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Old 16th December 2015, 01:00 PM   #1
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Join Date: Nov 2015
Location: Fife, Scotland
Default value in humour

This may look like a double post, but read on, and you will see why I need to show you the communication. I posted a reply to a plea from someone with an F34b - I was personally undergoing a trauma caused by my own Amp fault.
I think the data here is quite valuable, but have a laugh at the thinking.
I managed to communicate with Yarland by e mail, but the reply was a bit broken English, assuring me I should take my faulty FV34b to a skilled technician, despite me reassuring them that I was skilled, just completely out of touch, not wanting to spend the time tracing the circuit, and in need of a diagram - I am an ex TV engineer, qualified in all sorts of solid state Hi - Fi like B & O, Sonab, Nad,etc.
Low on valve experience.
I did manage to re - bias my Marshall JCM 900 to go back to its original valve line up - involved changing a few resistors - no probs - works beautifully.
Problem - Yarland died age 4 years old.
Power supply MR67 diode blown. Replaced and blew again - replaced, checked all that I could going by the cct diagram Yarland had sent me - which was hopelessly wrong - even just going by the used components.
I only found a transformer tapping wire looking suspiciously poorly insulated - so I corrected that and tried again - Eureka - the sound of music - for 3or 4 minutes, then an annoying hum and no music. Darn!
I have a fault I cannot see, and lack of time - it is very close to defeating me. Attached circuit diagram as supplied - mine has no chokes, and 2 200 ohm resistors.
Dave.

I have just had an epiphany - you know one of those that make you feel a fool - I haven't tried the amp with no valves since it first blew up - that's what these diodes feed - the HT to the valves - can't wait to attack it now - might be simply a short in a valve - maybe with it being upside down, and electrode has sagged back to the way it should be, until it warmed up again - then bang..........
More good news - I replaced MR67 diode and took all valves out - tried pre amp first - all 3 ok - O/p stage left - OK after 2- 3 minutes (all with original 3A fuse, so I hoped this would blow before a component - last 2 o/p el34's - one had a peculiar mark round the top, and I had noticed that this same valve was 6-8mm taller than the others - so it didn't feel like a matched pair for a start - has the retailer been a bit naughty?? fortunately, I had changed My JCM900 4100 El34's for quad matched 5881's (after changing the resistor values to re bias) so I had a spare pair - put them in and eureka - result.
This was just as well, for I had ordered a 'Little Bear' valve phono pre - amp, and it had arrived - I put it in line to replace the solid state phono, and it all sounds just beautiful - value for money!
Remember that if you change valves, especially the type (no.), they will need re biasing anyway, and if you change the type, they may run very hot to damage, or too cool to sound correct. I have a good article on biasing if anyone wants it.
Incidentally, I have just realized, I am probably talking to myself on this one, since the original article was 5 years ago - I must be in a time warp..........
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Old 17th December 2015, 09:48 AM   #2
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Join Date: Sep 2003
Location: London
Talking more generally about humour with tube amps.......

I went into a used equipment shop in the 70s with a mate who was a drummer (I was a bassist then). There was an old guy behind the counter who didn't seem to know much about his stock but was very enthusiastic about selling it. We looked at one amplifier in particular, and he brought it out and put it on the counter. He proceeded to look at the back of it and read what was printed there. Then he came out with this:

"This is what you want, guys! This is a real good'un. Look at the back! It says it gives out a full 15 ohms!! That'll be really loud!!"
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Old 20th December 2015, 07:26 AM   #3
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Join Date: Nov 2015
Location: Fife, Scotland
Brilliant! I wonder how many bolts it took to deliver that!
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Old 20th December 2015, 07:58 AM   #4
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Location: London
Quote:
Originally Posted by fastdave View Post
Brilliant! I wonder how many bolts it took to deliver that!
Measurements in regard to bolts per ohm are usually done with the FFF system. See Wiki:

https://en.wikipedia.org/wiki/FFF_system

The correct use in this case would be Furlongs per Fortnight. This can as usual be expressed in such units as microfurlongs per nanofortnight.
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Old 20th December 2015, 09:00 AM   #5
Enzo is offline Enzo  United States
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Join Date: Sep 2004
Location: Lansing, Michigan
One of my favorite gags:
when I go into a Radio Shack for a fuse or something, inevitably a clerk will ask if he can help. So I pull a piece of paper from my pocket and look at it, and ask as earnestly as possible, "Yes, I need some 16 ohm speaker cables. Do you have them?"

Nine times out of ten they start trotting off to the back to get me some.
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Old 20th December 2015, 10:42 AM   #6
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Location: London
Why you should use a SET amplifier:

"As everybody knows, high power amplifiers use larger electrons to achieve this high power. The bigger electrons don't start or stop as fast as normal electrons resulting in much heavier, less nimble Watts. So high power amplifiers can never have the finesse of low power amplifiers. High sensitivity speakers only work with the smaller electrons (the smallest are produced by tube amplifiers). Thus if you use a high power amplifier with sensitive speakers you need a transformer that slims down the electrons and makes them swifter. Such transformers are available from Jenny Craig Audio Inc., Phen-Fenophile Corp. and the US Nuclear Agency."

PS. Don't forget to elevate the amplifiers above the speakers, so the signal can flow easier.
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Old 20th December 2015, 10:44 AM   #7
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Location: London
The SATRI principle:

Q. Does anyone possess any information about amplifiers using the SATRI principle?
A. Of course! Jean-Paul Satri was a famous French philosopher who invented boredom. He wrote the hit song sung by Janis Joplin : "Freedom's just another word for nothing". He and his friend Genet built amplifiers out of abandoned bidets found behind brothels. Many Pacific Rim restaurants use his menu stylings. Sorry, no other info available.
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Old 21st December 2015, 12:57 PM   #8
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Join Date: Nov 2015
Location: Fife, Scotland
SATRI.
Brilliant - He met morph one day, turned into a beatle - wasn't he glad watt he turned out to be, but he went ohm to a SET........Oh dear, I haven't done well at this one, and it's too early to use drink as an excuse......
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