Topping A70 Pro HP & Preamp Review

[Yersinia Bestmate]

I suspect it is because:

• The A70 Pro's output gain is +6dB on the XLR vs RCA, so the volume towards your speakers is twice as strong as the signal the subwoofer. That may or may not be the same as from the NAD, but I suspect your NAD took care of ensuring volume amplification levels were matched between what it sent to the floor speakers vs the subwoofer.
• The A70 Pro is now sending the full audio frequency towards the floor speakers, including low frequency below the cutoff that would have been applied by the NAD. So anything in the range that your floor standing speakers can produce is now being added (at perhaps 2x the volume) to whatever your subwoofer is producing (at only 1x the volume). For example, the bass in the 50Hz. And the stuff in the subwoofer below 35Hz (which is below what your floor speakers do) is potentially only coming through at half the volume (i.e., 0dB gain vs. +6dB gain) relative to the volume coming from your floor speakers.

Thanks for your reply!

There was no high-pass filter in my ancient Nad for the main speakers so that cannot be the case, ie. the full frequency range went to the main speakers. Moreover, I cranked up the sub's gain a fair bit trying to match the volume difference between xlr and rca outputs.

I just measured the response and there was a 20db mountain at 55Hz and -15db deep canyon between 20Hz and 45Hz, centered at 35Hz. Perhaps there's something wrong with my sub. It used to get mono signal from the Nad, now it recieves stereo signal from the A70pro (the sub has stereo in, of course). It's an old sub, from around 2005 I think. It's been recapped and worked like a charm until this upgrade. I'll try to get a stereo to mono cable tomorrow and see if it helps. Weird stuff indeed.. and frustrating.

edit: elaborated the -15db canyon anomaly.

 

[WillBrink]

Would make a great pre amp with some good active speakers too. If it had room correction as MiniDSP does, would be a no brainer for me at some point.

 

[huts]

Got one of these to replace my Topping L50 as a headphone amp which I enjoyed over the years. Loving the additional I/O options and UI. Power is amazing, can drive -7.5db EQ'd HD800s with clarity and power. Also did a A/B test with my old amp and it sounds so good I'm pretty sure something in the L50 burnt out. Sounds shrill and scratchy in comparison, funny what you get used to as something degrades over time.

 

[SubtleOrc]

I too have a similar problem. I am using d70 pro octo -> a70 pro -> pa7+ connected with XLR and 12V trigger.

In my case, a popping sound comes from both speakers when the power is turned on, and a popping sound comes from the right channel when I switch between headphones and speakers using the remote control. And there is a small pop sound periodically from the right channel.

Topping has determined that the product is not normal and will be exchanging it.

I have this issue as well. For me it only happens when volume is below -30 DB with my XLR output. I think the A70PRO has issues at these low volume levels. I noticed on your pics there you were at -50.

Did you have the same issue with your replacement unit?

 

[Yersinia Bestmate]

I have this issue as well. For me it only happens when volume is below -30 DB with my XLR output. I think the A70PRO has issues at these low volume levels. I noticed on your pics there you were at -50.

Did you have the same issue with your replacement unit?

How long have you had the unit and did it have that snapping issue out of the box or did it appear later?

 

[EddNog]

...You can buy a passive switched relay volume control from eBay for £50 or less...

Not with a remote control you can't.

-Ed

 

[Ken Tajalli]

Not with a remote control you can't.

-Ed

My information must be a bit dated.

 

[EddNog]

My information must be a bit dated.

I found that to get a passive pre with remote control costs well over $100. Even more so for balanced/XLR.

-Ed

 

[Ken Tajalli]

I found that to get a passive pre with remote control costs well over $100. Even more so for balanced/XLR.

-Ed

Pardon our interruption...

www.ebay.co.uk

 

[EddNog]

Pardon our interruption...

www.ebay.co.uk

Well that’s…I must admit I can’t do anything with this. I’m not a build-it-myself kind of person, but great if you can!

-Ed

 

[binaryblaze]

Should I update my A70 Pro to firmware version 2.05? Currently it's on 2.02

 

[marcom22]

Should I update my A70 Pro to firmware version 2.05? Currently it's on 2.02

Me too ..... i read some strange behaviours with the firmware 2.05, is it safe to updgrade to 2.05 from 2.02?

 

[binaryblaze]

I'm getting popping sounds when driving the HE6se at >-10 dB on high gain for testing. Is it normal or is my unit defective?

 

[formdissolve]

I'm getting popping sounds when driving the HE6se at >-10 dB on high gain for testing. Is it normal or is my unit defective?

Is it only when you change the volume, or is it constant? If it's constant.. then you may have a problem.

 

[Rover]

I used two A 70 PRO, both had to be returned under warranty. I had to switch to an amplifier from another company

 

[EddNog]

I used two A 70 PRO, both had to be returned under warranty. I had to switch to an amplifier from another company

How did they fail/how were they malfunctioning?

I’m curious since I am running a pair of B100 monobloc power amps and they use the same amplification circuit design as A70 Pro with T’ang-Ku-La architecture.

-Ed

 

[Roland68]

I used two A 70 PRO, both had to be returned under warranty. I had to switch to an amplifier from another company

I would also be interested to know what problems your A70 Pro had.

How did they fail/how were they malfunctioning?

I’m curious since I am running a pair of B100 monobloc power amps and they use the same amplification circuit design as A70 Pro with T’ang-Ku-La architecture.

-Ed

But it has already been said several times here that the failure problems of the A70 Pro cannot have anything to do with the B100.
The materials, components and circuits affected in the A70 Pro do not exist in the B100 and the topology really has nothing to do with it.

 

[Rover]

How did they fail/how were they malfunctioning?

I’m curious since I am running a pair of B100 monobloc power amps and they use the same amplification circuit design as A70 Pro with T’ang-Ku-La architecture.

-Ed

When turned on, a black screen appears with a message about protection of constant voltage. The loading did not proceed further. Reflashing did not change anything. We took it under warranty.

 

[charliecola]

When turned on, a black screen appears with a message about protection of constant voltage. The loading did not proceed further. Reflashing did not change anything. We took it under warranty

I just bought a used A70 from ebay then read all these accounts of failure. Should I be worried?

 

[Bleib]

I just bought a used A70 from ebay then read all these accounts of failure. Should I be worried?

Well, I had one for almost a year and had no issues with it