Porting my cabinets...

[StevieD_FenderP2009]

I was thinking of porting my Marshall 4x12 bass cabinet but I don't know if it's a safe idea.

When I opened up the back of the cabinet, it seemed like they're fully sealed so if I was to add a port, where would I add one and how is it you do it?

Here's a picture of the inside of one:



Would it work or not?

Cheers

*edit, I've just noticed my 2x15 has one port hole in it but no porting cup, a cup needed? The cab has the speakers set out diagonally with a (roughly) 8" hole in one of the corners. Could I just put an 8" porting cup in there or what?*

Edited August 28, 2011 by StevieD_FenderP2009

[icastle]

[quote name='StevieD_FenderP2009' post='1354038' date='Aug 28 2011, 01:16 AM']I was thinking of porting my Marshall bass cabinets[/quote]

Why?

[Mr. Foxen]

Those speaker probably won't benefit from porting. It is fairly specific to speakers. Those look a lot like speakers that are worth money.

[xgsjx]

But if you do decide to port, I can recommend a jigsaw is a better tool for making the hole than the head of a bass (although it's not as Rock n Roll).

[StevieD_FenderP2009]

Why? 'cos I'm bored haha. I was playing through an Ampeg with a horn and 3 porting holes which sounded fantastic and just had that extra top end my Marshall's dont. Didn't realise porting was speaker specific to be honest. I'm definitely going to fit a horn in the cabinets though.

Speaker value? Roughly £200 a piece apparently. But if you don't think it'll benefit from porting, I'll leave it be.

Tools for it? The head of an Epiphone T-Bird will do just fine xD

[icastle]

[quote name='StevieD_FenderP2009' post='1354459' date='Aug 28 2011, 04:26 PM']Why? 'cos I'm bored haha. I was playing through an Ampeg with a horn and 3 porting holes which sounded fantastic and just had that extra top end my Marshall's dont.[/quote]

The Ampeg cab has a horn.
The Marshall doesn't.

If you start cutting holes in an attempt to make your Marshall sound like the Ampeg all you are going to achieve is sawdust!

[Phil Starr]

Just so you know. The hole in your 15 is a port and it is meant to be the thickness of the board. The hole and the air trapped in the cab act as a tuned circuit and are tuned to a frequency which matches your speakers. if you added a tube it would be tuned to a different and worse frequency.

If you wanted to port your 4x12 then the port would have to have exact dimensions to tune with the volume of air in the cab to match your speakers. Ideally you would also have to change the volume of the cab to match your speakers. The magnets on your speakers don't look huge and they are probably high Q speakers not particularly suited to reflex loading (ported cabs).

I'd always encourage people to experiment with building their own cabs but you aren't going to improve these with a jigsaw. Speaker design isn't rocket science, but it is a bit complicated and it does involve maths and science unless you get a ready published design.

If you start hacking bits out of your cab it is going to reduce it's value and probably make it sound worse unless you are prepared to spend a few months reading up about Thiele/Small parameters. I'd start experimenting on something a bit less valuable.

Cheers

[BasH]

You could always experiment by creating an additional back-panel first (just get a nice piece of multiplex), so if you screw up, you just scrapped a cheap piece of wood.
The port does not care on which side of the cab it is located.

Than download [url="http://www.linearteam.dk/default.aspx?pageid=winisd"]WinISD[/url] and look up the specifics of the speakers in your cab (and measure the cab).

This will give you some graphs to experiment with. You can even compare the cabs current state with any possible 'improvement' you'd like to try....

[MoonBassAlpha]

I think it may be the higher frequencies you find appealing, so you might be better off just starting with adding a tweeter of some sort external to the cab and leaving the cab well alone. As others have said, you may make the cab worth less, though not necessarily worthless (to you!)
I added my own "bright box" on top of my Compact cab and am really pleased with the result so far (one gig in).
See the recent thread "DIY Bright box"

[Prime_BASS]

[quote name='StevieD_FenderP2009' post='1354459' date='Aug 28 2011, 04:26 PM']Why? 'cos I'm bored haha. I was playing through an Ampeg with a horn and 3 porting holes which sounded fantastic and just had that extra top end my Marshall's dont. Didn't realise porting was speaker specific to be honest. I'm definitely going to fit a horn in the cabinets though.

Speaker value? Roughly £200 a piece apparently. But if you don't think it'll benefit from porting, I'll leave it be.

Tools for it? The head of an Epiphone T-Bird will do just fine xD[/quote]

If you want high end, porting won't change that.
Having a port on cabs is sully to increase the low end ouput and smooth out the low end roll off. Lots of variables to consider though.
Speakers are sometimes designed to be in certain boxes with or without ports but It's not really a deal breaker.
I would say focus on a tweeter box, trying to port cabs is a dangerous and mathematical nightmare IMO.

[StevieD_FenderP2009]

Thank you so much to everyone here. Honestly, you've straightened out a lot of questions I had before I even asked them. As for cabinet value, believe it or not I only paid £300 for the pair (in all, 4x12 was £210 and the 2x15 was £90, bargain!) and they both have all original speakers apart from one of the 12"s got replaced by the last owner with some un-named p.o.s. so maybe I do keep an eye out for a matching original speaker. But yeah, if the value of the cabs decreases, it wont really matter to me as I never plan on selling these (unless my back problem gets even worse and I can't play bass anymore) so I think i'll just stick to adding a horn/tweeter (aren't they the same thing?) in to the 4x12 and possibly one in the 2x15 as well (but that's very very unlikely that i'll put on in the 2x15)

The reason for all this is I've played through Ampeg and Orange 4x10 (Ampeg's 410HLF and Orange's OBC410) which both have horns in them and they just made my bass sound that bit better (they had the added top end that I am after, this was obviously down to the horns in them) but the Marshalls are my dream cabinets (it's something about having a pair of Marshalls booming away behind me that I love) so I don't want rid of them, I'd rather just modify them

I may even try buying/building a bright box... we shall see!

Edited August 29, 2011 by StevieD_FenderP2009

[StevieD_FenderP2009]

So this is the horn I think would be perfect for my cabinet: [url="http://www.ebay.co.uk/itm/Eminence-APT80-45W-Super-Tweeter-HF-Driver-/140586613504?pt=UK_ConElec_SpeakersPASystems_RL&hash=item20bb9d7b00#ht_3167wt_905"]Eminence APT-80[/url]

Would it be alright to just run it off the input on the cab or do I [b]HAVE[/b] to put a crossover in there?

[Mr. Foxen]

I think only piezo one's don't need a crossover. I think this might be more complicated than you imagine to sound right. Definitely a try and get actually suitable cabs sorta thing, Marshall badges are easy to pick up an stick on, much easier than making a crossover.

[Balcro]

[quote name='StevieD_FenderP2009' post='1355432' date='Aug 29 2011, 05:25 PM']So this is the horn I think would be perfect for my cabinet: [url="http://www.ebay.co.uk/itm/Eminence-APT80-45W-Super-Tweeter-HF-Driver-/140586613504?pt=UK_ConElec_SpeakersPASystems_RL&hash=item20bb9d7b00#ht_3167wt_905"]Eminence APT-80[/url]

Would it be alright to just run it off the input on the cab or do I [b]HAVE[/b] to put a crossover in there?[/quote]

I'm no expert on HF stuff, but as Mr Foxen says, that unit seems to need a crossover. There's no reference to "piezo" in the spec.

By the way, it costs a lot more on Ebay than on the sellers own web-site. On the Ebay shop it's £27.93, while on the bluearan web-site it's £23.49! A high-pass crossover will probably will be an additional cost. For example, the Emnence PXB-3K5 is £21.

More complications come later as you can't guarantee to match it to the existing speakers exactly how you'd like.

Balcro.

Edited August 29, 2011 by Balcro

[EdwardHimself]

Maybe you could consider building a bright box (a tweeter in a box) rather than cutting holes in your cab?

[StevieD_FenderP2009]

[quote name='Mr. Foxen' post='1355439' date='Aug 29 2011, 05:30 PM']I think only piezo one's don't need a crossover. I think this might be more complicated than you imagine to sound right. Definitely a try and get actually suitable cabs sorta thing, Marshall badges are easy to pick up an stick on, much easier than making a crossover.[/quote]

Okay, cheers for that.

[quote name='Balcro' post='1355520' date='Aug 29 2011, 06:33 PM']I'm no expert on HF stuff, but as Mr Foxen says, that unit seems to need a crossover. There's no reference to "piezo" in the spec.

By the way, it costs a lot more on Ebay than on the sellers own web-site. On the Ebay shop it's £27.93, while on the bluearan web-site it's £23.49! A high-pass crossover will probably will be an additional cost. For example, the Emnence PXB-3K5 is £21.

More complications come later as you can't guarantee to match it to the existing speakers exactly how you'd like.

Balcro.[/quote]

Thanks for linking me to that, if I can get hold of the one that they say is "cabinet ready" then I'll have an attempt at building my own bright box or I might even make a replica of the back panel from my Marshall so I can mount the crossover in that but if it doesn't work how i want it to, i've still got the original back panel in perfect condition to put back on.

How many tweeters/horns can you run off of the one cross over? The horn I want is 8ohm horn and it says to only mount 8ohm horns to it but i don't know if you can mount multiple horns to it or not.


[quote name='EdwardHimself' post='1355544' date='Aug 29 2011, 06:56 PM']Maybe you could consider building a bright box (a tweeter in a box) rather than cutting holes in your cab?[/quote]

As said, I've got 2 options, build a bright box or to build a new back panel for my cab and mount the crossover to that. I'll make my mind up some time haha

[icastle]

[quote name='StevieD_FenderP2009' post='1355432' date='Aug 29 2011, 05:25 PM']So this is the horn I think would be perfect for my cabinet: [url="http://www.ebay.co.uk/itm/Eminence-APT80-45W-Super-Tweeter-HF-Driver-/140586613504?pt=UK_ConElec_SpeakersPASystems_RL&hash=item20bb9d7b00#ht_3167wt_905"]Eminence APT-80[/url]

Would it be alright to just run it off the input on the cab or do I [b]HAVE[/b] to put a crossover in there?[/quote]

You can only run a piezo without a crossover.
This isn't a piezo.

The way to do it would be to make up a box for this unit with the crossover in it.
Feed your amp into this box and wire up a feed from the crossover to take the unfiltered feed down to your Marshall.

[StevieD_FenderP2009]

Yesterday I had a band practise and as my Thunderturd was the only bass I had with me (i'm not staying where all my basses and equipment are a.t.m.), I had to take it with me to use.
Now, if you haven't seen before, I had started a thread about how terrible the pick ups in my new Epiphone Thunderbird White and Chrome limited edition bass are. It uses guitar pickups (obviously rejects from the Epiphone Les Paul or SG guitars) that produce no high end what so ever so I was looking for the right pick ups to replace them with and settled on the Seymour Duncan Livewire Classic II humbuckers which produce a lot of high end, barely any mids and average bottom end. So this brings me to the band practise... I got there and they supply you with back line for no added cost (which is cool) and th bass amp there is a Hartke VX2510 combo which isn't the best of amps out there but I managed to get a fairly decent sound from it with the Thunderbird but I always get a quite a good sound from it with my Squier Jazz bass and Tobias Toby Pro 4 but here's the important question...

What does this combo have that my cabinets don't?
-drum roll-

A HIGH FREQUENCY DRIVER!

It's settled, the sensible option is to stick a horn and crossover in my cabinet. I have limited money and it was either going to be crossover and horn in my cabinet or pick ups for the thunderbird.
If I was to go for the pickups, it would make 1 bass sound better and leave the rest of the stuff sounding as it does. Plus it would set me back £150 where as if I got for the horn and cross over, I can get those for about £80 in all, maybe even less if I hunt eBay and the net but this would make all my basses sound better (to me anyway, it'll add the top end I've been missing out on) so it's the sensible option.

I can't be bothered to build a seperate box for the horn or to get a bright box, it's just easier to fit one to the cab, then i have less to carry about and it'll always be there.

Now... OFF TO SCOUR THE NET!