neonmagic

Valve amp questions...

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Sorry guys, I've had to babysit my 4 year old niece yesterday/today and tonight (parents are on a cruise), haven't even remotely had time to do anything further.  

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Any outcome with the amps, not the niece!!

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no updates yet - had an endoscopy on last Thursday and a reaction to the anaesthetics too post procedure, so haven't been too well the past 4 days.  Have been mostly sleeping non stop :(

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On 10/12/2018 at 11:46, neonmagic said:

no updates yet - had an endoscopy on last Thursday and a reaction to the anaesthetics too post procedure, so haven't been too well the past 4 days.  Have been mostly sleeping non stop :(

Good luck with your recovery! I have also been sleeping more, trying to make the most of staying in. Nice to see when I do pop out to Hammersmith things are improving.

Had a registered post tracked package delivered to my address for the local branch of Halifax! Gave it to the lady earlier today. She could have been more nice :....

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1 hour ago, Millennium said:

Good luck with your recovery! I have also been sleeping more, trying to make the most of staying in. Nice to see when I do pop out to Hammersmith things are improving.

Had a registered post tracked package delivered to my address for the local branch of Halifax! Gave it to the lady earlier today. She could have been more nice :....

I don't handle the Australian heat very well (that's what happens when you have Celtic, Germanic and Nordic blood in your veins - thanks mum & dad! lol!).  

I seem to be back to normal with regards to the procedure, but I have had to look after my 4 year old niece nearly all week :-/  she is a TERROR and you cannot take your eyes off her for a single second...and you can't do anything like play with cables or amps etc around her, it'll just fuel her mind to do silly things...

I won't dare touch the setup on the weekend whilst she's home, so Monday will be the earliest, but unlikely as I have a lot of chores to do on Monday nights and will undoubtedly be too tired...so prolly Tuesday is more likely.  *sigh*.  

The good news are the amps haven't blown up (true, they haven't even been powered up yet lol ):nuts:

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17 hours ago, notevenclose said:

Rats or valve amps?

Rats are easy - feed them well, and scratch them behind the ears.  They also like being tickled (and they do actually laugh, although we can't hear it as it's at 50khz...).  

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On 10/12/2018 at 21:33, George 47 said:

Any outcome with the amps, not the niece!!

OK, an hour and a quarter tonight and all AC power cables and cords have been checked.  The 2 long 5m cables that run to the power point were both partially chewed and replaced (note: I have no option other than to run these long power cable runs - it's that or no audio...).  Both power boards look OK.

AC power cords were mostly all good, except for Murphy's law - the only One that was a captive AC power cord (my beloved Nakamichi CR5-e).  It's well...the worst chewed cable lol...this means repairs, and this is going to take me a long while to get organised.  No, I cannot solder.  I've tried to learn, and I suck so badly at it it isn't funny.  There's zero chance of me doing it myself.  An old, but hasn't been used Pioneer DVD player (used as a CD transport years ago) has a chewed AC cable, but I'm not really fussed with it as the player was pretty much problematic (skipping discs) the last time that I used it 6 years ago.  I realised that both Aujdiolab 8000M monobloc amps cables are missing (probably used to replace something else in the past, since I wasn't using these amps).  I have replacements for them, so no issue there.  And finally, the REL Stadium II subwoofer's AC cable has been chewed and needs to be replaced (I also have a replacement for it).

Interconnect cables were also checked (as best as possible - my cabling is a rats nest and runs under furniture, so I cannot easily check everything.  Given the nature of my room, this is as good as it gets).  One half decent Silver plated Copper IC partially chewed (maybe OK, my eyes aren't good enough to be 100% sure - it seems the PTFE outer casing has been chewed, but not the actual signal cables, at least as far as I can tell).  They may be OK, but should probably be replaced just to be sure.  

So, in summary, as best as I can tell, 1 dud IC cable, and 1 dud captive AC cable (the largest concern).  

As it's been very hot here all day and is currently near 26 C @ 11:30 PM and I am sweating like a pig, I am leaving it at this point tonight. 

I hope to find my instructions on biasing the Cyber 845 amps, my biasing cables, and my multimeter.  If all goes well, I shall have tested them both sometime tomorrow!  

I really wish manufacturers would NOT use captive AC cables for equipment (should be made illegal imho).  

Edited by neonmagic

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OK, I have finally worked up the courage to try and set the bias to the amps to 0 (whilst powered off) but something isn't right...I'm not really electrically inclined (that was my father)...

I don't see an on/off switch for my voltmeter.  I don't see a battery compartment.  The crappy manual that came with it isn't much help.  Is this normal?  If I tilt the voltmeter Left/Right, the needle moves a bit on the scale.  Is this normal?  (I presume not, but it is a cheapie voltmeter - for the amount that I'd use it, I couldn't justify an expensive unit).  

Here is what the voltmeter looks like (see attached).  

If I understand correct, I want the DCV A line (2nd from top).  And it reads 0 on the Left side of the scale and goes to 10/50/250 depending on what I have the DCV rotary dial set to (I believe I should set it to 10 VDC) on the Right hand side of the scale.  

When I plugged the probe into the Left channel monobloc (power currently turned off), the meter stays at ZERO.  I would have expected it to move to 4.5 (nearly halfway along on the 10 scale that i'm currently using), as that was what it was last biased to.  So..this leads me to several questions...

a) is my voltmeter stuffed?  (hasn't been used since the last time I biased the amps, roughly 4 years ago)

b) is it possible that the amps bias would have drifted to zero (0) since the, especially when they haven't been used?  

c) said amps won't show any bias reading UNLESS they are powered on (which contradicts what was said earlier on in this thread).  

Help!  (a very non-electrically inclined normal user).  I am now very confused...

multimeter.jpg

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Super Wammer

When setting up my Icon audio monos, it requires me to trap the BLACK electrode/probe in the negative speaker output (my banana Jack's have a bare cable hole) and then use the RED in the relevant hole on the amps top plate. It also asks me to set the meter at 2V/2000mV DC. 

(My meter is also a cheap and chearful one I bought primarily for fault finding on my motorcycles) 

Don't know if this helps but am sure others more knowledgeable will be along soon. 

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Super Wammer
2 hours ago, neonmagic said:

OK, I have finally worked up the courage to try and set the bias to the amps to 0 (whilst powered off) but something isn't right...I'm not really electrically inclined (that was my father)...

I don't see an on/off switch for my voltmeter.  I don't see a battery compartment.  The crappy manual that came with it isn't much help.  Is this normal?  If I tilt the voltmeter Left/Right, the needle moves a bit on the scale.  Is this normal?  (I presume not, but it is a cheapie voltmeter - for the amount that I'd use it, I couldn't justify an expensive unit).  

Here is what the voltmeter looks like (see attached).  

If I understand correct, I want the DCV A line (2nd from top).  And it reads 0 on the Left side of the scale and goes to 10/50/250 depending on what I have the DCV rotary dial set to (I believe I should set it to 10 VDC) on the Right hand side of the scale.  

When I plugged the probe into the Left channel monobloc (power currently turned off), the meter stays at ZERO.  I would have expected it to move to 4.5 (nearly halfway along on the 10 scale that i'm currently using), as that was what it was last biased to.  So..this leads me to several questions...

a) is my voltmeter stuffed?  (hasn't been used since the last time I biased the amps, roughly 4 years ago)

b) is it possible that the amps bias would have drifted to zero (0) since the, especially when they haven't been used?  

c) said amps won't show any bias reading UNLESS they are powered on (which contradicts what was said earlier on in this thread).  

Help!  (a very non-electrically inclined normal user).  I am now very confused...

Having done a quick search online it appears that the bias connection for the meter night be a jack, ie  it has positive and negative connections to the jack and is not just a matter of inserting the meter probe in the hole.

The manual I found online indicates a bias of 4.8v in which case you need to make sure your meter has the 0 to 10v DC range selected. That will effectively probably also turn the meter 'on' (it probably does not need batteries for the voltage measurement)

Edit to say that you can check the DC volt reading of your meter by testing a normal battery volts just to make sure it is working.

Edited by Fourlegs

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1. Online manual as Nick says above states that the bias measurement is from a jack plug, so you need a plug and it will have a positive and negative connection. Don't just stick a probe in the hole, or you'll possibly short it out.

2. A multimeter doesn't need a battery to measure voltage.

3. The amp will need to be on to set bias. There won't be any voltage otherwise.

4. 845 tubes are pretty robust electrically, but surrounding circuits may not be and 845s run at very high voltages. The bias being a little out is very unlikely to do any damage and 845s tend not to drift.

Unless you're certain about what you're doing, I'd personally suggest trying to find someone who is.

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12 hours ago, Lurch said:

When setting up my Icon audio monos, it requires me to trap the BLACK electrode/probe in the negative speaker output (my banana Jack's have a bare cable hole) and then use the RED in the relevant hole on the amps top plate. It also asks me to set the meter at 2V/2000mV DC. 

(My meter is also a cheap and chearful one I bought primarily for fault finding on my motorcycles) 

Don't know if this helps but am sure others more knowledgeable will be along soon. 

The Cyber 845s come with a probe that has negative/positive tails, which I have attached to the negative/positive testers of my voltmeter and then insulated with electrical tape.  The 845S amps (newer version of my amps) has an inbuilt bias meter to make life a bit easier, so all you have to do is adjust the bias pot and watch the inbuilt meter(s).  I'm surprised that Icon Audio makes bias setting so difficult (at least, in my eyes).  

10 hours ago, Fourlegs said:

Having done a quick search online it appears that the bias connection for the meter night be a jack, ie  it has positive and negative connections to the jack and is not just a matter of inserting the meter probe in the hole.

The manual I found online indicates a bias of 4.8v in which case you need to make sure your meter has the 0 to 10v DC range selected. That will effectively probably also turn the meter 'on' (it probably does not need batteries for the voltage measurement)

Edit to say that you can check the DC volt reading of your meter by testing a normal battery volts just to make sure it is working.

Yeah, the online PDF manual says 4.8v now (it used to save 4.3v years ago).  Greg [Osborne], the Australian distributor for Opera Consonance has personally advised me to set them to 4.5v.  Yes, I have the 0 to 10 vDC range selected.  Good to know that it doesn't need batteries.  I would test the voltmeter on a 9 vDC battery that I have lying around (it's new), but I'm loathe to remove the Opera probe from the voltmeter's tester cables etc.  But, I may just have to do that...

9 hours ago, rabski said:

1. Online manual as Nick says above states that the bias measurement is from a jack plug, so you need a plug and it will have a positive and negative connection. Don't just stick a probe in the hole, or you'll possibly short it out.

2. A multimeter doesn't need a battery to measure voltage.

3. The amp will need to be on to set bias. There won't be any voltage otherwise.

4. 845 tubes are pretty robust electrically, but surrounding circuits may not be and 845s run at very high voltages. The bias being a little out is very unlikely to do any damage and 845s tend not to drift.

Unless you're certain about what you're doing, I'd personally suggest trying to find someone who is.

1.  Yup.  I have set the bias for these amps before (4 or so years ago).  Opera provides a probe with positive/negative connectors that can be (obviously) connected to the voltmeter tester/probe cables  

2.  Good to know.  I wish the manual would state this.  Is it normal for voltmeters to not have an on/off switch?  That seems rather alien to me!

3.  Ah...I swear someone said that I could set the bias to 0 with them turned off as a safety precaution before even turning them on.  Then let them idle at 0 bias for Ten minutes and ONLY then, if stable, set the bias to it's proper level (4.5 vDC).  I'll re-check the thread just to make sure that I haven't misunderstood someone or gone looney lol!

edit: 2nd post in the thread (George 47) indicated to set bias to 0 with the units turned off..which someone else after him also agreed with.  

So, what is it...what is right?  Can I change/set bias with the units powered off, or cannot I not do this...this is how newbies get confuzzled :P

4.  This is good to know.  If there are issues with the valves or circuit, then I am stuffed :(  

I have biased the amps once before, what is making me nervous is my lack of knowledge about electrical stuff, and the fact that the amps haven't been powered on for just over 3 years.  

Edited by neonmagic

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Super Wammer
6 hours ago, neonmagic said:

3.  Ah...I swear someone said that I could set the bias to 0 with them turned off as a safety precaution before even turning them on.  Then let them idle at 0 bias for Ten minutes and ONLY then, if stable, set the bias to it's proper level (4.5 vDC).  I'll re-check the thread just to make sure that I haven't misunderstood someone or gone looney lol!

edit: 2nd post in the thread (George 47) indicated to set bias to 0 with the units turned off..which someone else after him also agreed with.  

 So, what is it...what is right?  Can I change/set bias with the units powered off, or cannot I not do this...this is how newbies get confuzzled :P

What they would have meant was simply adjusting the bias screw all the way to the minimum setting with the amps switched off. Of course in order to do this you need to know which way to turn the screw to be sure you are adjusting it in the right direction.  On the Icon Audio 845 amps one of the adjustments is actually turned clockwise to reduce the bias. 

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1 hour ago, Fourlegs said:

What they would have meant was simply adjusting the bias screw all the way to the minimum setting with the amps switched off. Of course in order to do this you need to know which way to turn the screw to be sure you are adjusting it in the right direction.  On the Icon Audio 845 amps one of the adjustments is actually turned clockwise to reduce the bias. 

Ahh...now I get it.  Thanks for clarifying!

OK, took my voltmeter into the store where I purchased it from...*sigh*.  It does have batteries (2 x AA plus a 9v battery).  The AAs were badly corroded.  Batteries were replaced, but the unit wasn't doing a buzz test at all (no sound, LED not lighting up) and it wasn't displaying the right output voltage on the meter for both a 9V and 12V battery that they had around to test...so, I had to buy another voltmeter, which I can barely afford...at least I know that the unit uses batteries and why I wasn't getting any reading last night with the units off...

So, tonight, after it has cooled off (we're having a lovely heatwave here - please note that I'm using extreme sarcasm when I say lovely!) I aim to test the SACD and preamp (headphones) and then sort the amps out (hopefully without any issues).  My audiolab 8000Ms should be powered up too, they haven't been used in like in probably 5-6 years...with my luck, prolly both the 845s and 8000ms are cactus...

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