so left it on for 10 mins and the current stayed pretty much around 11-12mv on both channels
heatsink is now a much more reasonable 36c
playing music again now and the current does go up and down quite a bit as i guess it would? ,but nothing realy high
temp of heatsink still less that 40c even at loud volumes
i wouldnt say it was anymore distorted with the lower current but that is with my old ears 😉
my thoughts on the amp? not as clear as my nad through a pair of KEF concord1v's or my fyne audio 303's, it seems confused sometimes at higher volumes
still not a bad amp though and it has been nice to do something different even though i didnt like having to keep moving the transformer around everytime i wanted to check something
heatsink is now a much more reasonable 36c
playing music again now and the current does go up and down quite a bit as i guess it would? ,but nothing realy high
temp of heatsink still less that 40c even at loud volumes
i wouldnt say it was anymore distorted with the lower current but that is with my old ears 😉
my thoughts on the amp? not as clear as my nad through a pair of KEF concord1v's or my fyne audio 303's, it seems confused sometimes at higher volumes
still not a bad amp though and it has been nice to do something different even though i didnt like having to keep moving the transformer around everytime i wanted to check something
That sounds all good then 
In practice you will find anything over a milliamp or two (so even 0.5 millivolt across 0.22 ohm) will remove audible distortion. You probably need to listen to a few more different amps to get a feel for audible differences but I would (and without hearing one) suspect the NAD is the more musical performer. The Creek probably sounds more like good HiFi, the NAD just makes music despite any flaws.
In practice you will find anything over a milliamp or two (so even 0.5 millivolt across 0.22 ohm) will remove audible distortion. You probably need to listen to a few more different amps to get a feel for audible differences but I would (and without hearing one) suspect the NAD is the more musical performer. The Creek probably sounds more like good HiFi, the NAD just makes music despite any flaws.
yepill button it all up tomorrow, then its onto the arcam alpha, see whats wrong with that
time for tea and TV !
time for tea and TV !
so im trying to investigate this 'lamp on' 'lamp off' senario
First thing is it only does it in intergrated mode(switch out) and with the mute switch out
If you oput it into 'split' mode and the mute switch (SW9) depressed the light never comes on, except for the usual few seconds of charging the filter caps
first problem is there is no drawing showing the pre amp/power amp split
the bridge mode switch is sticky though, but i cant see why that would be part of the issue, but without out the drawing its hard.
depress these switches in and out while the amp is on and the lamp stays off regardless of where the final positions are
one thing though i did monitor the idle with this all going on and the current is about 165mv with the lamp on, depress the switch in and out and it goes back to 11mv where i set it.
most odd
First thing is it only does it in intergrated mode(switch out) and with the mute switch out
If you oput it into 'split' mode and the mute switch (SW9) depressed the light never comes on, except for the usual few seconds of charging the filter caps
first problem is there is no drawing showing the pre amp/power amp split
the bridge mode switch is sticky though, but i cant see why that would be part of the issue, but without out the drawing its hard.
depress these switches in and out while the amp is on and the lamp stays off regardless of where the final positions are
one thing though i did monitor the idle with this all going on and the current is about 165mv with the lamp on, depress the switch in and out and it goes back to 11mv where i set it.
most odd
I can't begin to guess at that without knowing what the switches do and what configuration changes it makes to the amp.
This might help you figure it all out though.
1/ Bridge mode usually inverts one channel (180 degree phase shift) and the load is connected between the two outputs. So as one side goes 'up' in voltage the other goes 'down'.
2/ A parallel mode would place both outputs in parallel (usually with low value balancing resistors). Any difference in output between the two amps (such as different offset voltages) means they 'fight' each other with one side trying to pull or push current into the other. If both outputs are identical that can not happen.
So if the bias current alters in one mode then its possible the two channels are fighting each other but without details of what really happens it is all guesswork. We need to know what each switch actually does and what all valid combinations are.
This might help you figure it all out though.
1/ Bridge mode usually inverts one channel (180 degree phase shift) and the load is connected between the two outputs. So as one side goes 'up' in voltage the other goes 'down'.
2/ A parallel mode would place both outputs in parallel (usually with low value balancing resistors). Any difference in output between the two amps (such as different offset voltages) means they 'fight' each other with one side trying to pull or push current into the other. If both outputs are identical that can not happen.
So if the bias current alters in one mode then its possible the two channels are fighting each other but without details of what really happens it is all guesswork. We need to know what each switch actually does and what all valid combinations are.
so clarification
the lamp does not light when it is in split mode(pressed in)- regardless of mute switch position.
the lamp does not light when in intergrated mode(intergrated switch out)-mute switch in(muted)
lamp lights when above cenario reversed.
problem, no drawing that shows the intergrate/split switch operation, so i dont know if its pre or power amp, my guess would be pre amp.
mute circuit attached(if its a correct final version drawing)
Attachments
not sure if this is relivent, but when the lamp is on its flickering quite violently, not just on and a stable light
the bit i dont get is when either switch is depressed, the lamp goes off and stays off.
the bit i dont get is when either switch is depressed, the lamp goes off and stays off.
You have the means to find out 🙂
How many switches has it got in total. I see Mute and you mention 'Split and Integrated'. Is that one switch for split/integrated?
The lamp lights because the amp starts drawing current. So think why!
You could use the scope to look at the power amp inputs and see if they are getting something unwanted on them .
You could try adding a link here to short each channel input to ground. Do it before the coupling as shown here. Does that stop the bulb lighting?
(could the switch be doing some weird like shorting a supply out and that is what zapped the resistor and bridge ? don't overlook anything. Get it with the lamp lit and then pull the mains plug out and see if you can measure any short on that resistor that burnt up)
It is just one switch for the split/intergrate
so im not sure if this is also relivent, its almost like its related to a charge, to a cap?
turn it on and the lamp lights, push the switch and the lamp goes off ok
if you turn it off and back on within 2 or 3 seconds the lamp does not come on, it only comes on again if you leave it for 5 or more seconds, then turn it back on.
so im not sure if this is also relivent, its almost like its related to a charge, to a cap?
turn it on and the lamp lights, push the switch and the lamp goes off ok
if you turn it off and back on within 2 or 3 seconds the lamp does not come on, it only comes on again if you leave it for 5 or more seconds, then turn it back on.
You said this which doesn't sound normal at all tbh. A flick of light is one thing but pulsing needs investigating. It is possible it may all behave normally on full mains but I would want to be sure first and that means trying to find why it does what it does now. If you short the power amp inputs we can say for certain that its nothing from the preamp section doing this, or at least nothing upsetting the power amp inputs. That is the first thing to prove or disprove.
lets say just for a moment nothing is wrong, and the reason i say this is
with it plugged into the lamp tester and monitoring the idle current it goes to 160+mv untill i press the switches
if i touch nothing, unplug it, leave it for 1 min, then plug it into the mains, the current is 11mv, and no matter how many times i turn it on or off, or push switches in and out the load does not change, yet when i plug it back into the lamp we go back to where we were.
so if everything is ok, what could the lamp be doing to the amp?
maybe its just the way it is as i used it for over 4 hours yesterday and the current stayed stable
Im quite happy to do as you suggested, just wondering if i will ever find what possibly isnt there.
with it plugged into the lamp tester and monitoring the idle current it goes to 160+mv untill i press the switches
if i touch nothing, unplug it, leave it for 1 min, then plug it into the mains, the current is 11mv, and no matter how many times i turn it on or off, or push switches in and out the load does not change, yet when i plug it back into the lamp we go back to where we were.
so if everything is ok, what could the lamp be doing to the amp?
maybe its just the way it is as i used it for over 4 hours yesterday and the current stayed stable
Im quite happy to do as you suggested, just wondering if i will ever find what possibly isnt there.
It really is impossible to say without further tests...
Work with something 'real' that you can measure.
So the question is whether it is a short glitch that occurs when the switch is operated and the possibility that the amp in some way locks up in an invalid state because of that... meaning there is no real issue when on full mains.
You either have to find the reason why it does with the bulb (even if there is no actual fault as such) or just try it on full mains and see if it behaves.
The joys of fault-finding and the decisions to take 😉
Work with something 'real' that you can measure.
160mv across 0.22 ohm is 0.72 amps. That is a lot and with the bulb lit it means the rails are going to be low.
So the question is whether it is a short glitch that occurs when the switch is operated and the possibility that the amp in some way locks up in an invalid state because of that... meaning there is no real issue when on full mains.
You either have to find the reason why it does with the bulb (even if there is no actual fault as such) or just try it on full mains and see if it behaves.
The joys of fault-finding and the decisions to take 😉
im going to leave it as it is.
I could damage something trying to find what might not be there and im using it at the moment and the current is very stable, hardly moving at all
so my final thoughts and my own opinions on the amp
When i test an amp with music i always use the same 4 tracks as i think it covers most spectrums
Level 42 -a live version of a track called Mr pink-it covers most things that you would expect from live band music
Frank sintra-luck be a lady
George michael-Through-from his symphonic album
Verdi-Brindisi(la traviata)-it has very high vocal transients and picks out the weak amps that may confuse things at elevated volumes
quite happy to try any others at peoples suggestions.
so what about the creek 5050
IMO it was best with the classical stuff and i didnt realy get any hint of distortion, even at high volumes and provided an enjoyable listen.
a good amp IMO and it was good to work on somethibng different.👍
I could damage something trying to find what might not be there and im using it at the moment and the current is very stable, hardly moving at all
so my final thoughts and my own opinions on the amp
When i test an amp with music i always use the same 4 tracks as i think it covers most spectrums
Level 42 -a live version of a track called Mr pink-it covers most things that you would expect from live band music
Frank sintra-luck be a lady
George michael-Through-from his symphonic album
Verdi-Brindisi(la traviata)-it has very high vocal transients and picks out the weak amps that may confuse things at elevated volumes
quite happy to try any others at peoples suggestions.
so what about the creek 5050
IMO it was best with the classical stuff and i didnt realy get any hint of distortion, even at high volumes and provided an enjoyable listen.
a good amp IMO and it was good to work on somethibng different.👍
OK, that's fair enough 🙂
So you like the Creek (I've never had a play with one). Did you like it better than the NAD?
Other amps you could look at would be Pioneer A-400 and A400X which had quite a reputation back in the day. The little Rotel RA820 is another.
So you like the Creek (I've never had a play with one). Did you like it better than the NAD?
Other amps you could look at would be Pioneer A-400 and A400X which had quite a reputation back in the day. The little Rotel RA820 is another.
yes it was ok, not a great thing to work on tbh, but it was nice to try something else
Ive get the arcam alpha 6 to do next, i think these are a cambridge audio amp
Ive get the arcam alpha 6 to do next, i think these are a cambridge audio amp