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AVCC 2.1 - module update

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Russ White

Russ White

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Joined 2005
twistedpearaudio.com
#1
Hi folks,

While I was laying out the Buffalo III-SE PCB - I decided it was about time to refresh the AVCC module. So I designed PCB version 2.1 of that module.

A couple of key improvements:

- We started using the same improved error amp we are using for the Trident - it is the dual version.
- There is better local feedback around at the shunt element by adding degeneration. This promotes better stability and RF rejection.
- There is compensation added to the feeback loop to give the circuit a much improved phase margine. It is as a result very stable and rejects EMI better.

The result is a module that does a better job at regulating - and truly does sound better than the previous version. I don't say that lightly.

This updated module can be operated at slightly higher input voltage like the new Tridents can.

This mean that input voltage up to 6V should be just fine.

I also improved some aspects of the layout making better use of top and bottom planes. It is thermally and electically a better solution.

It is a much more robust drop in replacment for B-II and B-III.

It will be available soon. We are getting them made now.

Here is a picture of one Brian built up by hand for testing.

Cheers!
Russ
 

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#3
thomaspf said:
That is a strong statement. Does this improvement also manifest itself in any measurement on the actual audio outputs?

Cheers

Thomas
Click to expand...

I wish I could answer that. I simply don't have access to gear with which I could measure that at the moment. 🙂

I would be very glad to see results from any of our users who does.

One note though is that these changes are exactly the same kind I made to the Trident. Those changes did have positive measurable effects on the regs themselves (wider phase margine and lower noise and output impedance in the critical band), but alas those tests where not done by me, but by a user, and I am not sure he has shared those yet.

For now - I can only offer my subjective opinion. They sound better. 🙂

Cheers!
Russ
 
#10
Erlend Sæterdal said:
In what way ? What is better sound for you ?
Click to expand...

I hate it when people ask me questions like this. 🙂

Because while I know what I like - it is hard to find the right adjectives to describe why. 🙂

I spent quite a lot fo time the last few weeks listening to the new BUF-III SE - so keep in mind this comment will be based on that setup with Legato 3.1 driving various headphones.

Since you force me (just kidding) I will say that what I like better is what I would call a sense of control and precision. Also the background is crystal clear and clean. No noise is present accept that which was recorded.

I would say that the AVCC module is *the* single most important regulator on the Buffalo.

I am not as eloquent as others, so I hope some other folks will write better reviews. 🙂

Cheers!
Russ
 
#11
Hey...

Good news Russ, thanks!
And guys, in the past, Russ has been reluctant/unwilling to share his personal, subjective, opinions on sound quality/improvements. In this thread he has actually taken a risk in offering his personal subjective opinion, I thank him for that, but we can also see (in the responses to his opinion) why he has been reluctant to give it. Let's not badger him, and give him the third degree when he offers his subjective opinion. We would do better to thank him and just accept it for what it is is.
When we try the new AVCC regs we can also form our own subjective opinion, as it should be...
 
#12
Well put Burrows:cheers:
yup the best way to find out how something sounds is to listen and make our own minds up.

i'm still loving my B3 🙂🙂🙂 just sounds great IMHO to my ears in my system😎

looking forward to trying the new AVCC

thanks Russ
 
#14
Russ,

Very nice product. Should be a nice upgrade as it is the most important regulator in the DAC. is it still specified for 3.3V?

I've seen photos where the leds have different brightness (including mine). Although that is not an issue, is the new design better at having equal brightness?

I'll like to order mine machine soldered (not hand soldered like in the photo 🙂)
 
#15
Magnitude of LED brightness was not a design priority. But yes, if you operate it at 5.5 to 6V the intensity of both should be pretty close in any case. 🙂

I know your kidding, but it's actually a pretty good job of soldering for a prototype. Brian does excellent work.

It is just a bit more than 3.3V. Right around ~3.5V
 
#19
Nice description off sound performence

Russ White said:
I hate it when people ask me questions like this. 🙂

Because while I know what I like - it is hard to find the right adjectives to describe why. 🙂

I spent quite a lot fo time the last few weeks listening to the new BUF-III SE - so keep in mind this comment will be based on that setup with Legato 3.1 driving various headphones.

Since you force me (just kidding) I will say that what I like better is what I would call a sense of control and precision. Also the background is crystal clear and clean. No noise is present accept that which was recorded.

I would say that the AVCC module is *the* single most important regulator on the Buffalo.

I am not as eloquent as others, so I hope some other folks will write better reviews. 🙂

Cheers!
Russ
Click to expand...

🙂🙂🙂
 
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