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i blew my speakers.... :(

Instruments and Gear
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RA  
6 Dec 2008 22:32 | Quote
Joined: 24 Sep 2008
United States
Karma: 16
@ Phip do you know a lot about this electrical hocus pocus because i was wondering if you knew how to bias a power tube i know how to get the watts going in to it (black to ground and red plate to cathode) but i don't know how to adjust it. i seen an amp with little thing to do it with but mine doesn't have it.
Phip  
6 Dec 2008 23:28 | Quote
Joined: 23 Dec 2007
United States
Lessons: 1
Karma: 45
Moderator
@ RA,
yeah, I'm an electronic tech, been in the business for 33 years. All tubes have some sort of specs set down by the manufacturer as far as max voltage to the anode and normal grid voltages (bias). it's all based on the designed operating capability of the tube. So what is the tube number and maybe we can find out the specs on the tube? however if you have a specific amp we can look at the diagram for the amp and the specific tube and decide how we can install a variable trim pot to adjust bias. we can also compare your amp to the amp that had the adjustable bias and copycat the design. It's all doable.
get me some model numbers and tube numbers and we'll start there ok?
Phip
P.S. I was born and grew up in Attleboro. Born at sturdy memorial hospital. grew up in south attleboro just off Rt 1A. Small world!
Hell, if we come up with a good idea maybe you can take a drive to the cape and we'll do the modification in my shop.
lance  
7 Dec 2008 06:32 | Quote
Joined: 03 Mar 2008
United States
Karma: 1
preamp tube elliot. just replace them all. they cost about $15-20 a
piece for good ones and required no adjustment(biasing) just plug
and play. just be sure to write down which preamp tube plugs where.
chances are atleast 1 will be different from the rest(clean channel).

also since you mentioned it was bumped around,make sure all the tubes
are properly seated in their sockets. tubes can easily unseat themselves
during transport if they dont have retainer springs.
EMB5490  
7 Dec 2008 07:03 | Quote
Joined: 10 Feb 2008
United States
Lessons: 1
Licks: 1
Karma: 31
4 clear tubes, thats not the problem. its outta either the blue tubes or silver ones.
lance  
7 Dec 2008 07:54 | Quote
Joined: 03 Mar 2008
United States
Karma: 1
the big glass looking ones are the powertubes,the preamp tubes are
smaller and also glass,but sometimes have covers to keep them
real hot. the blue ones are not tubes but capacitors.

the tube layout should be (o o o O O O O) the three on the left would
be the preamp tubes,4 on the right power tubes. the blue ones behind
the preamp tubes and right of the power tubes are the capacitors.
the layout could also be (o o o O O)but i'm pretty sure that's
a 50 watt layout.
EMB5490  
7 Dec 2008 08:08 | Quote
Joined: 10 Feb 2008
United States
Lessons: 1
Licks: 1
Karma: 31
no its 100 watt, im not about to go futzing around in ther anyway, im just gona get it repaired.
Musical_Magic  
7 Dec 2008 15:53 | Quote
Joined: 29 May 2008
United States
Karma
Blew you speaker? Been there done that....50 times xD
EMB5490  
7 Dec 2008 16:18 | Quote
Joined: 10 Feb 2008
United States
Lessons: 1
Licks: 1
Karma: 31
didnt blow, broke a tube. red prior posts for ful story.
Ozzfan486  
7 Dec 2008 16:57 | Quote
Joined: 01 Oct 2008
United States
Licks: 1
Karma: 18
Aww man. Hes alive.....now my post with Elliot as a fried head of a Hawaiian pool light means nothing. =[. lol Kiddin'
EMB5490  
7 Dec 2008 21:31 | Quote
Joined: 10 Feb 2008
United States
Lessons: 1
Licks: 1
Karma: 31
lol. cheer up, im sure someone will die soon enough...
soy.el.che  
9 Dec 2008 16:01 | Quote
Joined: way back
Mexico
Lessons: 1
Karma: 9
ure lucky, a friend of mine blew his ears.
Ozzfan486  
9 Dec 2008 19:58 | Quote
Joined: 01 Oct 2008
United States
Licks: 1
Karma: 18
lol. Oh I hope!! rofl. j/k.
soy.el.che  
9 Dec 2008 20:09 | Quote
Joined: way back
Mexico
Lessons: 1
Karma: 9
seriously, he couldnt hear for about 2 months, then he recovered
RA  
9 Dec 2008 20:30 | Quote
Joined: 24 Sep 2008
United States
Karma: 16
@ Phip - Sorry for the delay. the amp is a Class A cathode bias and uses a EL84 power tube. I have been doing some research and if i understood any of it cathode bias means is nonadjustable but tinkering can fix anything (my motto). also i know that Mesa Boogie amps are nonadjustable but can me modded something to due with a resistor and changed to a pot. I can't read the diagrams and don't know a exact model but i know most marshals have a adjustable bias(i hate to make you look up things sorry). i have already changed the preamp because it doesn't need to be bias(Again if i understood it) and i want to change the power tube because the stock tubes where/are horrible. if you need me to look up anything else just ask. i also noticed that you live in sandwich it's funny because i go to a cape house (owned buy dad's friend) every summer it is walking distance to the end of canal. unfortunately i am between jobs right now but if you can come up with something and you don't mind me coming down sometime so you can do something that would be "wicked" cool as long as i get to watch (I like messing with things but doing things to the board is beyond my knowledge.)
RA  
9 Dec 2008 20:31 | Quote
Joined: 24 Sep 2008
United States
Karma: 16

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