New speaker in GK MB Combo. Options?

[Owen]

I need to put a new 12" speaker into a GK MB combo. I can buy a replacement from GK for £65ish and fully understand that the cab is sized for that driver.

However, more is more and hotrodding is ALWAYS better. Can anyone suggest an alternative driver which will give EVEN BETTER performance with deep and sonourous lows and sparkling highs etc etc etc? The internal measurements for the box are

190mm deep
340mm high
320mm across

and there is a transformer of about 90mm x 60mm x 70mm in there as well. It is a sealed cabinet but I would be more than happy to cut ports in if it made any difference.

I already know that the answer is replace like for like, but you just never know until you ask

The answer 5 years ago was this http://basschat.co.uk/topic/152993-gallien-krueger-mb150-what-speaker/

[Owen]

The cab itself had no wadding in there. When, inevitably, I put the replacement GK driver in, should I put some wadding in as well?

[Beer of the Bass]

It's a very, very small box for a 12", to the point that it would be small for most 10" speakers. If you can get an original replacement that might be your best option. I suppose you could make an adaptor ring for a high quality 8" like the Faital 8pr200 (used in the Crazy 8 cabs) and install appropriate ports if you really fancied a project.

[Phil Starr]

I've had a quick look at how the Eminence Beta and the 3012HO model in that cab. As said it is very small for a 12" cab, so small that I doubt the decision to make it that size was based solely on sound. The Beta has a big hump in frequency response at 120Hz and rolls off after that. I suspect what you had does the same. there wouldn't be deep bass but plenty of the bass you do have with the Beta. The 3012 models really well, do you want to spend £200 on hot-rodding?

I'd go for the original at that price.

[Owen]

Thanks everyone! I love options.

The Faital looks interesting, but on reflection, when I was thinking about modding the cab, I forgot to take into account my tragic lack of practical skills. You know when you write or mix something late at night and it is THE BOMB and then you listen to it in the morning and think "Ah................ maybe not". My GAS is usually exactly like that.

Phil, when you say the 3012 models well, could you briefly expand on that? That is the speaker which a lot of the super 12" cabs is based, no? I totally understand that they are in bigger cabs and that would have a serious effect on speaker performance. I was surprised at how big my ACME 12" cab was, but it was a thing of joy to play through (regrets..... I have a few.......). I presume the 3012 would be less prone to farting out than the original speaker?

[Owen]

Also Phil, do you know my friends J and Lizzie who live in Chard?

Edited December 1, 2016 by owen

[Phil Starr]

I do know J and Lizzie, they live just down the road next door to one of our best friends and the singer in my first band, lovely people, small world. Do you live down this way?

The 3012HO models well in that it has a flat response in your cab down to the cut off frequency and then the slow roll off sealed cabs usually exhibit, ideal for a bit of tweaking on the tone controls. Your cab could have been built for it in fact. The 3012 won't exceed it's excursion limits until you put out 250W at any frequency, so no farting out I would think at all. It also has quite a nice top end and sounds good with bass.

[url="http://www.bluearan.co.uk/index.php?id=EMIKLIT3012HO&browsemode=manufacturer"]http://www.bluearan....de=manufacturer[/url]

Edited December 1, 2016 by Phil Starr

[Owen]

J and Lizzie are some of our favourites! We do not live at your end but have stayed with them so must have passed Chez Phil at some stage. We met them when they were in Bangor in University.

The GK does not owe me anything so I might just treat it to a better speaker. The one thing that did come up in the last thread where this was asked was - "The speakers in these are more like giant hi-fi speakers - they've got foam surrounds and about 3cm of cone travel". Would that be an issue if I used the 3012HO instead? Sorry, I understand enough about speakers/boxes to get myself into trouble, but not enough to get me out of trouble.

[stevie]

Phil, would you mind double-checking your simulations? I'm pretty sure that a 3012HO would produce absolutely no bottom end in a 20-litre sealed cab.

[Phil Starr]

Hi Stevie, depends what you see as 'no bottom end'. It's Q=0.8 which is almost maximally flat from this driver. The response rolls off from 200Hz but is only a couple of db down at 100Hz and -10dB at 70Hz.. Porting the same volume you'll get a couple more dB output from 100Hz down and roll off from 150Hz. The main difference is that the excursion below 40Hz is pretty much uncontrolled with a ported cab, making any bass boost a bit problematic. Giving modest bass boost (say 3dB) to the sealed cab would be an option which wouldn't threaten damage to the speaker but would restore bass to the sorts of levels a ported cab would give.

The OP has an 18l cab or thereabouts. You aren't going to get a huge bass output from a cab that size with a 12" speaker His original driver probably gave him the usual bass hump above 100Hz with little deep bass anyway. I think the 3012 would give him a clean sounding bass, although definitely a bit bass light. My advice was to return it to original though. It's a lot of money if you find out you don't like that sort of a tone, and a bit of a waste of a good driver to put it into such a restricted cab. I took the question to be 'would it work?'.

The only reason I looked at the 3012 was because a tiny box requires a decent sized magnet to achieve good levels of damping it was the just the first speaker I thought of that I know I have stored parameters for.

There you are Owen, we disagree slightly, Stevie is right to challenge me probably. I've only had a quick look so don't rush out and spend £200 yet.

[Owen]

Thanks Phil and Stevie!

Phil did very clearly state that I should return to the original. I just cannot stop myself from tinkering. I have two basses with a full piezo + nice buffer pre-amp in them. I never ever use the piezo. I knew this when I put it into the 2nd one, but I just cannot stop myself. It is like a disease. I am still in two minds about the speaker. The amp itself will never be a LF monster but it is fun to look at options.

[Phil Starr]

Critical question really, would you ever build yourself a cab from scratch? If you would then the 3012HO is still one of the best drivers out there and, were it not for the cost, the driver I might have gone for in the Basschat 12" design. Build one of our cabs and swap the 3012 into that if you don't like what it does in your GK and you'll have a lovely cab.

[stevie]

I can see where you're coming from, Phil, but I'm fairly confident that that Eminence driver in such a little cab will sound like a transistor radio. The problem is, as you have already said, it's a bit too pricey to start experimenting with.

I think the solution has to be to go with the original driver, which is more akin to a car audio driver than anything else. I've heard these combos, and they don't go very low even with the original driver. If it were mine, I'd modify the cab to take a smaller driver. A modern 8 or 10 would work quite well. It's not that hard to do - as long as you have enough space between the front grille and the speaker to take a spacer ring.

[Owen]

Hmmmm....... smaller speaker options again. The Faital 8pr200 was suggested by BOTB. Any suggestions on a 10"? Of course, if I need ports I can actually get someone who knows what they are doing to cut them.

By a spacer ring do you mean just a circular piece of something to make the hole smaller for a smaller driver and seal it properly?

I am not looking for ULTIMATE VOLUME from a small box, I have a bigger box to do that. I would not object to enhanced LF extension compared to the stock driver if it is possible.

Again, thanks to all who are contributing.

[stevie]

The Faital is a very nice driver, but it's expensive and needs a ported cabinet.

There is currently an Eminence BP102 on eBay with a starting price of £25. That works well in a sealed box and will save you messing with ports. If you download the cabinet design PDF from Eminence for that driver, you'll see a design for a cab not much bigger than yours (Med Sealed 1x10 Bass Guitar Cabinet).

Yes, you've described a spacer ring perfectly. Cut a piece of 1/2" MDF slightly bigger than your current 12" driver. Use the driver holes in the baffle to screw the spacer in. As long as the grille allows you to have the speaker 1/2" further forward, it's straightforward. Use foam between the ring and the baffle, or just glue it on.

I would expect the results to be really good.

Edited December 3, 2016 by stevie

[Owen]

I have a bid in on the Eminence BP102. We shall see what happens

[Owen]

Again, thanks everyone for chipping in. I love this place.

[Owen]

I won the Eminence. I shall report back.

[Owen]

I did it all. I bodged it all, but it works very nicely for what I want. It does not have earth moving LF, but extends down in a consistant way and that is good enough for me. I did a rehearsal tonight and carried my amp in like a heavy handbag. Happy days. I have not put any wadding in there amd probably will not cos once something is functioning I am usually too lazy to do amything else to it. But if I did, what would I buy off ebay?

TIA as ever.

Edited July 13, 2017 by owen