2x12 bassman cabinet: which speakers???

[2saddleslab]

i really do appreciate the "critical" mentions of the simple fact that the fender cabinets back then were pretty poorly designed for bass, physics wise. they had no idea what they were doing. but they look cool, and most of the problems associated with them were the crappy speakers and subpar power. i've seen all kinds of praise from them when people put in more powerful and appropriate speakers, and that gives me some hope that the cool little shallow fender cabinets aren't a complete lost cause for very basic purposes.

Well I know of 2 who have done this successfully, @treyandres & me.

Having said that, if I was new to all of this I'd probably take @agedhorse's advice and not look back. Maybe my experience is just dumb luck, but it's worked and I'm happy with the results.

 

[bon viesta]

Are you asking a sincere question here, a question that you want to receive an accurate answer for, or are you simply seeking confirmation that a bad idea is good?

The size of that cabinet is simply too small for all of the drivers that I am aware of that would work well in a sealed cabinet. Nothing can change that fact.

If you were to simply remove one driver and seal off the opening, the box would better support a single suitable driver with almost no loss of performance and quite possible better low end characteristics.

As an example of a cabinet that actually performs well (an order of magnitude beyond your current cabinet) is the Rumble 112 extension cabinet, and has the vintage fender look too:
View attachment 4371485

does this mean to remove the center baffle and use the cabinet as a 1x12? with all the other obvious changes like making an opening and sealing things etc etc.

 

[groovaholic]

Are you asking a sincere question here, a question that you want to receive an accurate answer for, or are you simply seeking confirmation that a bad idea is good?

The size of that cabinet is simply too small for all of the drivers that I am aware of that would work well in a sealed cabinet. Nothing can change that fact.

If you were to simply remove one driver and seal off the opening, the box would better support a single suitable driver with almost no loss of performance and quite possible better low end characteristics.

As an example of a cabinet that actually performs well (an order of magnitude beyond your current cabinet) is the Rumble 112 extension cabinet, and has the vintage fender look too:
View attachment 4371485

If OP's intent is to continue using a 20 watt guitar head, I think it's safe to presume he isn't obsessed with maximum low-frequency performance, and doesn't need a ton of power handling.

In that case, he'll need to maximize volume, so the call would be for a very efficient speaker - and possible angle the baffle so it can be heard better.

 

[agedhorse]

does this mean to remove the center baffle and use the cabinet as a 1x12? with all the other obvious changes like making an opening and sealing things etc etc.

If the center brace is a solid brace (plate) that separates the chambers, then you will need to cut say 2 holes 4" in diameter creating a single (acoustic) chamber. This now gives you a single air space with approximately .75CF inside volume.

Because of the small air space (which was unrealistically small for 2 drivers), you now have the option to use the Eminence Legend BP-122 which is optimized for this application and will give you reasonably decent performance in such a small box (F3=71Hz, F6=61Hz and F10=49Hz at ~95dB/1W/1M sensitivity) which is about as good as you are going to get, and much better than what you have currently with 2 drivers.

This is a good example of why sticking drivers in boxes without understanding the math behind the performance just doesn't work well.

 

[azureblue]

From my experiences with the Bassman 2- 12", I can say that it's not a good box. I upgraded from the stock Jensens to JBL D120, and that helped a little. I ran into a guy who rear ported one and his sounded great but I don't know what speakers he was using. Also I saw a cabinet that was designed to look like a bassman 2 -12, but had maybe 8" more depth, and it sounded good with front ports. For comparison, I have a MB212 and it sounds really good and loud and it uses neo 12".

 

[agedhorse]

From my experiences with the Bassman 2- 12", I can say that it's not a good box. I upgraded from the stock Jensens to JBL D120, and that helped a little. I ran into a guy who rear ported one and his sounded great but I don't know what speakers he was using. Also I saw a cabinet that was designed to look like a bassman 2 -12, but had maybe 8" more depth, and it sounded good with front ports. For comparison, I have a MB212 and it sounds really good and loud and it uses neo 12".

The newer Rumble cabinets are designed to look like their vintage Fender counterparts, but use realistic (larger) dimensions to achieve MUCH better performance than the older enclosures (by a huge margin).

 

[MattZilla]

Ooh, I like this single driver idea.

Then you can hide a neat old-timey graphic on the plate covering the other speaker hole.

or

 

[Jonathan C]

The newer Rumble cabinets are designed to look like their vintage Fender counterparts, but use realistic (larger) dimensions to achieve MUCH better performance than the older enclosures (by a huge margin).

Andy, it's always interesting to read your comments. Cab and driver designs have obviously improved massively since this cab was born, was there no engineering or thought behind these? Why were there so many that simply are boxes with drivers thrown in them?

 

[agedhorse]

Andy, it's always interesting to read your comments. Cab and driver designs have obviously improved massively since this cab was born, was there no engineering or thought behind these? Why were there so many that simply are boxes with drivers thrown in them?

Yes, the understanding of speaker design evolved simultaneously with the growth of amplifier power (by necessity) and as the music evolved to require greater performance and reliability.

Like today, back then there were some designers who understood this stuff (not at the level of today), but the engineering models evolved considerably, the analysis tools have improved, the materials improved and the interest in improving performance has improved. That said, there are still plenty of folks who pass themselves off as designers who think stuffing a speaker into a box without doing the math is plenty good and for some customers frankly, it probably is. For more demanding customers however, that would be leaving a lot of performance and reliability on the table.

 

[AGCurry]

Yes, the understanding of speaker design evolved simultaneously with the growth of amplifier power (by necessity) and as the music evolved to require greater performance and reliability.

Like today, back then there were some designers who understood this stuff (not at the level of today), but the engineering models evolved considerably, the analysis tools have improved, the materials improved and the interest in improving performance has improved. That said, there are still plenty of folks who pass themselves off as designers who think stuffing a speaker into a box without doing the math is plenty good and for some customers frankly, it probably is. For more demanding customers however, that would be leaving a lot of performance and reliability on the table.

At the time that the small 2-12" Bassman cabinets were introduced (1962? '63?), designers of high-fidelity and PA equipment understood pretty well the physics of bass speakers. Altec, JBL, ElectroVoice, etc... even Ampeg was relatively sophisticated with the B-15. I'm convinced that Fender's choices had much more to do with what would sell to a large market than anything as irrelevant as ... sound. I remember going to high-school dances, where that cabinet would really boom on certain notes and not be heard on others.

That said, OP has stated that he's not planning on using the speaker in a serious live situation. The great Carol Kaye recorded with an open-back Fender combo on hit records. For playing in your house, virtually anything would do, so I say: Have at it!

 

[S-Bigbottom]

Fender Rumble cab, all the "Upgrade" work has been done including the wood.

Making it vintage, rub dirt on it until proper vintage is met.

 

[MIMike]

I used two things that I already had, plus some calculations provided by Eminence to make something work for my application.
I acquired a 72' Bassman 100 with a matching 4x12 cab. The cab had no speakers in it, but I had an idea to make it work as a 2x12. I had traded a trem pedal for an SWR Bigfoot 2x12 cab that had Eminence Basslights in it. I emailed Eminence with the width and depth of my cab, figuring I could modify the height as needed. I got a reply right away with the last dimension and recommended port size. I then went to work on "resizing" the cabinet to fit my needs. I think it looks and performs just great and I have gigged it many times.
The biggest shortcoming of the original 2x12 Bassman cabs is the very short depth. My 4x12 had that goofy reverse pyramid baffle design and is much deeper than the 2x versions.
I took a bunch of pics durning the project, but none are very high quality. Here is the finished product:

 

[LoveJackBruce]

Are you asking a sincere question here, a question that you want to receive an accurate answer for, or are you simply seeking confirmation that a bad idea is good?

The size of that cabinet is simply too small for all of the drivers that I am aware of that would work well in a sealed cabinet. Nothing can change that fact.

If you were to simply remove one driver and seal off the opening, the box would better support a single suitable driver with almost no loss of performance and quite possible better low end characteristics.

As an example of a cabinet that actually performs well (an order of magnitude beyond your current cabinet) is the Rumble 112 extension cabinet, and has the vintage fender look too:
View attachment 4371485

I'd trade my mint 2x10 V3 for that lightweight 12.

 

[Bill Whitehurst]

If you want vintage Fender looks and serious performance try a Super Bassman 300 on a fEARful 15/6/1 with the dimensions tweeked to match the old 212.

Seriously, they are very nearly the same size and I am pretty sure that if you made slight changes but kept the volume the same, the ports would be happy.
Extra vintage cool points for white tolex, tilt back legs and amp to cabinet mount brackets.
Last time I checked you could still get all the hardware, early tolex and grill cloth.

 

[Chickenwheels]

Fender Pro Neo 410 is bonkers good. And lightweight. I did an A/B with one and a vintage style sealed 212 and there was absolutely no comparison. I reckon even a 100watt Bassman with the Pro Neo would be amazing.

 

[Wild Rice Chris]

If the center brace is a solid brace (plate) that separates the chambers, then you will need to cut say 2 holes 4" in diameter creating a single (acoustic) chamber. This now gives you a single air space with approximately .75CF inside volume.

Because of the small air space (which was unrealistically small for 2 drivers), you now have the option to use the Eminence Legend BP-122 which is optimized for this application and will give you reasonably decent performance in such a small box (F3=71Hz, F6=61Hz and F10=49Hz at ~95dB/1W/1M sensitivity) which is about as good as you are going to get, and much better than what you have currently with 2 drivers.

This is a good example of why sticking drivers in boxes without understanding the math behind the performance just doesn't work well.

I own a Mojotone repro Bassman 2x12" cab. This is super interesting to me. Since my vintage Bassman head is 4 ohm only, is there a similar 4 ohm 12" speaker that would work? Or is 8 ohms an acceptable mismatch on an old Fender?

(I also wouldn't be opposed to a pair of 8 ohm 10s with adapter rings or opening it up for a 4 ohm 15")

 

[6thplanet]

Did I read that right..a 2/12 cab that's only 3/4 of a cubic foot?

 

[agedhorse]

I own a Mojotone repro Bassman 2x12" cab. This is super interesting to me. Since my vintage Bassman head is 4 ohm only, is there a similar 4 ohm 12" speaker that would work? Or is 8 ohms an acceptable mismatch on an old Fender?

(I also wouldn't be opposed to a pair of 8 ohm 10s with adapter rings or opening it up for a 4 ohm 15")

There is not an off the shelf 4 ohm version of the BP-122 that I am aware of.

You might measure the inside dimensions of your cabinet to be sure it's ~.75CF as it might be a more liberal (and better IMO) interpretation of a reproduction. If you are lucky, it's ~4" deeper which opens up more options.

 

[agedhorse]

Did I read that right..a 2/12 cab that's only 3/4 of a cubic foot?

Yes, the inside dimensions minus the driver volume displacement is very small. That's a serious limiting factor in the cabinet's suitability for bass guitar.

 

[6thplanet]

Yikes, yup that's an issue.