Replacing an 8-ohm spkr. with a 4-ohm skpr.?

[BassmanPaul]

After all many companies offer cabs with 8 and 4 ohm choices and the cabs are exactly the same.

Yes because the TS parameters of both the 8 and 4Ω drivers are likely designed to allow that.

Yes our friend from Kentucky got lucky and I for one am pleased for him but not everyone will have such good fortune.

BTW @MrCash why do I keep on wanting to call you Johnny??

 

[Downunderwonder]

It depends on whether or not the amp can fully drive the 8 ohm one. If it can't you can get a little louder with the 4 ohm. But only to the extent it fell short at 8 ohms, and if efficiency suffers you wipe that gain.

 

[drittal]

Rule of thumb: To double loudness, you either double cone area or double power.

If you replace a 8ohm with a 4ohm of the same size and type in a single speaker cab you are fine as long as your amp can handle the 4ohm load. Don't mix speakers and impedance though.

 

[BassmanPaul]

Rule of thumb: To double loudness, you either double cone area or double power.

Incorrect you have to increase power by ten times not two.

 

[Nickweissmusic]

Is it possible to replace an 8-ohm bass speaker with a 4-ohm in the same cabinet. It's a 15" Bag End bass cabinet? It's not a D series speaker/cabinet.
I've asked Bag End and they're very good at responding. I thought of asking TalkBass too. Maybe someone out there has done this and could tell me about the results. Thanks to all!

Does Bag End make a 4 ohm 15 speaker? I assume you've already asked them, and I assume not. Different speakers respond differently, but if you find something with similar specs it could work, you'd need the spec sheet for the original to compare, I bet the Bag End people would provide that. Honestly, for a non sealed, bulletproof box like Bag End makes, it might not be that critical, you don't have to worry as much as a sealed box, but it will certainly sound different. Probably the most critical thing would be how the speaker is physically mounted, it's been a while since I took mine apart so I'm not sure how their "speaker claw" method would work on other speakers. You know the best way to drop to 4 Ohms? Get another cab! They're the smallest 15's in the business. A dual Bag End 15 stack is a heck of a setup, still only takes one trip to get into a gig (with a cart or wagon). You might even consider putting their coax Tweeter equipped one on top, it sounds pretty good. Am I biased? maybe a little... Today's practice amp...

 

[drittal]

Incorrect you have to increase power by ten times not two.

Hats true. I was going by the +3 dB, instead of perceived volume.

 

[MrCash]

Yes because the TS parameters of both the 8 and 4Ω drivers are likely designed to allow that.

Yes our friend from Kentucky got lucky and I for one am pleased for him but not everyone will have such good fortune.

BTW @MrCash why do I keep on wanting to call you Johnny??

Well let my tell you something.
My daddy left home when I was 3 and he didn't leave much for ma or me just this old Bass and an empty bottle of booze.

And he gave me an awful name. And I had to fight my whole life through.
True story!

So when I listen to a boy named sue by johnny cash. It really could be a song about me. So instead of using my name or another handle I choose MrCash in homage to the man in black. Who wrote a song eerily like my own tale.

 

[BassmanPaul]

You should write a song, make it a hit and retire a rich man! I always feel for single moms and what they go through and sacrifice for their kids. My thoughts are with the both of you.

 

[primusfan1989]

Is it possible to replace an 8-ohm bass speaker with a 4-ohm in the same cabinet. It's a 15" Bag End bass cabinet? It's not a D series speaker/cabinet.
I've asked Bag End and they're very good at responding. I thought of asking TalkBass too. Maybe someone out there has done this and could tell me about the results. Thanks to all!

It is totally possible, however you have now made that cab 4ohm instead of 8 ohm which you need to keep in mind if you plan on combining that cab with anything else. If you plan on using just the one cab there is nothing wrong with it being 4ohm however Id recommend using 8ohm so for the flexibility of combining other cabs

 

[johnhenry]

Not to be Captain Obvious or anything but will BE sell you a 4 ohm version of the same speaker?

Thanks...I'm glad this stirred up some interest. I called BagEnd and they will have one soon. I can't find the details, thought I took notes on it but...

 

[johnhenry]

+ about 3db if the replacement is the same excepting ohmerageness. Can the 4 ohm handle about double the wattages and more mechanical stress? If you can make it fart now, I think not much point in an otherwise identical speaker.

The pitfalls of a "better" or upgrade speaker have been covered above, but if the BE happens to be a sealed cab, ill effects of guessing are minimized compared to ported. Of course you can just not guess by modeling, or for sealed see if they offer a cab volume spec like eminence does. Shooting for a sealed cab speaker the requires a volume that your cab matches near the middle of the range should be a good compromise of spl and cone control/antiflatuance. It seams to me that volume for a particular speaker tends to be about half the cab size winisd will suggest if you enter the TSPs and let the software determine the cab volume. Essentially, ignoring tone goals, larger = more spl and smaller = more cone control. Smaller cuts spl, but gets a cleaner bass sound and safer as far as mechanical limits.

Edit: spel checkerized it.

ArrGh! You lost me in there and it seems to be good information!! The cabinet has a port in back. Could you spell out for me: spl, winisd, TSPs ? Thanks.

 

[johnhenry]

What head are you running?

If you use the same type speaker except 4 ohms you should be fine as long as you're not running another 4 ohm cab( unless your amp can handle 2 ohms).

Cabs are usually made for specific speakers. What speaker does Bag End recommend?

I'm using a Walter Woods. An old one, 1988. Roughly rated at 100 (+) watts - 8ohms. I've read reviews that thought it was actually more.
Bag End told me about a replacement speaker they will have available soon. Otherwise nothing specific. I'm looking at Eminence 15".

 

[BadExample]

ArrGh! You lost me in there and it seems to be good information!! The cabinet has a port in back. Could you spell out for me: spl, winisd, TSPs ? Thanks.

Yah, SPL is sound pressure level. essentially how loud the speaker is with a given input, so higher is better. winisd is free download speaker cab modeling software. It's made for modeling a cabinet to a known speaker, so it won't tell you what speaker will work unless you enter the TSP for speakers until you find one that does work. And TSP is Thiele Small Parameters, a bunch of electrical and physical specs on a speaker, measured or obtained from the manufacturer. Here are some: Thiele / Small (T/S) Speaker Parameters I have a $100 gizmo that measures some of the specs for me, good enough for my purposes anyway. Measuring by hand, the old fashioned way is a PITA and takes more money. I only mess with it for fun.

In all honesty, your best bet is probably to find some one that has upgraded the same cab and see what they used.

 

[agedhorse]

I'm going to encourage that you be sure to relabel the cabinet as 4 ohms so that there are no unfortunate surprises down the road resulting in a blown amp when somebody tries to add another speaker to a 4 ohm stable amp and damages it unknowingly.

 

[deathness]

OP, what exactly are you hoping to get out of replacing the stock BE speaker with a 4 ohm one? If it's volume, seems doubtful you can do better than the 103 dbs of spl at which Bag End rates the stock speaker. If it's a different tone, you may find it in a replacement speaker, but the internal volume on that cab is pretty tight due to its compact design. As mentioned above, not a ton of 4 ohm 15 inch speakers out there. Rather than kicking off a wild goose chase, maybe looking for a cab designed with your needs -- volume wise or tonally -- in mind might be a better way to go?

 

[Joedog]

103 dbs? Wow! OP, if you go w/a diff. brand 4 0hm speaker, you may actually LOSE some volume. I once swapped out a GK 15" 4 ohm and installed an EVM 15B 8 ohm (so I could run an add'l cab), and that's exactly what happened: the 8 was louder than the 4!

 

[johnhenry]

Thanks to everyone who has taken the time to respond to this! I've decided to add a second 8-ohm cabinet from BagEnd. If I'm still unhappy, look for another amp I guess. I've got to decide how to describe the sound I want, but a matching 8-ohm skpr/cab is the best idea for now.

 

[agedhorse]

Thanks to everyone who has taken the time to respond to this! I've decided to add a second 8-ohm cabinet from BagEnd. If I'm still unhappy, look for another amp I guess. I've got to decide how to describe the sound I want, but a matching 8-ohm skpr/cab is the best idea for now.

I think this is your best bet. If you are not happy with this, you sure wouldn't have been happy converting your single cabinet.

 

[freshbass]

Is it possible to replace an 8-ohm bass speaker with a 4-ohm in the same cabinet. It's a 15" Bag End bass cabinet? It's not a D series speaker/cabinet.
I've asked Bag End and they're very good at responding. I thought of asking TalkBass too. Maybe someone out there has done this and could tell me about the results. Thanks to all!

I swapped the 8 ohm 15 eminence made for ampeg in my ampeg RB115 for an eminence CA154 (4 ohm same speaker) to get the full 200 watts to the internal speaker and have no issues going on 2 years. It's now louder and fuller sounding w/o distortion at higher volumes. I stayed w/ eminence CA as they were made for the cab design. IMO that's the real issue...cab design fit.

 

[agedhorse]

I swapped the 8 ohm 15 eminence made for ampeg in my ampeg RB115 for an eminence CA154 (4 ohm same speaker) to get the full 200 watts to the internal speaker and have no issues going on 2 years. It's now louder and fuller sounding w/o distortion at higher volumes. I stayed w/ eminence CA as they were made for the cab design. IMO that's the real issue...cab design fit.

Be sure to label your combo as having a 4 ohm internal load so that nobody down the road tries to use an extension cabinet not knowing what’s in there.