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Author Topic: "help with a Freedom amp please "  (Read 16799 times)

dg

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"help with a Freedom amp please "
« on: December 03, 2009, 02:04:51 PM »
Hi Guys and girls just joined the forum I have had several vintage amps and I have a question?I recently moved house and came across my old Mike Matthews Freedom Amplifier it’s the 10” non battery version plugged her  in and “unbelievable “it sounds as great as it did the day I bought it .It take a while vto power down but I think it always did? I took it to a friends and he loved the sound but was concerned it had a 2 pin power cable so it wasn’t grounded? I know its an old amp and if I,m going to use now should I get it converted to a 3pin grounded plug? And can I do this myself I build acoustic guitars so I’m relatively practical,any help most welcombe
Many thanks
DG
PS Concerned about this switch of “death” that pervades the internet

joecool85

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Re: "help with a Freedom amp please "
« Reply #1 on: December 03, 2009, 04:44:39 PM »
Hi Guys and girls just joined the forum I have had several vintage amps and I have a question?I recently moved house and came across my old Mike Matthews Freedom Amplifier it’s the 10” non battery version plugged her  in and “unbelievable “it sounds as great as it did the day I bought it .It take a while vto power down but I think it always did? I took it to a friends and he loved the sound but was concerned it had a 2 pin power cable so it wasn’t grounded? I know its an old amp and if I,m going to use now should I get it converted to a 3pin grounded plug? And can I do this myself I build acoustic guitars so I’m relatively practical,any help most welcombe
Many thanks
DG
PS Concerned about this switch of “death” that pervades the internet


You should be able to simply get a 3 prong cord, wire it the same except bolt the ground wire to the metal chassis somewhere.
Life is what you make it.
Still rockin' the Dean Markley K-20X
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dg

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Re: "help with a Freedom amp please "
« Reply #2 on: December 03, 2009, 05:55:48 PM »
Hi joecool85 Many thanks if I may impose on your knowledge again

Both of the wires going to the plug are black ,at my friends house he told me that the mains plug was in the wrong way round as it hummed louder ,when the guitar jack plug was in the input (but not connected to the guitar) but dangling in front of the speaker? And we put the plug back in rotating it  and it did reduce the hum considerably is this correct ? as he only remembers this from distant conversation over 20 years ago and
as the two wires going to the socket are both black?
 
many thanks
dg

J M Fahey

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Re: "help with a Freedom amp please "
« Reply #3 on: December 04, 2009, 04:51:29 AM »
Hi DG.
Try to post a more specific title, such as "help with a Freedom amp", or it becomes impossible to find it using search.
Excellent picture, sharp and big.
Popst a couple extra ones, from the front and another showing the controls panel.
These amps were meant to be powered by 40 C cells, +60VDC.
The power supply was added later.
It *looks* like you have a side mounted male power sock, to which you plug a female 2 pin connector, is that so?
It also *looks* that the power switch handles DC (as in the battery one), and the transformer is always on.
I also don't see any "death cap", but it might be present in the power supply itself.
Neither do I see a fuse !!!!
The green and yellow seem to be soldered to the negative (ground?) lug at the power supply capacitor, but if they are ground, why does the yellow one go straight to the board, and the green one is switched?
I think you should open the black tape bundle and draw a schematic of the power supply wiring.
Take a picture there too.
This is *not* a conventional amplifier.

dg

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Re: "help with a Freedom amp please "
« Reply #4 on: December 04, 2009, 07:42:28 AM »
Hi Guys
Quote
These amps were meant to be powered by 40 C cells, +60VDC.
The power supply was added later.
It *looks* like you have a side mounted male power sock, to which you plug a female 2 pin connector, is that so?
It also *looks* that the power switch handles DC (as in the battery one), and the transformer is always on.
I also don't see any "death cap", but it might be present in the power supply itself.
Neither do I see a fuse !!!!
The green and yellow seem to be soldered to the negative (ground?) lug at the power supply capacitor, but if they are ground, why does the yellow one go straight to the board, and the green one is switched?
I think you should open the black tape bundle and draw a schematic of the power supply wiring.
Take a picture there too.
This is *not* a conventional amplifier.
hi it is a female 2 pin connector,this is a picture un wrapped ,no fuse i can see,as to draw a schematic i dont know how sorry,Can I easily convert this back to batteries? as I would love a little portable amp
Many thanks
Dg
No idea when it was converted I have obviously been lucky not to electrocute myself (some would say a wasted chance to hasten my demise)
LOL




joecool85

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Re: "help with a Freedom amp please "
« Reply #5 on: December 04, 2009, 08:31:31 AM »
Hi DG.
Try to post a more specific title, such as "help with a Freedom amp", or it becomes impossible to find it using search.
Excellent picture, sharp and big.
Popst a couple extra ones, from the front and another showing the controls panel.
These amps were meant to be powered by 40 C cells, +60VDC.
The power supply was added later.
It *looks* like you have a side mounted male power sock, to which you plug a female 2 pin connector, is that so?
It also *looks* that the power switch handles DC (as in the battery one), and the transformer is always on.
I also don't see any "death cap", but it might be present in the power supply itself.
Neither do I see a fuse !!!!
The green and yellow seem to be soldered to the negative (ground?) lug at the power supply capacitor, but if they are ground, why does the yellow one go straight to the board, and the green one is switched?
I think you should open the black tape bundle and draw a schematic of the power supply wiring.
Take a picture there too.
This is *not* a conventional amplifier.


Good advice, I didn't realize we were dealing with an oddity like this.

**edit**

I merged the two threads for you.
« Last Edit: December 04, 2009, 08:33:41 AM by joecool85 »
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dg

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Re: "help with a Freedom amp please "
« Reply #6 on: December 04, 2009, 09:07:41 AM »
Thanks joe cool 85 I,ve never been referred to as an oddity before LOL any thoughts of how to convert  it back to a battery amp please
Thanks

J M Fahey

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Re: "help with a Freedom amp please "
« Reply #7 on: December 04, 2009, 01:29:57 PM »
Thanks Joecool and DG.
Now I understand it.
To begin with, the supply is quite amateurish, the amp itself seems to have been rebuilt, that's why asked for a front panel picture.
The original one had an L shaped chassis, to which was mounted the PCB, and the pots were direct soldered to it.
This one has a flat, presumably home made front panel, some *very* strange, home made twisted brackets, the pots are wired, etc.
The power supply clearly (now) has the transformer *always* connected to 110V (or 220V), its *secondary* is switched, is rectified by a too small W02 bridge , and filtered by an unknown, although large, electrolytic.
As I see it:
 the black wires are 110V (or 220V) , no fuse, no switch, an accident waiting to happen. The *first* short there will set the amp in flames, no kidding.
So, first task is to cut a rectangular opening on the side (say, 2.5"x4"), where now the power socket rests, and mount there a somewhat larger piece of 1/8" Masonite or MDF , with 3 holes for: power cable, power switch and fuse holder (2A for 119V ; 1A for 220V)
I'll post a drawing for you to play it safe.
The transformer will have its primary switched and fused, its secondary will feed the amp.
You must also change the puny round 1A bridge rectifier for a rectangular, flat, 6Amp x 200V (or better) bridge rectifier.
Then you can use your fine amp for other 35 years.
You *can* battery power it, but buying 40 D cells every 4 hours playing will break your wallet.
You *can* use 5 x 12V 1.2 AH gel lead acid batteries in series, but better add some wheels and/or consider it the intensive workout the Doctor ordered.
In short, for a few bucks you can enjoy safely this light (for its power), very portable and attention getter historical amp; but battery powering it isn't practical for monetary reasons.
Please post the front panel pictures.

dg

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Re: "help with a Freedom amp please "
« Reply #8 on: December 04, 2009, 08:06:05 PM »
Hi j m fahey many thanks  I think that’s all a bit technical for me to do ,you lost me after drill three holes LOL but thank you for the help ,it really is a great sounding little amp  but I prefer my limbs intact and when amateurish and fire are use together I’m usually looking for the nearest exit LOL It seems rather difficult for a novice to fix
Thanks
dg

J M Fahey

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Re: "help with a Freedom amp please "
« Reply #9 on: December 06, 2009, 09:14:14 AM »
Hi DG.
Get a friend who can work with electricity safely.
Some Pizza and a couple Beers will help a lot, but give him the Beers only *after* the job is finished.  :)
Your "mods" are not Electronic but plain electrical in nature.
Buy the excellent switch/power socket/fuse holder you showed me, and post front and back pictures to indicate the exact wiring.
We're talking wiring a desk lamp complexity level here.
You can also buy separate switch-power socket-fuse holder and mount them side by side on the piece of Masonite.
I'm attaching pictures of the "official" Freedom Amp, where you'll see the L shaped chassis, with the boards securely mounted
Yet it has the same improvised power supply, although a little more complex.
I guess the amps, although advanced and excellent sounding, weren't selling because of the enormous battery expenses, so they were somewhat amateurishly converted at the factory.
You can easily correct that and enjoy your fine amp.
Your only personal task will be cutting the side slot and mounting the switches , etc. on the Masonite piece, let your friend do the wiring.

joecool85

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Re: "help with a Freedom amp please "
« Reply #10 on: December 06, 2009, 10:15:35 AM »
Thanks joe cool 85 I,ve never been referred to as an oddity before LOL any thoughts of how to convert  it back to a battery amp please
Thanks

I meant the amp, not you lol. 
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dg

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Re: "help with a Freedom amp please "
« Reply #11 on: December 06, 2009, 12:12:57 PM »
Hi J M Fahey many thanks I am gouing to try and do it my self then have it properly seviced,  I don’t know anyone with any electrical experience most are just like me plug in and play, but I intend to change that .I am in the UK (so its 240V) in a rather remote part of Norfolk but I am careful used to doing things properly and an eager to learn I will get the switch and is this square one in picture  correct
Quote
1A bridge rectifier for a rectangular, flat, 6Amp x 200V (or better) bridge rectifier
ther seems to be a lot of codes shall i just ask for a 6amp x200v?
many thanks
david
very excited

dg

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Re: "help with a Freedom amp please "
« Reply #12 on: December 06, 2009, 02:50:39 PM »
HI juan just a quick question so i can get all the bits at the same time
Quote
You must also change the puny round 1A bridge rectifier for a rectangular, flat, 6Amp x 200V (or better) bridge rectifier.
the bridge rectifier, better in what way more amps?more volts? are there other bridge rectifier options ,i will get the one you think best.
and is there anything else i will need , specific wire or any other components ect i can buy at the same time, i have plenty of mdf but also some 6mm birch ply that might be better, stronger? and a decent soldering gun and a new found enthusiasm
many thanks and i think the panel must be the original one with the writing on?

david
ps hi joecool85 i,ve been called worse LOL

J M Fahey

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Re: "help with a Freedom amp please "
« Reply #13 on: December 07, 2009, 02:42:35 PM »
Hi DG, that's the SSGuitar spirit !!!
1) Post the link of where you shop, so I can give you a specific part number, but anyway, "6 Ampere, 200 PIV bridge rectifier" will get what you need.
It's 4X the current capacity of the one fitted (6A vs 1.5A)
The one I use is rectangular, with a diagonally cut corner to help in alignment (also 2 pins are shorter than the other 2) and all pins exit aligned on one side, but that's a minor matter.
I'm not at my shop now, tonight I may post the exact code, but it will be better to follow your supplier's.
2) If your transformer is 110/120V and you use your amplifier with an external 240>120V transformer, it might be interesting to buy an equivalent new 240V primary transformer and avoid carryinf useless weight.
I you can't do that now for "$tec$nical$ rea$on$", consider it for the future.
3) That 6mm birch will be fine.
4) Maybe your friends aren't experienced because they buy their IPods and PCs ready made, but perhaps you can find some "greybeard" with some solder smoke filled lungs who can help you.
UK has a mighty fine tradition of electronics builders.
I still have roof-high stacks of Practical Electronics, ETI, Practical Wireless and many many others where I learnt a lot.
I shouldn't even mention this, which shall send me straight to the Mummy Room at the British Museum, but I even have an old (well, it was new then) issue of "Beat Instrumental" where they talk about that "new, promising" band, called Deep Purple, who were playing for free just to show those "new, promising" amplifiers called Marshall. ;D

dg

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Re: "help with a Freedom amp please "
« Reply #14 on: December 07, 2009, 05:04:01 PM »
Hi Juan the link is http://www.maplin.co.uk/Module.aspx?ModuleNo=19088
Quote
2) If your transformer is 110/120V and you use your amplifier with an external 240>120V transformer, it might be interesting to buy an equivalent new 240V primary transformer and avoid carryinf useless weight.
its 240v in the UK i dont use an external transformer ,i thought it would blow up if you plugged a 110v appliance into a 240v socket?
it seems to work? how can i tell if its a 110v or 240v?
 
Quote
UK has a mighty fine tradition of electronics builders.
yes I think we do but because its so cold all the time there is  a general apathy towards everything LOL
Quote
those "new, promising" amplifiers called Marshall
I have had two Marshalls loved both but my mesa boogie was the most wonderful thing, heavy as hell but a sound to die for .sadly divorce left me with no Gretsch or mesa (liquidation of assets) but I got the kids so it was excellent exchange.
My son has gone over to the dark side after two years of guitar lessons he has just taken up the bass !!!!!!!!I bought him a mini
one " Smoke on the Water Bass line "great the first time by the 200th Ahhhhhhhhhhhhhhhhhh
Thanks
david