Considerations for 2x12 cab conversion with different speakers

[Guerny]

Before I begin I'm aware this is a similar post to another on this site: https://www.talkbass.com/threads/can-i-put-both-guitar-and-bass-speakers-in-the-same-cab.1298905

However, my use case is different in a way I will explain below.

I have come into possession of a Harley Benton G212 Vintage guitar cab fitted with Celestion Vintage 30 G12 speakers. My aim is to swap one of the speakers out with a Celestion BN12-300S (4).

Each speaker having its own amp (guitar for guitar and bass for bass speaker) but signal coming from bass guitar through pedal board with a y-split for separate signal chains (cleanish low end, distorted/fuzzy highs). Essentially trying to minimise footprint of a dual amp/cab setup.

I also wanted to experiment with using a passive crossover at 200hz to extend range as an all purpose practice cab.

My concern with all of this is less whether it will sound "good" but rather if it will work at all or have some deal breaking issue for purposes on/off stage.

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

 

[Wasnex]

My concern with all of this is less whether it will sound "good" but rather if it will work at all or have some deal breaking issue for purposes on/off stage.

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

Assuming both drivers share the same volume of air, it will work at low volume. I wouldn't expect it to be useful at stage level. But who knows, maybe you will get lucky.

My expectations:
As the power level is increased, the bass driver will cause the guitar driver to move out of phase. This will cause cancellation down low. As the power is increased further, the bass driver will probably destroy the guitar driver.

The RMS power rating is basically how much the voice coil can handle long term without overheating. RMS power rating is only valid at higher frequencies where cone excursion is relatively small. For lower frequencies, the mechanical power rating tends to be more important than the RMS power rating.

FYI, The tuning of the cab effects mechanical power handling. Put the same driver in different cab designs and it impacts low frequency response and mechanical power handling.

FYI it's not unusual for mechanical power handling to be significantly lower than the driver's RMS power rating, even in a properly designed cab. Since this is not a properly designed cab, the mechanical power handling may be extremely low.

Since you plan to ignore sensible advice. Let's us know how it goes.

 

[agedhorse]

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

Then why be disrespectful by asking the question with no intent of listening to the advice and waste our time?

 

[eniac]

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

 

[basscooker]

A pair of purpose-designed 1x10 combos will achieve your end goal, and you won't have wasted money on a failed project made from a cab that you can sell as it is now.

 

[el murdoque]

Assuming both drivers share the same volume of air, it will work at low volume. I wouldn't expect it to be useful at stage level. But who knows, maybe you will get lucky.

My expectations:
As the power level is increased, the bass driver will cause the guitar driver to move out of phase. This will cause cancellation down low. As the power is increased further, the bass driver will probably destroy the guitar driver.

The RMS power rating is basically how much the voice coil can handle long term without overheating. RMS power rating is only valid at higher frequencies where cone excursion is relatively small. For lower frequencies, the mechanical power rating tends to be more important than the RMS power rating.

FYI, The tuning of the cab effects mechanical power handling. Put the same driver in different cab designs and it impacts low frequency response and mechanical power handling.

FYI it's not unusual for mechanical power handling to be significantly lower than the driver's RMS power rating, even in a properly designed cab. Since this is not a properly designed cab, the mechanical power handling may be extremely low.

Since you plan to ignore sensible advice. Let's us know how it goes.

If I read the documentation right, the bass driver chosen by the OP needs 50 liters of space.

Looking at the HB cab mentioned and estimating the internal volume of the box, I guess about a hundred liters there.

Would it be a (good) idea to glue in a piece of plywood in the middle to create two sealed chambers instead of one?
By doing so, one would eliminate cross pollination between the two speakers and therefore the strong bass speaker would not overpower the weak guitar one?

 

[Wasnex]

Would it be a (good) idea to glue in a piece of plywood in the middle to create two sealed chambers instead of one?

Not sure it would qualify as a good idea, but most likely an improvement.

If I were committed to the idea, I would model the results before doing any mods.

IMHO a better idea would be to leave the guitar cab "as-is," and build a separate bass cab from known-good plans.

 

[bottomzone]

Why create a thread seeking the advice of some very knowledgeable and experienced professionals knowing you are going to ignore their advice? Not cool.

 

[Hoochie Coochie Man]

Guerny, don't listen to these naysayers.

I highly recommend that you do the speaker swap and report back here with the results.

Experience can be a great teacher.

 

[Wasnex]

Why create a thread seeking the advice of some very knowledgeable and experienced professionals knowing you are going to ignore their advice? Not cool.

Maybe he just wants observers

 

[Bar Band Bassman]

I started saying "no" before I finished the first sentence. I'm no expert, but why waste all that effort when 2 cabs and 2 heads stacked on a hand truck will take care of the "footprint" issue? Then I realized: some of us, including me, are sometimes powerfully compelled to re-invent the wheel. Having said that, I will say that access to the prodigious talent resources on this forum might have convinced me to steer clear of some of the more foolhardy projects I undertook in my youth. But, being young, perhaps not.

BBB

 

[fdeck]

I'd advise against it if the two speakers share the same air space. The reason is nobody can predict the effect without doing the math, which they haven't done. The familiar equations and software used for analyzing designs assume equal drivers. How it will sound is a crap shoot, and the potential downside is one driver damaging the other.

 

[Tim Skaggs]

Before I begin I'm aware this is a similar post to another on this site: https://www.talkbass.com/threads/can-i-put-both-guitar-and-bass-speakers-in-the-same-cab.1298905

However, my use case is different in a way I will explain below.

I have come into possession of a Harley Benton G212 Vintage guitar cab fitted with Celestion Vintage 30 G12 speakers. My aim is to swap one of the speakers out with a Celestion BN12-300S (4).

Each speaker having its own amp (guitar for guitar and bass for bass speaker) but signal coming from bass guitar through pedal board with a y-split for separate signal chains (cleanish low end, distorted/fuzzy highs). Essentially trying to minimise footprint of a dual amp/cab setup.

I also wanted to experiment with using a passive crossover at 200hz to extend range as an all purpose practice cab.

My concern with all of this is less whether it will sound "good" but rather if it will work at all or have some deal breaking issue for purposes on/off stage.

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

I’ll bet your idea will work like a charm. I can’t believe speaker manufacturers haven’t put a similar design in production. You will likely be getting calls from Darkglass, Markbass, Aguilar, and others asking to use your idea. (I’d hold out for the offer from Mesa Engineering if I were you).

Ignore this advice at your own risk of losing millions of $$.

 

[bherman]

Before I begin I'm aware this is a similar post to another on this site: https://www.talkbass.com/threads/can-i-put-both-guitar-and-bass-speakers-in-the-same-cab.1298905

However, my use case is different in a way I will explain below.

I have come into possession of a Harley Benton G212 Vintage guitar cab fitted with Celestion Vintage 30 G12 speakers. My aim is to swap one of the speakers out with a Celestion BN12-300S (4).

Each speaker having its own amp (guitar for guitar and bass for bass speaker) but signal coming from bass guitar through pedal board with a y-split for separate signal chains (cleanish low end, distorted/fuzzy highs). Essentially trying to minimise footprint of a dual amp/cab setup.

I also wanted to experiment with using a passive crossover at 200hz to extend range as an all purpose practice cab.

My concern with all of this is less whether it will sound "good" but rather if it will work at all or have some deal breaking issue for purposes on/off stage.

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

I call jackassery.

 

[mmon77]

RIP perfectly usable guitar cab and drivers. But, hey, you do you I guess.

 

[Geri O]

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

So what the hell is the question and who the hell are you asking?

(Actually when I saw “Harley Benton Vintage”, I could smell where this was going….)

 

[Nev375]

I think it's a fantastic idea and you should definitely do it! (you are going to anyway)

Please video every step of the process and share that with us along with the results when you are done!

 

[Wesley R]

Do it, sometimes for some people playing around with gear is fun.

It should work to some degree in that some sound will come out of the speakers.

It will be more effort, money and energy than I would toss at it.

 

[ardgedee]

My concern with all of this is less whether it will sound "good" but rather if it will work at all or have some deal breaking issue for purposes on/off stage.

Your idea is basically to have two speaker cabinets as conjoined twins. The catch right now, as you outline your plans, is that the speakers will be sharing the same airspace, which isn't good for reasons people outlined above. Adding a divider to isolate each speaker will help a lot -- at a minimum it will help keep the bass speaker from destroying the guitar speaker.

If you plan to use this at performance volume rather than plunking-around-in-the-bedroom volume, you really ought to do some engineering -- figure out what kind of cabinet space the bass speaker needs. Otherwise the best case scenario is that the bass speaker simply won't go particularly low, worst case scenario is it destroys itself because can't handle low frequencies at the volume level you want. Another likely scenario is that it ends up out of phase with the guitar speaker at the frequencies they overlap, which leads to all kinds of weird tones (or just plain absence of tone) that you probably don't want.

I mean, people are waving red flags for a reason, it's not because they hate you or your idea. It's not actually that bad an idea but it needs more detailed planning than you seem to have put into it so far. Bass speakers don't work like guitar speakers, for better or worse, and you have to work with that or else they'll do their thing despite what you're thinking.

No matter what happens, it's not going to sound like it does now only with more bass. You'll have created a totally new loudspeaker.

 

[shoot-r]

Happy to have the lectures about how this is a terrible idea to dissuade the less foolhardy but I will for the most part be ignoring them.

I'm out.

There's things I'd like reply but I'm pretty sure the moderators wouldn't be happy with me!