GBE1200 Power Ratings...

[svtb15]

I got the new Magazine today and read through many of the articles.
I have to say that I really like it allot!
The ads are very well done and very tasteful. Great layout!
And the equipment reviews are very well done and far better than Bass Player magazine with much more in depth reporting than Bass Player mag too. There may be a few things that I would do differently but it is very pro looking and I wish great success to the publishers. And the iPaper is very cool! I have never seen that before and very useful..

But while reading the GBE1200 article I noticed something. And that one little thing may be the reason they got the numbers that they did. As well as the thermal condition which I have not experienced while I running my amp very hard in horrible conditions.

I was looking at the published output into the 8 ohm and 4 ohm loads that were published and then the 2 ohm load. And the numbers do not make sense to me.

The reading they got into the 8 and 4 ohm seems rather low.

For folks that don’t know, the Genz Benz GBE series has a rocker switch on the rear of the amp that optimizes something in the power supply so it can easily do the 2 ohm load.Its called the Powerflex switch.

It says to engage to one side for 2 ohm operation or flip it to the other side for 8 and 4 ohm operation. .

Agedhorse correct me if I am wrong…

But if I am correct, and if the user has the Powerflex switch in the 2 ohm position, while operating a 4 or 8 ohm load, you will get less power into those higher loads.
It will basically become the power output of a GBE750, roughly,, give or take.

The amps power output will be lowered.
That reviewer/users error may be why they got the readings that they did.
The reviewer was NOT be lying, but just collecting wrong data for having the switch in the wrong position for the duty cycle.
I was not there so I don’t know, but that is the only thing that I can think of that may cause that.

And on the other hand, if the switch is reversed, and being in the 8 - 4 ohm setting while operating a 2 ohm load, It may cause lower power output, and may cause the amp to thermal as the reviewer claimed..

I remember reading something in the article where the reviewer said it was “complicated to review” Page 71- because of all of the features.
And I was wondering if he meant the POWERFLEX switch that I am calling attention to here. The switch is on the rear of the amp.

Because if that switch is in the wrong position I believe it will give you what they state.
I am only speculating here since I really don’t know why they got such low readings, since my GBE1200 can easily keeping up with my crown amp, and it never did a thermal even under extreme conditions on maybe 250 gigs.

Another thing I read on page 71 was where he stated the heat sink got very hot, but he was "impressed" at how the transformer "remained very cool and stable".

Again I was not there to inspect the procedure.
But the only way to feel if the transformer was cool would be :
#1 to have thermal sensors placed on the transformer or
#2 to touch it with your hands..

Either #1 or #2 can be done with the top cover of the amp removed.

#1 can be done with thermal sensors adhered and the wires run through a channel and the cover replaced.
When I worked for the federal Government doing aerospace electrical inspection in the early 1980s before my music career… that is how we would do it.
We would Run the device with the cover on, and the thermal sensors running through a special channel to exit the chassis to the measuring device.
#2 can only be done with the cover of the amp removed. If the cover of the amp was removed, then that may be the reason the amp went into thermal shutdown.

I say that because the amps cooling is by forced air.
The air must be pulled in through the amps side by the fan, then circulate the cool air through the internal chassis and allow it to exit by passing over the heat sink and out the rear of the amp ….thus cooling the amp.

If it were #2 there would be no seal to allow forced air cooling since the cover was off. No seal would equal no cooling taking place since no air would circulate through the amp and over the heat sink, thus allowing thermal buildup, the heat will not dissipate and the amp will thermal if it is run for extended periods of time.
Almost any amp will do that if you stopped the air circulation. Unless the amps chassis itself is the heat sink of which I can only think of one amp that does that.

Is it possible that the reviewer had the Powerflex switch in the wrong position? And the cover off? After all he did say that it was complicated to review...

There must be some error in the test that caused thermal shutdown as it said in the article.
Once again I recently ran my amp at an outdoor show into 2 ohms very loud with ambient air in Austin Texas at about 105 degrees and the amp did Not thermal…

Just wondering.. And if I am wrong I am hopeful that Agedhorse will correct me or even Tom Bowlus.

Again, I am only asking questions to find how they got what they did..
Thanks

 

[tombowlus]

Thank you for the kind words!

The PowerFlex technology is, indeed, very cool. I wish more amp manufacturer's would use this type of a design (the Mesa/Boogie M6 Carbine we reviewed has a similar setup).

However, I can confirm that the switch was in the 4/8-ohm position for the 4/8-ohm tests, and in the 2-ohm setting for the 2-ohm tests.

I can also confirm that the thermal testing was done with the top on.

Tom.

 

[Mark Reccord]

There must be some error in the test that caused thermal shutdown as it said in the article.
Once again I recently ran my amp at an outdoor show into 2 ohms very loud with ambient air in Austin Texas at about 105 degrees and the amp did Not thermal…

Again, that's actually nowhere near as tough a test as 1/2 power sine wave test for 30 minutes straight. There is literally almost 0 possibility of being able to achieve that operating condition under any real world circumstance. Even if you were clipping on just about every note, the average power delivered would still be in the range of 1/4 power or less. Especially when you factor in rests and breaks between songs where the amp isn't producing any output power.

Like I said before, thermalling out under this particular test is not an indicator that there's something wrong with the amp. I'd guess that most amps will thermal out under this test. Class D amps, maybe not, because they're so much more efficient than Class AB ones.

EDIT: You should see what happens when amps don't have thermal protection.... I must say that I enjoy destructive testing.

 

[tombowlus]

Again, that's actually nowhere near as tough a test as 1/2 power sine wave test for 30 minutes straight. There is literally almost 0 possibility of being able to achieve that operating condition under any real world circumstance. Even if you were clipping on just about every note, the average power delivered would still be in the range of 1/4 power or less. Especially when you factor in rests and breaks between songs where the amp isn't producing any output power.

Like I said before, thermalling out under this particular test is not an indicator that there's something wrong with the amp. I'd guess that most amps will thermal out under this test. Class D amps, maybe not, because they're so much more efficient than Class AB ones.

Agreed. And to be honest, we viewed it as a positive feature that when pushed this hard, the GBE 1200 did properly engage the thermal protection circuit, shut down without damage, and then recovered quickly. This ability to safely handle a thermal situation will keep your amp out of the shop and on the road, and we were glad to see it recover so well, with no damage (and not even any need for user input).

Tom.

 

[svtb15]

thank you for answering my questions promptly..

Thank you for the kind words!

The PowerFlex technology is, indeed, very cool. I wish more amp manufacturer's would use this type of a design (the Mesa/Boogie M6 Carbine we reviewed has a similar setup).

However, I can confirm that the switch was in the 4/8-ohm position for the 4/8-ohm tests, and in the 2-ohm setting for the 2-ohm tests.

I can also confirm that the thermal testing was done with the top on.

Tom.

 

[svtb15]

EDIT: You should see what happens when amps don't have thermal protection.... I must say that I enjoy destructive testing.

I dont think the thunderfunk has thermal protection.. I want pictures of that one going thermal ... I love to see burnt up ****!!

 

[Vic]

Agreed. And to be honest, we viewed it as a positive feature that when pushed this hard, the GBE 1200 did properly engage the thermal protection circuit, shut down without damage, and then recovered quickly. This ability to safely handle a thermal situation will keep your amp out of the shop and on the road, and we were glad to see it recover so well, with no damage (and not even any need for user input).

Tom.

+1

I never really thought of this before, but while manufacturers might not allow test/reviewers to intentionally try to push products into failure mode, due to the potential for product destruction, results from particularly grueling testing might be very interesting to folks who spend a lot of time on the road, potentially a great distance from any decent repair facility.

 

[tallboybass]

Genz reduced the weight of the Neox cabs in this latest round. If you get a brand new one, it should weigh the 50 pounds. If yours is a slightly older one (maybe sat around the music store for a while, or you bought a used one?) it could weigh a few pounds more. The 62 pounds was never accurate ... most of us who bought early ones weighed ours and found them to be 55-57 pounds, so even an older one isn't too bad.

Cheers,
Liam

Mine's 56.5 lbs.

Any idea what they did to knock 5-7 lbs. off? Hey Roger.....!!!!

 

[hasbeen]

Mine's 56.5 lbs.

Any idea what they did to knock 5-7 lbs. off? Hey Roger.....!!!!

If I recall correctly, changed to a different type of ply....same thickness etc. but different wood.

 

[aussiebassdude]

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.

+1

When I first got my 1200 I was certainly a bit surprised when the red clip light was coming on when it wasn't really being pushed that hard. After some tweaking I realised that I had my "gain structures" all mixed up.
It didn't take much tweaking to realise the error of my ways and to witness the sheer power of this beast.

 

[Eublet]

Okay, after hearing you guys talk about this I definitely believe that the half-power 30 minute test is brutal with the possible intention of making the heads go thermal. But I guess most people won't know that, and they'll think that these shutdowns indicate poor design or something, and will cause them to stay away from heads such as this because they think there is an underlying issue. Information is only as good as the understanding the person has of it. Maybe there's as explanation of all this in the magazine that I missed and need to go back and review, but for the non-tech readers many of these tests might convey something completely opposite.

 

[alexclaber]

Severe clipping with program material is considered to be about 1/3 power whilst occasional clipping with program material is about 1/8 power, so continuous 1/2 power is extremely demanding. Note that program material will have a much smaller crest factor (peak:average power ratio) than bass guitar unless the bass guitar is heavily compressed or overdriven and is incessant 8th notes.

In my experience an amp that is regular bouncing off the limiter (or gently clipping) during a gig is unlikely to be sustaining an average power output of more than 10% of full power despite frequently reaching full power on peaks.

If you look at the specs for a lot of high power PA amps you will see that few can sustain full power for long without demanding too much current from the wall or overheating. Despite that these same amps are used for demanding loads like subwoofers where they will be regularly putting out full power for peaks yet very rarely having any thermal problems even on the hottest, longest and loudest of gigs.

Alex

 

[Eublet]

Severe clipping with program material is considered to be about 1/3 power whilst occasional clipping with program material is about 1/8 power, so continuous 1/2 power is extremely demanding. Note that program material will have a much smaller crest factor (peak:average power ratio) than bass guitar unless the bass guitar is heavily compressed or overdriven and is incessant 8th notes.

In my experience an amp that is regular bouncing off the limiter (or gently clipping) during a gig is unlikely to be sustaining an average power output of more than 10% of full power despite frequently reaching full power on peaks.

If you look at the specs for a lot of high power PA amps you will see that few can sustain full power for long without demanding too much current from the wall or overheating. Despite that these same amps are used for demanding loads like subwoofers where they will be regularly putting out full power for peaks yet very rarely having any thermal problems even on the hottest, longest and loudest of gigs.

Alex

That makes sense, but for those of us who don't understand this type of thing, simply getting some raw numbers about an amp that don't display it's ability to handle huge transient peaks in power, and that shutdown during a test a few times sounds like a VERY BAD thing when all we have is the raw data. If the tests where given a grade (A+, C-, etc) along with an reviewers note about the purpose of the test or what it means in real-world use, then it could be useful information even for non-techs.

Again, for a head like the GBE 1200 that is such a fine unit, it's apparent that a lot of people here think all these tests mean really bad things, and they are walking away from the review with what seems to be an ill-formed opinion based on the techinicalities of the test. They are being advised to consider these number along with the in-hand review section. I understand Tom's point in saying that, but we have to be cognitive of the impact of how test data is digested. If the tests are either:

a) wrong,
b) not appropriate to really demonstrate the design strengths of the unit, or
c) factually flattering, but not understood as such by the reader,

then the end result is the same. People think the head has underlying issues and might avoid it altogether. The ideal scenario is to have the test data be right (flattering or not) and understood as such by the reader. I don't think that was the case here.

 

[tallboybass]

If I recall correctly, changed to a different type of ply....same thickness etc. but different wood.

Thanks Roger.

It's really cool to have this kind of responsiveness from a manufacturer here at TB.

 

[seamonkey]

... The ideal scenario is to have the test data be right (flattering or not) and understood as such by the reader. I don't think that was the case here.

Instantly understood, or with some effort on the part of the reader?

Bass Gear just threw out what they measured and observed. It's up to the reader to interpret it. Discussing the results here is a good way to understand the measurements and if they mean anything to you.

Over time it will be the same measurements for all brands of amps, and so these individual results should have more relationship to real world results.

In this day and age I'm very happy to see some consumer advocacy by a third party just trying to get raw facts out. It keeps honest companies honest.

I can't help but buy on the internet. This is a great tool to help me sort out what I want to try.

 

[macmrkt]

...If the tests where given a grade (A+, C-, etc) along with an reviewers note about the purpose of the test or what it means in real-world use, then it could be useful information even for non-techs...The ideal scenario is to have the test data be right (flattering or not) and understood as such by the reader...

Exactimo! And that's what we do. Focusing on any single part of the data, by itself, is misleading. YOU MUST LOOK AT THE WHOLE REPORT. We give a summary SCORE of each product - so you can deal with our OVERALL impressions from ALL the data, in 2 simple numbers. And what did we report?

THE GENZ BENZ GBE1200 GOT THE HIGHEST IN-HAND SCORE OF ANY AMP IN THE ISSUE!
THE GENZ BENZ GBE1200 GOT THE SECOND HIGHEST ON-BENCH SCORE OF ANY AMP IN THE ISSUE!

Specs, by themselves are only part of the story. Listening tests, by themselves, are only part of the story. Evaluating a complex electronic component, that helps you make music, requires a detailed, thoughtful evaluation. I'll crawl back into my hole now. Thank you very much.

 

[tallboybass]

...Bass Gear just threw out what they measured and observed. It's up to the reader to interpret it. Discussing the results here is a good way to understand the measurements and if they mean anything to you....

I think Bass Gear made it quite clear in the write-up that this was one powerful amp with more than enough power for most any gig.

 

[vision]

Instantly understood, or with some effort on the part of the reader?

Bass Gear just threw out what they measured and observed. It's up to the reader to interpret it. Discussing the results here is a good way to understand the measurements and if they mean anything to you.

Over time it will be the same measurements for all brands of amps, and so these individual results should have more relationship to real world results.

In this day and age I'm very happy to see some consumer advocacy by a third party just trying to get raw facts out. It keeps honest companies honest.

I can't help but buy on the internet. This is a great tool to help me sort out what I want to try.

+1...I like that the format has a hands on review, which gives you the subjective, opinionated aspect of how the amp rates, and then you have the bench test, which is an objective review of how the amp performs. The numbers are what they are. There may be confusion with the first issue becuase we haven't seen these review before, but from now on there will be a basis for comparison. We'll see over time how a particular amp performs relative to another.

 

[tombowlus]

The ideal scenario is to have the test data be right (flattering or not) and understood as such by the reader. I don't think that was the case here.

Well, we do believe our test data to be accurate. And we certainly don't want to mislead people. But to be honest, I think our expectations were that most people would in fact understand the general nature of the test results (if they choose to read the full 'in-hand' and technical reviews).

Specifically, in the 'Amp Lab', Shane mentions that although it went into clipping a couple of times during the test, it recovered quickly, per design. He goes on to say that the transformer stays cool and stable, and mentions that the power supply has excellent headroom and appears to be 'over-engineered.'

Now, he does go on to mention that in his opinion, it could have used a 'little better cooling design' to keep up with all the power that the output section is capable of putting out. But Shane is an experienced amp tech, who is used to seeing things in his shop for repair. He can be very picky in this regard (which is why we asked him to do our reviews). That test is pretty brutal, but it can tell you a lot about an amp's thermal handling capabilities. For instance, it definitely told us that if you push the GBE 1200 into thermal clipping, the protection circuits work well and protect against potential damage.

Hey, I am all for making things more clear to people, and if possible, we'll try to make it more clear that the results of one or two tests should not be used as the main determining factors when deciding if a product is 'good' or 'bad.' We had tried to do just this, but again, if there is room for improvement, we will certainly try to do what we can to improve.

Tom.

 

[Eublet]

Instantly understood, or with some effort on the part of the reader?

I guess it depends on the agenda of the magazine, any magazine. If you want your readers to understand what it is you're writing without requiring/hoping that they've done their own homework to grasp it, then you might have to help them. To that end, you have to understand your target audience. How many readers of BGM will understand the in's and out's of a 1k sine wave test, or half-power half-hour test? If the publisher thinks most will, then perhaps they're doing just fine. I think most won't, and the negative reaction here about the raw numbers seems to support my view, even though the sample size is probably fairly small.

Bass Gear just threw out what they measured and observed. It's up to the reader to interpret it.

I disagree with that very much. It's too easy for raw data to say things about something that a person doesn't understand. Interpretation is best left to experts, which most readers will not be. I know in my own line of work who I can and who I can't spit out raw numbers to. Some don't have a knowledgeable basis to do anything with it.

Discussing the results here is a good way to understand the measurements and if they mean anything to you.

Good for us, yes.

Over time it will be the same measurements for all brands of amps, and so these individual results should have more relationship to real world results.

In this day and age I'm very happy to see some consumer advocacy by a third party just trying to get raw facts out. It keeps honest companies honest.

I'm over the measurements themselves. But the questions being raised here about the performance of the head is obvious enough to show the confusion on the side of some readers. It appears to many as if the in-hand review and the bench tests are opposed to each other. So if the test isn't wrong, then it's the understanding of the test.

I'm not just thinking of the GBE 1200 here. I'm wondering how I'll form opinions about future technical reviews since it appears that I don't know how to extract the right things.