GK Backline 210 farting speakers quandrum

[Quoth'd]

I have a Gallien Krueger Backline 210 combo (bought late last year when I downsized my full rig to something more transportable)...

It's rated at 300w into 4Ohms, has built in 2 x 10" speakers (total 8 Ohm load) and a spare jack on the back for an extension cab.

My problem is that whenever I play it at half volume (or more) the speakers start popping when I pluck the strings. It's fine at lower volumes - just the attack when turned up.

So I'm wondering what to do as in my opinion, the built in speakers should be easily powerful enough to handle the 180watts the amp is advertised to deliver into 8Ohms at just about any volume + when plugging in an extra cab (1x15 or 2x10) to take the load down to 4Ohms, the amp should then be capable of delivering it's full 300watts.

If the existing speakers are breaking up at half volume, what route should I take:-

a. Add an extension cab (not sure if I want to add an extra cab at this stage as the amp should be capable of delivering more power before the speakers start breaking up as it is) + it's heavy enough as it is.

b. Replace the existing speakers (have seen some Eminence LEGEND BP102-4 (4Ohm 200w) which look like would make good replacements and still leave room for an extension cab later on if I wanted.

c. Replace the existing speakers (Eminence LEGEND BP102 (8Ohm 200w) wired in parallel to drop the total load to 4Ohms. Which would allow me to run the full 300w of the amp into the combo speakers.


Any pointers welcome, replace the speakers + leave room for an extension cab in the future or is it not worth it & should I replace the speakers and forgo the option of an extension cab in the future. If anyone has similar configuration - I'd welcome your comments on which way to go.

Thanks

Simon

[Quoth'd]

PS I should add that the existing speakers are

GK 10" 100Watt 16Ohms

[url="http://www.beyerdynamiconline.com/Product.asp?Prd=082-0016-D"]http://www.beyerdynamiconline.com/Product.asp?Prd=082-0016-D[/url]

For what it's worth

[chris_b]

Sounds like User error to me!

Turn the gain down. Raise the strings. Lower the pickups. Stop hitting the strings so hard.

[Quoth'd]

[quote name='chris_b' post='1299514' date='Jul 11 2011, 01:13 AM']Sounds like User error to me!

Turn the gain down. Raise the strings. Lower the pickups. Stop hitting the strings so hard.[/quote]

No! I bought it for it's power / volume & my bass is set up fine thanks.

[Monckyman]

Well, it could be a a gain issue.
Passive or active bass?
Was it always like this or has it only started happening recently?
Have you tried reducing the gain on the input a lot and using the output stage for volume?
Have a try and note the difference.
Try an extension cab without the internal speakers to check the amp and gain setup.
Lastly have you another amp you can try the drivers through,maybe borrow the guitarists etc just to see.

Good luck
MM

[chris_b]

[quote name='Quoth'd' post='1299556' date='Jul 11 2011, 06:54 AM']No! I bought it for it's power / volume & my bass is set up fine thanks.[/quote]
Well it's only a 210 so it has limitations. Where do you have the Gain, Master and Bass controls set?

[Quoth'd]

Thanks for the comments

I've only had it at practice in the last couple of weeks so has been the first time I've been able to turn it up that loud so can say it's been happening since got it.

Passive jazz bass
Passive level pedals
The input is about 50%
Gain is about 40%
Trying to turn master above 50%

I'm going to take the scope to practice tomorrow & see what the signwave has to say. (If I remember) That should shed some light on if it's an amp / speaker problem.

[MoonBassAlpha]

It may not be the speakers at all, it could be a dry joint on some component in the power stage getting the 'ump as it passes more current, or even one of the big caps in the psu if they're board mounted.
I've actually had this in a Sessionette bass combo - took a bit of tracking down.

Edited July 11, 2011 by MoonBassAlpha

[Dave Vader]

Worth remembering that GK stuff works backwards, you turn the master right up and use what would normally be the gain control to set volume levels. The boost control is what gives you the grindy noise.
Quirky but true, try that.

[51m0n]

If the settings are set right for gain (ie the gain overload lamp isnt coming on) at low levels, and you get no speaker flap, then if you get speaker flap when you turn the master volume right up then you are exceeding the limits of the speaker.

The wattage is merely an indicator of the thermal rating of the speakers, it is in no way a real indicator of the excursion limits of the speaker design.

You have effectively reached the excursion limit of the speakers when trying to cope with very high transient levels. You need either new speakers that can cope with the transients, and also work correctly with the cabinet in question - not an easy thing to guarantee, or you need to change either your playing style, or eq and gain settings to no longer exceed the design of the speaker.

If you dont you will damage them.

[Lozz196]

I think the easiest way round this would be to get a matching 2x10 cab, for gigs only, providing the combo is ok for rehearsals.

I`ve personally found - after going through many different set-ups/configurations - is that a lightweight amp head, and lightweight 4x10 cab is the best option for me. Much easier to cart about, especially with a decent set of castors on the cab.

[ThomBassmonkey]

What head are you using?

As someone already mentioned, the GK RB series heads' controls are aren't as intuitive as you might want.

Also if you're using a GK head, they're far louder than the wattage rating would have you believe.

[Quoth'd]

[quote name='ThomBassmonkey' post='1301753' date='Jul 12 2011, 11:37 PM']What head are you using?

As someone already mentioned, the GK RB series heads' controls are aren't as intuitive as you might want.

Also if you're using a GK head, they're far louder than the wattage rating would have you believe.[/quote]


It's the backline 210 combo (300w built in head) - which is why I was expecting it to be able to deliver more before breaking up...

I had no idea that GK worked backwards though i.e. master up then turn up the level to get the volume you want

[Quoth'd]

Update . . . . Belated

OK. I've finally got round to running it through the scope.

Higher frequencies come through OK, the problem only manifests it's self with the low frequencies. The output sinewave to the speaker is unbalanced - no DC bias but for every full wave e.g. positive +5 volts, negative -10 volts. As I turn up the gain it increases it averages a 2:1 / 3:1 ratio of positive to negative as you look at the sinewave.

[attachment=88043:photo.JPG]

The output from my bass has a symmetrical sinewave so I know it's being induced somewhere in the amp. It gets tricky as if I use a tone generator then I get a symmetrical sinewave coming out of the amp. But if I use the bass, it's symmetrical at the higher frequencies and messed up at the lower.

Has anyone else experienced this (or anything similar)?

[Quoth'd]

**BUMP** Anyone?

[MarkBassChat]

[quote name='Quoth'd' post='1353916' date='Aug 27 2011, 11:02 PM']The output from my bass has a symmetrical sinewave[/quote]I doubt it. A symmetrical sinewave sounds like cheap keyboard. Can you scope it and post a photo?
[quote name='Quoth'd' post='1353916' date='Aug 27 2011, 11:02 PM']so I know it's being induced somewhere in the amp. It gets tricky as if I use a tone generator then I get a symmetrical sinewave coming out of the amp.[/quote]The proper way to check the amp is to use a tone generator and a dummy load. The signal looks like this because the input is not sinusoidal wave and maybe tone controls are not set to the middle position. The contour filter has to be disabled. Before you start replacing speakers you have to verify the amp. If it's OK, you can verify the amp with external cab (you can borrow it instead of buying new speakers).

Mark

[Quoth'd]

[quote name='MarkBassChat' post='1354752' date='Aug 28 2011, 09:18 PM']I doubt it. A symmetrical sinewave sounds like cheap keyboard. Can you scope it and post a photo?
The proper way to check the amp is to use a tone generator and a dummy load. The signal looks like this because the input is not sinusoidal wave and maybe tone controls are not set to the middle position. The contour filter has to be disabled. Before you start replacing speakers you have to verify the amp. If it's OK, you can verify the amp with external cab (you can borrow it instead of buying new speakers).

Mark[/quote]

Hi Mark,

I have already replaced the speakers (last post was a follow up from a month or two ago) and am having the same problem.
Contour is off & all tone controls are set mid way.

Running a tone generator into it produces a clean wave at 100hz & 1khz. The sine wave from the bass is good both at low and high frequencies. The problem only seems to occur when playing low frequencies (bottom string) through the amp.

Can you help?

Cheers

Simon

[Quoth'd]

PS will get a pic of the bass through the scope

[MarkBassChat]

[quote name='Quoth'd' post='1354797' date='Aug 28 2011, 11:25 PM']I have already replaced the speakers (last post was a follow up from a month or two ago) and am having the same problem.
Contour is off & all tone controls are set mid way.[/quote]So you already spent a lot of money and the problem is still there. The proper way to do it is to find out what is wrong and only then start spending money :-).
[quote name='Quoth'd' post='1354797' date='Aug 28 2011, 11:25 PM']Running a tone generator into it produces a clean wave at 100hz & 1khz. The sine wave from the bass is good both at low and high frequencies. The problem only seems to occur when playing low frequencies (bottom string) through the amp.[/quote]As I said, you need to verify the amp in test environment (generator->amp->dummy load->oscilloscope). If you get clean sinewave at full power (I repeat: at full power), there is nothing wrong with the amp. You may test it at 40-80 Hz.
You have to understand that signal from bass guitar is not a sinewave. And tone controls modify the signal even more. Also I'm not sure whether middle position in GK corresponds to "neutral" frequency response. It seems to me that some GK amps are exceptions to this rule.
Have you already verified the amp with another cabinet (more powerful than the one you have now)?
If none of this ideas help, I think it's time to take the amp to a tech. He will know how to verify the amp.

Mark

[Quoth'd]

Thanks for pointers.

I'm going to see about getting my hands on a larger cab to test (usual practice venue doesn't have anything big enough) and have a play. I don't think I know anyone I can borrow a dummy load from though.

Would an Ashdown MAG 115 provide enough headroom to test with?

[Mr. Foxen]

Di you replace the speakers with duplicates of the ones in there, or with different ones? Might of opened a whole new can of works there. The Mag cabs don't handle very much power at all.

[Quoth'd]

I replaced with different speakers that had more power (200w per cone instead of the 100w that the GK stock came with) and got the same symptoms for my troubles

Hopefully trying out a new rehearsal venue in Derby this week, so fingers crossed I'll be able to run the amp through a selection of external cabs to see if I get the same problem or not.