Which SS poweramp to drive a Marshall 1960A?

Brick_top

Brick_top

Power User
Hi there...

Any advice? I would like to have headrrom..

I've been looking at the Art Sla-2, Qsc GX-5 and GX-3

Wondering if these are underpowered for a 4x12

Thanks a lot
 
I have no experience with the other amps you listed, but the Art Sla-2 is more than adequate enough for a single 4x12.
 
Brick_top said:
Will it give me aproximately the power of a 100watt tube amp?
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My experience so far is that you want some serious headroom with a SS amp if you are looking for 100 watt tube head kind of volume. My 4x12's are 16 ohm, so I have been using SWR Power 750's that are rated for 450 at eight ohms, probably around 250-300 at 16 ohms, and that gets me in similar territory volume wise.

I have a Tech 21 PE-400 that should be showing up today - it is rated at 200 into 8, 150 into 16, so we'll see how that fairs.

With SS, I would look for something that can put roughly double your cabs power handling capacity at rated impedance to have adequate headroom if you are looking for serious volume. Any more than that, and you really have to be careful to not fry your speakers (their rating is for thermal, and does not account for max excursion, which is why you can make them fart out with much less than their rated power if you EQ in excessive lows).

JR
 
I'm driving two 4x12 cabs with my GX5, one is a 1960 cab... And if I crank the volume half way, it rattles the entire neighborhood!!!!!
 
Brick_top said:
Will it give me aproximately the power of a 100watt tube amp?
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The general rule of thumb is with SS power you need 5 times the power rating to achive the (head room) of a 100 watt tube head. So going by that rule you would want to use 500 wats of power. The SLA-2 Bridged would give you this. The GX series amps are not bridgable so the GX5 would be the better choise with the QSC
 
Sixstring said:
Brick_top said:
Will it give me aproximately the power of a 100watt tube amp?
Click to expand...

The general rule of thumb is with SS power you need 5 times the power rating to achive the (head room) of a 100 watt tube head. So going by that rule you would want to use 500 wats of power. The SLA-2 Bridged would give you this. The GX series amps are not bridgable so the GX5 would be the better choise with the QSC
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You generally hear about this more in the bass guitar community, where folks are much much more power hungry. When comparing tube to SS power, the rule of thumb is generally 2-3X the SS power for comparable performance to a tube head. So you go with 600-900 watts of SS to get the same oomph of your SVT, depending on the quality of your power amp. That said, the general rule of thumb for matching your head to your cab (in terms of power handling) is 1.5 - 2X your cab's power handling. I wouldn't go to 5X even on bass, and especially not with guitar speakers - you really run the risk of smoking your speakers.

JR
 
So if for example I buy a QSC GX3 which is rated for:

2x 500W/4ohm, 2x 350W/8ohm

And since my cab is 4ohm/16ohm - mono or 8ohm - Stereo

I would probably have enough power right?
 
Taken from QSC's website:

The GX Series amplifiers were designed to power sound reinforcement loudspeakers most commonly used by entertainers, musicians and DJs use. If you don't see your loudspeakers in the list, check the Program (or Music) Power Rating (usually found on the loudspeaker manufacturer's website) and refer to the chart below: If the manufacturer doesn't provide a Program Power Rating, multiply the Continuous (or RMS) Power Rating by two.

Your Speaker's Program Power Rating

Model
GX3 For 8 ohm speakers: 250 W - 350 W
GX5 For 8 ohm speakers: 400 W - 600 W
GX3 For 4 ohm speakers: 350 W - 500 W
GX5 For 4 ohm speakers: 550 W - 900 W

If you're using...
loudspeakers with a higher power capacity
or more than two 8 ohm loudspeaker per amp channel
or more than one 4 ohm loudspeaker per channel
...you should consider the RMX Series or PLX2 Series professional power amplifiers.
 
Brick_top said:
So if for example I buy a QSC GX3 which is rated for:

2x 500W/4ohm, 2x 350W/8ohm

And since my cab is 4ohm/16ohm - mono or 8ohm - Stereo

I would probably have enough power right?
Click to expand...


Yes
 
Brick_top said:
what about sound quality and noise?

Which is better ART Sla-2 or QSC GX3?
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They are both pretty flat and sound good. The ART will have more headroom when bridged. Some have mentioned a hum with the ART while idle and someone had posted a simple fix for it. I never noticed it when I had mine. If your going to go with the QSC I would run with the GX5 just for the headroom.
 
I use a ART SLA2 into my 1960A, and it can go as loud as my 6505+ (120 watt) head does at show volume in a loud rock band setting, with a small bit of headroom left to spare.
 
Fat Albert said:
I use a ART SLA2 into my 1960A, and it can go as loud as my 6505+ (120 watt) head does at show volume in a loud rock band setting, with a small bit of headroom left to spare.
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Would that be in bridged mode?
 
I ran my SLA-2 in stereo using two 16 ohm 412's and I had no issues keeping up with the drummer that hit fairly hard. Problem is your ripping the heads off of the people that are directly in front of your cabs. When ever I could I would cross fire the cabs on stage and point them directly at the drummer :twisted: :twisted: . Then the long awaited "can you please turn it down" would be uttered by the stick slinging man and my reply would be hit softer.

An SLA-2 in bridged mode into your 1960 cab will be plenty... trust me.
 
Brick_top said:
[quote="Fat Albert":2wwfz47b]I use a ART SLA2 into my 1960A, and it can go as loud as my 6505+ (120 watt) head does at show volume in a loud rock band setting, with a small bit of headroom left to spare.
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Would that be in bridged mode?[/quote:2wwfz47b]

Yes. :)
 
Sixstring said:
An SLA-2 in bridged mode into your 1960 cab will be plenty... trust me.
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Do keep in mind that this amp cannot run bridged into a 4 ohm load, so the cab would need to be set for 16 ohm mono. In which case, it will get exactly as much power as when running the amp in stereo with the cab in 8 ohm stereo mode. So bridged mode alone doesn't offer any power advantage in this case, the only advantage would be plugging in one speaker cable vs two. Personally I would run it in stereo to get some spread in the FX, even if you run mono to FOH.
 
tubetonez said:
Sixstring said:
An SLA-2 in bridged mode into your 1960 cab will be plenty... trust me.
Click to expand...

Do keep in mind that this amp cannot run bridged into a 4 ohm load, so the cab would need to be set for 16 ohm mono. In which case, it will get exactly as much power as when running the amp in stereo with the cab in 8 ohm stereo mode. So bridged mode alone doesn't offer any power advantage in this case, the only advantage would be plugging in one speaker cable vs two. Personally I would run it in stereo to get some spread in the FX, even if you run mono to FOH.
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Actually the manuel says the amp is stable into loads as low as 2 ohms stereo and 4 ohms mono bridged. For how long it can do that... who knows. My guess it would hold it's own if not pushed to the max.
 
I just went through this myself - ended up swapping my Mesa 2:90 with an ART SLA-2. For what it's worth I can tell you that, in my situation, 5x the wattage would have been way more than I needed. I run my cab in stereo, which makes it 4 ohm per channel. According to specs, the SLA-2 puts out exactly 3 times the wattage at 4 ohm as my 2:90. During the last week's rehearsals I've had my power amp volume at about the same spot as it was before - about 60%. Our other guitarist plays through a Mesa Mark IV (master vol on ~7) and I've had no trouble keeping up with him. I've even been asked to turn down a few times. ;)
 
Call me stupid but I need confirmation on something from this image

851899800.jpg


Does this mean:

Mono operation

Left input = 4ohm
Right input = 16ohm

Stereo Operation

Left input = 8ohm
Right Input = 8ohm

?
 
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