Topping LA90 Review (Integrated Amplifier)

[solderdude]

Thanks. Are you able to make out whether output goes through the caps like the standard single ended example?

The caps are decoupling/reservoir caps. Not output caps. Internal voltage is +/- 32V (most likely)

 

[TheBatsEar]

please do not offend and do not attack personally, I did not.

Didn't mean to, didn't think you did. Peace mate.

 

[pjug]

The caps are decoupling/reservoir caps. Not output caps. Internal voltage is +/- 32V (most likely)

Thanks. Can you or @pma point me to how they would be likely to do the internal +64V to +/- 32V conversion? I'm not looking to make any judgments on the amp just curious to know.

 

[Eneko]

Sorry for the probably silly question but there is something that I don't think I am understanding correctly (I have always owned active systems, so I am new to the speaker-amp pairing)... I am tempted to buy a pair of KEF LS50 meta and this amp to drive them, but I have some concerns considering the debate about how much power the amp can deliver.

So, if the amp is able to deliver 36 watts before clipping (at 8 ohms), and the LS50 meta sensitivity is around 83 dB, my naive interpretation is that at max power the amp will push the speaker to 98.5 dB SPL (at 1m, 3.3feet) according to http://www.hometheaterengineering.com/splcalculator.html. If according to the LS50 meta review in here https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/ the speaker is not handling well 96 dB SPL... does it mean that the amp is able to drive the speakers reasonably well (well meaning to their max before things start to fall apart)?

Sorry for the long question!

 

[Deleted member 46664]

4A is really not good. In playback acoustic can become 2 or 1 ohm or less. I saw acoustic that needs 50 W, but in playback to play peaks it needs 30A.
I really want this, but I afraid that it will loose all peaks

Relax ... that's why these amplifiers have huge bulk capacitors in them ... they bolster the supply and maintain peak outputs.

 

[Deleted member 46664]

I do not think there is anything wrong with me, I am making objections based on evaluations that can be shared or not, please do not offend and do not attack personally, I did not.

Two points here ....
First on the subjective level there is a more or less hard limit to what you can and can't hear. In general a "sinad" over about 90 is going to be just fine, audible perfection. Arguing over 100 and 120 is about the same as arguing over 10miles or 12miles when you only have 9 miles of string.

Second...
The numbers here are impressive, a great achievement, so long as there are no reliability issues this amp tops the list. But they are differences you will never hear.

 

[solderdude]

Thanks. Can you or @pma point me to how they would be likely to do the internal +64V to +/- 32V conversion? I'm not looking to make any judgments on the amp just curious to know.

Either the 3 pin connector does not show a gnd pin (so is +/- 32V).
Or an internal DC/DC converter is present.
Or a virtual ground/rail splitter is used.

Only John can tell what's inside.

 

[pma]

Thanks. Can you or @pma point me to how they would be likely to do the internal +64V to +/- 32V conversion? I'm not looking to make any judgments on the amp just curious to know.

There are many other ways how to do it according to your needs.

 

[F1308]

Loudness did not change past 3 o'clock.

I would like to understand this, if you please.

 

[Deleted member 46664]

The caps are decoupling/reservoir caps. Not output caps. Internal voltage is +/- 32V (most likely)

That would fit in nicely with the measurements.

 

[Deleted member 46664]

I would like to understand this, if you please.

Because the amplifier was already at it's limit.

 

[solderdude]

Sorry for the probably silly question but there is something that I don't think I am understanding correctly (I have always owned active systems, so I am new to the speaker-amp pairing)... I am tempted to buy a pair of KEF LS50 meta and this amp to drive them, but I have some concerns considering the debate about how much power the amp can deliver.

So, if the amp is able to deliver 36 watts before clipping (at 8 ohms), and the LS50 meta sensitivity is around 83 dB, my naive interpretation is that at max power the amp will push the speaker to 98.5 dB SPL (at 1m, 3.3feet) according to http://www.hometheaterengineering.com/splcalculator.html. If according to the LS50 meta review in here https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/ the speaker is not handling well 96 dB SPL... does it means that the amp is able to drive the speakers reasonably well (well meaning to their max before things start to fall apart)?

Sorry for the long question!

The LS50 is designed for 40-100 W amps.
Imp is 8 ohm with dips at 3.5 ohm.

The LA90 can do 50W in 8 ohm and has no issues with the 3.5ohm. The amp thus is suitable and falls in the 40-100W range.
A 100W/8 ohm amp can play 3dB louder.

 

[pjug]

Either the 3 pin connector does not show a gnd pin (so is +/- 32V).
Or an internal DC/DC converter is present.
Or a virtual ground/rail splitter is used.

Only John can tell what's inside.

Amir said that the brick was +64V splitter/converter would be internal.

 

[solderdude]

Yes, is easy to do like this for instance. It must be able to source/sink 5A.

 

[pjug]

There are many other ways how to do it according to your needs.

So this is more or less a power amp itself. Seems like it would nake more sense to use +/- power supply. But I said I didn't want to judge!

 

[ROOSKIE]

Sorry for the probably silly question but there is something that I don't think I am understanding correctly (I have always owned active systems, so I am new to the speaker-amp pairing)... I am tempted to buy a pair of KEF LS50 meta and this amp to drive them, but I have some concerns considering the debate about how much power the amp can deliver.

So, if the amp is able to deliver 36 watts before clipping (at 8 ohms), and the LS50 meta sensitivity is around 83 dB, my naive interpretation is that at max power the amp will push the speaker to 98.5 dB SPL (at 1m, 3.3feet) according to http://www.hometheaterengineering.com/splcalculator.html. If according to the LS50 meta review in here https://www.audiosciencereview.com/forum/index.php?threads/kef-ls50-meta-review-speaker.25574/ the speaker is not handling well 96 dB SPL... does it mean that the amp is able to drive the speakers reasonably well (well meaning to their max before things start to fall apart)?

Sorry for the long question!

I will it keep short.
I my room which is 12 feet wx24lx8.5ft high & where I sit 11 feet from the speakers I do not think this amp has enough power for 83db sensitive speakers.
I would want a couple hundred.
I use 300-500 per channel which allows for some room to play and the ability to go loud.
You do get SPL boost from room gain but peaks and difficult movements will require more power and every 3db require a doubling of power so even 6db compressed peaks require 4 times as much power as the average SPL. Plus take a look at the impedance graph, in some areas the speakers require far more voltage to play at 83db SPL.(140hrz-700hrz is well below 5ohms and mainly 3.7)
Not enough for me and there is a reason Amir uses high powered amps.
Why pay $800 for clipping? Most people can tolerate 3-6db of clipped power before they even notice it but again why pay for that ? Might as well use a high powered lesser quality unit.
Now in a small room this amp would be enough or if you never listen to average SPLs above 85db.

 

[Deleted member 46664]

So this is more or less a power amp itself. Seems like it would nake more sense to use +/- power supply. But I said I didn't want to judge!

The three pin plug is a pretty big hint.

 

[Eneko]

I will it keep short.
I my room which is 12 feet wx24lx8.5ft high & where I sit 11 feet from the speakers I do not think this amp has enough power for 83db sensitive speakers.
I would want a couple hundred.
I use 300-500 per channel which allows for some room to play and the ability to go loud.
You do get SPL boost from room gain but peaks and difficult movements will require more power and every 3db require a doubling of power so even 6db compressed peaks require 4 times as much power as the average SPL. Plus take a look at the impedance graph, in some areas the speakers require far more voltage to play at 83db SPL.
Not enough for me and there is a reason Amir uses high powered amps.
Why pay $800 for clipping? Most people can tolerate 3-6db of clipped power before they even notice it but again why pay for that ? Might as well use a high powered lesser quality unit.
Now in a small room this amp would be enough or if you never listen to average SPLs above 85db.

Thank you for the answer but I don't think that I am understanding it, if the speaker can't handle anything above 86dB SPL (1m) without falling apart... why would you want an amp able to drive it further (and this will do it at >98dB SPL)?

 

[Eneko]

The LS50 is designed for 40-100 W amps.
Imp is 8 ohm with dips at 3.5 ohm.

The LA90 can do 50W in 8 ohm and has no issues with the 3.5ohm. The amp thus is suitable and falls in the 40-100W range.
A 100W/8 ohm amp can play 3dB louder.

Thanks!

 

[pjug]

The three pin plug is a pretty big hint.

That's what I thought but Amir measured and it is +64V as labeled. So the +/- 32V is done inside the LA90 box.