GBE1200 Power Ratings...

[agedhorse]

It's not just one harmonic that's generated, but a weighted distributed series. The series varies somewhat with both frequency and amplutude of the signal as it begins to overdrive. This is one componenet of how a tube amp overdrives as well.

 

[seamonkey]

It's not just one harmonic that's generated, but a weighted distributed series. The series varies somewhat with both frequency and amplutude of the signal as it begins to overdrive. This is one componenet of how a tube amp overdrives as well.

I knew a lot of analysis and engineering went into this. And this is one of the areas not counted in the tests.

 

[tallboybass]

I knew a lot of analysis and engineering went into this. And this is one of the areas not counted in the tests.

Yeah, I guess this is part of the 'GB sound'? I know the additional harmonic content vs. 'other' brands is welcome IMO.

 

[60bass]

is the unique type of limiting circuitry that Genz Benz uses that adds in the tube-type distortion elements when the limiter kicks in.

I've used umpteen amps over 30 years and can tell you that the limiter on the 1200 is an essential part of why these amps sound so good (IMHO). Without exception, I've switched off the limiters on every other amp I've used that had them. They always seemed to clamp too much output and choke off dynamics.

The limiter on the 1200 is very musical sounding and actually seems to increase the amps punch and dynamics (again IMHO). I once turned it off at a very loud practice session and after a couple of songs, the drummer asked me what was wrong with my amp. I said what do you mean? He responded that he felt like the punch went away. I turned it back on and all was well. I don't know exactly how the GB limiter circuit is implemented in the 1200 and probably wouldn't understand the technical stuff anyway. I do know that it works and it works well. A description in layman's terms might work for me though.

Even on the rare occation when I've actually driven it hard and seen the clip light come on, the amp has remained very musical and has none of the raspy distortion we all know and hate so well when a SS amp is pushed really hard. I believe the limiter circuit is the big reason for this. It lets the amp respond in a very straight forward and dynamic way. You never feel as if the amp is being pushed to the limit so to speak. Sure, I can make it crap out big time if I want to, but you can do that to any amp. In normal use, this is a hard amp to beat.

For those of you that have never played the 1200, it's hard to describe without playing one. It's almost like the harder you push it, the more it responds.

Since the limiter is such an essential part of this amps design, it probably should be used when any testing is done on the amp.

 

[agedhorse]

I've used umpteen amps over 30 years and can tell you that the limiter on the 1200 is an essential part of why these amps sound so good (IMHO). Without exception, I've switched off the limiters on every other amp I've used that had them. They always seemed to clamp too much output and choke off dynamics.

The limiter on the 1200 is very musical sounding and actually seems to increase the amps punch and dynamics (again IMHO). I once turned it off at a very loud practice session and after a couple of songs, the drummer asked me what was wrong with my amp. I said what do you mean? He responded that he felt like the punch went away. I turned it back on and all was well. I don't know exactly how the GB limiter circuit is implemented in the 1200 and probably wouldn't understand the technical stuff anyway. I do know that it works and it works well. A description in layman's terms might work for me though.

Even on the rare occation when I've actually driven it hard and seen the clip light come on, the amp has remained very musical and has none of the raspy distortion we all know and hate so well when a SS amp is pushed really hard. I believe the limiter circuit is the big reason for this. It lets the amp respond in a very straight forward and dynamic way. You never feel as if the amp is being pushed to the limit so to speak. Sure, I can make it crap out big time if I want to, but you can do that to any amp. In normal use, this is a hard amp to beat.

For those of you that have never played the 1200, it's hard to describe without playing one. It's almost like the harder you push it, the more it responds.

Since the limiter is such an essential part of this amps design, it probably should be used when any testing is done on the amp.

Yes, you understand exactly what I was trying to convey when describing why the limiter must be in for full power testing.

In a brief description of how a (conventional) limiter works, when the signal crosses a preset threshold (like the clip threshold of the power amp), a control circuit detects this and depending on the attack, hold, and release time constants used, plus any frequency weighting and averaging of the peaks versus detecting the peaks, the GAIN of the amplifier is reduced for a period of time, thus eliminating clipping. The problem with a bass signal is that the necessary time constants vary across the spectrum and as you move around quickly the signal can pump if the time constants are too fast or can audibly turn down if they are too slow. In many instances, for a simpler limiter, there is no happy medum. Our limiter does not worry about trying to second guess a gain reduction equation but looks specifically at what is happening during the overload process and manages the signal in a way similar to how a tube output stage overloads. So, as the signal approaches clipping the drive signal gradually becomes less efficient at driving the power amp's output stage, gently enters a soft clipping period and when driven harder, enters a more stiff cliping until the power amp actually clips. Since the power amp is a (relatively) low feedback design (also like a tube power amp), it's behavour is very graceful when it does finally clip. All of this happens over a 6dB range.

So to put it in a nutshell, it's not a traditional limiter but it acts like one in that the natural compression/limiting of this circuit emulates quite nicely a tube output stage. Sometimes you have to go back and make sure that the solution (conventional limiting) isn't worse than the original problem. In this case, MY opinion is that it's a more useable, playable solution even if it looks numerically "wrong" by conventional standards.

For example, nobody seems to worry that a 400 watt tube amp isn't going to be loud enough... and it's because of all of the things I have been mentioning in this thread. Power by itself is just power, but there are more effective ways to harness it to deliver better results.

 

[60bass]

Yes, you understand exactly what I was trying to convey when describing why the limiter must be in for full power testing.

In a brief description of how a (conventional) limiter works, when the signal crosses a preset threshold (like the clip threshold of the power amp), a control circuit detects this and depending on the attack, hold, and release time constants used, plus any frequency weighting and averaging of the peaks versus detecting the peaks, the GAIN of the amplifier is reduced for a period of time, thus eliminating clipping. The problem with a bass signal is that the necessary time constants vary across the spectrum and as you move around quickly the signal can pump if the time constants are too fast or can audibly turn down if they are too slow. In many instances, for a simpler limiter, there is no happy medum. Our limiter does not worry about trying to second guess a gain reduction equation but looks specifically at what is happening during the overload process and manages the signal in a way similar to how a tube output stage overloads. So, as the signal approaches clipping the drive signal gradually becomes less efficient at driving the power amp's output stage, gently enters a soft clipping period and when driven harder, enters a more stiff cliping until the power amp actually clips. Since the power amp is a (relatively) low feedback design (also like a tube power amp), it's behavour is very graceful when it does finally clip. All of this happens over a 6dB range.

So to put it in a nutshell, it's not a traditional limiter but it acts like one in that the natural compression/limiting of this circuit emulates quite nicely a tube output stage. Sometimes you have to go back and make sure that the solution (conventional limiting) isn't worse than the original problem. In this case, MY opinion is that it's a more useable, playable solution even if it looks numerically "wrong" by conventional standards.

Thanks, you put it nicely so even a layman like myself can understand what is going on in the amps limiter circuit.

For example, nobody seems to worry that a 400 watt tube amp isn't going to be loud enough... and it's because of all of the things I have been mentioning in this thread. Power by itself is just power, but there are more effective ways to harness it to deliver better results.

Just ask any SVT user, the thing is only 300 watts but you'd never know to hear or play through one.

 

[KJung]

Just ask any SVT user, the thing is only 300 watts but you'd never know to hear or play through one.

Separate topic, but remember that when SVT's get really loud, they also get quite dirty. Those 300 watts driven into distortion can be very loud. However, if you are into a totally clean, accurate tone, not so much

 

[tombowlus]

Separate topic, but remember that when SVT's get really loud, they also get quite dirty. Those 300 watts driven into distortion can be very loud. However, if you are into a totally clean, accurate tone, not so much

I think Andy's point, in part, is that tube amps get so loud by introducing some 'distortion' (added even-order harmonics, etc.), and that a similar technique is used in their 'Output Limiter' (which might be more accurately described as a 'tube emulator circuit' or something).

Tom.

 

[KJung]

I think Andy's point, in part, is that tube amps get so loud by introducing some 'distortion' (added even-order harmonics, etc.), and that a similar technique is used in their 'Output Limiter' (which might be more accurately described as a 'tube emulator circuit' or something).

Tom.

+1... I wasn't really commenting on the 1200 any more, just the SVT example, which IMO was not a good one.

 

[tallboybass]

So, as the signal approaches clipping the drive signal gradually becomes less efficient at driving the power amp's output stage, gently enters a soft clipping period and when driven harder, enters a more stiff cliping until the power amp actually clips. Since the power amp is a (relatively) low feedback design (also like a tube power amp), it's behavour is very graceful when it does finally clip. All of this happens over a 6dB range.

So does this mean that on my Shuttle 6.0, when the output limiter light comes on it's at 150 watts? (600w - 6db = 150w)

 

[alexclaber]

So does this mean that on my Shuttle 6.0, when the output limiter light comes on it's at 150 watts? (600w - 6db = 150w)

That's certainly my understanding of it.

Alex

 

[tallboybass]

That could explain why some of us (myself included) feel like it's a bit weak for a 600 watter. When I see the red light I figure it's done, but maybe it's "preparing" to clip.

 

[60bass]

That could explain why some of us (myself included) feel like it's a bit weak for a 600 watter. When I see the red light I figure it's done, but maybe it's "preparing" to clip.

When I first got the 1200, I got all paranoid when I saw that red light come on and started to turn down the amp. After using the 1200 for awhile I started to see that even though the red light was coming on every now and then, the amp still sounded really tight.

It was mostly just blinking on when I would get on the low E pretty heavy. It never stays on for more than a brief moment. I've never had it stay on continously so I can't comment on that. I might be wrong on this, but I tend to see the clip light on my 1200 as more of an indication that the amp is delivering more power to cover a demand placed on it rather than actually clipping as the amp stills sounds loud and punchy even when the red light is blinking somewhat.

 

[Lia_G]

Any GB owners really should, imho, study how the limiting circuitry works, as described in several places here on the board by Andy et al. It's very different from any other SS amps, imho, and approaching it with the mindset of "red light means turn down immediately" severely hamstrings these heads.

Cheers,
Liam

 

[Eublet]

Liam's got it right, and it has come up in several threads here. The flashing light doesn't mean your clipping the unit. It means that the "magic mojo" is starting to kick in, and you have plenty of room left. Whether or not you like the tone of that "mojo" is subjective. It is not on the order of SVT distortion whatsoever. Most ears wouldn't hear a thing. When you really start to push it, it does get louder, much louder, but it does emulate the feel of a tube head, without necessarily sounding like one (the overdrive). While this is defeatable on the GBE heads so that you can push them without this effect (and the volume differences aren't really noticable at all), the limiter is always on with the Shuttle 6.0. I think that's why some love the Shuttle and others prefer the LMII for example. If you like a tube feel, the Shuttle gives it much more so than the LMII, especially as you drive the thing harder. It's a musical feel that is imparted by that technology. The LMII on the other hand, with my limited use of one so far, is much different. It goes and goes until you start noticing a bit of compression on the low end, and then it just reaches the end and you know you need to turn down because of the distorted bottom end. The LMII is cool because you get the same feel throughout the amps useful power. The Shuttle is cool because you get to really open things up like a tube head as you push it. That's why I keep saying these two heads don't really compete in many ways. They react differently to your playing style and volume needs.

Example. I really like the Shuttle on top of a 112. The volume isn't as loud, but you could really push the head hard and get a cool feel happening. The same was true of the Neo-pak. The smaller 8 ohm 112 lets me get all this happening at much lowever sound pressure levels than if I connect a 212. At that point, the gig better be really loud to get the same feel.

Better or worse? Neither. Just different. The 1200 let's you have a both by turning the limiter on or off. Again, it really doesn't affect useable volume by turning it off. It will prevent you from getting the same feel out of the head as you approach the limit.

And Andy can correct me if I'm wrong, but I believe turning off the limiter only affects the "soft limiting" circuitry he's still talking about. There's still a brick wall limiter of sorts that is not defeatable and will kick in if ultimately needed.

 

[wave rider]

Any GB owners really should, imho, study how the limiting circuitry works, as described in several places here on the board by Andy et al. It's very different from any other SS amps, imho, and approaching it with the mindset of "red light means turn down immediately" severely hamstrings these heads.

Cheers,
Liam

Perhaps if the clipping light started out yellow then shifted to red, there would be less confusion.

Most are familiar with the adage "If it's yellow, it's mellow..."

=wr=

 

[Eublet]

Perhaps if the clipping light started out yellow then shifted to red, there would be less confusion.

Most are familiar with the adage "If it's yellow, it's mellow..."

=wr=

Yeah, I agree it would help. Even better to me is that it shouldn't come on until it's really time to turn down. I even found myself watching the lights too much instead of using my ears, not because I was worried, but just because I was wondering if I was hitting that "mojo" stage yet. I got over it after a while, but as a newbie Genz user it was too tempting to stare at the head and see what it was doing!

 

[KJung]

Yeah, I agree it would help. Even better to me is that it shouldn't come on until it's really time to turn down. I even found myself watching the lights too much instead of using my ears, not because I was worried, but just because I was wondering if I was hitting that "mojo" stage yet. I got over it after a while, but as a newbie Genz user it was too tempting to stare at the head and see what it was doing!

The Glock Heart Rock and Soul have a similar thing at the input stage. The pre's in those two particular Glocks are designed to 'give a bit' and emulate a tube pre when pushed. Originally, they had a red 'clip' light that came on when you were barely pushing the pre. It was a similar thing. It was designed to tell you that the pre was going into some sort of 'limiting/emulation' mode that would warm up the tone versus a 'nasty clip-turn it down' sort of thing.

You know me I emailed back and forth with their design engineer a few times (as I assume others did also), and now, I believe they have some sort of 'multi colored LED' that goes from green to yellow to orange to red, or something like that, which is more in keeping with the idea of 'limiting/warm but not clipping in a bad way'.

Also, +1 totally on your description of how the 6.0 versus F1/LMII behave as you crank them up.... exactly right given my experience.

 

[tallboybass]

Yeah, I agree it would help. Even better to me is that it shouldn't come on until it's really time to turn down. I even found myself watching the lights too much instead of using my ears, not because I was worried, but just because I was wondering if I was hitting that "mojo" stage yet. I got over it after a while, but as a newbie Genz user it was too tempting to stare at the head and see what it was doing!

Yes, it IS too tempting to get "hypMOtized" by the flashing lights. They've already got you with the blue ones, the red is just icing.

Now that I think back, I have already learned how this limiter works....and maybe because of old age, forgotten it. It's still alarming to look back in mid-gig and see RED!

Alan

 

[tallboybass]

The LMII on the other hand, with my limited use of one so far, is much different. It goes and goes until you start noticing a bit of compression on the low end, and then it just reaches the end and you know you need to turn down because of the distorted bottom end.

This reminds me of a max volume test I did with the SD800. I slowly cranked it up until it just hit a limiter, it never distorted. I guess MB was thinking it would blow some stuff up if they allowed this monster amp to go into clipping! I actually prefer this method of limiting. You could put everything on 10 and it would never distort, just render you deaf!! (huh?)