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Rig/Volume Issues

amos

amos

Oct 23, 2003
1,692
8
40
SE Portland Oregon
#1
Setup:

Carvin LB70 active into

BBE Bmax-Tube into
QSC PLX1602 into
Aguilar GS112 x2

I'm having problems getting an undistorted/unclipped sound at volume/hard plucking without turning the compressor on.

I'll set the the Gain at 3 and the Volume at 4-5 with the eq flat, compressor and sonic maximizer off, my carvin onboard preamp flat, one hard pluck and its loud enough to clip something. The BBE b-max preamps do not have a clip light, and it's not clipping the power amp.

Next time I get to my practice space I plan to:
Run in parallel/stereo instead of bridged mono. I don't know if the high-gain preamp will clip the power amp like this but it's worth a shot because I am really really broke at the moment so I'm looking into any options that are free. IF I had money I would put a lower-gain tube in there (yeah, I'm that broke).

Running the signal(gain) super low (1-2) seems to suck a lot of the tone of my amp, so if changing from bridged (1600w@4ohm) to parallel/stereo (300w@8ohm per side) does not help should I send my preamp off to get the input gain mod? or should I wait until I have some money and try changing the tube for an AU7 instead of AX7 first?

I also need to try changing the battery, but I do not have an amp here where I am at, and there is only a 1% chance that is the case

*UPDATE*: The answer to this original post was too much power going to my speakers. I fixed that but now have an issue with clipping my power amp (see below).
 
#7
Is your carvin 9v or 18v? The BBE may not be rated for 18v inputs regardless of the onboard settings. If you have a passive mode on the bass I would try running that into the BBE as usual to see if it is the bass output clipping the input of the Preamp. I don't know that it should make all that big a difference though since I am sure a lot of other people are running 18v pre-s all over the place and not clipping thier rigs.
 
#8
schillzilla said:
Is your carvin 9v or 18v? The BBE may not be rated for 18v inputs regardless of the onboard settings. If you have a passive mode on the bass I would try running that into the BBE as usual to see if it is the bass output clipping the input of the Preamp. I don't know that it should make all that big a difference though since I am sure a lot of other people are running 18v pre-s all over the place and not clipping thier rigs.
Click to expand...

The Carvin is 9v. I wish it had a passive mode as I do not like the onboard pre-amp. If I get the Bill Lawrence pickups that drop right into my Carvin, most likely I am going to take the onboard preamp out aka convert it to a passive bass.
 
#9
schillzilla said:
Is your carvin 9v or 18v? The BBE may not be rated for 18v inputs regardless of the onboard settings. If you have a passive mode on the bass I would try running that into the BBE as usual to see if it is the bass output clipping the input of the Preamp. I don't know that it should make all that big a difference though since I am sure a lot of other people are running 18v pre-s all over the place and not clipping thier rigs.
Click to expand...

9v or 18v has nothing to do with the output level of a bass. There is very little correlation even between active versus passive bass output level across basses (e.g., the active F bass has a lower output level than most passive basses, and the passive Reverends have a higher output level that just about any bass I've ever experiences).

Per the above, you first need to identify what is clipping.... is it truly the speakers 'farting' or is it your preamp being overdriven. First thing is to turn the preamp gain down and the power amp up and see if that helps.

It would not surprise me if your GS112 stack clips at high volume. First, any 1 x 112 stack is somewhat volume limited in the deep low end, and the low end extension and somewhat mid shy voicing of the GS112's makes them (IME) particularly sensitive to 'bottoming out' at high volumes. While the EpiUL, Bergantino, etc. 112 seem to gently compress at high volumes, I have heard the GS112 stack go into 'full fart' when really pushed. I find that most 112 cabs pretty much reach their limit with 300 or 400 watts pumping into them.. i.e., just a touch over the maximum suggested power rating.

My guess is, you are pumping some deep bass in there that needs to be removed. That stack should be plenty loud is you make sure the 40hz and below boom is dialed out a bit, and the mids (400-600) are punched up a touch. IMO and IME.
 
#12
So I have an update since I went to practice and switched to stereo. The problem I described in my original post I believe was a result of too much power going to the speakers. My ex-bandmate who pinned my 4-pole speakon for bridged I am pretty sure did not do it right, but that's besides the point because now I am running in stereo, 300W to each GS112 @ 8 ohms on each channel. ch.1 and ch.2 power amp gains at 50%

My problem now is clipping the poweramp pushing the master volume past @3.5 with the gain at 3 or higher.

First thing I tried was turning the filter position dip-switch [on the power amp] to "50hz" instead of "30hz", did not work, not to mention the bass suffered.

I believe this is purely related to the BBE Bmax-T preamp I am using. It seems like the gain is not matched well with the QSC poweramp. After messing around with it for what seemed like forever, I came to these settings:

Gain: 3
EQ: Flat (Bass:2 Mid:10 Bass:2)
Para-Mid EQ: Flat (Mid Gain: 5)
Compressor OFF
BBE SonicMaximizer ON (same results with it off with the lo contour at 4)
Master volume: @3.5

and of course the EQ settings on the Carvin LB70 are flat.

I'll try to elaborate a little further on my exact experience for technical clarity (yeah right):
With the Gain at 3, If have the the master volume any higher than 3.3 (+/-0.1) I clip the poweramp (red lights) when I dig in or thump/pluck, at which point I have tried turn down the preamp gain usually to about 2, just after the point where it makes sound, and of course with the input gain so extremely low the tone is pretty worthless, eq won't do jack, etc. Turning up the poweramp gains (past 50%) will make it somewhat louder, but it pretty much sounds like crap with the [preamp] signal so weak. Compressor sort of helps but I shouldn't need it..I do not care much for the built-in comp. I also do not not overdrive the preamp (e.g. gain 8 master 3).

I am sorry this is so damn long guys....anyways my conclusion is my speakers are a lot happier being run with their rated power coming out of the power amp...Now I just need the preamp to not clip the poweramp so easily, so here are the things I have come up with:

1. Install a passive mode/switch into my bass (I want to do this anyway, would this help at all?)

2. Replace the Groove Tubes 12AX7 with a lower-gain 12AU7 (recommendations for 12AU7 or others?)

3. Send it off to BBE to have the input gain modified?

4. (not economical) Go back to bridged and get speakers with higher power handling

Ugh too many parenthesis...a big thank you in advance to anyone who reads and responds to this, and a big apology for anything that does not make sense I have yet to go to college and am self-taught at this stuff.

-David
 
#13
Wow I am so incredibly frustrated. Running an uncompressed signal; in stereo I clip the poweramp, in bridged mono I clip the speakers. My only solution I've found is to turn down. Maybe time to upgrade the speakers, though I do not understand why two 112s are not adequately loud enough for practice. Some of it has to do with the practice room (tiny), the 12s seem to be plenty loud at lower gains in bigger rooms.

I have yet to try it with a properly wired speakon cable. Last time I tried running bridged it was only getting 1+ I think
 
#14
amos said:
3. Send it off to BBE to have the input gain modified?
Click to expand...

Could be. A buddy gave me his older BMax (not the T model though) to mess with for a while. The gain was absurdly hot. Turning it up to 3 would've clipped the input like crazy. Have you tried the gain at 1 (or less even) and the master wherever it needs to be to compensate? That's the only way I could use the BMax at all until I modified it for a lot less gain at the input end. Sounds fine now. This was using various QSC PLX amps, BTW.

You could bring your rig out to Hood River this Sunday for the GTG. Maybe we can help you figure it all out. ;)
 
#15
Passinwind said:
Could be. A buddy gave me his older BMax (not the T model though) to mess with for a while. The gain was absurdly hot. Turning it up to 3 would've clipped the input like crazy. Have you tried the gain at 1 (or less even) and the master wherever it needs to be to compensate? That's the only way I could use the BMax at all until I modified it for a lot less gain at the input end. Sounds fine now. This was using various QSC PLX amps, BTW.

You could bring your rig out to Hood River this Sunday for the GTG. Maybe we can help you figure it all out. ;)
Click to expand...

Thanks for the reply. With the gain at 1 (the first dot) I do not get any sound. The sound starts at @2.

is there a thread for the hood river GTG? I would love to go.

-David
 
#16
amos said:
Thanks for the reply. With the gain at 1 (the first dot) I do not get any sound. The sound starts at @2.
Click to expand...

The knob on the one I tried may have been calibrated a little differently. Anyhow, for me it only worked cleanly at the lowest audible setting, pretty much. The gain mod's not too hard for a qualified tech to do, but I think the factory may do it for free anyway?

is there a thread for the hood river GTG? I would love to go.


Here you go. PM me if you need any more details, since I seem to be the "host" again this time.;)
 

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