Vera Audio Class-D Amp Build Quality

[AnLaoJin]

The advantage of the amplifier (called P150/600) with Purifi is lower distortion as you point out. It also remains cooler and therefore has no backup fans. But with less power and the cost will also be higher. Whether this lower distortion is audible or not is something that would require an objective test and "the jury is still out".

You can bridge two P150/600 amplifiers (Purifi based) to achieve continuous 600W but obviously the cost will be much higher than one single P400/1000.

Thank you, Bjorn. Are you an vera engineer?

 

[Bjorn]

Thank you, Bjorn. Are you an vera engineer?

I'm the one who started Vera Audio but I'm not an engineer. Armand is technical responsible.

 

[Armand]

Besides, I have a new idea. My DAC output voltage is 4.5 VRMS. I want to get rid of the voltage amplifier and make the DAC and P400 dial 1000 straight-through, so that the volume can be controlled by the gain adjustment of the P400 dial 1000. Will this work? How much gain is appropriate for P400A 1000?

The gain settings on our amplifiers are fixed settings in 3dB steps. 12-15-18-21-24-27-30dB. Since the gain settings knobs are on the back this is not suitable for volume control. But with optimal gain settings the volume control in the DAC can normally be used. This is one of the really good functions on our amplifiers. Many of our customers experience that lower gain settings on the amplifier leads to lower noise and better system performance.

 

[AnLaoJin]

The gain settings on our amplifiers are fixed settings in 3dB steps. 12-15-18-21-24-27-30dB. Since the gain settings knobs are on the back this is not suitable for volume control. But with optimal gain settings the volume control in the DAC can normally be used. This is one of the really good functions on our amplifiers. Many og our costomers experience that lower gain settings on the amplifier leads to lower noise and better system performance.

Thank you，Armand.My DAC voltage is 4.5 vRMS. If I am directly connected to the P400, it seems that I need the gain of the 21dB to achieve the maximum power. If I use the gain control of the P400 as the volume, can I adjust the volume between the 12dB-21dB? I really want the DAC to connect directly to the P400 and leave out the previous level

 

[direstraitsfan98]

Thank you，Armand.My DAC voltage is 4.5 vRMS. If I am directly connected to the P400, it seems that I need the gain of the 21dB to achieve the maximum power. If I use the gain control of the P400 as the volume, can I adjust the volume between the 12dB-21dB? I really want the DAC to connect directly to the P400 and leave out the previous level

Be very careful doing this. When starting up windows you could potentially blow your tweeter out or worse, your hearing. I use the wasapi plugin often which bypasses windows audio, so if you for some reason reset your volume on your dac, you could really have a bad day. I think most dac's with a volume control will remember where you set the volume, though. Still something you need to be cautious about regardless.

 

[AnLaoJin]

Be very careful doing this. When starting up windows you could potentially blow your tweeter out or worse, your hearing. I use the wasapi plugin often which bypasses windows audio, so if you for some reason reset your volume on your dac, you could really have a bad day. I think most dac's with a volume control will remember where you set the volume, though. Still something you need to be cautious about regardless.

My DAC does not have volume adjustment function, I want to adjust the volume through the gain switch on P400

 

[direstraitsfan98]

My DAC does not have volume adjustment function, I want to adjust the volume through the gain switch on P400

I would advise against doing this, in most situations. It's unlikely you will blow a tweeter up in this day in age with modern speaker designs, but, the volume being very loud on apps that reset the volume upon reboot will lead to some pretty uncomfortable situations where you attempt to play something and its ear shattering loud.

 

[March Audio]

The advantage of the amplifier (called P150/600) with Purifi is lower distortion as you point out. It also remains cooler and therefore has no backup fans. But with less power and the cost will also be higher. Whether this lower distortion is audible or not is something that would require an objective test and "the jury is still out".

You can bridge two P150/600 amplifiers (Purifi based) to achieve continuous 600W but obviously the cost will be much higher than one single P400/1000.

IIRC, need to check, Purifi specifically advise against bridging the modules.

EDIT found it

bridging two 1ET400A Designs will result in performance degradation as the circuit is not configured to sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs. Bridging is therefore not recommended. All operation and performance specs are void in this configuration.

 

[AnLaoJin]

I would advise against doing this, in most situations. It's unlikely you will blow a tweeter up in this day in age with modern speaker designs, but, the volume being very loud on apps that reset the volume upon reboot will lead to some pretty uncomfortable situations where you attempt to play something and its ear shattering loud.

My sound source is CD + DAC. It does not have volume adjustment function, so if there is no problem, it should be full output level. I want to ask if the DAC direct P400 uses 12dB gain. After calculation, the P40 can only output 80W power. Does the speaker make a very loud sound?

 

[AnLaoJin]

The gain settings on our amplifiers are fixed settings in 3dB steps. 12-15-18-21-24-27-30dB. Since the gain settings knobs are on the back this is not suitable for volume control. But with optimal gain settings the volume control in the DAC can normally be used. This is one of the really good functions on our amplifiers. Many og our costomers experience that lower gain settings on the amplifier leads to lower noise and better system performance.

My sound source is CD + DAC. It does not have volume adjustment function, so if there is no problem, it should be full output level. I want to ask if the DAC direct P400 uses 12dB gain. After calculation, the P40 can only output 80W power. Does the speaker make a very loud sound?

 

[Armand]

My sound source is CD + DAC. It does not have volume adjustment function, so if there is no problem, it should be full output level. I want to ask if the DAC direct P400 uses 12dB gain. After calculation, the P40 can only output 80W power. Does the speaker make a very loud sound?

You cannot use the DAC directly to any amplifier if the DAC level is fixed.
With your DAC's voltage level of 4,5V RMS and the lowest gain of 12dB (4x) the voltage on the amplifer will be 18V. That is as you say 80W into a 4 Ohms speaker. This is looooooud. Very very loud.
Sound pressure increase 3dB per doubling of power
Example: Your speaker has a low sensitivity of 86dB SPL per watt. Two speakers will have 89dB SPL/W
2W gives 92dB SPL
4W gives 95dB SPL
8W gives 98dB SPL
16W gives 101dB SPL
32W gives 104dB SPL
64W gives 107dB SPL
80W gives 108dB SPL !!

This is at least 20dB too loud for a system to be useful. You need a preamplifier.
You can calculate using the calculator called "Sound pressure level and amplifier power" on this site:
http://www.sengpielaudio.com/calculator-efficiency.htm

 

[Armand]

IIRC, need to check, Purifi specifically advise against bridging the modules.

EDIT found it

bridging two 1ET400A Designs will result in performance degradation as the circuit is not configured to sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs. Bridging is therefore not recommended. All operation and performance specs are void in this configuration.

The circuit in our Vera P150/600 is made so that it does in fact "sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs". That is why we can offer the bridging capability. We have of course tested this configuration and also demonstrated the performance as shown in post #32.
550W into 8 Ohms with less than 0.0005% THD+N.
This is measured with Rohde & Schwarz UPV audio analyser and we are at the limits of what this instrument is capable of. Probably the numbers are even a tad better, but there is only one instrument that can verify this today and that is AP 555x.

 

[AnLaoJin]

The circuit in our Vera P150/600 is made so that it does in fact "sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs". That is why we can offer the bridging capability. We have of course tested this configuration and also demonstrated the performance as shown in post #32.
550W into 8 Ohms with less than 0.0005% THD+N.
This is measured with Rohde & Schwarz UPV audio analyser and we are at the limits of what this instrument is capable of. Probably the numbers are even a tad better, but there is only one instrument that can verify this today and that is AP 555x.

Thank you, Armand. I would like to ask the Vera P150 / 600's gain adjustment range?? Do you have a plan for pre amplification? It is better to support 0dB gain preamplifier

 

[AnLaoJin]

The circuit in our Vera P150/600 is made so that it does in fact "sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs". That is why we can offer the bridging capability. We have of course tested this configuration and also demonstrated the performance as shown in post #32.
550W into 8 Ohms with less than 0.0005% THD+N.
This is measured with Rohde & Schwarz UPV audio analyser and we are at the limits of what this instrument is capable of. Probably the numbers are even a tad better, but there is only one instrument that can verify this today and that is AP 555x.

Can Vera P150 / 600 BTL continuously load 2 ohm impedance?

 

[A800]

You cannot use the DAC directly to any amplifier if the DAC level is fixed.
With your DAC's voltage level of 4,5V RMS and the lowest gain of 12dB (4x) the voltage on the amplifer will be 18V. That is as you say 80W into a 4 Ohms speaker. This is looooooud. Very very loud.
Sound pressure increase 3dB per doubling of power
Example: Your speaker has a low sensitivity of 86dB SPL per watt. Two speakers will have 89dB SPL/W
2W gives 92dB SPL
4W gives 95dB SPL
8W gives 98dB SPL
16W gives 101dB SPL
32W gives 104dB SPL
64W gives 107dB SPL
80W gives 108dB SPL !!

This is at least 20dB too loud for a system to be useful. You need a preamplifier.
You can calkulate using the calculator called "Sound pressure level and amplifier power" on this site:
http://www.sengpielaudio.com/calculator-efficiency.htm

One can't have enough sensitivity.

 

[AnLaoJin]

The circuit in our Vera P150/600 is made so that it does in fact "sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs". That is why we can offer the bridging capability. We have of course tested this configuration and also demonstrated the performance as shown in post #32.
550W into 8 Ohms with less than 0.0005% THD+N.
This is measured with Rohde & Schwarz UPV audio analyser and we are at the limits of what this instrument is capable of. Probably the numbers are even a tad better, but there is only one instrument that can verify this today and that is AP 555x.

It would be great if we could introduce the pre amplifier with optional gain of 0dB, 6dB and 16dB, and the volume control adopts R2R

 

[Bjorn]

Vera Audio 150/600 can drive a 2 ohm load continously, but the output power decreases with lower impedance. We need to come back with what it can deliver with different loads.

We do plan to offer a preamplifier at some point. Most likely with a built in DAC.

 

[March Audio]

The circuit in our Vera P150/600 is made so that it does in fact "sense the voltage differential that exists between the (now unused) OUT- terminals of the two 1ET400A Designs". That is why we can offer the bridging capability. We have of course tested this configuration and also demonstrated the performance as shown in post #32.
550W into 8 Ohms with less than 0.0005% THD+N.
This is measured with Rohde & Schwarz UPV audio analyser and we are at the limits of what this instrument is capable of. Probably the numbers are even a tad better, but there is only one instrument that can verify this today and that is AP 555x.

Really?

And yet the designer of the module says no.

Please don't get me wrong, it's not my intention to criticise what could be considered a “competitors“ product.

As Bjorn stated he is not technical I presumed it could be just a misunderstanding.

When the designer of the module (especially someone like Bruno) explicitly states something, I tend to take it seriously.

I confess I haven't tried a bridged configuration precisely because of this advice, and I can see the potential (excuse the pun) for it being problematic (it's gonna shift around) , even if you move the sense point. Perhaps I should try

 

[Armand]

Really?

And yet the designer of the module says no.

Please don't get me wrong, it's not my intention to criticise what could be considered a “competitors“ product.

As Bjorn stated he is not technical I presumed it could be just a misunderstanding.

When the designer of the module (especially someone like Bruno) explicitly states something, I tend to take it seriously.

I confess I haven't tried a bridged configuration precisely because of this advice, and I can see the potential (excuse the pun) for it being problematic, even if you move the sense point. Perhaps I should

He clearly states why it is not recommended, and not implemented correctly bridging will cause performance degradation. There are also error situations that must be handled correctly for this to work properly.

 

[Tks]

I know this is a bit off topic, but I just have to say. Finally.. one company (that I know of on the planet, regardless of industry) has decided to take active cooling a bit more seriously and realized the best are essentially Noctua (in the air cooling department). Also realized, they're not so cheap fans really, and still decided to include them in as the stock fans in the system. Freaking finally...

Seems like everyone in electronics that needs fans will do anything to avoid biting the bullet and including Noctua fans in their systems because they seemingly don't do partnerships, discounts and things of that nature for consumer products.

Can't tell you how much it's appreciated.

You mention before how having fans in a system turns some people off or something of that nature. In the PC Desktop realm people dread noctua for their color-way (I love the creamy and chocolate color scheme on almost any build, I just think the majority of the world is insane in this respect on some level). Well in a blacked out amp like this, that excuse for undesirable colorway is gone, and all you get is their amazing performance per-dB of noise (or virtually none of it).