Topping pre90 - how to test?

[tonapo]

Hi there,

I sold a Topping pre90 last year which was working perfectly in my experience, I used it with a topping d90 DAC and NAD M23 power amp connected via xlr. Anyway, I changed to a different pre-amp, so I sold the Topping pre on ebay. Unfortunately the buyer got in contact a few days later to say he was experiencing a hissing sound when using the Topping pre90, both with XLR and phono connections. I had not experienced any issues previously but accepted the return of the unit. I then spent a short amount of time trying to recreate the issue. I tried with my desktop set-up with some Adam speakers and using a spare Topping D10 DAC but I could not reproduce any issue with the pre90.

I have not got around to testing any further and the pre90 has sat in my cupboard since last year. Are there any tests a non-technical person could do, to see if there is a fault somewhere with the unit? I might try plugging into a few units around the house, and see I can re-produce the issue. As it is I am not comfortable selling, but it is not being used which is a shame.

Thanks for reading.

 

[RayDunzl]

Maybe rhe buyer just didn't want it.

 

[DVDdoug]

All active analog electronics generate SOME noise. Whether it's audible or not depends on the sensitivity of your speakers (or headphones), the amount of gain and the volume control setting (including the following stages like a power amplifier), how close you are to the speakers, and other noise in the room, etc.

 

[Roland68]

All active analog electronics generate SOME noise. Whether it's audible or not depends on the sensitivity of your speakers (or headphones), the amount of gain and the volume control setting (including the following stages like a power amplifier), how close you are to the speakers, and other noise in the room, etc.

There's probably no problem, so you can't test anything.
- As @RayDunzl said, the buyer might not have wanted it. Unfortunately, blatant lies are enough on eBay to force a return.
- He did indeed have a problem, and it was due to incompatibility between the devices, grounding issues, ground loops, etc. Not a PRE90 problem.
- He already had a hissing noise in his system and thought he could solve it with the PRE90. Not a PRE90 problem either.
- He has some high-efficiency horns, e.g., at 109 dB, which make background noise audible, which otherwise doesn't matter.
If you have absolutely no problems, you can sell the PRE90 with a clear conscience.

Maybe you could just put it up for pickup at a local classifieds site and show it off.

 

[tonapo]

Thanks for the replies.

Yes, my first thought at the time was the buyer just did not want it. I was worried about passing on a potential defective unit though in my use-case it appears not to be. Its annoying. Oh well, I suppose I should try selling again then...

 

[Zinda]

Thanks for the replies.

Yes, my first thought at the time was the buyer just did not want it. I was worried about passing on a potential defective unit though in my use-case it appears not to be. Its annoying. Oh well, I suppose I should try selling again then...

What are you asking for it? Im deciding on a pre at the moment and picked up a topping DX5II. It works fine with zero noise, but I don't need the headphone amp and I'm not a fan of the limited inputs. I haven't looked at the 90 yet but I'm interested in it. One more thing I don't care for is the need to use my computer to set up the eq. I wish they had a phone app to do that.

I'm still doing some tests but I'm detecting a slight loss in realism while it. I have been running my dbx dual 31 band eq as a pre before I got the topping, mostly got it so I can connect my tv to my system that consists of an active xover connected to a high pass Carver Sunfire 300w x2 and a low pass connected to a QSC GX5, powering a set of ML Prodigy's that I have bypassed the internal xover. I did that to fix the bass problems due to MLs bad decision of building in a room mode correction circuit that's is not able to be switched off. Their special circuit disrupts the projection of the bass toward the listening position.

Bypassing the xover network has done wonders for their overall sound. I was getting absolutely perfect sound playback while using my phones AUX output hardwired directly to the EQ and with the topping, I'm forced to use the Bluetooth connection. Now I know using the Bluetooth with the same phone but having it be received by a very inexpensive audio interface made by Pyle that cost $25 had no issues with degradation of sound. I've seen this same thing happen when I tried a MiniDSP (and several other DSPs made by Behringer and a few Brazilian DSPs while using a cable), all 5 I tried had the same loss of fringe details.

That's not acceptable to me and giving me the convenience of a remote and connecting my TV hasn't been great either. I actually prefer the TVs tiny speakers over the pre, I'm forced to use the toslink output from my TV which removes any TV sound enhancments and I can't use the TV volume on it's remote which makes me change channels on one remote and the volume on the other. But there's such a degradation of sound with the TV that it's really useless to use it.

I truly expected a vastly improved sound from the TV but the limited inputs on the topping have forced me to use only 1 option which makes the TV sound have huge swings in audio, can't hear it, then way too loud without changing the volume. And this is just while watching OTA TV, commercials are way loud and the sound varies so much during each show I gave up after a day of using it. Needless to say it's going back.

I can't say you're buyer experienced this same thing but I do offer another viewpoint on why I dislike mine.

I don't understand why car audio has been able to sell head units (for the last 30 years} that have eqs, xovers, play different digital sources and have a built in tuner and can sell it for under $100 and anything geared toward home stereo would be considered a $10k piece if it did all that, like it takes NASA to put it together? But the reality is, there isn't even anything made that can do it for home audio at any price. Even home DSPs have nothing over car DSPs I almost bought 30 years ago, same terrible UI with minimal buttons that need repeated pushes to page through settings and clunky chunky settings that are minimized by limited memory and computing ability.

I'm also not a fan of tiny things, tiny screens that can't be seen from 10ft away makes it useless unless it's right next to you. If I do that, then I can't connect it to my TV at all since I'd need a 30foot long optical cable which I doubt they make plus the price would be ridiculous, I'm better off with my EQ as it is next to me using 30 foot XLR cables, which are cheap and work perfectly,

I'm curious if you heard any degradation in your system before and after using the tiny topping stuff or if you've tried listening without anything in the chain?

I understand the idea of trying to keep the signal digital but I've not found this to not be advantageous at all in my system, the DAC has always striped away the fringe details in every situation other than the one cheap Bluetooth device I bought to connect a test mic to a computer and I have ditched that idea for a good phone app which is far easier to use and offers the same or better results. I sold the mic but kept the interface. I can't believe that Pyle has a better DAC for $25 than the topping, but I know what I'm hearing is real.
Ty for reading.

 

[Kal Rubinson]

The Topping Pre90 has a relatively low input impedance (2k ohms balanced, 10k ohms unbalanced) and sources with a relatively high output impedance may struggle with that.