A Few Thoughts On My New T39

[wespaul]

I'm still not finished with the exterior of my T39 (24" wide, 2 BP102s), but I have been fussing with it out in the garage. I intend to use it as part of my bass rig, and though I plan to build an omnitop 12, right now the mid-highs are carried by my Eden 4x10 w/tweeter. I found an old 31 band EQ in the basement, an Omnifex GEX131 (can't find any info about it on the web), and plugged it into the signal chain. I set up bi-amped, xover ~120 Hz, through my ampeg head, and plugged in a signal from an mp3 player.

I read someone here (Bill, I think) mention that 50 Hz supplied the chest-thump in sound. I know what I had with little EQ, or just the limited EQ on the bass amps felt muddy, so I boosted 50 Hz on the EQ. Other settings as follows:

-20 and 25 Hz cut all the way. I figured this would be an effective high-pass as recommended to protect and maximize relevant content from the T39.
-40 just a hair up
-50 boosted near full
-63 boosted a hair
The rest is not relevant to the T39, but just so you know,
-400, 500 and 800 cut a bit
-800, 1k cut a bit
-boost centered around 10k, with 8k and 12.5 up just less than the 10k
-all else flat

I disconnected the mp3 player and played my bass through it then, and really didn't find any settings I needed to change. This EQ setting, entirely by ear, tightened the sound up quite a bit, minimzing the muddy sound. Nothing actually sounds good in my garage, and I know different rooms will need different EQ, but this was like a practice run to try that old EQ, and see if I could simply make it sound better in a bad room.

I did use it at a gig last weekend, and liked what I was hearing, but I couldn't get away from it far enough to really hear it. I thought it was a little loose. Fat and thick, but loose. The band loved it! It certainly filled out our stage sound. For backline use, the sound isn't as critical as it is through the PA as long as we on stage are comfortable with it, but I wish I had thought of this EQ then. I plan to try it next gig.

Any suggestions on exactly where the muddy sound comes from, and how to EQ for the low thump but keep it tight are welcome. I made some progress, but I'm sure there is room for improvement. The T39 is a powerful tool with more lows available than I really need. I love it, but need to learn how to use it well.

Edit: Trying to include pictures for the first time-



DJPhatman, thanks! That did it!

[DJPhatman]

Try right clicking on the pic, then left click "properties". Copy the image address (URL) thats in the properties window that pops up, and paste it between the img tags.

[Tim A]

50 boosted near full

That's nuts. Every time you boost 3dB, it's like introducing double the power. So if you're boosting 12dB, well...

The thing is, even if you're well within the driver's limits you're eating up a lot of headroom that could be getting used elsewhere.

Keep in mind too that you're not just adjusting the frequency printed on the faceplate, you're also adjusting the frequencies around it.

If it were me, I'd start over. Sit down with the EQ dead flat, and start the process over using the SPL charts for your cabs. Then tweak by ear. Keep your boosts and cuts nominal going a little each way. In other words, instead of boosting 50Hz 12dB, try boosting it less and bringing the other frequencies down. It'll give you the same result without eating up all your headroom.

[Bill Fitzmaurice]

On most stages, or garages for that matter, the distance from the cab to the ceiling will give a null zone in the 40-60 Hz range close to the cab, so you can't expect to hear or feel much thump until you get back away from it. Boosting any frequency by 12dB could cause damage, you're just lucky that excursion in the T39 is minimal at 50 Hz. 6dB is as much as I'd use. If it needs that much boost it's because of the reason above. Mud from a T39 would be sourced above 100 Hz. You won't hear it in a bi-amped PA, but on the backline you may.
When it comes to EQ, with mine or any cabs, what you hear on stage is moot, it's what it sounds like in the audience that counts, and with the assistance of bandmates/soundman that's where you should be listening to it on soundcheck when you adjust it.

[Randall Dibble]

Back in the day I was always told that if I want more BASS that should turn down the treble and increase the volume!!

[Ron K]

Chopping 20-25 full does a not a HPF make. It will only chop it 12 db and everything below or above will rise anyway. At best its a notch filter and a poor one at that since it has a fairly wide Q! That said you may be close to x-max on those BP102s if you're putting any snot into them when you hit the E-string or tune down to D!

I'd put a real HPF on that if you plan on driving it hard or the magic smoke might just appear!

[Bill Fitzmaurice]

Chopping 20-25 full does a not a HPF make. !

Nope, but OTOH with the limited output down there from a bass, if any, it's probably adequate. I do the same. Not on PA though, especially with recorded media that may have content there.

[wespaul]

50 boosted near full

That's nuts. Every time you boost 3dB, it's like introducing double the power. So if you're boosting 12dB, well...

I wrote my settings down carelessly. I checked the EQ, and it turns out the boost is only about 6 - 7 dB at 50 and 10k. The stack of cabs and amps is a little more than 7 feet high, with the compressor/limiter on top, and the EQ on top of that. So when I wrote about it last night, I just looked up at the EQ and saw the settings without accounting for the angle of parallax. Tim's sanity check caused me to take it off the top of the stack to look at the settings again.

I did walk away from the cab as I adjusted settings, but I can't imagine that walking outside of the garage (into the wind and spitting snow) is going to give me a good idea of sound. I'm fighting terrible conditions trying to play with this. Hell, there ain't been a decent weather day since I got the bug to build this. It's like the elements are conspiring against me. When warmer weather gets here, I can do this more like I should, minus all the fancy measuring equipment - that means EQing by ear outside, and adjusting from there for each room I play in.

[Jim Van Streader]

+1 on not boosting the 50hz., (not even 6 or 7db)

As a builder who has by demand concentrated on subs for my first 12 boxes I can say I have learned much about bass and where everything lives. Like Bill said recently, the big wake up is learning that everything is higher than you may have thought.

I recently had a big stage rehearsal for one of my two bands at one of those rental studios where the backline was supplied. It was a Crate amp with a graphic over 2 15's. I plugged my bass in and pulled the lowest slider, 40 full cut and left everything else fairly flat. It was amazing. At the end of each tune (AC/DC tribute) the band would immediately start raving about my bass sound. It had such a defined thump that was the opposite of muddy. A super tight punch that melded with the kick to the point of perfection. I couldn’t stop grinning with each kick. It was a real eye opener for me and I've been playing bass for some 30 plus years. I just set it that way approaching it like I would a sub. I HP my T3630’s in a hip hop 600 capacity filled club at 45hz and they rattle and thump like an earthquake and are too much to be run full. Everything is higher.

I’ve had the best luck using the graphic primarily as a cutting tool where you're "carving out" your sound and if you have to boost, just a few db, but you can always fiddle with the knobs on your bass.

Now on that amp I went back to it after rehearsal and brought back 40hz up to flat to see what it sounded like. It made more rumble and it actually sounded good if you were just playing around by yourself at low volume. But full crank in the mix you loose definition and get that loose muddy sound. Plus it covers up a good part of the kick.

Personally I don't see the need for a sub in a bass rig, at least not for my style of music. Let the PA handle that. I might use it as part of a drum monitor for kick on bigger stages but not for bass guitar. Small sledge, you need a framing hammer. If the day comes that I actually get to build something for my own use, I'd like to try a couple Tallboys, probably the 12’s.

Eeks it’s a good think I don’t write often. Hope something was helpful.

[wespaul]

OK, it sounds like everything I am trying to do with my bass rig is wrong. Since I don't have an ear for EQing it, does the concept of RTAing the bass rig alone and using that to EQ for flat response make any sense? Once again, remember that I am not going for high volumes, just a good full on-stage tone that fits in the mix for us in the band. I will continue to let the sound guy worry about FOH.

[Bill Fitzmaurice]

OK, it sounds like everything I am trying to do with my bass rig is wrong. Since I don't have an ear for EQing it, does the concept of RTAing the bass rig alone and using that to EQ for flat response make any sense?

Flat response is the Holy Grail of hi-fi. Electric bass is anything but hi-fi. What counts is how it sounds, set it where you like it, but you have to be aware of the pitfalls of trying to get too much low end from any system when your listening position is close to the source. Perfect for you eight feet from the cab might be knocking bottles off the bar racks 50 feet away.

[wespaul]

What counts is how it sounds, set it where you like it, but you have to be aware of the pitfalls of trying to get too much low end from any system when your listening position is close to the source. Perfect for you eight feet from the cab might be knocking bottles off the bar racks 50 feet away.

I can understand that. I guess it's time to dig out my wireless, as much as I hate dealing with batteries and extra gear. Well, the extra gear thing is getting out of hand anyway, so what the heck......

[Bill Fitzmaurice]

What counts is how it sounds, set it where you like it, but you have to be aware of the pitfalls of trying to get too much low end from any system when your listening position is close to the source. Perfect for you eight feet from the cab might be knocking bottles off the bar racks 50 feet away.

I can understand that. I guess it's time to dig out my wireless, as much as I hate dealing with batteries and extra gear. Well, the extra gear thing is getting out of hand anyway, so what the heck......

I'm still wired, 20 foot cord. I find that's enough distance away to get a decent feel for the sound in the room versus on stage.

[WB]

Flat response is the Holy Grail of hi-fi. Electric bass is anything but hi-fi.

I agree. My best results have been to flatten the midrange only, using the DEQ2496 RTA. Then using the parametric eq to suit if necessary.

[BillyG]

I guess it's time to dig out my wireless, as much as I hate dealing with batteries and extra gear. Well, the extra gear thing is getting out of hand anyway, so what the heck......

I try to use my wireless at the sound check or even in the first set to be able to hear not only how my bass is sounding, but to see how it's sitting in the mix. I seem to have a good amount of lows and punch coming through when we use our large pa or when I use my OT12/T39. I use a 36" scale five string. It seems that the lower parts of the note are not heard as much felt! The real low parts of the notes make your pants flap and the punch seems to be at a higher freq., maybe 200 or 300 Hz??