FIVE STARS IF YOU GO IN BALANCED BYPASSING THE OPAMP
It is a real pleasure to deal with audiophonics. Questions are answered immediately. Problems are solved quickly in favor of the customer. Here and there you can find some items a few euros cheaper elsewhere in the net but it is not worth the hassle if something goes wrong.
Now about the amps:
Coming from a UCD400hxr and a purifi ET400 this is my third iteration of a class d amp. It is driven as part of an full range system in a professional environment with dedicated studio acoustics. The mains are cleaned and have private electrical neutral and savety earth lines for the audio gear to bring ground loop noise down.
I always drive class d amps balanced without input buffer using high current preamps that can drive low input impedance gear with ease.
Some comments about the implementation of the modules:
1. When i got the amp I pulled out the opamp and plugged in the dummy opamp hooked it up and let it play while. Coming back i compared it to the ET400 and was surprised that the audiophonics sounded quite veiled in comparison. The quick fix was to pull out the power supply cable going from the input buffer board to the xlr and cinch connector board. Audiophonics decided to make the unbalanced input balanced by using an active circuitry at the xlr and cinch connector board. Obviously the circuitry polluted the signal. Now I got clean sound. (Btw the previous model didn´t use this circuity).
The better fix is to pull out the xlr and cinch board entirely, to buy a xlr connector and solder it directly to the input board using a high quality shielded balanced cable .
2. Opamp implementation: the opamp is introducing more color than I expected. (I compared the op amp level matched in low gain setting to the unbuffered input.) I am convinced that a top notch implementation using a dedicated high end power supply for the opamp would bring down opamp noise down a bit...and price up obviously...As I don´use it I don´t care.
3. To have an opamp socket is nice to have for those customers who like playing around with different thd profiles of different opamps. But with time resistance is building up at the contact points. So plug the opamp in and out from time to time. More important for the same reason: toggle the xlr cinch input switch from time to time (it is not a gas tight relay) and plug in and out the signal cable at the buffer input board. I would like to have these things soldered, including the speaker cables at the buffer board.
4.The power supply is getting quite hot. For better heat dissipation I would prefer that it makes contact with the metal case. The purifi modules itself are running very cool.
5. I can´t comment on the quality of the single ended input in comparison to the balanced one as I have no use for it.
6. I do like the binding posts. They allow for cranking down the calble super tight.
Final words:
The purifi modules are ment to be driven balanced. To provide single ended inputs in my opinion is mainly a marketing decision. Unfortunatly here this decision impacts the purity of the signal when going in balanced.
Fortunately pulling out the power supply cable of the symmetry circuitry is an easy solution as long as you don´t need the single ended input.
In this implementation the modules should be driven without input buffer opamp as they color the sound too much for my taste. You miss out how beautifully clean these modules can sound when the opamp is not installed.
If you like uncolored amps, have an great room with great speakers, great upstream electronics and clean mains power you can enjoy absolutely truth telling amplification for little money. Therefore it is also excellent in revealing minuscule differences when you shoot out upstream gear.
If you are a mixing or mastering engineer these modules tell you everything to make the right decisions, especially in the top end where many amps lack accuracy. If it sounds harsh on these it is harsh and needs to be adressed.
Price of the amps is excellent. It is not worth building one youself. I can whole heartly recommend this purifi build if you go in balanced bypassing the opamp.
This review has been posted for AUDIOPHONICS AP300-M450ET Power Amplifier Class D Mono Purifi 1ET6525SA 1x450W 4 Ohm It is a real pleasure to deal with audiophonics. Questions are answered immediately. Problems are solved quickly in favor of the customer. Here and there you can find some items a few euros cheaper elsewhere in the net but it is not worth the hassle if something goes wrong.
Now about the amps:
Coming from a UCD400hxr and a purifi ET400 this is my third iteration of a class d amp. It is driven as part of an full range system in a professional environment with dedicated studio acoustics. The mains are cleaned and have private electrical neutral and savety earth lines for the audio gear to bring ground loop noise down.
I always drive class d amps balanced without input buffer using high current preamps that can drive low input impedance gear with ease.
Some comments about the implementation of the modules:
1. When i got the amp I pulled out the opamp and plugged in the dummy opamp hooked it up and let it play while. Coming back i compared it to the ET400 and was surprised that the audiophonics sounded quite veiled in comparison. The quick fix was to pull out the power supply cable going from the input buffer board to the xlr and cinch connector board. Audiophonics decided to make the unbalanced input balanced by using an active circuitry at the xlr and cinch connector board. Obviously the circuitry polluted the signal. Now I got clean sound. (Btw the previous model didn´t use this circuity).
The better fix is to pull out the xlr and cinch board entirely, to buy a xlr connector and solder it directly to the input board using a high quality shielded balanced cable .
2. Opamp implementation: the opamp is introducing more color than I expected. (I compared the op amp level matched in low gain setting to the unbuffered input.) I am convinced that a top notch implementation using a dedicated high end power supply for the opamp would bring down opamp noise down a bit...and price up obviously...As I don´use it I don´t care.
3. To have an opamp socket is nice to have for those customers who like playing around with different thd profiles of different opamps. But with time resistance is building up at the contact points. So plug the opamp in and out from time to time. More important for the same reason: toggle the xlr cinch input switch from time to time (it is not a gas tight relay) and plug in and out the signal cable at the buffer input board. I would like to have these things soldered, including the speaker cables at the buffer board.
4.The power supply is getting quite hot. For better heat dissipation I would prefer that it makes contact with the metal case. The purifi modules itself are running very cool.
5. I can´t comment on the quality of the single ended input in comparison to the balanced one as I have no use for it.
6. I do like the binding posts. They allow for cranking down the calble super tight.
Final words:
The purifi modules are ment to be driven balanced. To provide single ended inputs in my opinion is mainly a marketing decision. Unfortunatly here this decision impacts the purity of the signal when going in balanced.
Fortunately pulling out the power supply cable of the symmetry circuitry is an easy solution as long as you don´t need the single ended input.
In this implementation the modules should be driven without input buffer opamp as they color the sound too much for my taste. You miss out how beautifully clean these modules can sound when the opamp is not installed.
If you like uncolored amps, have an great room with great speakers, great upstream electronics and clean mains power you can enjoy absolutely truth telling amplification for little money. Therefore it is also excellent in revealing minuscule differences when you shoot out upstream gear.
If you are a mixing or mastering engineer these modules tell you everything to make the right decisions, especially in the top end where many amps lack accuracy. If it sounds harsh on these it is harsh and needs to be adressed.
Price of the amps is excellent. It is not worth building one youself. I can whole heartly recommend this purifi build if you go in balanced bypassing the opamp.
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