Topping LA90 Discrete Amplifier Review

[terryforsythe]

Thanks. I would prefer to go with the topping B200 but it's seem you can't connect the wimm ultra streamer with it or something

If the B200 is an issue, so too will be the LA90D - both the LA90D and B200 have balanced inputs, whereas the WiiM Ultra has single ended outputs.

EDIT: The B200 only has 22dB of gain, which is insufficient to achieve full rated power with a single ended 2.0V source.

You can use RCA to XLR cables, but your input voltage to the amplifiers will be lower. Thus, you will want to use the high gain settings on the amplifiers. Also, the potential for noise issues is higher with single ended outputs, but if the cables are short it should not be a significant issue.

Perhaps others that have used a WiiM Ultra with the B200 or LA90D will chime it with their experience.

Another option is to get a WiiM Pro and connect that to a DAC that has a SPDIF input and XLR outputs. But, you could use the WiiM Ultra with an external DAC if having the display is worth the extra money to you. Since you would be using an external DAC, there would be no difference in sound quality.

A further option is to try the WiiM Ultra with RCA to XLR cables. If it works well for you, great. If not, then you could add an external DAC. But, I think it will sound fine with the RCA to XLR cables.

 

[J84]

If the B200 is an issue, so too will be the LA90D - both the LA90D and B200 have balanced inputs, whereas the WiiM Ultra has single ended outputs.

You can use RCA to XLR cables, but your input voltage to the amplifiers will be lower. Thus, you will want to use the high gain settings on the amplifiers. Also, the potential for noise issues is higher with single ended outputs, but if the cables are short it should not be a significant issue.

Perhaps others that have used a WiiM Ultra with the B200 or LA90D will chime it with their experience.

Another option is to get a WiiM Pro and connect that to a DAC that has a SPDIF input and XLR outputs. But, you could use the WiiM Ultra with an external DAC if having the display is worth the extra money to you. Since you would be using an external DAC, there would be no difference in sound quality.

A further option is to try the WiiM Ultra with RCA to XLR cables. If it works well for you, great. If not, then you could add an external DAC. But, I think it will sound fine with the RCA to XLR cables.

Thanks. Can you recommend me a good RCA to XLR cable?

 

[BeeKay]

Benchmark offer SE to XLR, or Topping‘s SE to TRS. Both should work for the LA90.

 

[terryforsythe]

Benchmark offer SE to XLR, or Topping‘s SE to TRS. Both should work for the LA90.

They also should work for the B200.

EDIT: I just found the issue with the B200. Its high gain only is 22dB. That is insufficient gain to get full rated power using a single ended 2.0 V source and 6 ohm speakers. Max output power would be around 105 W/ch.

 

[terryforsythe]

Thanks. Can you recommend me a good RCA to XLR cable?

What BeeKay recommended, but also Amazon: e.g., https://a.co/d/hY5Xg3y or https://a.co/d/7lyhAxn

 

[stefanovesa]

Thanks. Can you recommend me a good RCA to XLR cable?

also this one:

enoaudio Mogami 2534 Quad Cable Pair (L,R) Professional | Neutrik Gold RCA - XLR Male | HiFi - 1m : Amazon.it: Musical Instruments

enoaudio Mogami 2534 Quad Cable Pair (L,R) Professional | Neutrik Gold RCA - XLR Male | HiFi - 1m : Amazon.it: Musical Instruments

www.amazon.it

I'm using from SACD player to LA90 Discrete. Wiring schema is the correct one

 

[mike7877]

also this one:

enoaudio Mogami 2534 Quad Cable Pair (L,R) Professional | Neutrik Gold RCA - XLR Male | HiFi - 1m : Amazon.it: Musical Instruments

enoaudio Mogami 2534 Quad Cable Pair (L,R) Professional | Neutrik Gold RCA - XLR Male | HiFi - 1m : Amazon.it: Musical Instruments

www.amazon.it

I'm using from SACD player to LA90 Discrete. Wiring schema is the correct one

The preamp section in the LA90 Discrete is passive - it's just a potentiometer (and not a very good one, at that, IMO. I mean, it'll do fine in a system that isn't perfect if it's one of a few weak links. But if it's [relatively] the only weak link, imaging suffers - get a preamp which uses a gate/relay controlled resistor array (like Topping A70 Pro), or at least a DAC with high dynamic range and digital volume control.

They also should work for the B200.

EDIT: I just found the issue with the B200. Its high gain only is 22dB. That is insufficient gain to get full rated power using a single ended 2.0 V source and 6 ohm speakers. Max output power would be around 105 W/ch.

That's unfortunate. It's pretty close, but it's better to be able to clip the amp from the source (and then some, of course - for tracks recorded more quietly)

I like the LA90 Discrete over the B200 for the ability to bi-amp or go active in the future. This has got me thinking - I think I need to pick up my third and final LA90 D so I can have two bridged amps for my woofers and a single stereo for tweeters. The woofers are 8 ohms and 85dB/W, and the tweeters are 6 ohms 91.5dB/W.

Then I need a fourth unit for backup. Maybe a fifth in case I decide to go 3-way at some point, maybe a sixth in case I decide to cross that mid low. Maybe a seventh because a single spare for all 6 amps? Crazy!
And there's $10K for secure amplification for the next, probably 60 years. Strategic cap replacements every 15 years, full cap replacements every 30.
3 maintenances, 4th is on someone else if they want to do it lol.

I feel like these amps are going to be highly sought after and nobody's going to make things that come anywhere close for under the price of a car for decades...

I wonder which gear from the past is like the Topping LA90D (specifically technologically)

 

[terryforsythe]

I like the LA90 Discrete over the B200 for the ability to bi-amp or go active in the future. This has got me thinking - I think I need to pick up my third and final LA90 D so I can have two bridged amps for my woofers and a single stereo for tweeters. The woofers are 8 ohms and 85dB/W, and the tweeters are 6 ohms 91.5dB/W.

I started with two LA90Ds; one for my right channel midrange and tweater and one for the left channel. It sounded fantastic. Later I got a wild hair up by @ss and bought two B100s for my tweeters and bridged each of my LA90Ds mono for my midranges. Probably overkill, but it is nice knowing that I have the extra power on tap for the rare occasion I turn up the volume while doing house cleaning and an uncompressed song comes on.

 

[mike7877]

I started with two LA90Ds; one for my right channel midrange and tweater and one for the left channel. It sounded fantastic. Later I got a wild hair up by @ss and bought two B100s for my tweeters and bridged each of my LA90Ds mono for my midranges. Probably overkill, but it is nice knowing that I have the extra power on tap for the rare occasion I turn up the volume while doing house cleaning and an uncompressed song comes on.

That is amazing! What are your mids?

 

[terryforsythe]

That is amazing! What are your mids?

Elac Uni-Fi Reference concentric drivers. It certainly was not the most cost effective way to approach this, but the last paragraph in the following link explains why I went that route: https://www.audiosciencereview.com/...-fi-reference-ubr62-bookshelf-speakers.51780/

 

[mike7877]

Elac Uni-Fi Reference concentric drivers. It certainly was not the most cost effective way to approach this, but the last paragraph in the following link explains why I went that route: https://www.audiosciencereview.com/...-fi-reference-ubr62-bookshelf-speakers.51780/

Ah, yes, I see why.

I agree - 200Hz is very low for a 4" mid with a tiny roll for the surround. And they probably used an iron core to reduce coil size to, right?

I have a small suggestion for you to try, depending on the ease of customization of your active eq:
Find out the baffle step frequency, and then cross to the midrange above that by 100-150Hz (it's probably somewhere around 650-750Hz

I grabbed this from another thread here. I forget exactly the polar pattern at the upper limit listed for each size at these frequencies, but it's excellent. And if you go by half the frequency it will radiate 360 degrees absolutely no problem. You don't have to go any lower, but for perfection in most cases, 20-30% lower is overkill

So if you center the crossover just below the baffle step, instead of pulling out or pushing back the speakers in the room to get the amount of body/volume to the sound, you can just adjust the entire low frequency driver!

Of course it takes some adjusting or trial and error. But it's fun! And something you might want to try one day when you're bored and if your EQ is easily customized.

I regret I can't do this with my 2-way. I _almost_ can, if I stay right at the listed value, because I could, technically, cross the tweeter at 1.4kHz, but I do also like to listen loud, and I think the baffle isn't optimized for a frequency that low (it's 2.1kHz and centered - my understanding off center would probably be required for good performance in the mid 1k range). 1.4kHz tone would start compressing from magnetic field strength variation at 99dB

 

[terryforsythe]

I agree - 200Hz is very low for a 4" mid with a tiny roll for the surround. And they probably used an iron core to reduce coil size to, right?

Two laminated steel core inductors on the woofer, but mostly air core inductors for the midrange and tweeter (there is one laminated steel core inductor in a series resonant circuit in parallel with the midrange, but in that use case the core type is not a significant issue). Also, the DCR of the two series inductors for the woofer was quite high, 1.2 ohms and 0.4 ohms respectively. The woofer is 4.15 ohms.

I have a small suggestion for you to try, depending on the ease of customization of your active eq:
Find out the baffle step frequency, and then cross to the midrange above that by 100-150Hz (it's probably somewhere around 650-750Hz

The woofer can be pushed much higher in frequency but, generally speaking, the lower the woofer/midrange crossover frequency the more linear the vertical off-axis response will be. I have tile floors with a thin floor rug, which makes that even more of an issue. I have experimented with crossover frequencies as high as 500Hz but, based on my listening tests, the sweet spot seems to be below 500Hz from a soundstaging and imaging perspective. However, below 350Hz or so the midrange dynamics suffer. Psychology comes into play here, and that very well could be my brain telling me to expect that frequency range to sound best, and thus I interpret what I think I should hear. As a sanity check, I just looked up the KEF R3 Meta. It uses a crossover frequency of 420Hz.

So if you center the crossover just below the baffle step, instead of pulling out or pushing back the speakers in the room to get the amount of body/volume to the sound, you can just adjust the entire low frequency driver!

Good thinking!

My Flex HTx has four presets, selectable at the push of a button. I have optimized the frequency response with the speakers pulled well into the room to minimize reflections and using a measurement window to try to get close as I can in the house to an anechoic response. Then I ran Dirac Live with the speakers pulled out around 1m from the front wall and optimized for my listening chair, with the speakers and my chair roughly forming a triangle. I saved that to preset 1. Then I ran Dirac Live with the speakers placed against the wall where I normally leave them and saved that to preset 2. That works well.

My next project is gathering much more thorough frequency response data with outdoor measurements using an automatically rotating measurement swivel I designed on top of a 19 ft. ladder, then importing that into VituixCAD and optimizing the DSP with that. I plan on getting to that before summer. I discuss the Swivel on the last page of my thread, and I posted a video of the prototype in action.

 

[mike7877]

Two laminated steel core inductors on the woofer, but mostly air core inductors for the midrange and tweeter (there is one laminated steel core inductor in a series resonant circuit in parallel with the midrange, but in that use case the core type is not a significant issue). Also, the DCR of the two series inductors for the woofer was quite high, 1.2 ohms and 0.4 ohms respectively. The woofer is 4.15 ohms.

You probably lowered woofer Q quite a bit then - did you have to compensate with EQ?

The woofer can be pushed much higher in frequency but, generally speaking, the lower the woofer/midrange crossover frequency the more linear the vertical off-axis response will be. I have tile floors with a thin floor rug, which makes that even more of an issue. I have experimented with crossover frequencies as high as 500Hz but, based on my listening tests, the sweet spot seems to be below 500Hz from a soundstaging and imaging perspective. However, below 350Hz or so the midrange dynamics suffer. Psychology comes into play here, and that very well could be my brain telling me to expect that frequency range to sound best, and thus I interpret what I think I should hear. As a sanity check, I just looked up the KEF R3 Meta. It uses a crossover frequency of 420Hz.

Yeah, that makes sense. Especially in the midrange you want good dispersion for phase - when it's off it sounds the worst and is most obvious right away IMO.
I kind of like two way designs for this reason - there's just the obvious problem of peak power handling and possibly power response across the upper frequency limit of the lower frequency driver

Good thinking!

My Flex HTx has four presets, selectable at the push of a button. I have optimized the frequency response with the speakers pulled well into the room to minimize reflections and using a measurement window to try to get close as I can in the house to an anechoic response. Then I ran Dirac Live with the speakers pulled out around 1m from the front wall and optimized for my listening chair, with the speakers and my chair roughly forming a triangle. I saved that to preset 1. Then I ran Dirac Live with the speakers placed against the wall where I normally leave them and saved that to preset 2. That works well.

My next project is gathering much more thorough frequency response data with outdoor measurements using an automatically rotating measurement swivel I designed on top of a 19 ft. ladder, then importing that into VituixCAD and optimizing the DSP with that. I plan on getting to that before summer. I discuss the Swivel on the last page of my thread, and I posted a video of the prototype in action.

That sounds like a really interesting project - are you going to do those measurements outside?
It sounds similar to what I plan to do - bury my speaker so its drivers are flush with the ground and taking measurements above, below, around it.

 

[terryforsythe]

You probably lowered woofer Q quite a bit then - did you have to compensate with EQ?

The woofer itself, no, but the circuit as measured from the binding posts, yes. I also plugged the ports, which also reduces the bass extension. It started to roll off bellow 70Hz when I measured it outside. It also has a baffle step response.

I have a shelving filter to address the baffle step response, but minimal EQ other than that. I cross it over to my subwoofer at around 100Hz and use Dirac Live for the final tuning. Mostly I have used 8th order filters, but currently I am evaluating the use of 4th order filters.

Yeah, that makes sense. Especially in the midrange you want good dispersion for phase - when it's off it sounds the worst and is most obvious right away IMO.
I kind of like two way designs for this reason - there's just the obvious problem of peak power handling and possibly power response across the upper frequency limit of the lower frequency driver

The Elac's were my first speakers with a concentric driver for the midrange and tweeter. So impressed with the performance of the concentric driver as a point source, I also got a pair of KEF LS60s, which I use in my office. (The boss said no to moving the LS60s into the family room. )

That sounds like a really interesting project - are you going to do those measurements outside?

Yes. At this point the plan is to mount the measurement swivel with the speaker onto my 19ft A-frame ladder, well away from the house. Also, I am contemplating trying to further mitigate the ground reflections by building an A-frame out of two sheets of plywood, covering it with insulation, and placing that between the ladder and the microphone stand. We'll see. I am still thinking about it. The last time I used an 8ft ladder, but ground reflections were an issue. Going to 19ft should reduce the impact of the ground reflections, but I don't know if it will reduce them enough to get good data without using some sort of contraption to deflect/absorb the energy directed toward the ground.

 

[stefanovesa]

If I undersood correctly, the Amir testing protocol of an integrated power amplifier as this one, do not take into account potentiometer added distortion or other detrimental effect of the pot, am I correct? Thanks.

 

[terryforsythe]

If I undersood correctly, the Amir testing protocol of an integrated power amplifier as this one, do not take into account potentiometer added distortion or other detrimental effect of the pot, am I correct? Thanks.

The LA90D has a volume control bypass (which is how I run mine). It is possible he had it set to bypass. You may want to reach out to him and ask him directly.

 

[stefanovesa]

The LA90D has a volume control bypass (which is how I run mine). It is possible he had it set to bypass. You may want to reach out to him and ask him directly.

I cannot use that way because I have 3 sources going to it and only the DAC has variable output.

 

[terryforsythe]

I cannot use that way because I have 3 sources going to it and only the DAC has variable output.

I have not seen any posts herein or comments by other reviewers discussing audible noise or distortion being added by the pot. If it was an issue, I think it would have been brought up by now. But, I have not read all 1000+ posts in this thread.

 

[stefanovesa]

I have not seen any posts herein or comments by other reviewers discussing audible noise or distortion being added by the pot. If it was an issue, I think it would have been brought up by now. But, I have not read all 1000+ posts in this thread.

Agree. Perhaps it is worth considering also that, at least with my speakers, I need to crank the pot until 12 o'clock, so probably to its most linear zone

 

[BeeKay]

Your sources all have XLR (or TRS) out?