Tangent PowerAmpster II - anyone familiar? Very noisy

[Zoli64]

I bought a Tangent PowerAmpster II. final stage in my small music system at home. My speaker is a Klipsch R-28F with a tuned switch. I had an SDS-470C final stage before it, it had no problems, only its performance was excessive. The Tangent PowerAmpster II sounds very nice, but when it is turned on, it has an audible noise in the default position....its connection is quite strange (unfortunately, I am not a very good technician, electronics). The input has a panel (pcb) that accepts both XLR and RCA signals, there is no selector switch. Plus, they have integrated a part that turns on for a sound signal, i.e. if it receives a sound signal, it turns itself on. I think this module has an unreasonably high gain (there are several opamps on it). I wrote to the manufacturer that it is noisy, they should help me with the switch. Of course, they rejected my request that's why I'm contacting you, there are many smart people here who have seen a lot. If anyone knows this type, maybe they have a tip on what can be done with it. I've had several IRS2092-based final stages, none of them were like this It's noisy. I can't find anything but the input module. Please help me with this. I'm using a Wiim Pro Plus at the input, I had to reduce the volume to 800 mV. to regulate, this stupid Tangent is so sensitive..... the link of the amplifier so that you can recognize it for sure:

PowerAmpster II
Thank you, with friendship, Zoltán from Hungary
Ps: I don't even understand how it got a good recommendation with such a large audible background noise, which I think is caused by the unreasonably high input gain....let's say its sound is very good, strong, dynamic, musical.

 

[Zoli64]

I looked at the input panel with a magnifying glass and then took a photo. It has 4 TL062C and 1 TL064C. I'm trying to upload a picture. (I have an idea, since I found the 2 audio input stackers on the main pcb, I will connect the input rca signal directly there. If there is no better idea.....

 

[restorer-john]

I'd be separating the front end gain/buffer stages from the power stage, shorting the power stage inputs (on the white sockets arrowed) and listening to the residual noise powered up into a pair of speakers. If the amp needs a signal to come out of standby, give it a signal in one of the inputs. You won't hear it when the two cables are disconnected. It's possible they are using one/two of the opamps as a comparator to drive the standby/on function of the output driver ICs.

That way, you can ascertain whether its a mess of noise in the front end causing all the noise, or it's inherent in the SMPS/Power stage itself.

The amplifier itself takes an unbalanced signal, so you really aren't gaining anything except noise from the front end and maybe a bit of gain you apparently don't want or need.

If the amplifier is quiet and realtively noise free with the front buffer/gain/XLR-unbalance disconnected, you can feed your signal directly into the power stage and things may be a whole lot better.

 

[Zoli64]

I'd be separating the front end gain/buffer stages from the power stage, shorting the power stage inputs (on the white sockets arrowed) and listening to the residual noise powered up into a pair of speakers. If the amp needs a signal to come out of standby, give it a signal in one of the inputs. You won't hear it when the two cables are disconnected.

That way, you can ascertain whether its a mess of noise in the front end causing all the noise, or it's inherent in the SMPS/Power stage itself.

The amplifier itself takes an unbalanced signal, so you really aren't gaining anything except noise from the front end and maybe a bit of gain you apparently don't want or need.

If the amplifier is quiet and realtively noise free with the front buffer/gain/XLR-unbalance disconnected, you can feed your signal directly into the power stage and things may be a whole lot better.

View attachment 378926

I tell you, I'm not a big electro guru, but I suspect that that little panel goes silent on its own if the input signal doesn't arrive. The front panel LED is also wired from it, either red (stabdby) or white (working). Do you think that the tons of TL62C can cause the high base noise, because it might be old or high gain maybe set? (in fact, I think they added more because of the XLR input)....I will try these soon, the input short circuit. Thanks.

 

[restorer-john]

I tell you, I'm not a big electro guru, but I suspect that that little panel goes silent on its own if the input signal doesn't arrive. The front panel LED is also wired from it, either red (stabdby) or white (working). Do you think that the tons of TL62C can cause the high base noise, because it might be old or high gain maybe set? (in fact, I think they added more because of the XLR input)....I will try these soon, the input short circuit. Thanks.

So, give it an input signal, but unplug the two connectors I marked-up. Short the pins on those connectors on the amp PCB. Leave everything else and power it up. Tell us how loud the residual noise is. Has it improved?

I would bet you have a combination of a noisy, too high gain front end and some noise from the power stage. Combined, it's too much for you. Let's remove the front end from the equation first.

Cheers.

 

[Zoli64]

So, give it an input signal, but unplug the two connectors I marked-up. Short the pins on those connectors on the amp PCB. Leave everything else and power it up. Tell us how loud the residual noise is. Has it improved?

I would bet you have a combination of a noisy, too high gain front end and some noise from the power stage. Combined, it's too much for you. Let's remove the front end from the equation first.

Cheers.

Unfortunately, the test did not work, the white noise remained the same level (to the ear). so the input of the final stage is set to too high a gain. I think all the SMDs are at the bottom of the main pcb, it's not easy to take it all apart, it's so small and compact. So now I don't even know if the IRS2092S ic itself is the driver, or if it's still there also got an opa...then the science stops here (I know that the IRS IC gain can be adjusted somehow. I already had an output stage with such a structure, but it made much less noise).

Thanks.

 

[restorer-john]

Unfortunately, the test did not work, the white noise remained the same level (to the ear). so the input of the final stage is set to too high a gain. I think all the SMDs are at the bottom of the main pcb, it's not easy to take it all apart, it's so small and compact. So now I don't even know if the IRS2092S ic itself is the driver, or if it's still there also got an opa...then the science stops here (I know that the IRS IC gain can be adjusted somehow. I already had an output stage with such a structure, but it made much less noise).

Thanks.

Well done! You've successfully determined where the noise is coming from, your logic is considered and you've done it without needlessly messing around with opamps in the front end stage. I'm glad to have saved you from wasting time in the opamp rolling arena.

Without a schematic or access to the bottom of the power stage PCB, you are kind of at an impasse at this point.

You would need to pull up the IRx-xxxx data sheet, compare the layout and gain setting components, compare them to your amplifier PCB and then look at changing (if possible) to a more suitable and less noisy combination. Perhaps you may improve it, perhaps not. Not sure it's worth it.

Cheers.

 

[MaxwellsEq]

I've looked at their site and the product datasheet and the specifications are limited. There's no mention of -3dB points, Signal to Noise Ratio or Noise Figure, which is frustrating. This might make it tricky to determine if you have a faulty unit or if the design is noisy.

 

[Zoli64]

I've looked at their site and the product datasheet and the specifications are limited. There's no mention of -3dB points, Signal to Noise Ratio or Noise Figure, which is frustrating. This might make it tricky to determine if you have a faulty unit or if the design is noisy.

The unit is 9 months old, otherwise it sounds very nice, only this idiotic base noise....I don't know, if I remove the motherboard and trace the path of the irs2092 pin3, check the series resistance, changing/increasing it is in principle related to the amplification. I don't know, is it worth a try? Yes, unfortunately there is no drawing, the manufacturer did not help (Tangent Audio), even though I asked for it. It annoys me because my new speakers are Klipsch R-28F, which is equipped with a high efficiency cone tweeter. With my previous sound wall, the noise was not so noticeable. However, the final stage amplifies too much, that's for sure. It's getting loud soon. What do you think, should I look at gain resistance, or is it not worth it?

 

[Zoli64]

I've looked at their site and the product datasheet and the specifications are limited. There's no mention of -3dB points, Signal to Noise Ratio or Noise Figure, which is frustrating. This might make it tricky to determine if you have a faulty unit or if the design is noisy.

There is really little data, but it received good reviews in the press anyway. The relative signal-to-noise ratio may be good because the base noise is high but the output signal is also high. My problem is that it would rather be a third of the noise and get louder later, i.e. at a higher signal. The Klipsch speakers add to the noise. Although I could solve it by replacing a resistor....unfortunately, I don't know much about the irf2092 ic. I don't know, do you understand what I'm saying? I use Google translator.

 

[Zoli64]

Dear members, technicians! Before I tear this miracle apart, we have established: the input auxiliary pcb is not noisy. The amplifier is noisy, on its own, even with a short-circuited input. But it also unreasonably strengthens it. IRS2092 experience needed now. I used to have an irs2092 and it produced only a fraction of this noise. Otherwise, it is completely classic white noise, there is no hum, nothing. In the pictures above, you can see that the Tangent has a built-in, approx. He solved the power supply with a double SMPS power supply around +-40-42 V. The amplifier sounds nice, the volume and power are more than sufficient. I would ask knowledgeable people what else can be done to reduce noise. Noisy even with a short-circuited input. If I were to increase the input resistance, maybe the gain would decrease, and the noise would also decrease? (besides that resistance, I have no idea what else to touch). I need specific professional advice on the IRS matter (there is no wiring diagram...) Even if I could cut the noise in half, that would also help. Unfortunately, I'm not that good at class D, but I can make specific suggestions. Thank you for helping....if there is an experienced IRS2092 builder or repairer among us....

 

[Zoli64]

If no one can help with professional advice, I'll have to sell it in the end. I don't know if I should buy a quality 2x100 Watts class AB output stage or dare to try a TPA3255 output stage. I don't know what their basic noise and basic power consumption are.

 

[Zoli64]

I'm selling it