Re: Tube amp safety


"Pooh Bear" <rabbitsfriendsandrelations@xxxxxxxxxxx> wrote in message
news:43A2005C.5A7B38EA@xxxxxxxxxxxxxx
>
>
> Iain Churches wrote:
>
>> "Bret Ludwig" <bretldwig@xxxxxxxxx> wrote in message
>> news:1134626648.233435.43060@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> > Best fix for the ST70, I think is to build a power supply on a second
>> > chassis and connect with a properly made cable. Many commercial amps
>> > were built this way and so were a lot of radio transmitters and
>> > transceivers. I would simply remove the preamp power/Biaset socket and
>> > replace it with a male 11-pin octal (yes there is) and follow the
>> > Heathkit/Collins convention.
>> >
>>
>> Hi Bret. I don't know the situation in the US, but here in Europe with
>> the
>> EU regs and CE marking etc, such a thing does not seem to be permitted
>> The good old octal plug and socket, (both 8 and 11 pin versions)
>> ubiquitous in the 50s and 60s are expressly forbidden for carrying
>> DC chassis to chassis.
>>
>> Even NATO connectors, rated at 600V are only aproved to 70V for
>> domestic use. Here in Scandinavia, we have to build what insurance
>> companies deem to be safe.
>>
>> Several of the studios where I work have rack mounted valve amps with
>> PSU mounted below, and connected by an armoured umbilical. This is
>> approved in the professional but not in a domestic environment (maybe
>> at home a Rottweiler will take his last bite - at your cable:-)
>>
>> I have discussed this matter with my own insurance company, my 50W
>> tube amp amp has a separate psu. They were not at all happy, even
>> though the psu had a female chassis connector. Their technical
>> assessor was later satisfied with an AC loop through the umbilical to
>> the mains switch, so that if either end of the umbilical was disconnected
>> the AC to the psu was disconnected and it would not start-up.
>> In the case where the amp was already running, they were fairly
>> happy with an internal power relay which (if the cable is disconnected)
>> switches a 10k 20W resistor across the last smoothing electrolytic,
>> and takes the B+ down to below 70V in 5 secs or less.
>
> Interesting.
>
> I'd have selected the 'safety cut out' arrangement too.

Hi Graham. What exactly did you have in mind?
>
> What style of connector did you end up with ?

The pics shows the NATO connector between my pre.amp
and separate psu. I later shorted the cord to 200mm
so that it could not hang low enough to catch under legs or wheels
of equipment racks.

http://www.kolumbus.fi/iain.churches/Pics/202+PSUrear.jpg
and
http://www.kolumbus.fi/iain.churches/Pics/202rear.jpg

Iain


.

Relevant Pages

  • Re: Tube amp safety
    ... > in article dnsakc$f5b$1@xxxxxxxxxxxxxxxxxxxxxx, Iain Churches at ... >>> chassis and connect with a properly made cable. ... >> PSU mounted below, and connected by an armoured umbilical. ... >> tube amp amp has a separate psu. ...
    (rec.audio.tubes)
  • Re: Tube amp safety
    ... >>> chassis and connect with a properly made cable. ... > The trouble is that even with the amp cable pins being male, ... The chassis connector on the psu is female, with a malke connector on the ...
    (rec.audio.tubes)
  • Re: Tube amp safety
    ... >> chassis and connect with a properly made cable. ... > PSU mounted below, and connected by an armoured umbilical. ... > tube amp amp has a separate psu. ... > though the psu had a female chassis connector. ...
    (rec.audio.tubes)
  • Re: Tube amp safety
    ... >> chassis and connect with a properly made cable. ... > Even NATO connectors, rated at 600V are only aproved to 70V for ... > PSU mounted below, and connected by an armoured umbilical. ... > tube amp amp has a separate psu. ...
    (rec.audio.tubes)
  • Re: Tube amp safety
    ... DC chassis to chassis. ... Even NATO connectors, rated at 600V are only aproved to 70V for ... PSU mounted below, and connected by an armoured umbilical. ... tube amp amp has a separate psu. ...
    (rec.audio.tubes)
Loading