Amplifier and speaker protection circuits - Page 14

Roberto Amato · 30th November 2002, 10:01 PM

Quote:

Originally posted by fcel
Roberto ... "two transformers per channel and 20,000uf of capacitors for the power supply" ... that is definitely very different from the original design!

The capacitance, yes. That's why the sound slowly fades out when you cut power out. The dual mono design with two transformers is mentioned by Nelson in the BOSOZ article.

ciao,
Roberto Amato

PsykoK · 22nd December 2002, 01:50 PM

Hi,
I just finish and test my Soft Start Circuit, it works fine

I want to drive the PS of my futur Zen4 and in this case I want to know what kind of fuse I may use in the SSC!

I have some T4 fuse, it's that a good value or not?

Roberto Amato · 22nd December 2002, 05:23 PM

Quote:

Originally posted by PsykoK
Hi,
I just finish and test my Soft Start Circuit, it works fine

I want to drive the PS of my futur Zen4 and in this case I want to know what kind of fuse I may use in the SSC!

I have some T4 fuse, it's that a good value or not?

..ahem, what does "SSC" means? Also I'm not quite sure about "T4" meaning. 4A?
In my monoblock SoZ I use a slow-blow 750ma fuse. The inrush current is so much tamed by the soft-start, that the fuse rating needed is just slightly above the current sucked from the AC line.

ciao,
Roberto Amato

PsykoK · 23rd December 2002, 01:45 AM

Hi,
sorry "SSC" means Soft Start Circuit!
For the fise you're right T4 is for Slow Blow 4A

Thanks for your help

Andy5112405 · 4th October 2010, 04:52 PM

My F5 has two 10A fuses in the AC supplies from the transformers to the bridge rectifiers. Immediately after the fuses I have two 30A relays which, in the event of a fault being detected short the AC rails causing the fuses to rupture. OK the PSU capacitors are still charged and will discharge through the speakers but this takes seconds. No relay contacts are in the path of the DC supplies, nor are there any contacts in the speaker paths. It's BRUTE FORCE I know but it has absolutely NO effect on the sonic performance of the amp and does give a degree of protection to the speakers.

You might argue that the mains fuse would probably blow in the case of major amp failure. I've never had a problem.

Tiroler · 08:49 PM

Recently I have lost two Focal woofers due to a failing DC protection circuit. Plus, it wasn't the first time that this happend to me. Thus I always considered speaker protection as an important issue and have wondered why so many amps are buildt without it. In my mind a poor protection circuit is worse than no protection ciurcuit!
Now I am in the process of building F5's without any protection circuits at all. As I need new speakers too, I really hope (and expect) that the F5's will work better and safe..!

pdhanwada · 30th January 2012, 03:40 PM

Quote:

Originally Posted by Tiroler

Recently I have lost two Focal woofers due to a failing DC protection circuit. Plus, it wasn't the first time that this happend to me. Thus I always considered speaker protection as an important issue and have wondered why so many amps are buildt without it. In my mind a poor protection circuit is worse than no protection ciurcuit!
Now I am in the process of building F5's without any protection circuits at all. As I need new speakers too, I really hope (and expect) that the F5's will work better and safe..!

I am in the same boat about speaker protection. What did you end up implementing.

Thanks
Pandu

Tiroler · 30th January 2012, 06:57 PM

My experience says that the F5 is very reliable. Now I think that is a pity that I made my F5's without DC-protection. And there is no room left to put such a circuit into the cramped F5's now. A good protection circuit probably needs more board surface than the amp itself... When I used the BoSoZ I felt pretty safe. Now I have the fantastic UGS preamp and my whole system is DC-coupled. That is not exactly without risk.
Therefore my next power amps must have an adequate protection. I think it should sit at the output and must disconnect the speaker or short the supply rails really fast. The electrolytics should not be allowed to discharge through the speaker.

AndrewT · 30th January 2012, 07:02 PM

Some of Apex protection circuits use the power of the fault condition to operate the protection. They could be located on, or in the speaker.

ch33ta · 18th February 2012, 07:46 PM

If someone wants to play with Velleman K4700 speaker protection:
VellemanK4700
PCB and all other info is there...

22nd December 2002, 01:50 PM	#132
PsykoK diyAudio Member Join Date: Sep 2002 Location: Mulhouse, France	Zen4 Soft Start Hi, I just finish and test my Soft Start Circuit, it works fine I want to drive the PS of my futur Zen4 and in this case I want to know what kind of fuse I may use in the SSC! I have some T4 fuse, it's that a good value or not?

4th October 2010, 08:44 PM	#136
Tiroler diyAudio Member Join Date: Jan 2010 Location: Austria	Recently I have lost two Focal woofers due to a failing DC protection circuit. Plus, it wasn't the first time that this happend to me. Thus I always considered speaker protection as an important issue and have wondered why so many amps are buildt without it. In my mind a poor protection circuit is worse than no protection ciurcuit! Now I am in the process of building F5's without any protection circuits at all. As I need new speakers too, I really hope (and expect) that the F5's will work better and safe..! Last edited by Tiroler; 4th October 2010 at 08:49 PM.

30th January 2012, 07:02 PM	#139
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Some of Apex protection circuits use the power of the fault condition to operate the protection. They could be located on, or in the speaker. __________________ regards Andrew T.

18th February 2012, 07:46 PM	#140
ch33ta diyAudio Member Join Date: Jun 2006 Location: Croatia	If someone wants to play with Velleman K4700 speaker protection: VellemanK4700 PCB and all other info is there... __________________ Nothing to see here...

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23rd December 2002, 01:45 AM	#134
PsykoK diyAudio Member Join Date: Sep 2002 Location: Mulhouse, France	Hi, sorry "SSC" means Soft Start Circuit! For the fise you're right T4 is for Slow Blow 4A Thanks for your help

4th October 2010, 04:52 PM	#135
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	My F5 has two 10A fuses in the AC supplies from the transformers to the bridge rectifiers. Immediately after the fuses I have two 30A relays which, in the event of a fault being detected short the AC rails causing the fuses to rupture. OK the PSU capacitors are still charged and will discharge through the speakers but this takes seconds. No relay contacts are in the path of the DC supplies, nor are there any contacts in the speaker paths. It's BRUTE FORCE I know but it has absolutely NO effect on the sonic performance of the amp and does give a degree of protection to the speakers. You might argue that the mains fuse would probably blow in the case of major amp failure. I've never had a problem.

30th January 2012, 06:57 PM	#138
Tiroler diyAudio Member Join Date: Jan 2010 Location: Austria	My experience says that the F5 is very reliable. Now I think that is a pity that I made my F5's without DC-protection. And there is no room left to put such a circuit into the cramped F5's now. A good protection circuit probably needs more board surface than the amp itself... When I used the BoSoZ I felt pretty safe. Now I have the fantastic UGS preamp and my whole system is DC-coupled. That is not exactly without risk. Therefore my next power amps must have an adequate protection. I think it should sit at the output and must disconnect the speaker or short the supply rails really fast. The electrolytics should not be allowed to discharge through the speaker.

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