Viola Forte Mono Powers.

[garylkoh]

Measurements from an Italian magazine:

Correct peak to peak power output should be 460/880/1300 watt in 8/4/2 ohms,
and 400/710/1150 watt continuous.

Output current - 44A
Output voltage cont. in 8/4/2 ohms - 55/52/48V
Freq. Response - 10-50k -2dB, 10-100k -5dB.
Damping factor in 8 ohm 10 kHz - 465
Slew rate - up 30V, down 40V
S/N - 126 dB Aw

Wow - actual measurements turned out to be BETTER than what the manufacturer states? I wonder if it's got anything to do with the Italian magazine having a 240V line instead of 115V here in the US.....

 

[rnsa2000]

My Viola Forte with Dynaudio Sapphire Edition Bordeaux, and the AR Ref250 with Focal.

 

[opus111]

....what exactly does such a gigantic choke do? I understand that choke filters can keep out unwanted noise from entering the rest of the signal path. Is that really what this 'choke' is doing?

Since the mains supply is AC and amplifiers need DC to operate, a rectifier is used to convert AC to DC. This comes with problems because it works by only sending the peaks of the AC waveform to the capacitor bank. Since the voltage only is at the peak virtually instantaneously, there's a need for a lot of current in a very short time. These current peaks are in effect big noise bursts - having a big choke allows the peak to be made much longer by acting as a short-term energy store. Having longer 'peaks' means much lower current and hence this translates to much lower noise.

As Gary says its not particularly easy to design such a supply - normally choke input has been used with class A valve circuitry, so the maximum (roughly the same as the minimum with classA) currents are known in advance. Having a choke feeding an AB amplifier (where the current draw varies with the signal) is a major design challenge

 

[LL21]

Since the mains supply is AC and amplifiers need DC to operate, a rectifier is used to convert AC to DC. This comes with problems because it works by only sending the peaks of the AC waveform to the capacitor bank. Since the voltage only is at the peak virtually instantaneously, there's a need for a lot of current in a very short time. These current peaks are in effect big noise bursts - having a big choke allows the peak to be made much longer by acting as a short-term energy store. Having longer 'peaks' means much lower current and hence this translates to much lower noise.

As Gary says its not particularly easy to design such a supply - normally choke input has been used with class A valve circuitry, so the maximum (roughly the same as the minimum with classA) currents are known in advance. Having a choke feeding an AB amplifier (where the current draw varies with the signal) is a major design challenge

Thanks, Opus. So what happens when you are using a Burmester 948 power conditioner? I think it does something to the DC in the line before the electricity is fed to the components hooked up to it?

 

[Occam]

Ricardo,

You should be justifiably pleased with your purchase. The Fortes are lovely amplifiers. I was lucky to provide the cables in rooms at CES and NY Audio Show with the Forte monoblocks (along with a Viola preamp) driving Hansen Prince speakers. The Fortes were extended and clean, lacking any hint of solid state grit. What was great about working with the Viola electronics is they clearly reflected any changes to what was feeding, supporting, powering... them. Subjectively, they are resolving, extended, and transparent, yet lacking those negatives, thinness, grit and glare often accompanying the former. With another pair, you can configure them for balanced-bridged operation, as dual chassis monoblocks.

Enjoy your wonderful amps,
Paul

PS - and the larger Viola amps driving the Ocean Way monitors (triamped) at CES was outrageous. Its got a great beat, and you can dance to it....

 

[joeinid]

Ricardo,

What a beautiful setup. Congratulations! I am so happy for you. I need to listen to Viola. They look like they make great gear. Enjoy in great health.

 

[rnsa2000]

Ricardo,

You should be justifiably pleased with your purchase. The Fortes are lovely amplifiers. I was lucky to provide the cables in rooms at CES and NY Audio Show with the Forte monoblocks (along with a Viola preamp) driving Hansen Prince speakers. The Fortes were extended and clean, lacking any hint of solid state grit. What was great about working with the Viola electronics is they clearly reflected any changes to what was feeding, supporting, powering... them. Subjectively, they are resolving, extended, and transparent, yet lacking those negatives, thinness, grit and glare often accompanying the former. With another pair, you can configure them for balanced-bridged operation, as dual chassis monoblocks.

Enjoy your wonderful amps,
Paul

Hello Paul,

thank you very much!!!

This system with Hansen and Viola you mentioned, if I remember correctly was considered one of the best in Audio show.

I have to make some adjustments and testing cables to further improve synergy setup.

Here in Brazil the Viola are not yet known, only by name.


Nice regards,
Ricardo Nonato.

 

[rnsa2000]

Joe,

thank you for the congratulations.

A while ago I was switching equipment all the time, looking for a setup that I liked and now I think I found.

I was looking darTZeel, Gryphon Diablo, etc ... but I'm sure I made a great choice.

Try listening to Viola, I believe you will be amazed!!


Nice regards,
Ricardo Nonato.

 

[mep]

Since the mains supply is AC and amplifiers need DC to operate, a rectifier is used to convert AC to DC. This comes with problems because it works by only sending the peaks of the AC waveform to the capacitor bank. Since the voltage only is at the peak virtually instantaneously, there's a need for a lot of current in a very short time. These current peaks are in effect big noise bursts - having a big choke allows the peak to be made much longer by acting as a short-term energy store. Having longer 'peaks' means much lower current and hence this translates to much lower noise.

As Gary says its not particularly easy to design such a supply - normally choke input has been used with class A valve circuitry, so the maximum (roughly the same as the minimum with classA) currents are known in advance. Having a choke feeding an AB amplifier (where the current draw varies with the signal) is a major design challenge

Chokes have been used in the power supplies of Class A/B tube power amps for many years. Chokes were as common as dirt in the old days. For example, every Dynaco tube amp had a choke in the power supply and none of them were Class A amps. The arrangement was known as CLC meaning a capacitor as the input filter followed by a choke and then followed by another capacitor.

 

[opus111]

So what happens when you are using a Burmester 948 power conditioner? I think it does something to the DC in the line before the electricity is fed to the components hooked up to it?

I went to the Burmester page and also saw them mentioning something about DC but there were not enough technical details given for me to understand what they are doing. Perhaps they're just removing DC from the mains supply which could only benefit the mechanical buzz levels from mains transformers connected to it.

 

[opus111]

Chokes have been used in the power supplies of Class A/B tube power amps for many years. Chokes were as common as dirt in the old days. For example, every Dynaco tube amp had a choke in the power supply and none of them were Class A amps. The arrangement was known as CLC meaning a capacitor as the input filter followed by a choke and then followed by another capacitor.

The capacitor at the input, prior to the choke tends to negate the advantages I was speaking of but does allow variable loading by providing for discontinuous inductor current. So its a kind of compromise approach for where the load current isn't tightly controlled. You'll note I was speaking of 'choke input' i.e. LC, not CLC.

This posting explains the details better than I : http://www.audioasylum.com/forums/tubediy/messages/16/165030.html

 

[LL21]

I went to the Burmester page and also saw them mentioning something about DC but there were not enough technical details given for me to understand what they are doing. Perhaps they're just removing DC from the mains supply which could only benefit the mechanical buzz levels from mains transformers connected to it.

Thanks...got it. someday, will try to listen to it.

 

[Occam]

The Forte's power supply's chokes are not differential chokes...
FWIW

 

[dallasjustice]

One day when I get my money and courage together, I'm going to compare my Soulution 710 to the Bravo II.

 

[rnsa2000]

Hello friends,

With each passing day I'm happier with the Viola, they raised the whole system viable, I'm sure!


Nice regards,
Ricardo Nonato.

 

[LL21]

Hello friends,

With each passing day I'm happier with the Viola, they raised the whole system viable, I'm sure!


Nice regards,
Ricardo Nonato.

Congrats! Enjoy!

 

[rnsa2000]

Iloydeltt21,

thank you!!!

In the next week, I will make some tests with the power cables Kubala-Sosna Emotion. Before the tests I Will post my impressions.


Nice regards,
Ricardo Nonato.

 

[LL21]

Iloydeltt21,

thank you!!!

In the next week, I will make some tests with the power cables Kubala-Sosna Emotion. Before the tests I Will post my impressions.


Nice regards,
Ricardo Nonato.

Great! I would enjoy reading your impressions of Viola as well! I have never had the chance to hear them, but have heard great things about them from many people, including Gary Koh of Genesis here on WBF.

 

[rnsa2000]

The first time I heard the Viola was last year, and I was delighted with the result. And within my financial means, this was the best choice I think I could have done.

At the moment I use the Cremona M, but I believe in buying the Amati Futura.

I'm curious to hear Hansen Prince, but here in Brazil is very difficult to find them.

 

[LL21]

The first time I heard the Viola was last year, and I was delighted with the result. And within my financial means, this was the best choice I think I could have done.

At the moment I use the Cremona M, but I believe in buying the Amati Futura.

I'm curious to hear Hansen Prince, but here in Brazil is very difficult to find them.

Interesting...I have heard both but not in the same system or at the same time. I would say they are certainly both competitors and are comparable in quality. This is more about system and personal preference. What i would NOT say is that if you could "only" buy the Amati that you should feel disappointed that you could not hear the Hansen Prince. They are both good speakers at about a comparable level. I personally would prefer the Amati...and that is partly because i am a big SF fan having owned by Guarneri original and SF Strad at one time, but i know of others who would say the opposite.