Topping Pre90 Review (preamplifier)

[daftcombo]

I am surpriced ...? If this is expensive .what is then cheap? I do not not get anything near this performance for such a price in any hifistore where I live
Most receiverers and stuff with «everything»at the same price is junk

Some Topping DAC are SOTA for 100 euros. I expext same prices for a pre-amp, whuch is more simple design.

 

[pma]

A test to be considered with preamplifiers is crosstalk from other inputs. We don't know whether unterminated inputs are shorted via a resistor, shorted to ground or floating.

An example of crosstalk (channel crosstalk) and CMR measurement, in one. There is only one stereo input, thus only the channel crosstalk is shown. However, the methodology would be the same. To me, CMR of balanced inputs is an important parameter. It tells the user how much the signal ground wire hum/buzz is attenuated (or another common-mode LF interference), especially if 2 class I components are interconnected. However, even capacitive currents in case of class II may create hum/buzz voltage across signal ground wire in the link cable.

Another plot shows an effect of a line transformer to CMR

CMR with and without line transformer

 

[Francis Vaughan]

Amir's stellar THD figure at 4V out is, (according to the dashboard) running into a 200K ohm input.

As a sincerity test the pre should be measured into the same impedance as it itself presents. This could go either way, but what is good for the goose is good for the gander as they say.
It would be most embarrassing if it could not sustain the performance into a low Z load. Trivially just cascade one channel into the other and see how it does.

 

[YSC]

I have a feel we here are being kind of much more picky about this Pre90 and d want Amirm to dig much deeper than other products measured.

But I want to say this is more of a no offense type nit picking, just because how affordable to basically everyone having a job, and that the quality is so astonishing that we demand much more just to expose what is left behind and not perfect at any sense, kind of the geeky requests.

And I do think that even say after extra torture test ran like actualy FR change for high output impedance source which have affected FR, or if it tops out for a low input impedance power amp, it's just a nice small remark at the bottom that: "this is not recommended in such extreme situation, mind your usage" type of remarks. personal suggestion is for if any practical perfect products emerge just do a few extra test to reveal what might limit it?

 

[Atanasi]

if it tops out for a low input impedance power amp

@JohnYang1997 promised that Pre90 is able to source significant power and should work for low input impedance power amps, even to 600 ohms.

 

[PeteL]

I have a feel we here are being kind of much more picky about this Pre90 and d want Amirm to dig much deeper than other products measured.

I think the point is that there is not as much of an history and benchmarking procedure here for pure preamps as there is for dacs and amps, and the performance metric depend on the type of products. I agree that Amir can't measure everything, in all cases it will always be incomplete but gives us a valid comparison, but there is always room for improvement, and no I do not believe that the suggestion that where made are tortured test only exposing extreme use cases. A preamp is a hub, meaning that you can hook it up to various load and sources and versatility might even be more important that pure SINAD.

 

[elevensheep]

so the Lowe

A test to be considered with preamplifiers is crosstalk from other inputs. We don't know whether unterminated inputs are shorted via a resistor, shorted to ground or floating.

Maximum output voltage should be looked at. Amir's test ends at 10V in this review and it appears there is some more voltage swing left in the unit.

Input and output impedance values are also of major significance. Amir's stellar THD figure at 4V out is, (according to the dashboard) running into a 200K ohm input. Hardly a typical input impedance for the following stage power amplifier.

So at one end, we have a super low input impedance and at the other end, we are giving the preamp no load at all! Let's load it down to the typical input impedance of an unbuffered Purifi or Hypex module (4.4K/2.2K unbal), or even 10K. Fair is fair.

what is the typical output value for modern Dacs?

 

[YSC]

so the Lowe


what is the typical output value for modern Dacs?

do you mean output impedance? for D/S dacs I think a lot is in the ~1ohm range, but for discrete R2R like my holoaudio Spring 2 I have 200ohm, that's what limits me when I choose a passive preamp or active pre for my use.

 

[jae]

@JohnYang1997 Great work as usual, I was looking forward to this product after hearing about it from you some time and seeing it recently on L7audiolab

My wishlist for future:

• A product to fill in the void between Motu M2/M4 and RME ADI-2 Pro. Specs at least A90/D90 performance but with ADC/preamp/phantom that should also support insensitive dynamic microphones, which the ADI-2 pro does not do. Make this product larger or double height.
• A more simple AMP/DAC combo (perhaps DX7Pro upgrade with 90-series specs, low output impedance). Bonus if someone compatible with the extender
• A single input, compact, USB-c powered single-mic preamp/ADC with phantom/mute button and gain control
• Power amplifier to compete with Benchmark AHB2/Purifi

 

[Veri]

do you mean output impedance? for D/S dacs I think a lot is in the ~1ohm range.

Depends. Many are >= 400Ω. A line-out is not expected to have a super low output impedance the way head-amps are (thankfully) optimized for nowadays.

 

[Michal]

@JohnYang1997
Is there a low-pass filter and a separating capacitor at the input of the Pre90?

 

[JohnnyNG]

To be fair. Topping Pre90 has excellent measurements and I would say it is the same league with Benchmark HPA4. Only disadvantage is its low input impedance.

Aside from that, Mrs. Lincoln, how did you enjoy the play?

It seems that some people want it to be excellent in all aspects and they want its price as cheap as possible.

I guess the question is how much it would have cost to raise the input impedance to a value not "lower than normal" and how much SINAD it would have sacrificed.

I'm probably buying it anyway, I'm a Topping fan and love my D90. Genius at work there!

 

[YSC]

Aside from that, Mrs. Lincoln, how did you enjoy the play?



I guess the question is how much it would have cost to raise the input impedance to a value not "lower than normal" and how much SINAD it would have sacrificed.

I'm probably buying it anyway, I'm a Topping fan and love my D90. Genius at work there!

that’s what I was interested in also, and even more so about how much more would it cost in both price and size to make it that way. As John said it would require a pair of extra opamp for each channel and considering the no. Of inputs.... I do suspect we will see a much larger unit with double the price at least for that?

 

[Vasr]

As a sincerity test the pre should be measured into the same impedance as it itself presents. This could go either way, but what is good for the goose is good for the gander as they say.
It would be most embarrassing if it could not sustain the performance into a low Z load. Trivially just cascade one channel into the other and see how it does.

You have posted some extremely insightful and informative posts in this thread. Just wanted to acknowledge that effort explicitly.

 

[Cujobob]

I think the point is that there is not as much of an history and benchmarking procedure here for pure preamps as there is for dacs and amps, and the performance metric depend on the type of products. I agree that Amir can't measure everything, in all cases it will always be incomplete but gives us a valid comparison, but there is always room for improvement, and no I do not believe that the suggestion that where made are tortured test only exposing extreme use cases. A preamp is a hub, meaning that you can hook it up to various load and sources and versatility might even be more important that pure SINAD.

A preamplifier is meant to provide a proper load to the power amplifier and control the volume. Many are also hubs with tons of inputs, but that’s never meant it has to be that. For most folks, the DAC would be the HUB these days. External DACs are extremely common now, that hasn’t always been the case.

 

[PeteL]

A preamplifier is meant to provide a proper load to the power amplifier and control the volume. Many are also hubs with tons of inputs, but that’s never meant it has to be that. For most folks, the DAC would be the HUB these days. External DACs are extremely common now, that hasn’t always been the case.

OK, but most external DACS can also can control the volume and provide a proper load. What would be the point of this product if you only have digital sources? "Most folk", it's arbitrary, A lot of us have analog sources, and it is what this product is about. Do you know many preamps, the product, not the topology, that has only a single source?, in this case, it is 2 stock with expansion options so you believe most peoples that will purchase that will strictly plug their DAC in it and only use it as a volume knob? Come on... We have better stuff to do with our money.

 

[bungle]

"Most folk", it's arbitrary, A lot of us have analog sources

I would say that most of us have digital sources. HDMI that is. A few of us have analog sources: a turntable. And some of us have digital sources (excluding the HDMI ones).

 

[F1308]

Talking about sources...Can I hear my headphones and the loudspeakers at the same time for an A/B comparison ?

 

[PeteL]

I would say that most of us have digital sources. HDMI that is. A few of us have analog sources: a turntable. And some of us have digital sources (excluding the HDMI ones).

Different need for different folks I guess. I don't have the sales data, and honestly I don't even have an opinion on this. I'm not sure exactly what is the debate here, If the point is that most people don't need a product like that, I won't disagree with this. This review is for those who do. The only electronic product that most people own is a cell phone.

 

[elevensheep]

do you mean output impedance? for D/S dacs I think a lot is in the ~1ohm range, but for discrete R2R like my holoaudio Spring 2 I have 200ohm, that's what limits me when I choose a passive preamp or active pre for my use.

Yes that’s what I meant. Sorry about the typo.
So if only intend to use a DAC as a source, the low impedance isn’t really an issue then right?