago, supertzar said:

Around South-West and Turku.

Think I made it as far as Turku three times in 16 years - to catch the ferry to Sweden and drive (ride motorbike) to England. 

Good luck with your search, I sold an Ashdown 4x10 when I left Finland in 2012, expect it's still out there somewhere!

[itu]

If your box is made of thin plywood, you need to have lots of braces to make it hard and tough enough. You want light, you need to sacrifice something: https://www.grbass.com/aerotech/

They seem to have a dealer in Finland.

I put some extra money to my cab, although amps look better with lights and knobs and all that, so I have a 2 x 12" aluminium cab which weighs 18 kg. I think it is already pretty light. A wooden 2 x 10" and under 15 kg, well, you may have pretty poor efficiency or the lowest frequency rises well over 60 Hz. Cheapo cab, cheap sound.

There is a nice thread here about a diy lightweight cab with pics. Check that out.

[supertzar]

2 hours ago, itu said:

If your box is made of thin plywood, you need to have lots of braces to make it hard and tough enough. You want light, you need to sacrifice something: https://www.grbass.com/aerotech/

They seem to have a dealer in Finland.

I put some extra money to my cab, although amps look better with lights and knobs and all that, so I have a 2 x 12" aluminium cab which weighs 18 kg. I think it is already pretty light. A wooden 2 x 10" and under 15 kg, well, you may have pretty poor efficiency or the lowest frequency rises well over 60 Hz. Cheapo cab, cheap sound.

There is a nice thread here about a diy lightweight cab with pics. Check that out.

As I said, I am fully aware of the limitations and compromises in this kind of project. I already have a rig that I like for both stage amp and going in di and this is not about replacing any of those. I have studied most of the popular plans for diy cabs both high-end and superlight and quite a few in between. This isn't something I absolutely NEED. It's something I WANT to do as I love diy projects almost as much as I love music. Something that I can just carry to my house basically for free is the very definition of cheapo 😄

You could always add a couple hundred to the price and get something better. Then add some more and it's even better. The trick is to find the product that meets the needs. I'm pretty happy with the design I have ran through winisd with the basslite, but the bb410 would be so cheap right now that I just have to consider it.

[itu]

I see, in that case it might be reasonable to concentrate on the box construction. Maybe most of the other parameters are just a nice extra. A too soft box will eat the performance of the elements, no matter how good the unit looks like from the simulation point of view.

Yes, self-made projects are always pleasant if not surprising. Enjoy your journey.

[Beer of the Bass]

If you can't find the specs for the Behringer drivers, it wouldn't be to hard to work out the volume and port tuning of the 4x10", and then design the new 2x10" box around half of that volume and the same port tuning.

[Lfalex v1.1]

10 hours ago, Beer of the Bass said:

If you can't find the specs for the Behringer drivers, it wouldn't be to hard to work out the volume and port tuning of the 4x10", and then design the new 2x10" box around half of that volume and the same port tuning.

Is it that simple? 

I'd have thought that the volume in the port would need to be halved, too, as it's the cabinet resonance you're trying to harness.

IIRC, the port should be tuned to just below the resonant frequency of the cabinet for "best" performance (optimum contribution, I presume!)

[supertzar]

Google tells me this cab is tuned to 38Hz-16kHz, which seems pretty good. A small 2x10 would lose the tweeter of course.

It's starting to intrique me more and more, but reverse engineering this is getting a bit too advanced for me. It has a shelf type port that for some reason is harder to understand for me. Is the volume of the port actually the deciding factor here? I know the size and length of the port does create a space inside but tuning by changing the length of a round port is just more logical concept inside my brain. Could this actually be as easy as just halving both the volume of the cab and the port?

[Matt P]

I'm not sure if this will be helpful but about 10 years ago I bought a bugera 1x15 cab to add to a peavey 4x10 for our church amp, it had the metal cone speaker and after testing it at the sellers house I took it to the church and promptly killed the driver, I swapped it out for a random eminence driver I bought second hand (I was young and foolish.) from what I remember the cab was chipboard and pretty sturdy, they are fairly basic cabs though, It is still in use and sounds OK but the driver was definitely the weak link. 

 

Matt

[stevie]

On 23/06/2020 at 18:52, supertzar said:

I'm assuming that there's quite a lot more to it than just roughly halving the internal volume of the whole 4x10? I think the porting would be a nightmare without proper way to measure the tuning of the cab.

No, in fact that's all you need to do. Halve the internal volume of the cab and halve the porting (which will maintain the current port tuning as stated by previous posters) and you've got yourself a 2 x 10.

If you're doing this for fun and to learn, it sounds like a good project. The good thing is that you could take all the parts like handles, corners, input panel, etc. from the 4x10, saving you a lot of hassle. You could certainly keep the tweeter if you wanted, but the crossover values will need to be changed. If you provide the crossover details, I'm sure someone on here will tell you what to do.

If it works out, you could then build yourself a 1 x10.

A build thread would be good.😁

[supertzar]

5 hours ago, stevie said:

No, in fact that's all you need to do. Halve the internal volume of the cab and halve the porting (which will maintain the current port tuning as stated by previous posters) and you've got yourself a 2 x 10.

If you're doing this for fun and to learn, it sounds like a good project. The good thing is that you could take all the parts like handles, corners, input panel, etc. from the 4x10, saving you a lot of hassle. You could certainly keep the tweeter if you wanted, but the crossover values will need to be changed. If you provide the crossover details, I'm sure someone on here will tell you what to do.

If it works out, you could then build yourself a 1 x10.

A build thread would be good.😁

You might just have talked your way to a build thread. The way I see it, I would have material for two 2x10's. What this means is that I could work my way through to a playable cab, then take what I learned from that and build a second, nearly identical but better cab, and I would end up with cool scalable 2x2x10.

I'll go ahead and haul that awful 45 kg to my basement and start measuring. My original goal with the 1x12 was to build it as light and mobile as possible. I think a slim vertical 2x10 would be the most convenient shape. Depending on how heavy the actual drivers end up being, I'm pretty sure something under 15 kg could be achievable with thin plywood if I copy the bracing from fearful cabs. I could also do some bracing on the outside and pretty easily shape them to be used as handles.

Exciting times!

[supertzar]

I got the cab so I guess I'm doing this. Should this thread be moved  to the "Build Diaries" or should I start a new thread?

Didn't play through it yet but it should be working fine. I did briefly open it up to take measurements and found out it's made of a combination of 15 and 17 mm MDF board. So I could probably shave like 15 kg just recreating the whole thing from plywood. Didn't weigh the drivers yet but I got the basic measurements done to start planning. It has some bracing on the inside, so my next thing would be figuring out how much of the internal volume is made of all the extra stuff inside.

Any tips on how to measure/estimate the volume the drivers take up?

Or do I even need to measure it this way? I mean if I just imagine moving one of the side walls into the middle the inside volume is halved. And because the port is a shelf type it is halved. And because there is bracing exactly in the middle, I can forget measuring that too and actually just keep the horizontal bracing as it is. Please someone tell me I'm wrong because it's starting to look like it's way simpler than I thought and that makes me nervous somehow.

[itu]

It is far more important to think about the bracing (and damping) than their minuscule volume. Use words "speaker cabinet bracing" or "speaker cabinet damping" and do some search. Let the pictures speak.

[supertzar]

5 hours ago, itu said:

It is far more important to think about the bracing (and damping) than their minuscule volume. Use words "speaker cabinet bracing" or "speaker cabinet damping" and do some search. Let the pictures speak.

You are absolutely right and I have been furiously studying and comparing the pillar and girdle braces in the fearless cab plans. And by volume I mean the litres and cubic cm of a cone that is kind of a cone and a cylinder but has holes in it and I'm not sure how much to subtract after measuring the internal volume of the cab. It is around 65 litres by the way, but as I said, I'm not 100% sure how much space the internal "organs" of the cab actually take out of that. But this is probably just overanalyzing the problem and I kind of also not sure they make that much of a difference in this kind of a project. I'm just sort of thinking out loud so people smarter and more experienced than me can point out obvious flaws while I figure stuff out.

I just weighed the speakers and two of them are about 8,8 kg. So this gets me to the ballpark of the weight of the end product. My concern now is that even if i made it from thick plywood and put a lot of braces, most of the weight will be in the speakers. Has anyone made diy 2x10 cabs vertically and if you have, do they stay upright if you have heavy speakers? I mean most of the weight would be attached to the front of the cab. Maybe put them in a small angle? Like only 10° just to shift the center of gravity a little? Too much thinking again?

Edited June 29, 2020 by supertzar
Clarification