In article <597cccdafcdave@davenoise.co.uk>, Dave Plowman (News)
<dave@davenoise.co.uk> scribeth thus
>In article <597cc31b15bob@sick-of-spam.invalid>,
> Bob Latham <bob@sick-of-spam.invalid> wrote:
>> In article <597c3ed8ccnoise@audiomisc.co.uk>,
>> Jim Lesurf <noise@audiomisc.co.uk> wrote:
>> > In article <597bd7e6b4dave@davenoise.co.uk>, Dave Plowman (News)
>> > <dave@davenoise.co.uk> wrote:
>
>> > > A relay uses contacts held together. No difference in principle
>> > > from a screw connection (or plug) used on amp output and speaker
>> > > input. If you distrust point to point contacts, you'd need to go
>> > > to soldered ones. ;-)
>
>> > The difference is that a relay for dodging a switch-on thump is
>> > broken and remade during every power off-on cycle. Another
>> > difference may be that it is connected when some voltage difference
>> > may remain. Matter of circumstances if that is the case - may
>> > 'clean' the contact or 'dirty' it.
>
>> > So not the same as something like a continued contact that remaind
>> > under contact pressure all the time.
>
>> +1
>
>> Also a relay has a tiny spot contact that isn't under considerable
>> pressure unless you use a contactor or something like that.
>
>How big the contact area is in a relay depends on its spec. As does the
>material used.
>
>
>> A banana plug has considerable wipe action when inserted and a large
>> contact area and maybe, quite a bit of pressure.
>
>Wish there was a plug and socket that never gave problems. If you work in
>broadcast audio, you'd be aware such a thing doesn't exist.

Dunno Dave, XLR's have been pretty good over time?...

>
>> [Snip]
>
>> > That said, if you're making the amp for yourself, any reasonably
>> > rated relay will probably work fine for some time. So after a few
>> > years you can decide to replace it should it start misbehaving.
>
>> Seems to me a relay from a car as suggested would be good choice or
>> you could use the relay used by Arcam in their amps as I suggested a
>> while back. Yes 24v but you said that wasn't a issue.
>
>> I got 14 years out of the worst 1 of 7 before piano music started to
>> sound odd.
>
>> I refer you again..
>
>> https://uk.farnell.com/omron/g2r-1-e-24dc/relay-spdt-250vac-30vdc-
>16a/dp/9949429?ost=994-9429
>
>> https://uk.rs-online.com/web/p/non-latching-relays/0366300/
>
>> They are 24v 1.1Kohms so 22mA.
>> The Arcam P7 is claimed to be ~180W /channel.
>
>You're quite likely on an old amp to have problems with switchgear, edge
>connectors, etc, too.
>
Thas wot servisol is for;)....

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

Dave Plowman (Pommy Cunthead) wrote:
==============================
> >
> > > > > Phil Allison <palli...@gmail.com> wrote:
> > > > >
> > > > > > There simply is no "best relay" - that is your wild, bullshit
> > > > > > assumption.
> > > > >
> > > > > Ok. If no best, than any will do.
> > >
> > > > ** Ridiculous non sequitur.
> > >
> > > > > You prat.
> > >
> > > > ** Recognisng simple facts is way beyond this vile moron's maggot infested brain.
> > >
> > > And answering the simplest of questions
> > >
>
> > ** Yours was a * bullshit* question based on a false assumption.
>
> > Anyhow - TW answered your idiot Q long ago.
>
> >
> Just wondering why you spend so much time replying to what you consider an
> idiot question.

** I didn't.

The general topic was discussed while your idiot, fake Q was ignored.
Happens a lot on usenet.

Go fuck yourself.

...... Phil

tony sayer wrote:
==============
>
> > Must have a look in My Audiolab amps they have relays, time perhaps for
> new ones and a re-capping:)

** Only if you are OCD.

" If it ain't broke, don't fix it "

> I see that the QUAD 405 Mk 1 and 2 never needed them?....

** Three reasons:

1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.

2. On its own, it makes only a small and tolerable switch on sound.

3. It has triac " crow bar" circuits on the speaker outputs to stop DC.

Relays are found mostly in integrated amps, receivers and home theatre amps.

..... Phil

In article <a904115e-df0b-466a-8e09-f6ae0297d6a5n@googlegroups.com>,
Phil Allison <pallison49@gmail.com> scribeth thus
>tony sayer wrote:
>==============
>>
>> > Must have a look in My Audiolab amps they have relays, time perhaps for
>> new ones and a re-capping:)
>
>** Only if you are OCD.
>
>" If it ain't broke, don't fix it "

Well they do deteriorate over time, if you had a second-hand 303 what
would be the first thing you'd do with it?...

>
>
>> I see that the QUAD 405 Mk 1 and 2 never needed them?....
>
>** Three reasons:
>
>1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.

Be interesting to see if it does with its AM 8/16 frequency splitting
pre-amp driver with a modern day THAT Corp balanced input...

We're replicating one of these!...

https://www.ebay.co.uk/itm/124961482132?ssPageName=STRK%3AMEBIDX%3AIT&_t
rksid=p2060353.m1438.l2649

>
>2. On its own, it makes only a small and tolerable switch on sound.
>
>3. It has triac " crow bar" circuits on the speaker outputs to stop DC.
>
Added in after they stated production....

>Relays are found mostly in integrated amps, receivers and home theatre amps.
>
>
>
>
>.... Phil
>

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

tony sayer is a bloody idiot wrote:
===========================
>>
> >> > Must have a look in My Audiolab amps they have relays, time perhaps for
> >> new ones and a re-capping:)
> >
> >** Only if you are OCD.
> >
> >" If it ain't broke, don't fix it "
>
> Well they do deteriorate over time,

** Like you have ?

> if you had a second-hand 303 what
> would be the first thing you'd do with it?...

** Red herring.
> >> I see that the QUAD 405 Mk 1 and 2 never needed them?....
> >
> >** Three reasons:
> >
> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.
>
> Be interesting to see if it does with its AM 8/16 frequency splitting
> pre-amp driver with a modern day THAT Corp balanced input...
>

** Yawnnnnnnnnnn....

> >2. On its own, it makes only a small and tolerable switch on sound.
> >
> >3. It has triac " crow bar" circuits on the speaker outputs to stop DC.
> >
> Added in after they stated production....

** Prove it - smartarse.

It is shown on even the earliest schems.

....... Phil

In article <qiZZWFNvEvchFwpp@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:
> >Wish there was a plug and socket that never gave problems. If you work in
> >broadcast audio, you'd be aware such a thing doesn't exist.

> Dunno Dave, XLR's have been pretty good over time?...

Ever rigged an outside broadcast? ;-)

And then there were jackfields...

--
*Laugh alone and the world thinks you're an idiot.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

In article <9jlMWeNeV+chFwao@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:
> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.

> Be interesting to see if it does with its AM 8/16 frequency splitting
> pre-amp driver with a modern day THAT Corp balanced input...

Yes. It's the BBC crossover that produces the squack. Not the input
balance transformer. But oddly not every example does it to the same
degree.

With one of those, it would make sense to put the relay (or whatever)
between the crossover and power amps.

Many a cup of coffee was spilt when switching the power on when the 5/8
first arrived. ;-)

--
*Never underestimate the power of very stupid people in large groups *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

In article <a68c22cf-4b9b-4240-b013-b5d094652f2en@googlegroups.com>,
Phil Allison <pallison49@gmail.com> scribeth thus
> tony sayer is a bloody idiot wrote:
>===========================
>>>
>> >> > Must have a look in My Audiolab amps they have relays, time perhaps for
>> >> new ones and a re-capping:)
>> >
>> >** Only if you are OCD.
>> >
>> >" If it ain't broke, don't fix it "
>>
>> Well they do deteriorate over time,
>
>** Like you have ?

Well takes one to know one or don't people age in Oz;?...

>
>
>> if you had a second-hand 303 what
>> would be the first thing you'd do with it?...
>
>** Red herring.
>

No not at all, due to the age of them thats the first thing you'd look
at the earliest ones will have thrown up over the PCB's, and any more
recent ones will be of some age now, and you can get in more uF's in the
same space which are useful in the power unit and in the output.

I'm sure P.W. would have use more if he had them available..

Remember these units are very old now, the 33/303 here dates from 1967
and is still in daily use driving a brace of LS3/5A's...

Got a few HP audio test sets here, re-capped ones, as anyone who has any
HP stuff of any age will advise them to be upgraded on the HP test
equipment forums...

>
>> >> I see that the QUAD 405 Mk 1 and 2 never needed them?....
>> >
>> >** Three reasons:
>> >
>> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.
>>
>> Be interesting to see if it does with its AM 8/16 frequency splitting
>> pre-amp driver with a modern day THAT Corp balanced input...
>>
>

Well if you were over her sure you'd like a listen;)...

>** Yawnnnnnnnnnn....
>
>
>> >2. On its own, it makes only a small and tolerable switch on sound.
>> >
>> >3. It has triac " crow bar" circuits on the speaker outputs to stop DC.
>> >
>> Added in after they stated production....
>
>** Prove it - smartarse.
>
>It is shown on even the earliest schems.
>
>

I'm sure you can find more than the one service manual online if that
link don't go, but it wasn't on the earliest ones it started on PCB
issue 8 on page 15 appx serial 9000...

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUK
Ewiiq52zv-HzAhUyAWMBHd7VDhAQFnoECAQQAQ&url=https%3A%2F%2Fwww.dadaelectro
nics.eu%2Fuploads%2Fdownloads%2F02_Quad-Service-Manuals%2FQuad-405-and-
405-2-Service-Manual-10-12-2010.pdf&usg=AOvVaw3PF076mb_fq33WH1K4Tpeh

>...... Phil
>
>

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article <597fe52a1adave@davenoise.co.uk>, Dave Plowman (News)
<dave@davenoise.co.uk> scribeth thus
>In article <qiZZWFNvEvchFwpp@bancom.co.uk>,
> tony sayer <tony@bancom.co.uk> wrote:
>> >Wish there was a plug and socket that never gave problems. If you work in
>> >broadcast audio, you'd be aware such a thing doesn't exist.
>
>> Dunno Dave, XLR's have been pretty good over time?...
>
>Ever rigged an outside broadcast? ;-)

Some, not as many as you i suspect!
>
>And then there were jackfields...

Spawn of Satan OK for phone exchange boards and thats about it.

The old XLR has done very well, well decent makes have, no ones come up
with better but these days as Fibre takes hold;!..

>

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
<dave@davenoise.co.uk> scribeth thus
>In article <9jlMWeNeV+chFwao@bancom.co.uk>,
> tony sayer <tony@bancom.co.uk> wrote:
>> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.
>
>> Be interesting to see if it does with its AM 8/16 frequency splitting
>> pre-amp driver with a modern day THAT Corp balanced input...
>
>Yes. It's the BBC crossover that produces the squack. Not the input
>balance transformer. But oddly not every example does it to the same
>degree.
>
>With one of those, it would make sense to put the relay (or whatever)
>between the crossover and power amps.
>
>Many a cup of coffee was spilt when switching the power on when the 5/8
>first arrived. ;-)
>

Well this version is a tad different to those;)...

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

tony sayer is a bloody idiot wrote:
===========================
> >
> >> >" If it ain't broke, don't fix it "
> >>
> >> Well they do deteriorate over time,
> >
> >** Like you have ?

> Well takes one to know one or don't people age in Oz;?.

** The word used was not "age" - fuckhead,.

>
> >> if you had a second-hand 303 what
> >> would be the first thing you'd do with it?...
> >
> >** Red herring.
> >
> No not at all,

** Wrong, the Q is not relevant.
Raised only to muddy the water.

>
> >> >> I see that the QUAD 405 Mk 1 and 2 never needed them?....
> >> >
> >> >** Three reasons:
> >> >
> >> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.
> >>
> >> Be interesting to see if it does with its AM 8/16 frequency splitting
> >> pre-amp driver with a modern day THAT Corp balanced input...
> >>
>> >** Yawnnnnnnnnnn....
> >
> >
> >> >2. On its own, it makes only a small and tolerable switch on sound.
> >> >
> >> >3. It has triac " crow bar" circuits on the speaker outputs to stop DC.
> >> >
> >> Added in after they stated production....
> >
> >** Prove it - smartarse.
> >
> >It is shown on even the earliest schems.
> >
> >
> I'm sure you can find more than the one service manual online if that
> link don't go, but it wasn't on the earliest ones it started on PCB
> issue 8 on page 15 appx serial 9000...
>
>
> https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUK
> Ewiiq52zv-HzAhUyAWMBHd7VDhAQFnoECAQQAQ&url=https%3A%2F%2Fwww.dadaelectro
> nics.eu%2Fuploads%2Fdownloads%2F02_Quad-Service-Manuals%2FQuad-405-and-
> 405-2-Service-Manual-10-12-2010.pdf&usg=AOvVaw3PF076mb_fq33WH1K4Tpeh

** Bullshit dead link.

FOAD you pommy ass.

In article <GFZifNOraIdhFwW1@bancom.co.uk>,
tony sayer <tony@bancom.co.uk> wrote:
> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
> <dave@davenoise.co.uk> scribeth thus
> >In article <9jlMWeNeV+chFwao@bancom.co.uk>,
> > tony sayer <tony@bancom.co.uk> wrote:
> >> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever does.
> >
> >> Be interesting to see if it does with its AM 8/16 frequency splitting
> >> pre-amp driver with a modern day THAT Corp balanced input...
> >
> >Yes. It's the BBC crossover that produces the squack. Not the input
> >balance transformer. But oddly not every example does it to the same
> >degree.
> >
> >With one of those, it would make sense to put the relay (or whatever)
> >between the crossover and power amps.
> >
> >Many a cup of coffee was spilt when switching the power on when the 5/8
> >first arrived. ;-)
> >

> Well this version is a tad different to those;)...

You've designed a totally new crossover using ICs?

--
*Speak softly and carry a cellular phone *

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
<dave@davenoise.co.uk> wrote:

> Yes. It's the BBC crossover that produces the squack. Not the input
> balance transformer. But oddly not every example does it to the same
> degree.

Curious. Any details?

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
biog http://jcgl.orpheusweb.co.uk/history/ups_and_downs.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article <59806976e4dave@davenoise.co.uk>, Dave Plowman (News)
<dave@davenoise.co.uk> scribeth thus
>In article <GFZifNOraIdhFwW1@bancom.co.uk>,
> tony sayer <tony@bancom.co.uk> wrote:
>> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
>> <dave@davenoise.co.uk> scribeth thus
>> >In article <9jlMWeNeV+chFwao@bancom.co.uk>,
>> > tony sayer <tony@bancom.co.uk> wrote:
>> >> >1. The 405 is a power amp and so will emit a thump if the pre-amp ever
>does.
>> >
>> >> Be interesting to see if it does with its AM 8/16 frequency splitting
>> >> pre-amp driver with a modern day THAT Corp balanced input...
>> >
>> >Yes. It's the BBC crossover that produces the squack. Not the input
>> >balance transformer. But oddly not every example does it to the same
>> >degree.
>> >
>> >With one of those, it would make sense to put the relay (or whatever)
>> >between the crossover and power amps.
>> >
>> >Many a cup of coffee was spilt when switching the power on when the 5/8
>> >first arrived. ;-)
>> >
>
>> Well this version is a tad different to those;)...
>
>You've designed a totally new crossover using ICs?
>

Near as dammit, right from the balanced inputs to the output needs a bit
of work but thus far has behaved very well!....

--
Tony Sayer

Man is least himself when he talks in his own person.

Give him a keyboard, and he will reveal himself.

In article <5980dbe7a3noise@audiomisc.co.uk>,
Jim Lesurf <noise@audiomisc.co.uk> wrote:
> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
> <dave@davenoise.co.uk> wrote:

> > Yes. It's the BBC crossover that produces the squack. Not the input
> > balance transformer. But oddly not every example does it to the same
> > degree.

> Curious. Any details?

Sadly not, although you'll find the circuit online easily enough, if you
want to make a guess.

It defeated the studio engineers at TVC when they arrived there. Many a
coffee was spilt when switching on a very quiet control room first thing -
until people came to expect it. But why seemingly identical ones made a
very different noise, I dunno.

With my original LS5/8 with Quad 405/2 amps (BBC AM 8/16) I fitted timed
muting relays on the crossover outputs. Not only did that stop the
crossover quack but stopped any thump from the pre-amp powering up too.

--
*I get enough exercise just pushing my luck.

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

On 30/10/2021 2:20 am, Dave Plowman (News) wrote:
> In article <5980dbe7a3noise@audiomisc.co.uk>,
> Jim Lesurf <noise@audiomisc.co.uk> wrote:
>> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
>> <dave@davenoise.co.uk> wrote:
>
>>> Yes. It's the BBC crossover that produces the squack. Not the input
>>> balance transformer. But oddly not every example does it to the same
>>> degree.
>
>> Curious. Any details?
>
> Sadly not, although you'll find the circuit online easily enough, if you
> want to make a guess.
>
> It defeated the studio engineers at TVC when they arrived there. Many a
> coffee was spilt when switching on a very quiet control room first thing -
> until people came to expect it. But why seemingly identical ones made a
> very different noise, I dunno.
>
> With my original LS5/8 with Quad 405/2 amps (BBC AM 8/16) I fitted timed
> muting relays on the crossover outputs. Not only did that stop the
> crossover quack but stopped any thump from the pre-amp powering up too.
>

**Amateurs. The power amp/s and the preamp I use are not fitted with any
muting system of any kind. No relays. Nothing. They can be switched on
in any order and there is no thump. Of course, the designer is very
clever and dedicated engineer, who knows how to design audio gear the
right way. The only protection system is as I described earlier. A relay
driven TRIAC disconnects mains power under various fault scenarios.

In article <iu44frFa899U1@mid.individual.net>,
Trevor Wilson <trevor@rageaudio.com.au> wrote:

> **Amateurs. The power amp/s and the preamp I use are not fitted
> with any muting system of any kind. No relays. Nothing. They can
> be switched on in any order and there is no thump. Of course, the
> designer is very clever and dedicated engineer, who knows how to
> design audio gear the right way. The only protection system is as
> I described earlier. A relay driven TRIAC disconnects mains power
> under various fault scenarios.

May I ask, is this pre-amp coupled to the power amp via a capacitor
or is it DC coupled?

Bob.

In article <iu44frFa899U1@mid.individual.net>,
Trevor Wilson <trevor@rageaudio.com.au> wrote:
> On 30/10/2021 2:20 am, Dave Plowman (News) wrote:
> > In article <5980dbe7a3noise@audiomisc.co.uk>,
> > Jim Lesurf <noise@audiomisc.co.uk> wrote:
> >> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
> >> <dave@davenoise.co.uk> wrote:
> >
> >>> Yes. It's the BBC crossover that produces the squack. Not the input
> >>> balance transformer. But oddly not every example does it to the same
> >>> degree.
> >
> >> Curious. Any details?
> >
> > Sadly not, although you'll find the circuit online easily enough, if
> > you want to make a guess.
> >
> > It defeated the studio engineers at TVC when they arrived there. Many
> > a coffee was spilt when switching on a very quiet control room first
> > thing - until people came to expect it. But why seemingly identical
> > ones made a very different noise, I dunno.
> >
> > With my original LS5/8 with Quad 405/2 amps (BBC AM 8/16) I fitted
> > timed muting relays on the crossover outputs. Not only did that stop
> > the crossover quack but stopped any thump from the pre-amp powering up
> > too.
> >

> **Amateurs. The power amp/s and the preamp I use are not fitted with any
> muting system of any kind. No relays. Nothing. They can be switched on
> in any order and there is no thump. Of course, the designer is very
> clever and dedicated engineer, who knows how to design audio gear the
> right way. The only protection system is as I described earlier. A relay
> driven TRIAC disconnects mains power under various fault scenarios.

You've missed your vocation. You should have designed speakers and amps
for the BBC, then. ;-)

--
*How many roads must a man travel down before he admits he is lost?

Dave Plowman dave@davenoise.co.uk London SW
To e-mail, change noise into sound.

On 30/10/2021 7:06 pm, Bob Latham wrote:
> In article <iu44frFa899U1@mid.individual.net>,
> Trevor Wilson <trevor@rageaudio.com.au> wrote:
>
>> **Amateurs. The power amp/s and the preamp I use are not fitted
>> with any muting system of any kind. No relays. Nothing. They can
>> be switched on in any order and there is no thump. Of course, the
>> designer is very clever and dedicated engineer, who knows how to
>> design audio gear the right way. The only protection system is as
>> I described earlier. A relay driven TRIAC disconnects mains power
>> under various fault scenarios.
>
> May I ask, is this pre-amp coupled to the power amp via a capacitor
> or is it DC coupled?
>
> Bob.
>

**DC coupled of course. Capacitors are so 1950.

On 31/10/2021 12:00 am, Dave Plowman (News) wrote:
> In article <iu44frFa899U1@mid.individual.net>,
> Trevor Wilson <trevor@rageaudio.com.au> wrote:
>> On 30/10/2021 2:20 am, Dave Plowman (News) wrote:
>>> In article <5980dbe7a3noise@audiomisc.co.uk>,
>>> Jim Lesurf <noise@audiomisc.co.uk> wrote:
>>>> In article <597fe5b064dave@davenoise.co.uk>, Dave Plowman (News)
>>>> <dave@davenoise.co.uk> wrote:
>>>
>>>>> Yes. It's the BBC crossover that produces the squack. Not the input
>>>>> balance transformer. But oddly not every example does it to the same
>>>>> degree.
>>>
>>>> Curious. Any details?
>>>
>>> Sadly not, although you'll find the circuit online easily enough, if
>>> you want to make a guess.
>>>
>>> It defeated the studio engineers at TVC when they arrived there. Many
>>> a coffee was spilt when switching on a very quiet control room first
>>> thing - until people came to expect it. But why seemingly identical
>>> ones made a very different noise, I dunno.
>>>
>>> With my original LS5/8 with Quad 405/2 amps (BBC AM 8/16) I fitted
>>> timed muting relays on the crossover outputs. Not only did that stop
>>> the crossover quack but stopped any thump from the pre-amp powering up
>>> too.
>>>
>
>> **Amateurs. The power amp/s and the preamp I use are not fitted with any
>> muting system of any kind. No relays. Nothing. They can be switched on
>> in any order and there is no thump. Of course, the designer is very
>> clever and dedicated engineer, who knows how to design audio gear the
>> right way. The only protection system is as I described earlier. A relay
>> driven TRIAC disconnects mains power under various fault scenarios.
>
> You've missed your vocation. You should have designed speakers and amps
> for the BBC, then. ;-)
>

**I am not the designer. The designer is MUCH clevererer than I am.

Trevor Wilson wrote:
=================
> >
> > May I ask, is this pre-amp coupled to the power amp via a capacitor
> > or is it DC coupled?
> >
> > Bob.
> >
>
> **DC coupled of course. Capacitors are so 1950.
>

** Are there any low frequency roll offs in the power amp ?
Or do subsonic inputs go right through to the speaker ?

....... Phil

Trevor Wilson wrote:
=================
>>
>
> **I am not the designer. The designer is MUCH clevererer than I am.
>

** Then you really have no way to evaluate his work.

....... Phil

On 31/10/2021 10:36 am, Phil Allison wrote:
> Trevor Wilson wrote:
> =================
>>>
>>> May I ask, is this pre-amp coupled to the power amp via a capacitor
>>> or is it DC coupled?
>>>
>>> Bob.
>>>
>>
>> **DC coupled of course. Capacitors are so 1950.
>>
>
> ** Are there any low frequency roll offs in the power amp ?

**Nope. Frequency response is DC to 150kHz @ -2dB.

> Or do subsonic inputs go right through to the speaker ?

**Yep. Until the subsonic protection system is triggered. With the
advent of CD players and other digital sources, subsonics are rarely a
problem anymore. There is a coupling capacitor from the phono section in
the preamp. Line inputs are all DC coupled.

On Sun, 31 Oct 2021 16:16:28 +1100, Trevor Wilson
<trevor@rageaudio.com.au> wrote:

>On 31/10/2021 10:36 am, Phil Allison wrote:
>> Trevor Wilson wrote:
>> =================
>>>>
>>>> May I ask, is this pre-amp coupled to the power amp via a capacitor
>>>> or is it DC coupled?
>>>>
>>>> Bob.
>>>>
>>>
>>> **DC coupled of course. Capacitors are so 1950.
>>>
>>
>> ** Are there any low frequency roll offs in the power amp ?
>
>**Nope. Frequency response is DC to 150kHz @ -2dB.
>
>> Or do subsonic inputs go right through to the speaker ?
>
>**Yep. Until the subsonic protection system is triggered. With the
>advent of CD players and other digital sources, subsonics are rarely a
>problem anymore. There is a coupling capacitor from the phono section in
>the preamp. Line inputs are all DC coupled.

As long as the phono section is capacitively coupled you're fine. You
can get speaker-destroying signals at 5-10Hz from a cartridge
depending on the quality of arm damping.

d

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Don Pearce wrote:
===============
>
> >>>
> >>> **DC coupled of course. Capacitors are so 1950.
> >>
> >> ** Are there any low frequency roll offs in the power amp ?
> >
> >**Nope. Frequency response is DC to 150kHz @ -2dB.
> >
> >> Or do subsonic inputs go right through to the speaker ?
> >
> >**Yep. Until the subsonic protection system is triggered. With the
> >advent of CD players and other digital sources, subsonics are rarely a
> >problem anymore. There is a coupling capacitor from the phono section in
> >the preamp. Line inputs are all DC coupled.
>
>
** So Don puked:
>
> As long as the phono section is capacitively coupled you're fine.

** Oh really ??

> You can get speaker-destroying signals at 5-10Hz from a cartridge
> depending on the quality of arm damping.
>

** How exactly is that then ??

When ( not if ) a tone arm is dropped onto an LP at volume - what stops a massive subsonic ?

Do no aux input items *ever* make one of them either ?

Many CD players are speced at being -0.5 dB at 5Hz.

Might be an issue ?

....... Phil