Topping Pre90 Review (preamplifier)

[rvsixer]

As would I. I'm not the one saying it doesn't work.

You did post its a shame Amir did not test SE-BAL, and maybe someone else has.

Since someone else has tested this, and that someone else was already mentioned prior to your post...I guess I mistakingly assumed I, like @ZestClub, that there was doubt as to Topping's product spec/test results. Sorry if I misinterpreted.

 

[Jimbob54]

You did post its a shame Amir did not test SE-BAL, and maybe someone else has.

Since someone else has tested this, and that someone else was already mentioned prior to your post...I guess I mistakingly assumed I, like @ZestClub, that there was doubt as to Topping's product spec/test results. Sorry if I misinterpreted.

No probs. Just meant it would be nice to point Zestclub to third party proof it works per specs. If there was a design flaw regarding se in xlr out it would have been pointed out well before now. So either something broken or user error.

 

[Kal Rubinson]

JA comments: "The maximum gain at the unbalanced outputs was the specified 10dB for both the balanced and unbalanced inputs; the maximum gain at the balanced outputs was the specified 16dB for both types of inputs."
His full measurements of the Pre90 are here: Stereophile Pre90

 

[dped90]

This page is very helpful telling what you can and cannot achieve with balanced and unbalanced lines. https://audiointerfacing.com/balanced-audio-cables/

But if you really want to learn what’s going on (or not, depending on the actual circuit design, which Topping and many brands won’t disclose) inside preamps or basic line stages you need to get learn some basic electronics. Here is the basic math which expresses the amplifying actions of a differential input stage (possibly of the Topping Pre90) of preamp or line stage, be that stage in IC chip form or built with discrete parts. The math there also expresses the common mode noise rejection action-which is only possible with a balanced (not single-ended) line feeding a diff amp stage.
https://toshiba.semicon-storage.com...urpose-of-using-a-differential-amplifier.html

For those who have a basic understanding of voltage divider circuits and (electron and hole) current flow in bipolar (npn or pnp) or FET (n channel or p channel) transistors, here’s good explanations of the circuit action in a discrete differential input stage; may see things easier by scrolling down to the discrete diff amp circuit, where waveform phase reversals via transistor voltage and current interactions are also shown. https://electronicscoach.com/differential-amplifier.html

https://ecstudiosystems.com/discover/textbooks/basic-electronics/amplifiers/differential-amplifiers/

Very good additional information here https://sound-au.com/project07.htm, but better so fleshed out here where those last two links better touch on the previously stated diff amp’s unique capability to reject noise of equal amplitude (voltage)-hence the need for a balanced line where both wires have equal impedances-when present to both the diff amp’s inputs. https://audioxpress.com/article/JFETs-The-New-Frontier-Part-2 and https://instrumentationlab.berkeley.edu/Lab5

Btw, another debate you may encounter the old (though now sensibly settled) debate between discrete vs. Op-amp fabricated diff amps. https://www.audiosciencereview.com/...rk-description-made-me-wondering.39816/page-4 No sweat these days, as chip fabrication technologies are loads more advanced than they were just ten years ago.

 

[Gibsonian]

Any way to use this preamp and the input extender to have a tape loop to insert a tone control/equalizer?

 

[staticV3]

Any way to use this preamp and the input extender to have a tape loop to insert a tone control/equalizer?

You can do
Source->Tone Control->Pre90+Ext90->Amp
or
Source->Pre90+Ext90->Tone Control->Amp

But an internal loopback is not possible with the Pre90+Ext90.

 

[Gibsonian]

You can do
Source->Tone Control->Pre90+Ext90->Amp
or
Source->Pre90+Ext90->Tone Control->Amp

But an internal loopback is not possible with the Pre90+Ext90.

Thanks. Not sure if number 2 would work as I don't know maximum input for my tone control but one would work fine but then you are stuck with using tone control with one source or unplug and plug situation ongoing. A feature (lack of actually) that may likely keep me from purchasing the Pre90

 

[Jimbob54]

Thanks. Not sure if number 2 would work as I don't know maximum input for my tone control but one would work fine but then you are stuck with using tone control with one source or unplug and plug situation ongoing. A feature (lack of actually) that may likely keep me from purchasing the Pre90

Put a switch box between multiple sources and the eq box?

 

[tuannguyetxm]

is there a difference in sound quality at high and low volume ? thanks

 

[ameerm]

I owned this preamp years ago and sold it because of the horrible remote. Now i have a use case where i could use this again.

Has the remote improved at all over these years?

 

[Rhamnetin]

I owned this preamp years ago and sold it because of the horrible remote. Now i have a use case where i could use this again.

Has the remote improved at all over these years?

I don't think there have been any design changes. I got mine in Dec 2023 and I still have to precisely point it at the device, and repeated taps on the volume control instead of holding it works best. My Topping A70 Pro is no different and uses the exact same remote, so I don't think Topping's remote control design has changed over the years.

 

[lordhumungous]

I owned this preamp years ago and sold it because of the horrible remote. Now i have a use case where i could use this again.

Has the remote improved at all over these years?

No, but I control it with a cheap BroadLink WiFi hub instead.

 

[theREALdotnet]

I owned this preamp years ago and sold it because of the horrible remote. Now i have a use case where i could use this again.

Has the remote improved at all over these years?

The latest version of the D90 DAC appears to have a Bluetooth remote, but I doubt this will ever make it into a purely analog device like the pre90.

 

[tuannguyetxm]

Is there any difference in sound quality at different volume levels (ex: 0db and -20 db)

 

[JohnnyNG]

None.

 

[Sokel]

Is there any difference in sound quality at different volume levels (ex: 0db and -20 db)

Just convert db>V or vice versa and you have your answer:

 

[tim5]

Ηi!.Can i connect these pre, with my topping E30,and Benchmark AHB2?Thanks!

 

[Rhamnetin]

Ηi!.Can i connect these pre, with my topping E30,and Benchmark AHB2?Thanks!

Yes.

 

[tuannguyetxm]

Just convert db>V or vice versa and you have your answer:

View attachment 351007

That mean same sound quality and dynamic,bro, i do not understand about the chart

 

[maudio]

Forget the word balanced and focus on just input and outputs. You absolutely can input an RCA source into the Pre90 and it can be output via the XLR outputs. Other than output level (I assume XLR out should always be 6dB more than RCA out) they should sound the same. That isnt what @maudio is reporting.

I assume @maudio has selected the right input and output options via the dials/ remote. Something is definitely wrong if the output level out of the XLRs is noticeably less than the RCA out. Checked all your connections? If you have both RCA and XLR out connected to the same amp is there a noticeable drop in level at the same volume level on the Pre 90 when you switch from RCA out to XLR out (and obviously select the relevant input on the power amp? I would test this at quite low levels in case you get a big jump from one to the other. What level on the Pre90 do you need to use for RCA out and XLR out to get the same perceived volume out of the speakers .I would have thought like you that the XLR output should be higher so you would turn that down compared to RCA output.

What is the poweramp by the way?

Thnx to all, although still bit confused, Topping says it converts, and for @ZestClub and me doesnt seem to work.

Yes i tested it, and it is not just a drop in dB but RCA in/XLR out sounds lot more dynamically constricted. Night and day to RCA all the way.
It makes me concerned if the amp's XLR input is ok. This amp has RCA/XLR switch and I actually 1st tried Pre90 XLR withouth switching to XLR on the amp. Thinking back it sounded similarly bad. With the XLR switch on amp it sounds bit better, more depth, but kind of too much - all is somehow quite in the background but bit more noisy than RCA.
I am about to sell the amp since i can't really test it cos I only have Pre90, and just sold the XLR cables today. (DIT) Ok i just ordered standard Amazon XLR to check what is the diff.

Someone asked about the remote - i had a (black) Pre90 before and sold it, remote was really bad, this Pre90 one is silver and remote is much better, the angle is greater compared to the previous one, although still not perfect, but i doubt this depends on the color of the Preamp