Hello from california!

[Bassistfreak416]

Long time viewer of this website, first time posting here.

I dont know if questions are often included with the introduction, but i dont know of another section to include or ask it in. So here we go:

Im planning to build a T39 and an Otop12 to be used as bass guitar cabinets. Got the wood and the stuff ordered for the Titan, but haven't ordered the stuff for the Otop yet. Im having a worry about the setup tho. My amp is a Mesa Boogie 400+.

My first concern is about the crossover. I bought the 8ohm Sub Only Crossover from Speakerhardware, so i know that the T39 will only get the low frequencies, i believe 100hz is the crossover frequency. I will be buying the prebuilt crossover for the Otop, but i dont think it will have a HPF for the speaker. Do i need to order a different crossover, or need an external rackmount crossover?

My second concern is the speakers and their response, or better to say is them not matching each other in either volume or frequency. I guess im worried that i will need to get a graphic equalizer or a Behringer DEQ2496/DCX2496 to get the speakers to sound flat and even then use my amp to get my tone without having to do a lot of extreme eq'ing to get an even sound. Also, should i worry about needing a HPF at 45hz?

Third and final question is about breaking in the speakers. My Mesa is really my only amp on hand, without having to improvise with a theater sound device or something of the sort. The problem i see is how to see how many volts my amp would be sending to the speaker, how to connect the speaker to the amp, and how to read the volts of the amp.

I hope the above questions are ok. While i have never heard or experienced a BFM cabinet before, the reviews and science behind it already having me convinced it will exceed my expectations, and i expect that whatever expectations im already coming up with, will again be exceeded when heard.

[Grant Bunter]

Hey Bassistfreak416,
Welcome to the forum

Of course it's ok to ask questions, always.
Even more so when it's your own thread and own goals.

Let's go at it a bit at a time.

First up, do you usually play with PA support or no?
If the answer is yes, or more than 50% yes, you might want to reconsider a bit, only because a T39 onstage and front of house subs aren't going to like each other a lot.
T39/Otop combo for bass is a Stadium sort of rig.
You'll find the majority of bass players here use one or multiple Jacks (with piezo arrays that have an off/half/full switching arrangement to adjust HF output) to get their desired SPL onstage.

We can lump a few of the other questions together.
Your Mesa puts out 100V. A premium driver loaded T39 has to be brick wall limted to 50-55V.
And High Passed at 45Hz. It should also be low passed at your crossover point to prevent phase issues with your top. Your top should be high passed at your crossover point.
To me, that means you need a DSP device (Like a Driverack or DCX), and your running a pro sound system to play bass so you need EQ (onboard on the driverack, might get by with the parametrics on the DCX plus your tone controls on the Mesa). This will most likely mean a two amp system BTW (or at least 2 amp channels).
Absolutely you should worry about a 45Hz HP. If you don't, you'll probably blow your driver quick smart

You can use your Mesa to break in your drivers.
You just need to plug a tone generator (there's a heap of ways to do this) into the input and set at 10V in output with a multimeter and no speaker attached until you get the right voltage (going from 0 on the volume knob and working your way up). Then connect your speaker and burn it in.

It's likely the Otop will overun the T39 a little. With the Driverack or DCX you should be able to adjust output to level it out some.

You sdon't need a crossover as well as the driverack or DCX. Those two items are corssovers as well.

Something for you to think about at least.

Enjoy your stay and builds, you'll end up with an awesome rig I'm sure...

[Gauss]

Here's an option that I chose: Use a cabinet designed for bass, and supplement it with a titan39. The plans include how to make a passive crossover that includes a high-pass out for a top. You can see the input/output jacks on the top front of the titan. I run the output of the amp into the crossover on the left, and take the signal from the output on the right to the bass cabinet's speaker. With my small gigs and practices, usually the combo amp is enough. I don't know if a Otop12 can be used as a bass cab by itself.

[jswingchun]

Im planning to build a T39 and an Otop12 to be used as bass guitar cabinets.

Curious why you wanted to go this route instead of the more traditional Jack route?

[Tom Smit]

Welcome to the forum!

[Bassistfreak416]

To throw in a few little details, the band i play in is a progressive technical metal band, so our tunings are usually in D Standard, or sometimes i will play a 5 string bass to play anything that needs a B Standard tuning or Drop A tuning. I do have a 7 string bass that has a low F# string, tho right now i dont immediately have to use it as we dont have any songs or guitars to play that low. But being able to properly, if not close enough, reproduce the note, seems like something worthy to brag about

Point being, i was of course seeking volume for shows, something to reach down low, and the Otop12/T39 appealed to me for being a recommended stack and feeling like it reaches both with ease. Maybe more the reason it appealed is i felt like either the Jacks wouldnt be enough, and this wouldn't be too much overkill. I currently use a Carvin LS1503 cab which i have enjoyed. So in keeping with a sorta PA like speaker setup, it would be able to get the widest and smoothest range of sound from a not too big or too heavy setup.

I have not heard or experienced a Jack before, so that may also be why i dont think it they would be enough, cause i still hold the doubt of it being enough when its design might say otherwise.

I like long post, hope not too big a problem. Just an early warning


Grant:
PA support varies. I cant say we play big venues, tho we have played the House of Blues in Anaheim and LA before (LA was only in an upstairs stage, and already the show had problems with not allowing any loud volumes. Long story)
Of course at the Anaheim venue, the house sound is doing the work and our stuff was only really for stage volume. The rest of the shows generally our stuff will run either DI or micing, but even then our stuff usually runs at volume that the house sound is probably only adding to ours and we do most of the work volumewise. As in we still do most stage and crowd volumes with our amps. Also the venues dont seem to really have subs, or at least i think the low bass would be more produced by me than the house.
If i did go with Jacks, i would look at the 15. Since i ordered the 3012lf for the Titan, im going to take a guess that the speaker would work in the Jack? At least to make use of it if i were to go with the Jacks.

Now a question/idea to the two amp thing. I would guess i could buy a power amp, which most come with 2 channels/volumes, so i could run the speakers separate. My worry, or feeling of loss, would be not making use of all the tubes in my amp and having to use solid state power. Sorta bought the amp because its all tube, so carrying it around to use as a preamp feels like a loss if the power amp tubes wont be included in the overall tone.
Tho i have had the idea of getting one of my guitarists amp heads to use, as i used it in recording to use the clean channel for a little extra clean brightness, and the dirty channel to add some distortion. In the end it would blend with my Mesa's warm and clean deep tone to get a good overall sound in the recording. I think it could also work and sound well live.
Point being, if i added it to my setup, i could run my bass into the Mesa to shape the sound, then using the effects loop to send the Post-Preamp signal to the DCX/Driverack, split it up/limit/crossover/eq, then send the low signal to the Mesa to go to the Titan, and send the highs to the guitar amp (100w tube amp) to be sent to the Otop. That way i have two volume controls for each speaker, and while already loudly designed speakers, i get the extra watts for the sub and less-but-still-plenty power to the Otop. (If i kept the idea of the two channels on the guitar amp in my tone, i could run into the guitar amp, send it Post-Preamp into the Mesa to the DCX/Driverack, or just send the two to the DCX/Driverack, if that would work. Not as important in the overall questions whether to include clean/dirty sounds in my setup, but figured i would include this anyway.)

I hope that makes sense. Again, i enjoy long posts.

On the Mesa and driver break in, how do you connect the multimeter to a 1/4" speaker jack? I have multiple plugs for different Ohms on my amp, does this matter? Maybe i dont see how a multimeter would connect because off the top of my head i think they only use those little, i guess you could say, crocodile grip/mouths? So i dont think can would connect to a 1/4" jack?


Gauss:
If read above, i do use an already PA speaker in my setup, and while its a 15", but it doesnt extend as low as the Titan can do, of course. If i used the LS1503 with a T39, while the highs go the LS and the lows to the Titan, i would guess there would be a problem between the two volume wise. If i were only using one volume control, then i could compensate by lowering the bass frequencies on my amp, if it would balance the sound.
And no i dont think the Otop12 is recommend to be used alone for bass. The Otop15 could as it extends down lower. But i was thinking a low/high split setup would be the way to go than just 1 or 2 "standard" speakers. As in Otops vs Otop/Titan.


Jswingchun:
I hope its ok if i simply refer to my first two paragraphs in this post. I felt like it would bring the best results. While probably completely true, my worry was more on not having enough than having too much.


Tom Smit:
Thanks!

Again, sorry for the many many words
Thanks for the replys!

[Bassistfreak416]

Just realized when i said to use the 3012lf in a Jack 15, i think in my head i was thinking of the 3015lf. My mistake.

[Grant Bunter]

Many words is good lol, you can post with many words and I can answer with them!

You brought up the idea of a power amp and, to achieve what you want, that is one way to go.
A good one I think.

I read the manual for your amp and it says (not as a direct quote) that you can use the effects send to make your head a preamp only unit.
You have to use the Effects Send jack, set Effects Blend at 10 and Master at Zero which makes it ok to not have speakers attached because you're not sending signal to the amplifier section of your amp.
The way I read this is that you couldn't then use a speaker output to run the T39.
I'm not quite sure this limits output the T39 driver to protect it, as you would have to set the Master level as a constant in order to set the limiter on the DCX.

Read the sections in your manual about using Slave Level/Slave output or 600Ohm balanced output, the answer to run signal to a DCX is in either of those options.
Edit, re read the manual and found your solution: In the manual it states the 600 Ohm output is derived at the speaker outputs and sent to the balancing transformer. While this requires you need to use a "dummy load" instead of a cab in the output, this means you will get all your valves humming and they will contribute to tone.

Hmm, from what I've read, F#O is 23.12Hz and I think you will struggle to find many cabinets capable of reproducing that well. It's certainly beyond what one T39 should be set at, which is a 45Hz high pass.

As far as using the Jack output and measuring it:
Obviously, use whichever output jack has the correct impedance for the speaker being broken in. The 3012lf is nominally 8 ohms, so that's the 8 ohm ouptut jack.
Plug in a speaker lead that has no jack plug on the other end that has the wires bared (as if you were making a lead up), but keep those wires separated. Put your multimeter probes on the bare wires, red on the "tip" wire, black on the "sleeve" wire, using the AC 200 setting on the multimeter. Set your voltage, turn off the amp, hook the lead up to the driver being broken in, turn amp back on, and you're off and running.

I'm not going to try to tell you if you should "waste" your Mesa amp by using it as a preamp only. You probably need to experiment quite a bit to see if it's going to give you the sound you want when run that way, but that's really your decision. If you have mates with a power amp, you could try it out. You won't get your top end as would be the same with an Otop, but it would at least give you confirmnation

If you do decide to go with this and a DCX, then output of the amp (with one of the methods mentioned above) goes to input of the DCX, then one output goes to one channel of a power amp to run the T39 and another output goes to the other side of the power amp to run the Otop.

Explore your otpions. You've certainly come to the right place for excellent cabs in terms of sound and output...

[Bassistfreak416]

Ok, got the speaker being broken in tonight.

While i know the DCX2496 is the choice with Behringer, the Driveracks have the PA+, PX, or the 260, if those would be 3 possible choices. I would assume the PA+ is the better model. Do they all come with RTS? Also they dont have 1/4" plugs, their XLRs i believe? I was planning to use 1/4" jacks on the cabinets since my Mesa only has 1/4" output jacks. The PA+ and the PX appear to have RTS in them, which i would be interested in to help flatten or balance the overall sound.

Which a question with RTS or if using a 31 band eq to flatten the speakers: does it matter if the RTS/31EQ sits before or after the Mesa 400+?

[Bruce Weldy]

Ok, got the speaker being broken in tonight.

While i know the DCX2496 is the choice with Behringer, the Driveracks have the PA+, PX, or the 260, if those would be 3 possible choices. I would assume the PA+ is the better model. Do they all come with RTS? Also they dont have 1/4" plugs, their XLRs i believe? I was planning to use 1/4" jacks on the cabinets since my Mesa only has 1/4" output jacks. The PA+ and the PX appear to have RTS in them, which i would be interested in to help flatten or balance the overall sound.

Which a question with RTS or if using a 31 band eq to flatten the speakers: does it matter if the RTS/31EQ sits before or after the Mesa 400+?

Ok, you are trying to put these devices in the wrong place. They are line signal devices that come before the power amp. The type of connector on the processor has no correlation to the connector on the speaker cabinet.

As far as the Driveracks, the PX model will be fine for a two way system. No need for the PA+.

[Tom Smit]

... Do they all come with RTS? Also they dont have 1/4" plugs, their XLRs i believe? I was planning to use 1/4" jacks on the cabinets since my Mesa only has 1/4" output jacks.

The best solution, DIY of course, is to make your own cables. Here is a page to help in wiring the different inter-connect cables. http://www.rane.com/note110.html

[Grant Bunter]

The DCX doesn't have RTA. RTA and more comprehensive EQ are in the "companion" unit, the DEQ2496.

Yes, the driverack series has 28 band EQ and RTA capability.

And the 600 Ohm ouptut is a XLR plug isn't it? Use that

[Bassistfreak416]

I think my confusion was getting the post-preamp signal to the DCX/PX, but i guess using a cable with different end pieces would work fine.

Is RTA really necessary, or is it something i can go without?
I think i like the Behringer over the DBX, but if i needed RTS then i would go with the PX.

[Bassistfreak416]

Idea: Would a power amp with built-in DSP be able to take the place of a DBX/Driverack?

[Tom Smit]

Idea: Would a power amp with built-in DSP be able to take the place of a DBX/Driverack?

Yes. EG, iNuke, XTi (II), etc.

PS. what to do mean by "RTS"? I keep thinking that you mean "TRS" (tip, ring, sleeve)