Confession time
 

Mike Gilmour wrote:

Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you -
promise.

Moving into my first flat many moons ago, I was only concerned with the
important stuff - floor cushions, coffee machine and hifi. After getting the
first of two big Kefs up the stairs (a top floor flat, of course), I decided
to take a coffee break before getting on with the rest. As the coffee
brewed, I connected the turntable to the amp and plugged in the speaker. I
get sounds, but realise that only having one speaker means I'm only hearing
one channel. I hit upon a bright idea for hearing both channels - plug both
amp outputs into the single speaker.

No sounds.


--
Wally
www.makearatherlonglinkthattakesyounowhere.com
Things are always clearer in the cold, post-upload light.

Confession time
 

Once i had some new homemade speakers using the Kef T27 tweeters and B200s.

A friend of mine came round for a listen. We were discussing speakers when
he pointed to the T27 with a screw-driver. Yes you guessed it, the magnet
in the T27 pulled the screw-driver right through the dome!

Not very funny, but bloody annoying at the time.

Confession time
 

Once i had some new homemade speakers using the Kef T27 tweeters and B200s.

A friend of mine came round for a listen. We were discussing speakers when
he pointed to the T27 with a screw-driver. Yes you guessed it, the magnet
in the T27 pulled the screw-driver right through the dome!

Not very funny, but bloody annoying at the time.

Confession time
 

On Thu, 20 Nov 2003 18:46:40 -0000
"Mike Gilmour" wrote:

Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you - promise.

Ok, heres mine...

Just rebuilt Quad405 (40 odd quid in parts,mostly big transistors), and realised that I needed a preamp.

thought 'I know, I'll use this tinypower amp with the gain set low'.

of course, it had a capacitor coupled output, so the first thingit did was runthe Quad405 flat out into its (thankfully connected and working) output protection board.

Anyone got a spare set out output transistors?

Anyhow, this is the event that made me decide to mod the amp. the current limiting on the 405 was too severe, which is what allowed the o/p trannies to blow (before the fuses could save them).

Im modding the amp (rebuilding the PCBs) such that:

the gain is halved (1Vp-t-p inputs, less noise)
use better quality parts in the input,particularly one resistor that sets the performance of the whole amp
double the input cap values
use a more modern op-amp and adjust the supply to it to avoid hiss
dc couple some transistors now that higher voltage parts exist - like the 606 design. eliminates a couple of passive components.
apply the 405-mkII current limiter (better performance, less blown outputs.

I'll make full parts lists and layouts available once Im ready.

Jim... did you ever look at the schematic I sent you ?

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Confession time
 

On Thu, 20 Nov 2003 18:46:40 -0000
"Mike Gilmour" wrote:

Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you - promise.

Ok, heres mine...

Just rebuilt Quad405 (40 odd quid in parts,mostly big transistors), and realised that I needed a preamp.

thought 'I know, I'll use this tinypower amp with the gain set low'.

of course, it had a capacitor coupled output, so the first thingit did was runthe Quad405 flat out into its (thankfully connected and working) output protection board.

Anyone got a spare set out output transistors?

Anyhow, this is the event that made me decide to mod the amp. the current limiting on the 405 was too severe, which is what allowed the o/p trannies to blow (before the fuses could save them).

Im modding the amp (rebuilding the PCBs) such that:

the gain is halved (1Vp-t-p inputs, less noise)
use better quality parts in the input,particularly one resistor that sets the performance of the whole amp
double the input cap values
use a more modern op-amp and adjust the supply to it to avoid hiss
dc couple some transistors now that higher voltage parts exist - like the 606 design. eliminates a couple of passive components.
apply the 405-mkII current limiter (better performance, less blown outputs.

I'll make full parts lists and layouts available once Im ready.

Jim... did you ever look at the schematic I sent you ?

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Confession time
 

Ian Molton wrote:

On Thu, 20 Nov 2003 18:46:40 -0000
"Mike Gilmour" wrote:


Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you - promise.


Ok, heres mine...

Just rebuilt Quad405 (40 odd quid in parts,mostly big transistors), and realised that I needed a preamp.

thought 'I know, I'll use this tinypower amp with the gain set low'.

of course, it had a capacitor coupled output, so the first thingit did was runthe Quad405 flat out into its (thankfully connected and working) output protection board.

Anyone got a spare set out output transistors?

Anyhow, this is the event that made me decide to mod the amp. the current limiting on the 405 was too severe, which is what allowed the o/p trannies to blow (before the fuses could save them).

Im modding the amp (rebuilding the PCBs) such that:

the gain is halved (1Vp-t-p inputs, less noise)
use better quality parts in the input,particularly one resistor that sets the performance of the whole amp
double the input cap values
use a more modern op-amp and adjust the supply to it to avoid hiss
dc couple some transistors now that higher voltage parts exist - like the 606 design. eliminates a couple of passive components.
apply the 405-mkII current limiter (better performance, less blown outputs.

I'll make full parts lists and layouts available once Im ready.


As the priest said to the sinner,
"My son, you aren't confessing, you're boasting."

--
Roger.

Confession time
 

Ian Molton wrote:

On Thu, 20 Nov 2003 18:46:40 -0000
"Mike Gilmour" wrote:


Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you - promise.


Ok, heres mine...

Just rebuilt Quad405 (40 odd quid in parts,mostly big transistors), and realised that I needed a preamp.

thought 'I know, I'll use this tinypower amp with the gain set low'.

of course, it had a capacitor coupled output, so the first thingit did was runthe Quad405 flat out into its (thankfully connected and working) output protection board.

Anyone got a spare set out output transistors?

Anyhow, this is the event that made me decide to mod the amp. the current limiting on the 405 was too severe, which is what allowed the o/p trannies to blow (before the fuses could save them).

Im modding the amp (rebuilding the PCBs) such that:

the gain is halved (1Vp-t-p inputs, less noise)
use better quality parts in the input,particularly one resistor that sets the performance of the whole amp
double the input cap values
use a more modern op-amp and adjust the supply to it to avoid hiss
dc couple some transistors now that higher voltage parts exist - like the 606 design. eliminates a couple of passive components.
apply the 405-mkII current limiter (better performance, less blown outputs.

I'll make full parts lists and layouts available once Im ready.


As the priest said to the sinner,
"My son, you aren't confessing, you're boasting."

--
Roger.

Confession time
 

On Fri, 21 Nov 2003 08:21:10 +0000
Old Fart at Play wrote:

As the priest said to the sinner,
"My son, you aren't confessing, you're boasting."

LOL ;-)

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Confession time
 

On Fri, 21 Nov 2003 08:21:10 +0000
Old Fart at Play wrote:

As the priest said to the sinner,
"My son, you aren't confessing, you're boasting."

LOL ;-)

--
Spyros lair: http://www.mnementh.co.uk/ |||| Maintainer: arm26 linux

Do not meddle in the affairs of Dragons, for you are tasty and good with ketchup.

Confession time
 

In article , Ian Molton
wrote:
On Thu, 20 Nov 2003 18:46:40 -0000 "Mike Gilmour"
wrote:

Any audio tales of stoopid actions .i.e. like plugging in when mains
selector set to 110V...come on, we'll laugh with you not at you -
promise.

Ok, heres mine...

Just rebuilt Quad405 (40 odd quid in parts,mostly big transistors), and
realised that I needed a preamp.

thought 'I know, I'll use this tinypower amp with the gain set low'.

of course, it had a capacitor coupled output, so the first thingit did
was runthe Quad405 flat out into its (thankfully connected and working)
output protection board.

Anyone got a spare set out output transistors?

Not clear what you are describing above. Are you saying that the *Quad 405*
blew its output devices due to your injecting an input spike when your
'preamp' sic was switched on? Or are you saying the preamp output
devoices blew?

Anyhow, this is the event that made me decide to mod the amp. the
current limiting on the 405 was too severe, which is what allowed the
o/p trannies to blow (before the fuses could save them).

Puzzled. The point of the current limiting is to ensure the output devices
*never* blow up. The severe limiting on early 405's gets in the way of the
music sometimes, but should avoid failures. Hence I am puzzled by your last
sentence above.

Im modding the amp (rebuilding the PCBs) such that:

the gain is halved (1Vp-t-p inputs, less noise) use better quality parts
in the input,particularly one resistor that sets the performance of the
whole amp double the input cap values use a more modern op-amp and
adjust the supply to it to avoid hiss dc couple some transistors now
that higher voltage parts exist - like the 606 design. eliminates a
couple of passive components. apply the 405-mkII current limiter (better
performance, less blown outputs.

I\'ll make full parts lists and layouts available once Im ready.

Have you checked the stability margin? Reducing the overall gain and
changing various devices to different types may affect this.

Jim... did you ever look at the schematic I sent you ?

I am afraid I haven\'t. :-/ Too many other things have been distracting me
over the summer - many of them unfortunate. Sorry about this, but I had
completely forgotten. Can you remind me of the details by email?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html