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#1 2011-10-16 16:36:57

cthendrico
Member
Registered: 2009-04-13
Posts: 56

GV-22 extension cab ohm's?

I have a 69 gv-22 and am trying to make sense of the extension jack in the back.  I was wondering what ohm that is set at?  I don't even know what olm the gv-22 is running in the first place. The problem is that the gv22 doesn't have a ohm selector that I know of.   Like is that ext. jack set for one type of ohm that i can just plug into?  Like if I have a 8 ohm ext. cab, can I just plug it into the ext. cab port in the back of the cab and not have to rewire my gv-22 speakers to 4 ohm?  But why put an extension cab jack in it then?  I am so confused, please help!!!!!

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#2 2011-10-17 07:32:42

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

as I recall,  the gv22 has two 8 ohm speakers ran in series, for 16 ohms.   when you plug a cab into the ext speaker jack it switches the output tap from 16 to 8.   

which means you should use a 16ohm cab.

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#3 2011-10-17 08:23:14

teledeluxe
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From: Chicago, IL
Registered: 2008-09-24
Posts: 467

Re: GV-22 extension cab ohm's?

hangman wrote:

as I recall,  the gv22 has two 8 ohm speakers ran in series, for 16 ohms.   when you plug a cab into the ext speaker jack it switches the output tap from 16 to 8.   

which means you should use a 16ohm cab.

The schematic I saw backs this up:
http://www.freeinfosociety.com/electron … php?id=743


2 wrongs don't make a right, but 3 lefts do!

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#4 2011-10-17 09:22:29

cthendrico
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Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

Oh my gosh, you don't know how helpful that information was.  Thank you very much!!!

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#5 2012-01-10 01:56:48

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

I have another general question then.  So the gv-22 is a 2x12 and running at 16ohms.  Could I plug a 4x12 16ohm cab  into the extension slot and everything be alright?  i.e. will the 4x12 change anything or does it need to be a 2x12 extension cab?

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#6 2012-01-10 08:21:03

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

As long as the second cabinet was 16 ohms you would be fine.

It's the load that is important.

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#7 2012-02-19 03:31:18

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

I have another quick question about the gv-22 I was hoping the forum could help me with.  I have heard all sorts of different wattage ratings for this amp.  From 88 all the way down to 30.  I have noted that 40 pops up alot.  What is this amp really rated at watt wise? Help! Its driving me crazy.

In other news......Ok so I finally got a 4x12 cab that is 16 olms and plan on doing as noted above.  I'm so scared. I don't want to burn up the transformers or something on the gv!!! But i'm going to do it!

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#8 2012-02-19 03:47:42

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

another quick question now that i am thinking about it.  Will it matter if the gv22 cabinet speakers wired in series for 16 olms and I plug a 16 olm cab that is wired parallel?  (fyi:  marshall 1960ax  that has 4 16 olm greenback speakers ran parallel for a 16 olm load cab)

i.e. series and parallel set ups through the ext cab jack?

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#9 2012-02-23 01:17:41

cthendrico
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Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

Bump for help!!!! i'm literally sitting her with a speaker cable in my hand....

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#10 2012-02-23 08:06:41

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

The gv-22 is 35 watts.   I am not sure what your impedance question is... It seems like you are asking the same question again?
If the speakers in the amp are wired for 16ohms,  and the cabinet is 16 ohms,  you are good.  It doesn't matter if tha amp speaks are series and the cab is parallel

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#11 2012-02-23 09:47:23

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

great, yes i'm an idiot and asked the same question for the 3rd time in 3 different ways.  but I wanted to be sure so I wouldn't screw up the gv-22.  Its in excellent condition and i am really diggin it.  but thank you very much for the reply hangman

Another question though is I keep getting shocked by walking around the jam room with my buddies and touching there gear.  will installing a 3 prong plug help me with this?  How hard is it to install 3 prong on these? there is a schematic up above for reference.  I wish i could read schematics, is there any good books or something that can help teach you by the way ?

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#12 2012-02-23 10:27:31

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

No doubt,  it is hard to finda gv-22 in great shape,  most of them have been monkeyed with.  So I can understand your concern,  I just didn't know if I was understanding the question.

Installing the 3prong will fix that problem.   Cut out c24 when you do the 3 prong upgrade.

As for books that teach how to read a schematic.... I don't know of any off hand.  You kinda need an understanding of what the components do to know what is happening in the schematic.  If electronics really interest you, any beginning electronics book would help.

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#13 2012-03-05 02:33:23

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

Hey thanks, I need to do that.  I about dropped my gibson after fiddling with my buddies bass amp controls after getting my ampeg vintage shock, letting me know i'm still alive.  I also read it might be good to put screen resistors in the gv on this site? And a cap job?  Its really quiet though already?  Like no hum whatsoever amazing quiet.  Still the cap job?

In other news, I read on a forum that the gv-22 is very similar to a fender vibrolux reverb?  Any truth to this at all?  Kinda like vt-22 is similar to a twin?

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#14 2012-03-05 03:36:38

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

I always advocate putting screen resistors in amps that don't have any.   
cap job is important to do soon,   you could wait a little... but truth is if you're using it often,  its a good idea to get it done.   you don't want to wait for a catastrophic failure. 

as for the gv-22 / vibrolux comparison... its a fair comparison of the two companies offerings... small 35-40 watt amp with reverb and tremolo. 
but that is where the similarities stop... the ampeg has vibrato, uses a capacitor coupled reverb circuit, uses a baxandall tone stack,  uses at pentode to drive a cathodyne phase splitter,  and does not have a Choke in the power supply.     and thats just the more general differences.   if we wanted to pull out the fine toothed comb,  there are more.

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#15 2012-03-05 11:02:25

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

K, thanks hangman.  When would a imminent failure manifest itself, in regards to the cap job?  I play 4 to 8 hours a week probably and run it hard with a band.

Also how much would the 3 prong, screen resistor, cap job likely cost a guy?  My one issue is I am in the most un-guitar friendly area of the world in southeast idaho.  I would worry about taking it to some smuck

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#16 2012-03-05 20:32:50

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

truthfully,  if you want it done right,  it wont be cheap.   The Gv-22 has two multi can caps   one inside the amp, and one mounted to the chassis.   
when we have done the recap we always end up punching a hole in the chassis for the extra multi-can.   there is plenty of room for this. 
The screen resistors are a little easier because the tubes are chassis mount.   so thats pretty quick. 

for a job like that i would be prepared to pay $200-250.   might be a bit cheaper out where you are,  being a bit less urban.

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#17 2012-03-05 21:18:27

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

Dang, I bought the amp for 350!  But I suppose this is the cost of doing vintage tube business. 

What are the warning signs of capacitor failure.  Is it something that I can spot?

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#18 2012-03-06 00:32:38

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

wow you got a great deal!   I would snag one of those in a heartbeat for that price. they usually go for $550 or higher.   

look on the bright side... had you spent $600 on a brand new amp... it wouldn't last half as long as that one already has,  nor would it sound nearly as good. 

the filter capacitors may or may not exhibit obvious signs of failure.   but you can look to see if they are bubbling, bulging or leaking at the end of the multi can that has the terminals.   
Ampeg usually used really great multi cans in that era,  so they tend to hold up well... but If I were you I would take care of them sooner than later.    it tends to be wise to replace components like that after 20-25 years of use.   those are coming up on 45 years.   

one of the most common restorative repairs we do at the shop is recaps.   most amps that are coming in from the 50s and early 60s with their original electrolytics show signs of eminent failure... or they already have.   in some cases the caps blow up and spew there guts into the amp....   in those cases that $250 price tag will double.   because I hate dealing with the nasty job of cleaning up those toxic (and probably cancer causing) messes. 

its just routine maintenance.  like changing the timing belt on a car.    its expensive to do... but its much more expensive to not do and have it fail.

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#19 2012-03-24 22:50:35

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

K, great.  I need to work up the nerve to drop the chassis (I have never done that to an amp).  How hard would it be to redo the recap job myself.  i'm a fair solderer.  I also know that these hold tremendous amounts of energy and could kill me.  But I was under the impression if you unplug the amp and let it sit like 1 or 2 weeks the caps will drain and allow me to tinker.

Another question about the amp.  The rocker switches are droppin out on me?  Do they just need a little deoxit?  I have looked everywhere online to see the right way to clean rockers.  Do you squirt it in the front or do I have to drop the chassis and squirt it in the back?

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#20 2012-03-24 23:51:25

hangman
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From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

for the rocker switches,  you'll have to open the amp up and squirt in the back.   don't use Deoxit.   use a contact cleaner that does not leave a residue.   Big Bath contact cleaner or equivalent.
often times they clean out nicely other times they need to be disassembled and cleaned.    but try to spay them out first.


the recap on the GV-22 is a little involved as i recall.  there is one  30uf 600V axial cap clamped inside the amp,  one 3x40uf multi can,  and then a 20uf 500 axial which I believe is also clamped inside the amp.

What I have done in the past is replaced the 30uf with 2 80ufs in series with bleeder resistors across them.   you could also get one of Webers 30uf 600V caps.  they are good quality. 

then I replace the multi can with a dual 50uf

and there is plenty of green chassis space,  so I cut another hole for a dual 32 multi can.  which I use to replace the 40uf and 20uf. 

so its not as simple as just dropping in some replacements.  although if you did get the weber caps,  they make a 40x40x40 multi can which would work too.   
so that would make the whole thing a lot easier.

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#21 2012-03-25 02:09:11

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

Hmm ok that does sound "involved".  When you say clamped, do you mean that it is just soldered to the pcd? 

From what you posted I think I am reading that the easiest method I could do is #1 replace 30uf 600v axial cap with a weber 30uf 600v #2 replace 3x40uf multi can with weber 3x40 uf multi can.  And #3replace the 20uf 500 axial with another weber 20uf of some kind or do they not make 20uf 500 axials?

Also are the 40uf and 20uf in parallel and thats why a dual 32 multi can can cover both or something?

Also, Big Bath is better huh?  I have been operating under the assumption that having the residue is good to keep moisture and contaminants out as well as to lubricate?  Should I be putting big bath in all my pots, switches and such instead?  I'm looking online for it and it says Big Bath 3.  Is that stuff I need.  Thanks for all the info its really helping me out!!

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#22 2012-03-25 12:19:07

hangman
Banned
From: Seattle Washington
Registered: 2006-09-03
Posts: 1848

Re: GV-22 extension cab ohm's?

it should be pretty strait forward if you just do the 30uf 600V weber and the 40x40x40 weber.   pull the chassis first and make sure my memory is correct of course.   this is all from memory,  and it may be that your gv22 has already seen some work... who knows?

the 20 and the 40 aren't in parallel.  the 20 is used at point E and the 40 and point D.     I use a dual 32,  which drops slightly the filter value at point D  but I rationalize it because I raised it slightly at point C and A. hard to find exact values for all the caps. unless you're willing to spend some real money.

I big bath is for tube sockets,  jacks and switches.   that oily residue that deoxit leaves behind attracts dust and over time it becomes a sticky mess.   
for faders I use the deoxit fader lube.   but you gotta be careful not to use too much.   otherwise it leaks out and you get an oily muck all over circuit boards or the inside of a chassis.

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#23 2015-02-22 16:27:19

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

PLEASE HELP! So in my gv22 I replaced the factory speakers with 2 altec lansing 417-8c's that are 8 olm.  I started looking at the wiring and got confused and am afraid that the amp had been incorrectly wired.  The schematic says that gv22 should have two 8 olm speakers wired in series for a 16 olm load. 

My question is that the speaker wires hardwired to the amp are green and black.  Which one is positive and which one is negative?????

also if I wanted to change the hardwire setup to mono phone socket which wire color (green or black) to the tip and sleeve terminals of the jack respectively?  p.s. i still want to use the external speaker jack.

heres the schematic if that helps

http://www.freeinfosociety.com/electron … php?id=743

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#24 2015-02-27 06:08:00

cthendrico
Member
Registered: 2009-04-13
Posts: 56

Re: GV-22 extension cab ohm's?

No help?

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