F5 Listening Impressions & Discussion - Page 45

EUVL · 01:32 AM

As for those who might be tempted to use separate power supplies for the front end and output stages, here is a friendly piece of advice :

Similar to the Aleph & Aleph-X, the output MOSFETs (both N & P) are driven at their gates by the drain resistor of the front end JFETs. These drain resistors are both connected to the top & bottom rails. If you split the rails between the front end and the output stage, then any difference (whether DC drift, or HF noise, or whatever else) between those rails will appear as changes in Vgs of the output MOSFETs, and hence in output current.

Of course, as in any circuit with global negative feedback, the feedback resistor network will attenuate this by a certain amount, in the case of the F5 about 30+ dB (if I remember correctly).

So the sound will change for certain, for better or for worse.

I personally would stick to tightly coupled rails between front end and output stage, and try to use a cap multiplier or Zen V3 type of regulated supply for the entire circuit.

But, by all means, feel free to experiment.

Patrick

Nelson Pass · 13th April 2010, 02:20 AM

In other words, don't even think about it.

a.wayne · 13th April 2010, 02:25 AM

jackies · 13th April 2010, 03:56 AM

Quote:

Originally Posted by EUVL

> Hey EUVL, if you don't mind me asking, did you share your pcb design?

No, and I do not have a habbit to.

That's what I thought.
I only asked because I was wondering how vitalica managed to build his amp exactly like yours... Just occured to me, it must be your boards in his amp?
Nevermind me...

vitalica · 13th April 2010, 03:32 PM

Quote:

Originally Posted by EUVL

Hey Vitali,

> After several days, I finished two F5 balanced monoblock.

That PCB looks familiar !!

I am glad that they are now sitting in a housing that is worthy of them.
Very well designed.
And I recognise that transformer as well.

But I still see Fairchild MOSFETs in your photos.
When did you change them to Toshiba's ?

> without revealing too many "secret details" over this way a number of experiments have been run regarding the power supply rails to the front end of the F5.
> It is daunting.
> Changes in that path appear at this point to radically effect the sound presentation!

You mean you are running separate rails for the input and output stages ?
Good luck.

Patrick

Hi Patrick ,

But I still see Fairchild MOSFETs in your photos.
When did you change them to Toshiba's ?

No, I changed nothing ,that was the beginning .
Do you think it would be better to change with TOSHIBA 1530/201?
Anyway, I am very happy as can be heard!
Thanks Patrick, great work!!
I feel happy with them

Best regards,
Vitali

EUVL · 13th April 2010, 04:56 PM

> In other words, don't even think about it.

Glad to have your support, Nelson.

Vitali,

Changing to Toshiba MOSFETs involves more changes than just the MOSFETs themselves. So I suggest you listen to your current F5s first. If they are good enough for Nelson, they are not by any means bad.

When after a few months you absolutely want to change to Toshibas, then contact me again by PM.

As I already said, I like your housing. Worthy home for those boards.

Patrick

vitalica · 14th April 2010, 07:39 AM

Quote:

Originally Posted by EUVL

> In other words, don't even think about it.

Glad to have your support, Nelson.

Vitali,

Changing to Toshiba MOSFETs involves more changes than just the MOSFETs themselves. So I suggest you listen to your current F5s first. If they are good enough for Nelson, they are not by any means bad.

When after a few months you absolutely want to change to Toshibas, then contact me again by PM.

As I already said, I like your housing. Worthy home for those boards.

Patrick

Thanks Patrick ,

I'm sure I will want to make Toshiba 1530/201.
I come back in a few months on PM

Regards,
Vitali

Luke · 14th April 2010, 10:08 AM

Quote:

Originally Posted by vitalica

After several days, I finished two F5 balanced monoblock.
I am very very happy sound!
We compared with F5, 5 Aleph, Aleph X.
F5 balanced - is my favorite!
I very much Nelson Pass and Patrick (EUVL) for everything!

Sorry for my English

Vitali

Hi Vitali, nice design, very original. Did you make the boards?

bear · 14th April 2010, 05:29 PM

Quote:

Originally Posted by Nelson Pass

In other words, don't even think about it.

Blasphemy!!

Not only that, we muck about with it!!

_-_-bear

Renron · 14th April 2010, 10:18 PM

Quote:

Originally Posted by bear

Blasphemy!!

Not only that, we muck about with it!!

_-_-bear

Is it possible to blaspheme oneself???
He is after all the creator, no?

Ron

13th April 2010, 01:13 AM	#441
EUVL diyAudio Member Join Date: Oct 2003	As for those who might be tempted to use separate power supplies for the front end and output stages, here is a friendly piece of advice : Similar to the Aleph & Aleph-X, the output MOSFETs (both N & P) are driven at their gates by the drain resistor of the front end JFETs. These drain resistors are both connected to the top & bottom rails. If you split the rails between the front end and the output stage, then any difference (whether DC drift, or HF noise, or whatever else) between those rails will appear as changes in Vgs of the output MOSFETs, and hence in output current. Of course, as in any circuit with global negative feedback, the feedback resistor network will attenuate this by a certain amount, in the case of the F5 about 30+ dB (if I remember correctly). So the sound will change for certain, for better or for worse. I personally would stick to tightly coupled rails between front end and output stage, and try to use a cap multiplier or Zen V3 type of regulated supply for the entire circuit. But, by all means, feel free to experiment. Patrick Last edited by EUVL; 13th April 2010 at 01:32 AM.

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13th April 2010, 02:20 AM	#442
Nelson Pass The one and only Join Date: Mar 2001	In other words, don't even think about it.

13th April 2010, 02:25 AM	#443
a.wayne diyAudio Member Join Date: May 2008 Location: Front Row Center

13th April 2010, 04:56 PM	#446
EUVL diyAudio Member Join Date: Oct 2003	> In other words, don't even think about it. Glad to have your support, Nelson. Vitali, Changing to Toshiba MOSFETs involves more changes than just the MOSFETs themselves. So I suggest you listen to your current F5s first. If they are good enough for Nelson, they are not by any means bad. When after a few months you absolutely want to change to Toshibas, then contact me again by PM. As I already said, I like your housing. Worthy home for those boards. Patrick

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