Topping Pre90 Review (preamplifier)

[bungle]

Um, Benchmark?

HPA4 paired with DAC3 paired with HDMI switch with audio extractor. Three remotes. Costs a lot.

^^^ Or ADI?

Very limited inputs. So e.g. ADI2 + Pre90 + HDMI switch with audio extractor. More affordable. Yet three remotes.

Trinnov (yes, but breaks the bank).

The Pre/Pros comes close to what I am looking for:
Anthem AVM70 or 90, Anthem STR Pre (with reservations), Yamaha CX-A5200, NAD 658 (with HDMI expansion), NAD M17v2i, NAD M12.

But they have severe performance issues or they cost a fortune. Take any of that as base, reduce design to stereo, remove DTS/DD etc. codecs (just plain PCM/DSD), remove room correction, add AES/EBU, add USB (optional)...

Basically make a good and transparent Digital / Analog source selector with volume control and remote with say 3xRCA inputs, 1xXLR Stereo input, 2xS/PDIF optical, 1xS/PDIF coax, 4xHDMI inputs and 1xHDMI output (with ARC support), 1xUSB (optional), 1xAES/EBU input and 1xAES/EBU output, 1xStereo XLR output. Actually I don't care much if it only does ADC or DAC to all the sources and just have either digital (AES/EBU) or analog (XLR output).

If you need EQ you just connect that to say ADI-2. If you need room correction, just connect that to MiniDSP DDRC, DSpeaker Antimode or use Genelec SAM monitors, and so on. I might be the the only one dreaming of such, :-(.

 

[pma]

Unfortunately there is no mechanism in Audio Precision to measure the input impedance of the device being driven. I know, shocking but true. I need to build a fixture to measure it. It is a simple one but I don't know that I have enough XLR connectors to make one and at any rate, it takes time. Really, I don't have a reason to doubt the 2 k ohm spec from the company.

You are not supposed to believe company data, you are supposed to measure and bring facts. The input impedance is one of the basic parameters.

Either company data (2k) or your measurement is wrong. If you say you measured 4V with 40 ohm generator impedance and 3.6V with 200 ohm generator impedance, then the load impedance was 1.44 kohm. This is the fact and I hope you can calculate it as well, or to use a simulator. Once again, company data or your measurement is wrong.

 

[Guerilla]

CAN AN EVENTUAL IMPEDANCE MISMATCH BE MITIGATED BY MANIPULALING INTERCONECT WITH A COMPONENT? - OR SOME?

Cheers!

 

[daftcombo]

I do not and that is a miss.

You could throw a miniDSP in-between.

 

[JohnYang1997]

You are not supposed to believe company data, you are supposed to measure and bring facts. The input impedance is one of the basic parameters.

Either company data (2k) or your measurement is wrong. If you say you measured 4V with 40 ohm generator impedance and 3.6V with 200 ohm generator impedance, then the load impedance was 1.44 kohm. This is the fact and I hope you can calculate it as well, or to use a simulator. Once again, company data or your measurement is wrong.

Just use the 4V output 40ohm measurement alone. Output from AP is 4V. Output from pre90 is 3.928V. This gives 2.1-2.2Kohm for the input impedance. Not far off from 2K. Just use actual measured number, not the roughly described ones for calculation ffs.

 

[misterdog]

@JohnYang1997 Is it possible to assign different gain structures to different inputs. Can the input using RCA from say a TT be assigned more gain so as to match the XLR input level from a DAC ?

 

[JohnYang1997]

@JohnYang1997 Is it possible to assign different gain structures to different inputs. Can the input using RCA from say a TT be assigned more gain so as to match the XLR input level from a DAC ?

You can save volume for different inputs or outputs (but not the same time).

The gain is automatic following the volume setting.

The outputs(rca and XLR) when both on at the same time, can't be set at arbitrary level.XLR is always 2*RCA level.

 

[kopczas]

Note that I had to put the A90 in medium gain to match the output of the Pre90. In its low gain mode it would likely do better. But even as it is, its performance is still excellent.

Except for the remote, I don`t have to move from A90 if differences are that insignificant.

 

[PeteL]

Unfortunately there is no mechanism in Audio Precision to measure the input impedance of the device being driven. I know, shocking but true. I need to build a fixture to measure it. It is a simple one but I don't know that I have enough XLR connectors to make one and at any rate, it takes time. Really, I don't have a reason to doubt the 2 k ohm spec from the company.

Thank you, no reason to doubt neither, just couldn't find that spec anywhere in the product info link from topping.

 

[JohnnyNG]

Such a shame. I had it in my cart at Apos before even finishing the first post then got to the input impedance discussion. I always check this spec due to my (gasp) tube phono stage. Pretty useless for that, although not an issue for my wonderful D90.

 

[pma]

Such a shame. I had it in my cart at Apos before even finishing the first post then got to the input impedance discussion. I always check this spec due to my (gasp) tube phono stage. Pretty useless for that, although not an issue for my wonderful D90.

Yes, that's why we need the complete set of standard parameters and not only the cherry-picking.

 

[AnalogSteph]

The tube phono stage would probably have unbalanced outputs though, wouldn't it? Then you'd be looking at a 10k input impedance. Unless the thing has an OTL plate output (that's the kind of stuff that does tend to require 50-100k), that should generally be acceptable.

 

[HDavidson]

It now remains to combine these three devices D90, A90, Pre90 into a single standard of 43 cm. I will agree to pay in advance.

like that

 

[Matias]

Now it remains to combine these three devices D90, A90, Pre90 into one 43 cm standard.
View attachment 98661

With variable gain too. Perfect.

 

[JohnnyNG]

The tube phono stage would probably have unbalanced outputs though, wouldn't it? Then you'd be looking at a 10k input impedance. Unless the thing has an OTL plate output (that's the kind of stuff that does tend to require 50-100k), that should generally be acceptable.

Thank you, yes, RCA out. It's got a 500 Ohm output impedance and recommended 10KOhm or higher for input. Just feels like I'm cutting it close if it's not quite the 10k claimed. Aside from that the Pre90 is exactly what I'm looking for short of an LA4.

 

[kopczas]

I will agree to pay in advance.

And button for every input ?? or it`s to much ?

 

[xema]

It now remains to combine these three devices D90, A90, Pre90 into a single standard of 43 cm. I will agree to pay in advance.




View attachment 98664
like that

LOL……but your pic is too wide. Single a/p/d90 are about 0.5u wide(22cm), so double the width will be just right.
————————
Oh I miss measured, your pic is allright

 

[HDavidson]

So, under the 43cm standard, JohnYang can start thinking about a power amplifier

 

[HDavidson]

LOL……but your pic is too wide. Single a/p/d90 are about 0.5u wide(22cm), so double the width will be just right.

Check it out exactly 43cm. Optical illusion.

 

[Labjr]

I don't care for the compact size of this preamp and having to stack components. However, it's a start. I hope some of these Chi-fi companies will make components with more traditional form factors.