Line 6 PA - bass surging, too hot

[Bredian]

Had a good, quick sound check. No issues until a few tunes in then the bass volume jumped (through the PA) without control, so I disconnected from PA until the next set.

Checked input via PA and it said I was "too hot", so I dialed down the DI input to "3" of 10 and we finally got it working happily again, but experienced similar issues later in the night. The Carvin DI ranges from -50 to +3db, so next is setting it at min DI out.

Carvin BX 700, EBMM Bongo active (18volt) with a few effects boxes.

With Carvin not producing these anymore, so far haven't heard back from them and Line 6 is a little baffled also, so I'm looking for input and similar experiences.

 

[Bredian]

Scrapped rehearsal for a PA vs Bass rig workout. Found...

1. my DI dial from the Carvin head, 0-10 =-50db to +4db worked best between "2" & "3" otherwise was too hot or zero output

2. one of my mic cables used for output to the PA was failing... don't know if it was the one.

Will try again this weekend.

 

[s0c9]

Scrapped rehearsal for a PA vs Bass rig workout. Found...

1. my DI dial from the Carvin head, 0-10 =-50db to +4db worked best between "2" & "3" otherwise was too hot or zero output

2. one of my mic cables used for output to the PA was failing... don't know if it was the one.

Will try again this weekend.

I have a similar issue with my Ampeg SVT7Pro amp.. the DI out has "normal 0dB" or -40dB switch. Normal is too hot for most digital consoles I have connected to, so the trim/gain level is basically off on the bass channel, and -40dB is far TOO LOW, requiring that gain to be cranked.. which raises the noise floor ans S/N ratio is not good.
I tried an inline [adjustable] attenuator which helped some, but it stuck too far out from the back of the amp (it's about 5" long) and when the weight of the XLR cable was added, it put undue strain on the whole shebang. So I looked for another solution
The amp does have a -15dB pad on the input side, which is [now] engaged when I use the amp and it works. The downside is I'm dumping -15dB ahead of the pre-amp stage.

 

[Wasnex]

I tried an inline [adjustable] attenuator which helped some, but it stuck too far out from the back of the amp (it's about 5" long) and when the weight of the XLR cable was added, it put undue strain on the whole shebang. So I looked for another solution

IMHO, the Shure A15AS is a great solution. The attenuator doesn't have to be plugged directly into the amp, so if you are concerned with it sticking out, or putting too much weight on the connector, plug a cable between the amp and the attenuator. Or, rather than having the player deal with it. Keep a short cable and the attenuator in your rack drawer at FOH, so you can patch it in at the board when needed. Should be safe and secure in the dog house.

Another solution would be to have a tech mod the DI on the amp. It's probably just a matter of changing the value of a few resistors. Some companies have developed factory mods.

 

[s0c9]

IMHO, the Shure A15AS is a great solution. The attenuator doesn't have to be plugged directly into the amp, so if you are concerned with it sticking out, or putting too much weight on the connector, plug a cable between the amp and the attenuator. Or, rather than having the player deal with it. Keep a short cable and the attenuator in your rack drawer at FOH, so you can patch it in at the board when needed. Should be safe and secure in the dog house.

LOL, I'M the player
I'll give your suggestion a whirl !!
Thx

PS: I try to keep things neat and tidy.. old habits.. so plugging it into the back of the amp was MY obvious choice.. I have a 6 foot cable I can use and store in the back of the amp case.

 

[Bredian]

The amp does have a -15dB pad on the input side

Most definitely use the pad if you're playing an active bass. Mine pads it -10db (or gains passive basses +10db). My main bass has 18 volts of active, so it matters.

I do think we got it dialed in. Will report back after gig.

Again, my DI dial is now set where the PA is happy. Low. Likely with more pad.

We've noticed when we pull gain off the mics we get rid of feedback also.

 

[Bredian]

We determined the DI setting on my amp head should be between 2-3 (of 1-10) to get a neutral output (0 gain/pad) measured at the PA input. My Carvin takes the feed post tube preamp.

Very happy gig.

The line 6 PA is able to measure the input and show to us.

In a previous band, I DI'd into a Presonus mixer. I don't believe there was any transparency but remember there were occasional issues that we couldn't figure out. Now I understand and owe an apology to that sound guy.