Amps without fuses and other protection, playing Russian roulette?

Bemopti123 · « **on:** 15 Feb 2010, 07:59 pm »

Hi, I have a question. I have read about NVA amps around different forums and they seem to have garnered extensive good will amongst the people who have heard them. One of the points of contention is that in order to arrive at such objective, the designed has decided to omit all protection, fuses and the like because he feels in the purist sense that amps with protection, regardless of how it is designed, they produce a sonic detriment.

Richard Dunn hawks his wares now in Ebay.co.UK and he puts a really heavy dosage of warning about his designs, that they must be used with speaker cables from a certain list that he has approved and favors his own designs in order to maximize sonic benefits.

Read the explanation that these designers give about why they go this route...

The question was "why there is no protection circuit in your designs" he answers:

A: Basically for purest reasons, there is no such thing as a protection circuit that doesn't influence the sound. We've tried numerous types, and we have come to the conclusion, that none of them work. Our customers are people with, hopefully, a modicum of knowledge and common sense. And we say in our instruction book: `If you want to switch speaker cables, please always switch the amplifier off first.' If they will do that, fine. If, take me as an example, I never do it, because I know how to do it - as long as you do not touch the positive to negative, you've got no problem at all. There is nothing else that can harm the amplifier. If you used a fuse, you can either put a fuse in the power supply rail, or a fuse in the speaker lines. The problem with a fuse is, you can always hear it. Get yourself a fuse, put it down in the circuit, pass current through it, and as you start increasing the current, you can actually watch the fuse wire flex, it flexes as it heats up. As it heats up, it increases the resistance and when the heat gets to a point, the fuse breaks. You can actually hear it in any amplifier that has a fuse in it, whether it will be in the power supply or in the output stage, or even in the mains input. The least you can hear it is on the mains, but you can still hear it. A fuse has a compression effect. You'll lose dynamics within the music. So we have come to the conclusion, even though some people say it is dangerous, we will not put a fuse in the amplifier. The reason we feel happy about it, is because it is totally sealed case. We write on the back: `Do not remove the covers, no user serviceable parts inside'. There are only two connections to the mains, and they are very well connected. If for any reason they should break off, wherever they should land is also electrically insulated, so no power can get into the case, the case is quite safe."

Richard Dunn.

Now, is it worthwhile to use such a design in order to achieve a sonic nirvana? or would this be simply looking for proverbial high with the possibility of dying from such rush?

His design and the noise about them seem to be quite interesting. Any opinions would be appreciated.

Paul

turkey · « **Reply #1 on:** 15 Feb 2010, 08:02 pm »

He's an idiot. Sorry to put it so bluntly, but it's true.

His amps are simply an accident waiting to happen. There was just another thread here about an amp that also had no protection mechanisms, and it probably was the reason why two expensive woofers were destroyed.

http://www.audiocircle.com/index.php?topic=76386.0

Dan Banquer · « **Reply #2 on:** 15 Feb 2010, 08:21 pm »

I hope Mr. Dunn has a good lawyer as he may well need one. For those of you who are contemplating purchasing this equipment, be prepared to to have money flying out of your wallet for assorted repair bills for speaker damage, and possible smoke/fire damage to your residence.
Keep a fire extinguisher handy and a smoke alarm nearby.
Have fun;
Dan Banquer

Bemopti123 · « **Reply #3 on:** 15 Feb 2010, 08:25 pm »

Wow. Keep the comments flowing.

NagysAudio · « **Reply #4 on:** 15 Feb 2010, 08:30 pm »

Amps without fuses = bad idea. If the amp has no fuses on the rail voltages and something should happen to the amp, your speakers will see a DC voltage of 60-80 volts. This means that the woofers will certainly blow as they don't have a protection capacitor and the tweeter will probably survive. Fuses have no effect on sound.

Brian Cheney · « **Reply #5 on:** 15 Feb 2010, 08:34 pm »

Fuses are too slow to protect an overloaded output stage from blowing. Actually many protection circuits are too slow to stop damage due to speaker wires shorting at even relatively low power outputs. I speak from experience.

However, dispensing with all fuses (particularly for the AC line) would be a fire hazard and prevent UL approval of the amp for use in the USA. There are protection circuits which are relatively benign and often effective, and these are what most SS designers opt for.

B Cheney
VMPS Ribbon
www.vmpsaudio.com

Dan Banquer · « **Reply #6 on:** 15 Feb 2010, 08:36 pm »

Let me take this one step further. I wouldn't make a piece of a equipment for myself that was a shock or fire hazard, and I wouldn't do that to anyone else either.
It's your call.
Dan Banquer

Bemopti123 · « **Reply #7 on:** 15 Feb 2010, 08:37 pm »

Although I am the gambler type, it seems to be that I am appreciative of my life, my house and my equipment. I might need to look for some other piece of gear that will give the rush without the associated, possible catastrophic failure.

NagysAudio · « **Reply #8 on:** 15 Feb 2010, 08:41 pm »

Take a look at Goldmund amps, truly the very best amps in the world. You can get them quite affordable on Audiogon once in a while. www.goldmund.com

Dan Banquer · « **Reply #9 on:** 15 Feb 2010, 08:43 pm »

A moment of sanity in audiophilia?
Moderator: Please make this thread a sticky.
Regards;
Dan Banquer

Quote from: Bemopti123 on 15 Feb 2010, 08:37 pm

Although I am the gambler type, it seems to be that I am appreciative of my life, my house and my equipment. I might need to look for some other piece of gear that will give the rush without the associated, possible catastrophic failure.

satfrat · « **Reply #10 on:** 15 Feb 2010, 08:51 pm »

Quote from: NagysAudio on 15 Feb 2010, 08:30 pm

FUSES HAVE ABSOLUTELY NO EFFECT ON SOUND.

There are those here who don't buy this statement and neither do I.

Cheers,
Robin

gerald porzio · « **Reply #11 on:** 15 Feb 2010, 08:52 pm »

Richard Dunn's thesis compresses the dynamics out of common sense (the rarest commodity in audio).

NagysAudio · « **Reply #12 on:** 15 Feb 2010, 09:06 pm »

Robin,

Electrically speaking, silver plating is better because it becomes a better conductor, less resistance. But for the amount that they charge for these fuses, you can rewire the entire power supply with 12AWG silver plated, Teflon insulated mil spec wire. That should have a much greater impact that the short 0.5" fuse.

Kevin Haskins · « **Reply #13 on:** 15 Feb 2010, 09:07 pm »

Yes... amps or any electrical device hooked to AC mains without a safety fuse/breaker are reckless and irresponsible.

There are plenty of ways to get your audio fix. Don't endanger your family members or others simply because someone thinks it sounds better. Tweaks are great.... but use your head.

jtwrace · « **Reply #14 on:** 15 Feb 2010, 09:13 pm »

Quote from: NagysAudio on 15 Feb 2010, 09:06 pm

Robin,

12AWG silver plated, Teflon insulated mil spec wire.

Best source for this?

satfrat · « **Reply #15 on:** 15 Feb 2010, 09:14 pm »

Quote from: NagysAudio on 15 Feb 2010, 09:06 pm

Robin,

Electrically speaking, silver plating is better because it becomes a better conductor, less resistance. But for the amount that they charge for these fuses, you can rewire the entire power supply with 12AWG silver plated, Teflon insulated mil spec wire. That should have a much greater impact that the short 0.5" fuse. Changing the fuse once again will absolutely have no audible impact. That whole thread is retarded.

With your logic then, you can also cut off the transistor legs and solder 10AWG silver wire instead and also cut off the capacitor legs and solder 10AWG wire to them and also the resistors, etc. Oooh, what about the circuit tracks? What if we solder a solid core 10AWG conductor along each track?

The problem then becomes that your solid state amp wouldn't even function properly anymore. There would be so much distortion and oscillation.

Yeah, I know what you mean by retarded as that's what I thought about your "Aerospace cables" thread. I have tried different types of fuses in my amps and will trust my ears as I always have.

Cheers,
Robin

NagysAudio · « **Reply #16 on:** 15 Feb 2010, 09:20 pm »

toobluvr · « **Reply #17 on:** 15 Feb 2010, 09:22 pm »

Cheers??

Are we in London?

Dan Banquer · « **Reply #18 on:** 15 Feb 2010, 09:34 pm »

Was this a thread about basic electrical safety for amplifiers?
You cable and fuse guys are ruining a perfectly good thread that could make an excellent sticky.

Sigh;
Dan Banquer

turkey · « **Reply #19 on:** 15 Feb 2010, 09:35 pm »

Quote from: NagysAudio on 15 Feb 2010, 09:20 pm

Robin,

Care to do a blind comparison then? I will switch the fuses without telling you which ones are installed and you will tell me if they are Acme, Furutech, or regular. And I will do the same for my aerospace cables, you can put my cables against whatever you have. To make it worthwhile, lets make a $3000 bet, that should cover any travel costs, etc. What do you say?

So you're saying that you'll bet $3000 that he won't be able to tell the difference between fuses or between cables?