GBE1200 Power Ratings...

[tombowlus]

This is where I have a problem... I can guarantee that the AC input terminal will vary as a function of current draw which is a function of output power. A large amp with high current capacity and an oversized power supply will cause the AC line voltage to sag more on an inadequate AC supply and this will directly (and greatly) affect the measured power output. The larger the amp. the greater this decrepency will be.

Additionally, on a lower feedback power amplifier with tube amp like characteristics, knowing when the power amp actually clips required knowing what exactly is happening as this takes place. There are ways to determine this but a casual glance may be very incorrect.

Regarding output power versus frequency, again the actual maximum output power was not used but instead the response was referenced to some arbitrary point and any preamp voicing (in our case an intentional rolloff) was subtracted from the reference point. This is no different than a frequency response plot of the preamp itself.

I hope to discuss this more with Tom so that everyone may benefit from a more uniform and useful technical testing platform.

Good points, Andy.

We use a good - albeit unregulated - power line because we felt that this is what a player is more likely to encounter in the real world. I do need to look into the actual voltage monitoring, though, and will report back.

In addition, if we would have tested the output section, only, we would have had much more output on the 'B-string' test, no doubt. But, in an effort to try and reflect actual usage to the extent possible, we felt that it would be more indicative of real-world usage to use a signal passing from the instrument input, through the preamp section (with the EQ controls set as flat as possible) and then into the output section for our rated power measurements.

Again, there are multiple viable methods of testing. We have tried to be clear about ours, but we definitely recognize the validity of other testing methods, and the guys at Genz-Benz certainly know their stuff.

Tom.

 

[Eublet]

My point being that I think BGM bench test all their stuff at the same place, with the same methodology.

The makes a level felid for all, at least if I'm understanding the procedure correctly.

Not necessarily. Think about what agedhorse is saying. If a larger more powerful amplifier causes any inherent flaw in the testing system to become magnified by an exponential factor, then the test results become skewed by an exponential factor. Whether or not that happened is different, but the argument is completely valid, and doesn't make for a level playing field at all if it occurred.

 

[Chef]

Would the draw of the GBE1200 not make the unregulated power at a night club or studio sag the same way?

 

[Lia_G]

One note: testing Genz amps with eq set flat will never work, imho. They aren't at their best when set flat, and most users here seem to post that they boost the bass and low mids: so testing the GBE1200 with all eq knobs set at noon is actually counter to your intention of duplicating real-world playing ... most do not use a Genz amp with the eq knobs at noon.

How about running the preamp into an RTA software package (like FDeck's very cool free RTA software) and set the preamp to truly produce as close to a flat curve as possible, and then do the output power tests with those preamp settings?

Cheers,
Liam

 

[vision]

We use a good - albeit unregulated - power line because we felt that this is what a player is more likely to encounter in the real world. I do need to look into the actual voltage monitoring, though, and will report back.

In addition, if we would have tested the output section, only, we would have had much more output on the 'B-string' test, no doubt. But, in an effort to try and reflect actual usage to the extent possible, we felt that it would be more indicative of real-world usage to use a signal passing from the instrument input, through the preamp section (with the EQ controls set as flat as possible) and then into the output section for our rated power measurements.

Again, there are multiple viable methods of testing. We have tried to be clear about ours, but we definitely recognize the validity of other testing methods, and the guys at Genz-Benz certainly know their stuff.

This makes good sense to me.

 

[Frankie Fender]

Would the draw of the GBE1200 not make the unregulated power at a night club or studio sag the same way?

Exactly . I get your point and agree. Real world application is what you are talking about.

However I do agree that the GBE1200 is a monster compared to most amps I have played. Then again I was totally floored by a 300 watt vintage SVT so go figure.

 

[Fretlessboy]

It beautiful...did it come with amanual?

I don't think any amplifier will help me with my playing skills
but my new bass was a great place to start

 

[Passinwind]

Would the draw of the GBE1200 not make the unregulated power at a night club or studio sag the same way?

Not really, unless you're playing a sine wave generator.

 

[Fretlessboy]

I think the key for getting the most out of any GB gear is how you set up your gain structures.. set wrong you can end up clipping it al low volumes...set right it is a beast indeed.

 

[vision]

One note: testing Genz amps with eq set flat will never work, imho. They aren't at their best when set flat, and most users here seem to post that they boost the bass and low mids: so testing the GBE1200 with all eq knobs set at noon is actually counter to your intention of duplicating real-world playing ... most do not use a Genz amp with the eq knobs at noon.

I think that the overall point of the testing is to have all things equal so that different amps will be tested under the same conditions. Adding EQ to an amp because most users run it that way isn't helpful when trying to create a fair testing enviornment accross the board for different amps. If an amp is shy in the mids, it doesn't make sense to boost the mids when testing to try to have a "flat" response - IMO, that defeats the point of the test.

 

[Chef]

ok then
See, I warned y'all I was no EE type...

Not really, unless you're playing a sine wave generator.

 

[Fretlessboy]

Let me also say that I do appreciate the test in a lab... but live is really where the geat equalizer to any gear is. It either works for you it doesn't

 

[Eublet]

If you're going to allow for sag in your test, then you have to control the conditions that allow it and include that as a value. Otherwise the talk about how a potential sag could have affected the test of two units is worthless..

 

[KsPiNeSh]

I think that the overall point of the testing is to have all things equal so that different amps will be tested under the same conditions. Adding EQ to an amp because most users run it that way isn't helpful when trying to create a fair testing enviornment accross the board for different amps. If an amp is shy in the mids, it doesn't make sense to boost the mids when testing to try to have a "flat" response - IMO, that defeats the point of the test.

Wouldn't EQ'ing an amp to flat on the scope provide a solid frame of reference/basis of comparison? As it is, different amplifiers are voiced differently with their respective EQ's flat (duh), resulting in a non-flat scope response. Say, if one amp had a naturally voiced bump at the test frequency, would it not inherently put out more power than an amp naturally voiced lower at that frequency? I hope that made sense .

I think the thing that really surprised me was the fact that the amp went into thermal protection in the half-power-half-an-hour test. To echo the others that have mentioned this about their GBE-1200's, I have played it wide-open in 100 degree heat for well over an hour on multiple occasions without incident. The fact that the Bass Gear guys experienced any issue with that makes me wonder about that particular unit.

On a slightly related note, I also love my 1200. All of my Genz Benz equipment, of which I have/have had plenty, has performed admirably and beyond expectations. My old GBE-400 / LS-410T pairing carried 300 person venues on its own with no PA. Whatever Genz is doing, however they're doing it, they're doing it very well.

 

[Vic]

a note to the moderators of TB- I sincerely hope I haven't infringed upon the CUP. I apologize if I've done so. Please feel free to edit if necessary.

I've tried to be as informative and fair as possible without positioning GB.

IMHO, you've been very much so, and I sure as heck hope your posts are left intact! There's too much good information in them!!

In the end, we knew it would come out here so, we weren't ducking it.

That, my friend, would be something I'd NEVER expect from you guys!

A big +1 to GB for their dedication to their profession by giving a thoughtful reply even while out on vacation!...

+1!!!

 

[Vic]

On the whole EQ thing, I think the reason not to boost or cut anything in the preamp is simply to keep the test case digestible. Once you start throwing all those variables in, it makes it even harder to make any potentially valuable conclusions. IMHO.

 

[bassman blue]

I do wish they would have had a chance to discuss methodology with the guys at Genz Benz before they did the testing (by no one in particulars fault...just timing)...this entire debate may have been avioded...

Ditto here... I've been following this thread and have considered jumping in earlier. The Genz GBE1200 is what it is... a great amp and the guys at Genz are the also the best in the industry. That in itself will always put you in the middle of controversy. I think most people who have played the Genz 1200 GBE would have been curious to have investigated the validity of these numbers further...

 

[Eublet]

I think the thing that really surprised me was the fact that the amp went into thermal protection in the half-power-half-an-hour test. To echo the others that have mentioned this about their GBE-1200's, I have played it wide-open in 100 degree heat for well over an hour on multiple occasions without incident. The fact that the Bass Gear guys experienced any issue with that makes me wonder about that particular unit.

BINGO! For those of us with gobs of experience, it causes the whole rest of the results to become questionable just based on this one piece. I'm willing to accept that the feeling of "power" I have gotten from using this head is subjective, but heat issues are easy. They exist or they don't. It's hot or it isn't. It's shutoff or it hasn't. This one just doesn't make any sense, and could be related to the rest of the numbers seeming so off.

Those of you who've only taste-tested the GBE might not be getting what some of us are saying. Imagine if the LMII had turned up numbers of 211 watts at 4 ohms. You'd think, "NO FREAKIN' WAY." Imagine if it had also had a couple of thermal shutdowns at that power. You'd be doubly perplexed because of how intimate you are with the performance of the head. That's where we 1200 users are right now. Totally perplexed.

 

[Eublet]

On the whole EQ thing, I think the reason not to boost or cut anything in the preamp is simply to keep the test case digestible. Once you start throwing all those variables in, it makes it even harder to make any potentially valuable conclusions. IMHO.

Agreed, and I'm glad that at least in the case of the 1200 they posted the curve of the PRE versus the power section. One thing that might be nice to see for all heads is a listing of the EQ settings that can be used to make the head as flat as possible since most heads aren't flat at all. At least that way the readers would have something to try on their own and see what happens.

And maybe it would be better to run the sine wave through the power section only, which of course would be problematic for heads like the LMII where you can't do that.

Which brings us back to point number 1 that Tom has been making, which is that no single standardized test is going to work well for all heads.

 

[bassman blue]

That's where we 1200 users are right now. Totally perplexed.

Haha... can we get BG Mag in print? I can think of some useful applications for it... Seriously, like Eublet says, something is not right here. It should have been pretty obvious.