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Lab Gruppen FP14000 clone amplifiers - Page 114

post #3391 of 4389
Thread Starter 
Quote:
Originally Posted by Pain Infliction View Post

Can somebody post the specs on this amp please? Also, do you need a 30amp line for this bad boy? I would think so.
Read the thread. You don't strictly need one, but if you push a lot of power with it you may trip a 20a breaker.

Gear mentioned in this thread:

post #3392 of 4389
Thread Starter 
Quote:
Originally Posted by SeekingNirvana View Post

I plan to build two boxes each consisting of 1 LMS 5400. Would one fp14k be good for that application? If so how would I configure it?

I run 2 LMS5400s off one clone. It's more than enough. You can run bridged at 8 ohms if you want them both on the same channel, or run them at 4 ohms per channel in stereo.
post #3393 of 4389
I would read the thread if it wasn't 3400 posts. Just wanted to know what the stereo specs were @4ohm.
post #3394 of 4389
Try the first page.
post #3395 of 4389
Thread Starter 
Quote:
Originally Posted by MKtheater View Post

Try the first page.

First post even wink.gif
post #3396 of 4389
Quote:
Originally Posted by SeekingNirvana View Post

I plan to build two boxes each consisting of 1 LMS 5400. Would one fp14k be good for that application? If so how would I configure it?

If you ran it in stereo it would be more than enough. Plenty of headroom with the FP14000

I am currently only using 1 channel of mine (still need to build another sub) and pushing an FI Q15 at 4 Ohm in an LLT box and it is more than enough power.

I can get everything in the house shaking at any frequency I want down to 15 Hz without a problem with the amp reading -10db on the front panel. And kudos to the folks at FI since the sub has no problem taking punishment at -4db.

It is nice to have headroom.
post #3397 of 4389
So what about this pumping thing? I will need to run in stereo so that I can adjust the gains separately. One sub is 3' from MLP and the other is about 15'. So in order not to have the close one not be localized I need to have the ability to adjust the gain.

Kinda off topic here but can anyone direct me to a good LMS build thread? I've seen a few but I'm looking for one that has specific details. Like box dimensions, how to construct the box, binding post types etc etc...
post #3398 of 4389
Quote:
Originally Posted by SeekingNirvana View Post

So what about this pumping thing? I will need to run in stereo so that I can adjust the gains separately. One sub is 3' from MLP and the other is about 15'. So in order not to have the close one not be localized I need to have the ability to adjust the gain.

Kinda off topic here but can anyone direct me to a good LMS build thread? I've seen a few but I'm looking for one that has specific details. Like box dimensions, how to construct the box, binding post types etc etc...

If the distances are that far apart, you'll need to adjust the gains and also the delay.
post #3399 of 4389
I have XT-32 so that should take care of that. I'm just worried about pumping.....should I just buy one amp per sub? Or is pumping not that big of a deal?
post #3400 of 4389
Quote:
Originally Posted by SeekingNirvana View Post

I have XT-32 so that should take care of that. I'm just worried about pumping.....should I just buy one amp per sub? Or is pumping not that big of a deal?

What is pumping?
post #3401 of 4389
Quote:
Originally Posted by bossobass View Post

It depends on the

The other issue I discovered while messing with amplifiers is a phenomenon called Bus Pumping. This happens particularly a low frequencies, so it was something I wanted to look into. For anyone interested, searching the term will lead to descriptions, but the short of it is that a simple cure for the problem is to bridge the amplifiers. I suspect this is why Speakerpower and the rest of the recent lightweight switching supply amps are not bridgeable, because they are a full bridge configuration out of the gate. IOW, each channel is already bridged, therefore the 2 channels cannot be bridged.

Basically, bus pumping occurs when voltage fluctuations result in reverse power coming back to the supply from the amp. The lower the frequency and the lower the load, the worse it is. And, we use extremely low impedance loads at extremely low frequencies at maximum power levels and current. The simple cure is to bridge the 2 channels so that the excess power is consumed by the out of phase channel. It eliminates bus pumping.

I suspect that this is why the clones failed under sine wave duress in 2 channel mode at 2 ohms at the lowest frequency used for the tests. It's my opinion that most of the failures cited in this thread are the result of driving subs in 2 channel mode. I could be mistaken but it might be something to look into as far as a failure and what mode of operation correlation. I also suspect that this is why I never have had a problem because I only ever use the amps in bridged mode. I also feed the amps into a 4 ohm nominal load with a signal chain that has virtually zero roll off to 2 Hz and, again, have never had a problem.

So, IMO, so-called tests of the LG or any similar versions that use sine waves at low frequencies into a low impedance load PER CHANNEL, are all bogus for my application, YMMV. I would not recommend using any switching power supply amplifier for subwoofer duty unless it's a full bridge configuration amp or unless it's bridgeable and you use it only in bridged mode. 2 channel mode above 100 Hz is not a problem at any load, IMO.

Rated power output is the most suspect number for comparisons and roll off and configuration are much more important is HT subs (ULF) are the end game. If the Peavey or whatever amp is down -15dB @ 3 Hz, then what is its actual output capability vs an amp that's down -4db @ 3 Hz when playing WOTW? Etc.

Am I getting to deep into it? Anyone else experience this pumping thingy?
post #3402 of 4389
Quote:
Originally Posted by SeekingNirvana View Post

So what about this pumping thing? I will need to run in stereo so that I can adjust the gains separately. One sub is 3' from MLP and the other is about 15'. So in order not to have the close one not be localized I need to have the ability to adjust the gain.

Kinda off topic here but can anyone direct me to a good LMS build thread? I've seen a few but I'm looking for one that has specific details. Like box dimensions, how to construct the box, binding post types etc etc...

Here's a link to many of the good server build threads. It's not just builds around the LMS, but you can tell by the description most of the time.

Dimensions will vary based on your requirements so they may or may not be of use to you if provided. As for binding posts, it's all preference really. I prefer to use Neutrik Speakon connectors, but any good quality 5-way binding post will work. I get most of my speaker building supplies from Part-Express.

Quote:
Originally Posted by SeekingNirvana View Post

Am I getting to deep into it? Anyone else experience this pumping thingy?

I've read most of the LMS Ultra and FP14K threads and this is the first that I've heard of it. Considering others are wondering what that is, I'd guess that this is a very rare occurrence. Or in the very least, this is something that has not been identified as the cause of the failures of this particular amp. If notnyt and company have not had this issue, I'm guessing most others will not either. This is just a guess I'm pulling out of my rear end so take it with a grain of salt.
Edited by duc135 - 9/25/13 at 3:24pm
post #3403 of 4389
Thread Starter 
bus pumping is real, and was described accurately earlier. There's lots of information on it. Running bridged should prevent it. You will really only run across it at extremely high output levels with these amps. I haven't had a scope on the output, so I can't really say to what extent. This is something common that you will find in just about everywhere. Power supply pumping and how to deal with it is one of the things you learn when you start building circuits.

tldr version, don't worry about it. You can bridge if you really care.
post #3404 of 4389
Quote:
Originally Posted by notnyt View Post

bus pumping is real, and was described accurately earlier. There's lots of information on it. Running bridged should prevent it. You will really only run across it at extremely high output levels with these amps. I haven't had a scope on the output, so I can't really say to what extent. This is something common that you will find in just about everywhere. Power supply pumping and how to deal with it is one of the things you learn when you start building circuits.

tldr version, don't worry about it. You can bridge if you really care.
you can't check the phenomenon with a scope at the output. it's only visible at the DC supply rail inside the amp.
bus pumping only happens with class d amp. or frequency switching amp (since manufacturer loves to create unique classes for their amp). the problem is fundamental to all switching amp and cannot be fully rectified with *any* clever solution except to bridge them.

it happens when the leftover current stored in the output inductor is fed back to the power supply, making it unstable. the problem is huge, and if you ever measured the power supply rail during operation, you'd be surprised as to how much the voltage could fluctuate because of this issue.


but for the fp14k, the fault might not entirely be because of bus pumping. it's just shooting in the dark since people also run into problem when it's not connected to anything.
post #3405 of 4389
Learn something new everyday. I'll bridge my amp then, just for the hell of it. Makes sense with inductive load (subwoofer) although I haven't had a chance to really dig in and understand this issue.

[edit]
This may help explain the issue in more detail:
http://www.maximintegrated.com/app-notes/index.mvp/id/4260
Edited by javi404 - 9/25/13 at 8:00pm
post #3406 of 4389
Thread Starter 
Quote:
Originally Posted by paskal9 View Post

you can't check the phenomenon with a scope at the output. it's only visible at the DC supply rail inside the amp.
bus pumping only happens with class d amp. or frequency switching amp (since manufacturer loves to create unique classes for their amp). the problem is fundamental to all switching amp and cannot be fully rectified with *any* clever solution except to bridge them.

it happens when the leftover current stored in the output inductor is fed back to the power supply, making it unstable. the problem is huge, and if you ever measured the power supply rail during operation, you'd be surprised as to how much the voltage could fluctuate because of this issue.

but for the fp14k, the fault might not entirely be because of bus pumping. it's just shooting in the dark since people also run into problem when it's not connected to anything.

I was referring to the output from the PS not the speaker facing output
post #3407 of 4389
Quote:
Originally Posted by javi404 View Post

Learn something new everyday. I'll bridge my amp then, just for the hell of it. Makes sense with inductive load (subwoofer) although I haven't had a chance to really dig in and understand this issue.

[edit]
This may help explain the issue in more detail:
http://www.maximintegrated.com/app-notes/index.mvp/id/4260
you could also reduce the issue (albeit not solve it) by running the other channel out of phase (to the first channel) and invert the output to put it back in phase.
if you're running minidsp or other equipment using xlr to the amp, invert the input signal then invert back at the speaker connection.
post #3408 of 4389
Quote:
Originally Posted by paskal9 View Post

you could also reduce the issue (albeit not solve it) by running the other channel out of phase (to the first channel) and invert the output to put it back in phase.
if you're running minidsp or other equipment using xlr to the amp, invert the input signal then invert back at the speaker connection.

I was only running one sub right now anyway, so I just bridged it to the one sub @ 4ohm. problem solved with a banana plug move and 1 dip switch change.

When I build second sub, I might use that method. that should solve the problem I think. Sounds reasonable. I'm wondering if that may already be implemented in this amp since bridging requires using RED of ch1 and BLK of ch2, most other amps I have use RED ch1 and RED ch2 to bridge.

Maybe someone can elaborate on this specific amp since I don't have the block diagram of it.
post #3409 of 4389
Just wanted to add that The Chinese agents sell other amps. For instance, it's better to use a bridged 9000 than a 14000 in 2 channel (and less expensive).

The problem is not that the clones suffer bus pumping at ultra low frequencies into low impedance loads and other amps don't. As I mentioned, ALL switching amps have this problem. The problem with the clones is that their protection circuitry doesn't always properly shut the amp down when the problem is at a fatal level. POOF. And, also as I've mentioned, the latest switching amps mentioned in this thread and elsewhere are not bridgeable, most likely because each channel is a full bridge design, to solve the bus pumping problem (just a guess, as I know little about the iNukes and IPRs of the amp world).

The FP9000 is technically around 2dB less max burst output vs the 14000 when both are bridged, and a 9000 technically has 1dB or so more output bridged that the 14000 in 2 channel.

Just sayin, FWIW. The only holdback with these amps is fear of failure. Running bridged seems to me to have been the single variable to explain my success vs failures with these amps, so I thought I'd pop in and mention it.
post #3410 of 4389
Thread Starter 
Quote:
Originally Posted by bossobass View Post

Just wanted to add that The Chinese agents sell other amps. For instance, it's better to use a bridged 9000 than a 14000 in 2 channel (and less expensive).

The problem is not that the clones suffer bus pumping at ultra low frequencies into low impedance loads and other amps don't. As I mentioned, ALL switching amps have this problem. The problem with the clones is that their protection circuitry doesn't always properly shut the amp down when the problem is at a fatal level. POOF. And, also as I've mentioned, the latest switching amps mentioned in this thread and elsewhere are not bridgeable, most likely because each channel is a full bridge design, to solve the bus pumping problem (just a guess, as I know little about the iNukes and IPRs of the amp world).

The FP9000 is technically around 2dB less max burst output vs the 14000 when both are bridged, and a 9000 technically has 1dB or so more output bridged that the 14000 in 2 channel.

Just sayin, FWIW. The only holdback with these amps is fear of failure. Running bridged seems to me to have been the single variable to explain my success vs failures with these amps, so I thought I'd pop in and mention it.

Interesting, I've been running mine in stereo without issue. If I end up moving stuff around or changing things up in any way I may switch to the bridged setup. There are two upcoming speakers which have my interest. One is taking a lot longer than I was originally told about and I don't know the schedule for the second. Either way, I'm in no rush.
post #3411 of 4389
Quote:
Originally Posted by notnyt View Post

Interesting, I've been running mine in stereo without issue. If I end up moving stuff around or changing things up in any way I may switch to the bridged setup. There are two upcoming speakers which have my interest. One is taking a lot longer than I was originally told about and I don't know the schedule for the second. Either way, I'm in no rush.

Or.....

8 TH.

I know of a few people right off hand that would love to scoop up your Ultras. Guess it all comes down to timing.
post #3412 of 4389
Quote:
Originally Posted by javi404 View Post

I was only running one sub right now anyway, so I just bridged it to the one sub @ 4ohm. problem solved with a banana plug move and 1 dip switch change.

When I build second sub, I might use that method. that should solve the problem I think. Sounds reasonable. I'm wondering if that may already be implemented in this amp since bridging requires using RED of ch1 and BLK of ch2, most other amps I have use RED ch1 and RED ch2 to bridge.

Maybe someone can elaborate on this specific amp since I don't have the block diagram of it.

Probably not the best idea given these Clones are not stable @ 4ohm bridged.
post #3413 of 4389
Quote:
Originally Posted by popalock View Post

Quote:
Originally Posted by javi404 View Post

I was only running one sub right now anyway, so I just bridged it to the one sub @ 4ohm. problem solved with a banana plug move and 1 dip switch change.

When I build second sub, I might use that method. that should solve the problem I think. Sounds reasonable. I'm wondering if that may already be implemented in this amp since bridging requires using RED of ch1 and BLK of ch2, most other amps I have use RED ch1 and RED ch2 to bridge.

Maybe someone can elaborate on this specific amp since I don't have the block diagram of it.

Probably not the best idea given these Clones are not stable @ 4ohm bridged.

Isn`t Bosso running his clones bridged at 4 ohms?
That`s what I read
post #3414 of 4389
Bosso I believe is using the Fp9000 or 7000 not the 14k.
post #3415 of 4389
Quote:
Originally Posted by chrapladm View Post

Bosso I believe is using the Fp9000 or 7000 not the 14k.

I've used the FP7000, FP9000, K12000 and FP14000, but that's irrelevant.

My point in popping in here it to reiterate that the amps are definitely 4 ohms bridged stable.

It's my opinion that 2 and 4 ohms stereo is a problem because of bus pumping. The protection circuits are not consistently up to the task when the amps are run in stereo and fed ULF at or near maximum power in stereo mode.

I run my systems typically with a +10dB L/T boost with a signal chain that's flat to 3 Hz playing extreme discs like WOTW. No one I'm aware of demands more from a subwoofer system.

I've run all of the amps in 4 ohms bridged, 120V-30A home run, to the extreme edge of their output capacity for 3-1/2 years with no problems.

YMMV.
post #3416 of 4389
Both of my FP14ks are run at 2.66ohm stereo but my cutoff is much higher @ around 29hz since i dont need much lower LF content.. I would love to try it at 2ohm stereo but they work fine as they are now and if it ent broke dont try to fix it..
post #3417 of 4389
Quote:
Originally Posted by bossobass View Post

I've used the FP7000, FP9000, K12000 and FP14000, but that's irrelevant.

My point in popping in here it to reiterate that the amps are definitely 4 ohms bridged stable.

It's my opinion that 2 and 4 ohms stereo is a problem because of bus pumping. The protection circuits are not consistently up to the task when the amps are run in stereo and fed ULF at or near maximum power in stereo mode.

I run my systems typically with a +10dB L/T boost with a signal chain that's flat to 3 Hz playing extreme discs like WOTW. No one I'm aware of demands more from a subwoofer system.

I've run all of the amps in 4 ohms bridged, 120V-30A home run, to the extreme edge of their output capacity for 3-1/2 years with no problems.

YMMV.

Whhhhhaaaa? This....is....huge....

I need this dummied down for me two more levels.

Your statement above implies that us Clone owners have been leaving some performance on the table...so I'll ask the question just to make 100% sure I am following.

Can we safely run the Clone bridged at 4Ohm?

Or is the YMMV statement a general disclaimer?
post #3418 of 4389
Quote:
Originally Posted by popalock View Post

Whhhhhaaaa? This....is....huge....

I need this dummied down for me two more levels.

Your statement above implies that us Clone owners have been leaving some performance on the table...so I'll ask the question just to make 100% sure I am following.

Can we safely run the Clone bridged at 4Ohm?

Or is the YMMV statement a general disclaimer?

Again, I've run several of these amps 4 ohms bridged for 3+ years with no problems.

The only problems I've had were with the 14k in stereo. Never had a failure of any kind in 4 ohms bridged, and, as I've said, I run all the way to 3 Hz at reference level.

The "YMMV" disclaimer is for those who have been saying you can't run in 4 ohms bridged, based on nothing I've seen but rumors, and to account for stupid human pet tricks.

Don't know how much more dumbed down I can make it than that? smile.gif
post #3419 of 4389
Glad to hear this. After learning about power supply pumping, doesn't look likes it is wise to just run a single channel of any class D amp by itself (which is the way I had it before.)

I'm also wondering if the lab or the clones are designed to mitigate that risk if both channels are driven with the same content but one inverted. I would think that would be an easy trick to make it safer. Obviously bridging the amp solves this all together.
post #3420 of 4389
I ran both of my 14k's in bridged mode and never had problems. They saw a nominal of 6.3 ohms but it went above and below that. I ran 10 dBs above reference on WOTW and -3 dBs at 4-5 hz.
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