3e Audio A7 [TPA3255 PFFB Stereo] Finished Amplifier - User Impressions | Owner's Thread

[sceptical1]

This sounds suspiciously like blaming the victim.

I accept that 3e Audio makes a high performance amp at modest cost. That's great. That's why I bought these.

I don't accept that therefore I should pay for a technical hardware modification to have this product work the way it's supposed to do.

You might argue that anyone who buys one of these amps should be prepared to de-solder tiny components off the PCB after opening up the case which normally voids any warranty. This is not a good argument; 99% of electronics consumers would laugh & shake their heads.

Finally, since all other 3e amps bought at the same time work acceptably, the same way, and this one is the exception, it clearly is not working right.

A technical support site or page would be better than nothing, but when it comes to any organized systemic support, there's nothing.

It's all pretty Mickey Mouse.

Separate the resistor from the traces with an exacto knife then pull away from the board.

 

[ziggurcat]

Any news about future projects soon?

I wouldn't mind a straight-up power amp with just an on/off/auto switch on the front, no volume control, and 12v trigger input.

 

[Guddu]

I wouldn't mind a straight-up power amp with just an on/off/auto switch on the front, no volume control, and 12v trigger input.

Would be great for sure but I guess now it’s time for @3eaudio to think beyond power amplifier as well.

 

[ziggurcat]

Would be great for sure but I guess now it’s time for @3eaudio to think beyond power amplifier as well.

Like a preamp, perhaps?

 

[Guddu]

Like a preamp, perhaps?

Sure…. Why not!
But I would rather say a DAC + Amplifier combo simply because that’s perhaps the most common next iteration for a power amplifier.
Preamp space has largely occupied by streaming devices now with even added features like PEQ & room correction (like all Wiim’s) and a good clean decently powerful DAC+Amp combo of 3e’s standard would be great.

 

[harkpabst]

Yes, and there will still be some demand for a pure power amplifier.

 

[pieterv1]

Sure…. Why not!
But I would rather say a DAC + Amplifier combo simply because that’s perhaps the most common next iteration for a power amplifier.
Preamp space has largely occupied by streaming devices now with even added features like PEQ & room correction (like all Wiim’s) and a good clean decently powerful DAC+Amp combo of 3e’s standard would be great.

I hope @3eaudio take note!

Would be great to see a nicely integrated DAC - poweramp combo!

 

[John.D]

@3eaudio Please help with this query- What’s the auto OFF timer now with the new version of A7?
Are there 2 values- a short wait and a long wait?

 

[TurtlePaul]

@3eaudio Please help with this query- What’s the auto OFF timer now with the new version of A7?
Are there 2 values- a short wait and a long wait?

Auto off is 15 minutes.

 

[3eaudio]

@3eaudio Please help with this query- What’s the auto OFF timer now with the new version of A7?
Are there 2 values- a short wait and a long wait?

20 minutes, i think we had writed this into user manual.

 

[r-36m2]

20 minutes, i think we had writed this into user manual.

Hello, dear developers of high-quality audio equipment!

I'm a proud owner of your 3e Audio SY-DAP 1002 amplifier and have done a lot to improve its sound, but it has its limitations, which you know. It's time to take it a step further.
I'm considering the A5 or A5se (my speakers are 90 dB, so I don't need more power), but I can't figure out which one is better (for the price).

I understand that the A5 has two TPA3251s on board, as well as an NE5532 (I can easily replace them with 1602s, 1612s, 1656s, etc.). And I saw a slightly lower THD on the A5se's graphs than the A5se's.

The main question is: is this difference between the BTL and PBTL audible, or is it only visible on the graphs?

Second question: I haven't seen the schematic, but I suspect the op amps are single-ended, meaning there are decoupling capacitors and, most likely, electrolytic capacitors in the audio path. Is there a way to convert the power supply to dual-ended to eliminate the capacitors?

Thanks!

If any of my esteemed colleagues have compared the sound of the A5 and A5se or changed the op amp power supply, I'd be grateful for your experience!

 

[Dave TR3A]

Second question: I haven't seen the schematic, but I suspect the op amps are single-ended, meaning there are decoupling capacitors and, most likely, electrolytic capacitors in the audio path. Is there a way to convert the power supply to dual-ended to eliminate the capacitors?

Why would you want to eliminate the decoupling caps? That would be taking a step backwards.

 

[r-36m2]

Why would you want to eliminate the decoupling caps? That would be taking a step backwards.

Is dual-polarity power supply for operational amplifiers a step backwards? This is news.
Electrolytic capacitors always degrade sound. Any serious audio equipment uses a dual-polarity power supply for op amps, if the datasheet specifies a dual-polarity op amp. This ensures proper operation of the op amp and eliminates unnecessary components in the audio path.

 

[Dave TR3A]

Is dual-polarity power supply for operational amplifiers a step backwards? This is news.
Electrolytic capacitors always degrade sound. Any serious audio equipment uses a dual-polarity power supply for op amps, if the datasheet specifies a dual-polarity op amp. This ensures proper operation of the op amp and eliminates unnecessary components in the audio path.

Why so snarky?

You wanted to know if it would be possible to eliminate the decoupling capacitors. You admitted that you don’t know if the op-amps are SE but that you suspect they are and that they use electrolytic caps.

I asked why you’d want to eliminate the decoupling caps. In your reply you asserted (without evidence) that electrolytic caps always degrade sound. I hadn’t mentioned electrolytic caps.

Here’s what TI says in the TP3251 datasheet:
10.2.1.2.1 Decoupling Capacitor Recommendations

In order to design an amplifier that has robust performance, passes regulatory requirements, and exhibits good
audio performance, good quality decoupling capacitors should be used. In practice, X7R should be used in this
application.

The voltage of the decoupling capacitors should be selected in accordance with good design practices. Temperature, ripple current, and voltage overshoot must be considered. This fact is particularly true in the selection of the 1μF that is placed on the power supply to each full-bridge. It must withstand the voltage overshoot of the PWM switching, the heat generated by the amplifier during high power output, and the ripple current created by high power output. A minimum voltage rating of 50 V is required for use with a 36V power supply.

X7R is a low-cost temperature-stable ceramic capacitor.

 

[r-36m2]

Why so snarky?

You admitted that you don’t know if the op-amps are SE but that you suspect they are and that they use electrolytic caps. Then you go on to assert that electrolytic caps always degrade sound. I disagree.

Here’s what TI says in the TP3251 datasheet:
10.2.1.2.1 Decoupling Capacitor Recommendations

In order to design an amplifier that has robust performance, passes regulatory requirements, and exhibits good
audio performance, good quality decoupling capacitors should be used. In practice, X7R should be used in this
application.

The voltage of the decoupling capacitors should be selected in accordance with good design practices. Temperature, ripple current, and voltage overshoot must be considered. This fact is particularly true in the selection of the 1μF that is placed on the power supply to each full-bridge. It must withstand the voltage overshoot of the PWM switching, the heat generated by the amplifier during high power output, and the ripple current created by high power output. A minimum voltage rating of 50 V is required for use with a 36V power supply.

Yes, I haven't seen the A5 schematic, but judging by previous 3eaudio amplifiers, I assumed the op amp's power supply was single-ended.

Why are you citing lines about the 3251 chip's power supply capacitors when you're talking about dual-ended op amp power supplies and interstage capacitors in the audio path?
You misunderstood the question.

I suggest we end this discussion. I was asking for advice from those who have converted a single-ended power supply to a dual-ended one, not from those who simply have an opinion.
Please don't reply any further. Thank you.

 

[melomane13]

1) is this difference between the BTL and PBTL audible, or is it only visible on the graphs?

2) I haven't seen the schematic, but I suspect the op amps are single-ended, meaning there are decoupling capacitors and, most likely, electrolytic capacitors in the audio path. Is there a way to convert the power supply to dual-ended to eliminate the capacitors?

1) Maybe, but only if your speaker has an impedance well below 4 ohms.
2) Your assumptions are incorrect, forget it, there's no benefit to doing what you're saying, it's snake oil audiophile..

 

[r-36m2]

1) Maybe, but only if your speaker has an impedance well below 4 ohms.
2) Your assumptions are incorrect, forget it, there's no benefit to doing what you're saying, it's snake oil audiophile..

1. Thank you. My speakers have an impedance of 8 ohms. Do you think the difference between btl and pbtl won't be audible?
2. I disagree. High-fidelity audio equipment tends to use dual-polarity power supplies for op amps if the datasheet specifies it, and also avoids capacitors in the audio path if they can be avoided.
I'm not the type to listen to the sound of wires and capacitors. I've studied many circuits from leading high-level audio engineers and built simple DACs and amplifiers myself. The best capacitor in an audio path is none at all. While a polypropylene or polystyrene capacitor introduces minimal distortion, an electrolytic capacitor can cause quite a noticeable mess. A bipolar power supply is quite easy to build. It's little more difficult than draping microcircuits with a pile of electrolytic capacitors.

It may well be that there won't be a noticeable difference in sound between the electrolytics and the non-electrolytics in this amp, but if there's a more direct way to convey sound, I prefer to do so.

 

[Dave TR3A]

Yes, I haven't seen the A5 schematic, but judging by previous 3eaudio amplifiers, I assumed the op amp's power supply was single-ended.

Why are you citing lines about the 3251 chip's power supply capacitors when you're talking about dual-ended op amp power supplies and interstage capacitors in the audio path?
You misunderstood the question.

I suggest we end this discussion. I was asking for advice from those who have converted a single-ended power supply to a dual-ended one, not from those who simply have an opinion.
Please don't reply any further. Thank you.

It’s clear to me that you exemplify the Dunning-Kruger effect and that you don’t appreciate when others try to aid you.

You’re on my “ignore” list.

 

[Guddu]

Any serious audio equipment uses a dual-polarity power supply for op amps, if the datasheet specifies a dual-polarity op amp. This ensures proper operation of the op amp and eliminates unnecessary components in the audio path.

Specific to the above mentioned statement, are you referring to supplying +/- 12v for opamps?

 

[r-36m2]

Specific to the above mentioned statement, are you referring to supplying +/- 12v for opamps?

Yes