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Markbass: modding the FX loop point?

gillento

gillento

Oct 15, 2005
4,451
1,602
Luxembourg, Europe
Disclosures
Nordstrand pickups
#1
a bit of background info:
I really like the way my SA450 sounds. But it can't handle the 2.67 ohms of my three Aggie GS112's load

After looking for a 2ohms capable head (and not yet having found something I dig), a friend suggested that I should buy a second MB head.

Now the "problem" is the following: I would like to use the second MB head as a slave unit (power amp style). Namely using a post-eq line out/fx send of the first head to a post eq line in/fx return
But the MB's fx loops is pre-eq. So there is no input that bypasses the whole preamp/eq.

Does anyone know if the Markbass can be modded that way?

I already contacted Markbass via their website, but got no reply.
 
#2
You can switch it from series to parallel but not pre or post-EQ. But really, you should forget about the loop. As on all amps, the effects loop is not great, and effects always sound better in line, even the ones that should be in the loop. I know you didn't ask, and it's just my opinion, but it's right ;)
 
#5
I've responded on basschat, but for the sake of those here you could go DI out on amp 1 to FX return (in series) on amp 2.

Job done.

Not elegant, but it would be post eq if you set the DI switch that way.
 
#6
51m0n said:
I've responded on basschat, but for the sake of those here you could go DI out on amp 1 to FX return (in series) on amp 2.

Job done.

Not elegant, but it would be post eq if you set the DI switch that way.
Click to expand...

I have thought about that, too.
But the signal would pass the eq stage on the second amp as well. One more thing to worry about.
 
#8
On all the current MarkBass Amps IIRC, the FX loop is in front of the EQ and can not be moved. I would not mod the amp.

My question would be which second MB amp would you pair with it? This matters as some of them have different inputs.

What I would do I believe (given I have two MB Heads) is run the DI out of one set Post EQ, into the second amp's input. Then set the VLE/VPF's all the way down and the EQ controls Flat. Then you'd need to set the input level for no clipping and the output master for your desired volume level.

With the VLE/VPF's turned down and the EQ Flat, essentially you have the same as a direct into the power amp.

Also you could run an amp switcher or AB Box but if you are using passive Basses loading will occur unless your AB Box is buffered. Throwing a Boss TU-12 between them will unload the signal as it has a Buffer in it.

Another way if you would like to use each as a separate entity is use a Lehle P Split II. I have one I use for various situations (mostly in the studio). The Lehle has and A and B out with ground lift, phase reversal, and total isolation between A and B.

You could also add something like a QSC PLX 180 and use just the Power amp for power and run the DI from MB to the QSC. You could then daisy on out your QSC's second channel to still have a DI signal to run to FOH if needed. The QSC is 1800 watts and 13 pounds.

I know I posted way more than you asked for but what the heck. :)
 
#9
Red Planet said:
....

You could also add something like a QSC PLX 180 and use just the Power amp for power and run the DI from MB to the QSC. You could then daisy on out your QSC's second channel to still have a DI signal to run to FOH if needed. The QSC is 1800 watts and 13 pounds.

I know I posted way more than you asked for but what the heck. :)
Click to expand...

You are right in everything you write.

But I think using a separate (heavy) power amp defeats the purpose of using a lightweight head.

Best case scenario would be a MB head capable of driving a 2 ohms load.

The idea of using a splitter (I have a P-split, too) came to me.
But again, this makes eqing stage sound quite difficult, making adustments to 2 amps.

I think my idea is just too simple to have a solution that involves that much more gear or setup time.

My goal is quite simple: having "my SA450/GS112 sound" in a big 3x12" package without lugging a separate heavy amp.
 
#10
gillento said:
You are right in everything you write.

But I think using a separate (heavy) power amp defeats the purpose of using a lightweight head.

Best case scenario would be a MB head capable of driving a 2 ohms load.

The idea of using a splitter (I have a P-split, too) came to me.
But again, this makes EQing stage sound quite difficult, making adjustments to 2 amps.

I think my idea is just too simple to have a solution that involves that much more gear or setup time.

My goal is quite simple: having "my SA450/GS112 sound" in a big 3x12" package without lugging a separate heavy amp.
Click to expand...

I feel your pain. Aint nothin ever easy is it? There is always some restriction dang it.

Well some other options.

Have two of your 1x12 drivers re-coned to 16 ohms, then you would have a 4 ohm load with all three cabs running.

I can get 10's re-coned here locally for $55.00 each all day long.

Also using the P Split concept (I like that little bugger) you rack both amps in one rack, put Velcro on the P Split and mount it in the rack, and just have to set the amps.

Also you might look at using an LMIII since it has an XLR input. Run an XLR cable from DI of SA450 into XLR in of LMIII, set LMIII flat and use the SA450 to control the LMIII.

Also for keep the overall rig small and light consider using two F1's or one F1 and one F500.

For the ability to run actual two ohms look at the Genz Benz Shuttle Max 12.0, the Eden WT550, the Thunderfunks etc......

Even though the Genz 12.0 will not run 2 ohms mono-block, it will run a 4 ohm load and a 4 ohm load (one per side).

Just trying to help. :bassist:
 
#11
Red Planet said:
...

Also you might look at using an LMIII since it has an XLR input. Run an XLR cable from DI of SA450 into XLR in of LMIII, set LMIII flat and use the SA450 to control the LMIII.

Also for keep the overall rig small and light consider using two F1's or one F1 and one F500.

For the ability to run actual two ohms look at the Genz Benz Shuttle Max 12.0, the Eden WT550, the Thunderfunks etc......

Even though the Genz 12.0 will not run 2 ohms mono-block, it will run a 4 ohm load and a 4 ohm load (one per side).

Just trying to help. :bassist:
Click to expand...

Thanks for your suggestion.

Getting a "2ohms" amp was my first step.
I got myself a Mesa Fathom (M6). But I am not sure I like its sound as much as the SA450's. The Shuttle sound isn't my thing either.

I think it might come to your "SA450-XLR-into-LMIII" suggestion.
That is what I was thinking from the beginning. But I was hoping, modding a MB was an easy thing to do.

Now, if I could only get the MB people to reply to my emails!
 
#13
totallybacan said:
If the entire FX loop is before the EQ, then do the fx send and return it to the other head, and set the Eq's to be identical. or from the send go into the input
Click to expand...

Not a whole lot of difference in that and just going into the input on second amp. Also by doing this one can see if he is clipping the second amp. I just don't see the advantage in using the FX loop for this purpose.

I do not see why MarkBass does not offer a stand alone power amp. Dang they have a gazillion different versions of amps.

Perhaps there is another way to do this that I'm not thinking about? I do know someone who could mod the amp to have a power amp input but I would not recommend this. I would not let just any Joe do something like this.

With two LMIII's one could link the inputs using a custom made XLR cable and I think this would avoid loading on Passive Basses. You plug your Bass into the 1/4" input on one then go from one XLR input to the other XLR input effectively linking the inputs of both amps, though they would function separately.
I think the simplest way would be use the DI on one to run the other. You can set the DI for Post EQ, that way the first amp EQs the second amp.

I suppose you could also use the Tuner out on the first amp to go to the input on the second amp.
 
#15
Red Planet said:
...

I do not see why MarkBass does not offer a stand alone power amp. Dang they have a gazillion different versions of amps.

...
Click to expand...

That might be a sensation !!!!

Red Planet said:
It would be nice if MB gave us a choice of the FX loop being Pre/Post EQ which then one could directly access just the preamp or just the power amp of any unit.
Click to expand...

That is so true!!!!!!!!!!!
 
#19
Looking at the MB block diagrams, the FX loop is way in the front of the amp. Makes one wonder why they even bothered, as a lot of folks prefer their Time based FX to be after EQ. Though perhaps this arrangement works well with Distortion Pedals and such. Even the cream of the crop MB amps do not give you this choice.

Does appear one could tap into the signal just after the EQ at the DI Pre/Post switch but one would need to disconnect what is behind that at the same time as I believe you would pick up a lot of noise.

I'm sure a number of folks could easily mod these but the circuits are so tiny you wouldn't want your average Tube Amp Tech doing it.

I guess the question is, would this really make running two MB heads that much easier/simpler?

Hmmmm.
 

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