ninjanki said:
Exactly, I use Schrack RT424048, they've never failed('ve used about 200).
http://relays.tycoelectronics.com/datasheets/RT2.pdf
They are only rated to break a few amps under 50V or so of DC. So how are you wiring them? As shunts to short to ground or inline with the speakers?
ewildgoose said:
The thing is they will break a long time before the amp output will reach 50V.
The offset trigger level is about 200mv which combined with the switch off time of the relay and electronics is sufficient to never reach the dangerous amp. levels.
Tried this with my Crecendo amps. by using a switch to induce a + or - 2V on the input, amp is completely dc coupled , with speakers connected. It switched of the speakers even before making a noise. Once in a while I had a Mosfet shortcut(they started oscilating and blew up).......no problem.
BTW they are in series with the output. For me the best protection, least damage way. Fuses are cheap(they are in my + and - lines).
We will not recommand an output relays, this will spoil the nice sonic
performance of the UcD amplifier. ( Output relays
pfff..
......)
In our power supplies we use the following setup, see PDF file.
Jan-Peter
performance of the UcD amplifier. ( Output relays
pfff........)In our power supplies we use the following setup, see PDF file.
Jan-Peter
Jan-Peter said:We will not recommand an output relays, this will spoil the nice sonic
performance of the UcD amplifier. ( Output relays
In our power supplies we use the following setup, see PDF file.
Jan-Peter
Jan-Peter,
So this circuitry it present twice on the supplies? I might consider to connect a third UcD400 to the HG supply for center channel duties, but I can't connect the DC protection of course...
So this circuitry it present twice on the supplies? I might consider to connect a third UcD400 to the HG supply for center channel duties, but I can't connect the DC protection of course...
Yves,
No we use only one circuit. It's only used for safety protection, in a case of a serious fault.
Jan-Peter
No we use only one circuit. It's only used for safety protection, in a case of a serious fault.
Jan-Peter
Jan-Peter said:
Sorry if i am stupid but i understand that dc-prot wire is connected to speaker terminal? If so, it can detect DC only from one UCD? If we have two or more UCD:s conected to one power supply, we need as many circuits as we have modules?
Ah, we use of course two DC detecting circuits on both power supplies (HG and ST). If you like you can add (by your self) more DC detecting circuits...
Regards,
Jan-Peter
Regards,
Jan-Peter
Bgt, don't forget that the level of fault protection is determined how easy it is to break the module. If experience show that the UcD modules are incredible good then a very serious protection may not be needed.
Jan-Peter,
Won't having the protection relay on the power supply rails have a similar sonic effect to a relay in the output? After all the MOSFETS are switching the supply rails or does the UCD use a feedback mechanism that compensates for the relay resistance in the power supply (PSRR)?
What about a technique that shorts the output to ground (or with a 1 ohm resistor) when DC is detected and blows the supply fuse? This way there is never a relay contact in either the output or the power supply.
Regards,
Dean
Won't having the protection relay on the power supply rails have a similar sonic effect to a relay in the output? After all the MOSFETS are switching the supply rails or does the UCD use a feedback mechanism that compensates for the relay resistance in the power supply (PSRR)?
What about a technique that shorts the output to ground (or with a 1 ohm resistor) when DC is detected and blows the supply fuse? This way there is never a relay contact in either the output or the power supply.
Regards,
Dean
Deandob,
It has NO sonic effect, there are sufficient local coupling capacitors on the UcD modules, so it will also not degreed the PSRR.
To put a relay in series with the output of the amplifier, this will have for sure sonic effect, that's the same as with fuses. A good relay is rated for a high current or for a very low current never both.
I would kindly close the discussion about DC protection, this is our way, and everybody is of course free to do it in an other way...
Regards,
Jan-Peter
It has NO sonic effect, there are sufficient local coupling capacitors on the UcD modules, so it will also not degreed the PSRR.
To put a relay in series with the output of the amplifier, this will have for sure sonic effect, that's the same as with fuses. A good relay is rated for a high current or for a very low current never both.
I would kindly close the discussion about DC protection, this is our way, and everybody is of course free to do it in an other way...
Regards,
Jan-Peter
Pasi P said:
Hello Pasi P,
Just to clarify for you. In the schematic that Jan-Peter posted, you should not connect the dc-prot wire to the speaker terminal. There is some additional circuit being used that does the additional DC detection. That additional (not shown) circuit is connected to the speaker output terminals and generates a signal that is connected to DC-prot. Hope this explains it.
Best regards
Gertjan
ghemink said:
Ah well, thank you for information. I bit wonder how this connection can be so simple.
Can you Jan-Peter show rest of the connection?
Pasi, if you don't mind I don't want to show the full schematic....😉
But any good DC detection circuit with an open collector output will do the job. We use a rather simple circuit with some transistors and zenerdiodes.
Jan-Peter
But any good DC detection circuit with an open collector output will do the job. We use a rather simple circuit with some transistors and zenerdiodes.
Jan-Peter
Is there real benefit for using a balanced vs single-end setup with the UcD400 module? Is it a true balanced circuit design ? I will install a volume pot and I was wondering if there is a real advantage of using two stereo pots to control both negative and positive signal for each channel or just connect the negative to the ground and use mono pots. I feed the amp directly from the source.
Thanks!
Thanks!
As long as you draw more than 10 mA or so there is no problem with "low" currents. 1mA or lower down to uA can cause real problems with power contacts (have sold relays for 20 years now)Jan-Peter said:
This is one way of solving the problem and I think it's OK. Since the relays never will switch any high current they will also last long. If you switch on these relays into capacitive load you might test wolfram contacts made for lamps and high inrush currents. the relay has two contacts which work in parallel. The first inrush is taken by the tingsten/wolfram contact and the continuous current is taken care of hardsilver. I can tell you more about if you are interested.Jan-Peter said:
Need I say that this special relay has an extremely high sonic impact ?
