Shaftesbury

[winnetou]

Hi,
Just got this amp, and I am wondering could anyone help me how and where to connect speakers and what to do with red and black bare wires.
Otherwise when switched on all tubes are on and glowing.
As you can I am an absolute beginer.

Thanks in advance.

[screamingbirdamps]

red and black wires

it looks like they are the speaker wires cos they come from the output tranny but dont take that as read, take some better pictures of their connections in the amp ,and a better pic of all those speaker wires and ill have another look for you

[winnetou]

Shaftesbury

Much appriciated.
I uploaded hopefully slightly better pictures.
On picture PB100475 there is a round mirror underneath the " connection point" of black and red ( not connected )wires.
Speakers are not connected to anything, except, I guess, external cabinet connection cable ( on the left ).
I am just wondering , as I said,should I connect speakers to those ( black and red ) wires, or should speaker wires be soldered somewhere else?
If somewhere else, what are those ( black and red wires for ).
Thanks a lot

[olddawg]

1. Do not power up the amp without the speakers connected.

2. Find out if the speakers are 4,8, or 16 ohm speakers. You need to know if it should be two 4 ohms in series or two 16 or8 ohm speakers in paralelle.

3. It would be a good idea to test them one at a time on another amp like a home stereo to make sure they are good, but check them with an ohmeter first so you don't damage that amp if they are shorted.

4. I would guess that the red wire is phase + and the black wire is phase - coming out of the OT if it is wired to convention.

5. I have no idea what that rca plug is for unless it has a tremelo footswitch.

[winnetou]

Shaftesbury

Hi and many thanks,
Speakers are actually 15 Ohms each ( printed on the speakers), and I just connected two ( black and red wires ) to speaker wires ( 'couse speakers are connected to each other ) following this :

Earth - Green and Yellow (Previously Green)
Neutral - Blue (Previously Black)
Live - Brown (Previously Red)

and it works and responds fine, tremolo is amazing, and starts distorting after volume apr. 4 , but there is a hum present, and I am wondering whether this could be eliminated or this is it ?
Any quick fix?

Thanks people

[olddawg]

It looks like a great little amp and a good score.

The 15/16 ohm speakers should be connected in parallel (for an 8 ohm combined load) to the output transformer secondary wires which seem to be the red and black wires. I would suggest that you rewire the whole speaker wiring dress to avoid problems.

The hum you have is most likely caused by that big aging and probably defective can type filter multi-cap. You do not have to replace it with a can type. You can use individual electrolytic capacitors of the appropriate value and rating although can cap replacements are available. Also, you would probably want to convert your AC mains to a modern 3 wire cord with an earth ground to avoid a shock hazard.

If what I am saying makes no sense to you and if you have no experience in troubleshooting/repairing tube amps, I should caution you that potentially lethal voltages can be present even with the amp unplugged. If you do not understand basic electronics, troubleshooting, and safety procedures I would highly recommend you take the amp to a qualified tech. You could really hurt yourself.

[winnetou]

Shaftesbury

Thanks a lot.
It is a three wire cord, and I allready rewired it to a standard 3 wire plug.
In regard to a -can type filter multi-cap- that is beyond my " expertise " ( I will have to do more googling ), as well as in regard to the parallel speakers connection.
I'll do my best to stay safe (thanks for the advice) , and will see what can be done to make it shine again.
None the less it sounds like a really nice tube amp,but it is difficult to find any more info, even about it's power,on the net.
You are really good guys, and I wish you all the best in the future.
Appriciated.

[olddawg]

The can cap is simply two or more electrolytic filter capacitors in one package. Usually it's a 20uf X 20uf or a 20,20,40 or some such. Like I said. You can use individual caps. These are the filter caps for the B+ line, thus if bad you get massive 60 cycle hum. My guess is that amp is similar to an 18 watt Marshall or a Vox AC15. Without you tell us the tube compliment it is hard to say, but I would guess that you have something like two EL84s output tubes and an EZ81 rectifier. A lot of people rebuild these uncommon amps into an 18 watt Marshall. It takes very little work and expense if that is indeed what you have.

[winnetou]

Shaftesbury

Just one more quiery olddawg,
Any idea of the value of this amp, taking into account that it is a quite an old one, I mean there are surely better and newer tube amps out there.

kind regards

[olddawg]

Just one more quiery olddawg,
Any idea of the value of this amp, taking into account that it is a quite an old one, I mean there are surely better and newer tube amps out there.

You never confirmed the tube complement. If it is indeed an EL84 PP compo amp with a tremelo channel and two vintage 12" speakers, I would say that it is worth at least $250, possibly more. But that's just a guess. The type and brand of tubes is important. The type and brand of speakers are important. The condition of the amp is important. If you have a complete picture of the amp and know what tubes are in it, plus any label designations it would help.

[winnetou]

Hi olddawg,

Sorry about late tube info, but there it is, with another picture attached.
Form the left to the right - They are all Mullard, - EZ81, 2x EL 86? ( one is 86 I guess, beacuse second number is almost gone , but it looks like 6 , but on the other one markings are gone completelly , so just presumed 86 ) and ECC 83 ( small one ).
And I might be wrong about hum, it sounds more like something cooking, boiling, but only affects overall sound to maybe 5 %.

cheers

[olddawg]

Hi olddawg,

Sorry about late tube info, but there it is, with another picture attached.
Form the left to the right - They are all Mullard, - EZ81, 2x EL 86? ( one is 86 I guess, beacuse second number is almost gone , but it looks like 6 , but on the other one markings are gone completelly , so just presumed 86 ) and ECC 83 ( small one ).
And I might be wrong about hum, it sounds more like something cooking, boiling, but only affects overall sound to maybe 5 %.

cheers

Great score. If those Mullard tubes are anywhere near fresh they are what people want. An ECC83 is the European designation for a 12AX7. I would take another look at the output tubes. With an EZ81 rectifier tube EL84s are more common and desireable. The amp probably needs a re-cap. With EL84s and two twelve inch speakers this amp should be loud enough to jam with or play small clubs. I use an 18 watt Marshall clone through a 4X10 cab all the time with 2 X ECC83(12AX7), 2 X EL84(6BQ50, and an EZ81 rectifier tube to play at stage levels with a sane drummer.

[winnetou]

Shaftesbury

Actually olddawg,

after better look, the two tubes in the middle are Mullard ELC 8 + any number( now definitelly not sure what number ). It's all fainted betond recognition. Nothing about Mullard ELC on Google.

cheers

[winnetou]

Shaftesbury

and the speakers are celestion 7442. For your info.

[olddawg]

Actually olddawg,

after better look, the two tubes in the middle are Mullard ELC 8 + any number( now definitelly not sure what number ). It's all fainted betond recognition. Nothing about Mullard ELC on Google.

cheers

.

Search on eBay. A good pair of Mullard EL84s goes from about $70 and up depending on the condition and circumstances. Mullards are considered the best by many people. Go to: 18 Watt Community Center and check out the schematics and posts.