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New Amp to Replace Topping Pa5

BoredErica

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Since Topping Pa5 nuked itself and Topping probably can't guarentee a fix that won't have the amp failing in the same way again, I don't think I want to pay shipping to Topping to get it fixed. (This is a little sad given allegedly the cause for early failures was discovered.) Now I need a new amp. Setup is: Computer -> Motu M4 -> Topping Pa5 -> Ls50 Meta. Also have a Rythmik F12se sub connected to the Motu M4. The concern once again is noise. Ideally no noise could be heard with ear at tweeter but I can settle for inaudible noise at a very quiet room at 20in from tweeter if I feel like I must. Volume adjustment is done digitally. With pa5 due to the low gain, I felt noise was inaudible w/ ear at tweeter. (19db gain. I could turn my M4 all the way up past 5v output.) I live in US and I need everything in the chain to be balanced.

Options:
Buckeye Purifi: $1037 + $45 cables or $12 TRS->XLR Converter
Motu M4 caps out at 5.24v output so can't hit the spec for low gain but I assume that's ok given my low power requirements. 20.5dB/4.02Vrms (Medium), 15.5dB/7.16Vrms (Low). On bright side, 15.5db gain is good and Purifi is not known to have longevity issues despite being widely used. Anyways, since 19db gain was OK, 20.5 should also be OK. So this should be perfect ignoring cost.

Topping LA90 Discrete: $812
Buying from APOS so I don't have to send defective unit to China. 19.25db/2.2v high, 9.3db/7.3v low. This is like a cheaper Purifi in that noise can't be an issue. But it's Topping, so... uh... Well, at least original LA90 has been out for over a year without a thread of people complaining. This is the LA90 Discrete though.

Buckeye nc252MP: $545 + $45 cables or $12 TRS->XLR Converter
There is a chance I would want a preamp to fix the 25.5db gain which is too high. But what preamp would that be? I have a Mayflower o2+odac combo but I don't think it works as a preamp. Even w/ preamp, nc252MP should still be cheaper than Purifi. [-10db XLR attenuators also an option? $31 cost. Adds bulk and attenuates by fixed amount, but cheap and are unlikely to break.]

Topping Pa7: $465
I don't like this option. Linearity is a little suspicious. It's like a more expensive, less well-performing Pa5 that hopefully has Pa5 issues fixed. It's the cheapest though.

My assumption is if an amp's gain is low, the voltage the amp requires increases. If my M4 can't outfit high enough voltage, what happens is I don't get full max specced power from the amp but apart from that nothing funky/crazy happens. Another idea: Wait until Buckeye has a sale and live with 1 channel audio. I lived over a year with 1 channel, surely I can survive several more. ...right?

Most of the noise comes from dac due to gain of the amp, so if I can reduce gain somehow I believe this will reduce noise. If I can't have an amp w/ adjustable gain, then I think I can use a 2 channel preamp to functionally reduce the gain on a fixed gain amp. Noise comes from mains and not the sub. Volume knob on Motu M4 is digital and suboptimal. I want to keep that at max. If I have an amp w/ 25db gain and I want 15db, the idea is the preamp would functionally act as -10db gain and -10 + 25 = 15db. Correct me if I'm totally wrong. :)

Power requirements I assume are low. I still have no idea how to actually measure how loud my music is even with a calibrated mic. Years ago I used an A weighted cheapo SPL meter and got 70-75 at high end. I do have a sub. Let's assume 15-20db DR tracks? I think that is safe. 5-10db EQ headroom. Sitting up to 6ft away. LS50 Meta. I think even LA90 will suffice.

So: Which amp to get? If nc252mp and noise is audible, how to attenuate signal before it hits the amp? I don't need a headphone amp. Or... send Pa5 to china and pray Topping fixes it. (Some say after repair attempt it was fine, some say it broke again.) I'm going to need therapy if after going through noise-induced hell and jumping into a failing amp, the next amp breaks in 5 years. Is it unrealistic to expect 10yr operation?
 
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maty

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Hypex NCx500 Amplifier, 2-channel $1,095

[ - The optional configuration uses our Buckeye buffer stage (OPA1612 OP Amp), allowing for Low/Med/High gain settings via toggle switches on the rear. This configuration is best for use in setups with a source/DAC capable of higher pre-out voltages. ]

Motu M4 -> NCx500 buffer gain: Med
 

Colonel7

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Since Topping Pa5 nuked itself and Topping probably can't guarentee a fix that won't have the amp failing in the same way again, I don't think I want to pay shipping to Topping to get it fixed. (This is a little sad given allegedly the cause for early failures was discovered.) Now I need a new amp. Setup is: Computer -> Motu M4 -> Topping Pa5 -> Ls50 Meta. Also have a Rythmik F12se sub. The concern once again is noise. Ideally no noise could be heard with ear at tweeter but I can settle for inaudible noise at a very quiet room at 20in from tweeter if I feel like I must. I do some digital volume control too. With pa5 due to the low gain, I felt noise was inaudible w/ ear at tweeter. (19db gain. I could turn my M4 all the way up past 5v output.)

Options:
Buckeye Purifi: $1037
Motu M4 caps out at 5.24v output so can't hit the spec for low gain but I assume that's ok given my low power requirements? 20.5dB/4.02Vrms (Medium), 15.5dB/7.16Vrms (Low). On bright side, 15.5db gain is good and Purifi is not known to have longevity issues despite being widely used. Anyways, since 19db gain was OK, 20.5 should also be OK. So this should be perfect ignoring cost.

Topping LA90 Discrete: $812
Buying from APOS so I don't have to send defective unit to China. 19.25db/2.2v high, 9.3db/7.3v low. This is like a cheaper Purifi in that noise can't be an issue. But it's Topping, so... uh...

Buckeye nc252MP: $545
There is a chance I would want a preamp to fix the 25.5db gain which is too high. But what preamp would that be? I have a Mayflower o2+odac combo but I don't think it works as a preamp. Even w/ preamp, nc252MP should still be cheaper than Purifi.

Topping Pa7: $465
I don't like this option. Linearity is a little suspicious. It's like a more expensive, less well-performing Pa5 with more power that hopefully has Pa5 issues fixed. It's the cheapest though.

The cables I have are TRS for pa5 but all options but Topping's require new cables ($30) or converter ($13?). TRS->XLR converters are fine, right? Also, my assumption is if an amp's gain is low, the voltage the amp requires increases. If my M4 can't outfit high enough voltage, what happens is I don't get full max specced power from the amp but apart from that nothing funky/crazy happens. Last idea: Wait until Buckeye has a sale and live with 1 channel audio. I lived over a year with 1 channel, surely I can survive several more. ...right?

Power requirements I assume are low. I still have no idea how to actually measure how loud my music is even with a calibrated mic. Years ago I used an A weighted cheapo SPL meter and got 70-75 at high end. I do have a sub. Let's assume 15-20db DR tracks? I think that is safe. 5-10db EQ headroom. Sitting up to 6ft away. LS50 Meta. I think even LA90 will suffice.

So: Which amp to get? If nc252mp and noise is audible, which preamp? I don't need a headphone amp, any preamp with it is useless to me. Or... send Pa5 to china and pray Topping fixes it. (Some say after repair attempt it was fine, some say it broke again.) I think I'm going to need therapy if after going through noise-induced hell and jumping into a failing amp, the next amp breaks in 5 years. Is it unrealistic to expect 10yr operation?
Are you sitting at a desk near field or less than 6 feet away? If that’s the case I’d go with https://www.audiophonics.fr/en/powe...lass-d-stereo-ncore-2x125w-4-ohm-p-12756.html
Edit: and rather than torture yourself with mono if you want to save money in the meantime get a Fosi B20A Pro
 
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staticV3

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Reduce Reuse Recycle
 
OP
BoredErica

BoredErica

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Hypex NCx500 Amplifier, 2-channel $1,095

[ - The optional configuration uses our Buckeye buffer stage (OPA1612 OP Amp), allowing for Low/Med/High gain settings via toggle switches on the rear. This configuration is best for use in setups with a source/DAC capable of higher pre-out voltages. ]

Motu M4 -> NCx500 buffer gain: Med
Yes, that is also an option. Price is the same as Purifi however.

Are you sitting at a desk near field or less than 6 feet away? If that’s the case I’d go with https://www.audiophonics.fr/en/powe...lass-d-stereo-ncore-2x125w-4-ohm-p-12756.html
Thanks for suggestion. I require TRS/XLR, balanced only. But I will spend more time investigating lower power ncore options.


Reduce Reuse Recycle
I posted in the thread several days ago. I have no idea how to do the repair neither do I have the tools to carry out the repair.
 

staticV3

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I posted in the thread several days ago. I have no idea how to do the repair neither do I have the tools to carry out the repair.
As far as I can tell, the only tools required are screwdrivers etc to open the enclosure.
Then you just plug out the stock module and plug in the replacement module, which you can order from PCBway or similar.
No soldering required.
 

NTK

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As far as I can tell, the only tools required are screwdrivers etc to open the enclosure.
Then you just plug out the stock module and plug in the replacement module, which you can order from PCBway or similar.
No soldering required.
I am pretty sure the module is soldered to the PCB. The repair would require desoldering the original potted module, and solder back the replacement module. See picture (second from top) in post:
 

staticV3

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I am pretty sure the module is soldered to the PCB. The repair would require desoldering the original potted module, and solder back the replacement module. See picture (second from top) in post:
I stand corrected.
I'd assumed the female connector was of this type, where the module is held in by friction:
PXL_20230506_152445826__01.jpg
In hindsight, it was a stupid assumption.
 

NTK

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The idle noise of PA5 from Topping's spec is 16 μV (A-weighted).

PA5.png


The idle noise from the Hypex NC252MP is 30 μV (unweighted, which will give a worse number than A-weighted). Its noise is therefore about 6 dB (worst case) higher than the PA5. The 6 dB number also corresponds to the double distance sound attenuation. Therefore, for example, if you can't hear noise from the PA5 at 4 inches, you shouldn't hear noise from the NC252MP at 8 inches.

nc252.png
 

mdsimon2

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I think it is highly unlikely that you have audible hiss with a NC252MP. I'd get a Buckeye or Audiophonics NC252MP and see how it goes. If it is too noisy get a 10 dB XLR attenuator. That will give noise performance slightly better than the PA5 and you will still be able to drive the NC252MP to full power.

Michael
 

sejarzo

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I'm confused by your comment about needing a preamp if the gain of the NC252MP is too high and you use digital volume control anyway.

Why would you use an active preamp to reduce the signal level between the M4 and amp rather than use a combination of digital control and the M4 output pot?
 

mdsimon2

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I'm confused by your comment about needing a preamp if the gain of the NC252MP is too high and you use digital volume control anyway.

Why would you use an active preamp to reduce the signal level between the M4 and amp rather than use a combination of digital control and the M4 output pot?

The pot on the M4 is still digital volume control and it does not operate on all channels which makes it useless if you have say a main / sub x-over implemented in software DSP.

Michael
 

notsodeadlizard

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"
Since Topping Pa5 nuked itself... I don't think I want to pay shipping to Topping...

Options:
...
Topping...
"

Well, this kind of logic is not forbidden.

PS
I haven't heard of burning amps in a long time, a very long time. It turns out that this can be achieved.
 

sejarzo

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The pot on the M4 is still digital volume control and it does not operate on all channels which makes it useless if you have say a main / sub x-over implemented in software DSP.

Michael

OK, but how does a 2 channel preamp fix that problem?

The OP suggested the LA90 as a solution, but it doesn't have any line level output.
 

sejarzo

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The other thing I don't get here is the assumption that low gain at the power amp stage necessarily means low noise.

Idle noise is a function of the amp stage. Sticking a preamp or buffer to adjust signal level in front of the stage that creates the noise doesn't reduce it.

If inserting a -10 dB attenuator in front of the power amp decreases noise, then the noise is coming from the upstream device.

What am I missing here?
 

Doodski

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I posted in the thread several days ago. I have no idea how to do the repair neither do I have the tools to carry out the repair.
I would not service the unit for Topping either. Topping should service them and do it properly and no mickey mouse club stuff! :D
I stand corrected.
I'd assumed the female connector was of this type, where the module is held in by friction:
View attachment 283869
In hindsight, it was a stupid assumption.
You are a wealth of info on most all days so don't go hard on yourself.
 

brandonhall

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@BoredErica I'm running the Audient ID14 MKII into the SMSL DA9. I have the Audient passing through at full power and use the volume control on the SMSL DA9. It's not perfect but it's the best solution I've found which allows me to use a remote and an audio interface.
 
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DMill

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I’m fairly certain if I’d been bitten by a faulty Topping product, I’d not be in any rush to replace it with another Topping option. Even though there is nothing to say that their other offerings have any issues. I’d personally choose Buckeye. The level of support he offers based on what I read on this site is commendable.
 

JeremyFife

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Sounds like you have a preferred budget of < 500$ USD? Any other preference, like small form?
How does something like the Sabaj A20a fit?
Newer designs like these don't have much track record yet (doesn't mean there will be problems) so your 10yr trouble-free wish is tricky to fulfill.
Plenty of 'traditional' integrated amps but they are less likely to offer balanced inputs.
Do you need the Motu ... the AUDIOPHONICS DA-S125NC measures pretty well (also new though)
 
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