# Found this old Sound Craft amp yesterday



## Tone Chaser (Mar 2, 2014)

I am guessing that it is early 1940's or so, maybe 5-15 watts of class AB1. It lights up a couple of tubes and needs a good cleanup, The 12" speaker has a bad section of paper. It is a model 470, made in Canada, made by N. H. Speight Laboratories, Toronto, Canada, Licensed under General Electric and Northern Electric. It is small and heavy. The guy I bought it from said there was an old steel guitar with it when he found it. He had already sold the guitar.





















I found one on Youtube that had a guitar playing through it.


----------



## dcole (Oct 8, 2008)

Whats the tube lineup?


----------



## Tone Chaser (Mar 2, 2014)

The 2 in the middle are 6V6, the one on the right has no writing, but has a similar plug in pattern as a 5U4 , the rest I don't know yet. I also don.t know what the 2 large silver cylindrical parts are on the left rear. There are numbers on those. I need some time to get a closer look and disassembly inspection.


----------



## shoretyus (Jan 6, 2007)

Is that a field coil speaker? Very cool


----------



## Tone Chaser (Mar 2, 2014)

dcole said:


> Whats the tube lineup?


I dug into the amp today. This is what I found.





















So it looks like 6V6 for power, 5Y3 rectifier, 6C5 and 6N7, with an inspection date of 12/1/46.

- - - Updated - - -



shoretyus said:


> Is that a field coil speaker? Very cool











It looks like it needs new paper, and I have to figure out how to test this speaker.


----------



## Tone Chaser (Mar 2, 2014)

Mark Bradac has one of these in working condition at his pawn shop, here locally in Windsor. Mark is a recorded musician of fame, who runs a pawn shop and has been participant on Pawnathon Canada. I believe he bought the one he has on the TV show.

His has a tweed covering, a 10" speaker instead of 12", and no phono jack on his.


----------



## Lincoln (Jun 2, 2008)

Very cool. We'll need some sound clips when you get it fired up. :smile-new:


----------



## Tone Chaser (Mar 2, 2014)

Lincoln said:


> Very cool. We'll need some sound clips when you get it fired up. :smile-new:


The tubes are questionable for many reasons. They all lit up when I got the amp, but no sound. The 6V6 light up only when plugged in a specific order. If I reverse them, only one will light in the one position. The unmarked 5Y3 no longer lit up, so I pulled a 5Y3 from the junk tube box and it lights up. If everything is in the mojo order, I now get sound amplification that is as loud as the unplugged guitar, perhaps a little louder.


I forgot to clean the only pot when I had it apart. It is scratchy, but works. So it is alive, but barely. It sounds like a little more maintenance, tubes, and new or repaired paper on the speaker, may give it some more mojo.


----------



## Lincoln (Jun 2, 2008)

don't forget to clean up the input jack too. Dirty jacks can cause all kinds of problems. The amp looks very original, it might need some caps.


----------



## jb welder (Sep 14, 2010)

The 6V6 heaters are wired the same for both sockets, so the problem with them suggests they are not mating properly with their sockets in one position. Cleaning and retensioning all the tube sockets should help, maybe cure some other issues too.


----------



## Tone Chaser (Mar 2, 2014)

jb welder said:


> The 6V6 heaters are wired the same for both sockets, so the problem with them suggests they are not mating properly with their sockets in one position. Cleaning and retensioning all the tube sockets should help, maybe cure some other issues too.


I believe you are 100% correct. The locater on the base is broken off and missing on one of the 6V6 tubes; so I am installing it by eye. I may be off one pin. The other tube is loose in the pin locater base; so how good can that tube be?

Should this amp be able to run on one 6V6 tube? That would be a cool option if that was possible. Maybe a 5 watter?

I have read about how much power these tubes should be able to put out on this kind of circuit. It may only be 12 to 15 watts with both 6V6 tubes. It is running like there is only 1/2 watt. I tried the Kingsley Jester pedal with it for a few minutes. It would not boost, but it would overdrive with no increase in volume.

It does sound pretty funky, but the speaker has a lot of paper damage. Can a standard speaker be used to test? If so, what ohm? How would I wire it. The current speaker has 4 wires to a plug that mates 2 large pins and 2 smaller pins to the chassis plug.


----------



## gtone (Nov 1, 2009)

I'd venture that amp is closer to 10-12W of output with that circuit. WRT the speaker, you can convert from a field coil unit to a more modern, permanent magnet speaker, but you'll need a choke or a large capacity resistor to do the conversion. There's lots of stuff on the net about those conversions (I had to have it done for an old Valco I had that had a blown field coil speaker).

Good luck and enjoy that one!


----------



## Tone Chaser (Mar 2, 2014)

jb welder said:


> The 6V6 heaters are wired the same for both sockets, so the problem with them suggests they are not mating properly with their sockets in one position. Cleaning and retensioning all the tube sockets should help, maybe cure some other issues too.


jb welder, Thanks for the tips. This is my first time dabbling with tube amp repair, (if you call what I am doing repair). I am just trying to make sure that I can take this as far as I can with the guidance of the internet and good people like you from this forum.

I once more removed the chassis from the cab. I then gave everything a good examination, I seem to notice things eventually.

I had to remove the old, unique pot from the chassis, and try to find a hole to spray some Deoxit into the pot. I found a couple of tiny holes on the front face of it where small copper rivets would hold internal parts. One of the holes allowed the money shot to happen. The feel of the pot improved considerably. I then reinstalled it.

I then took your advice and spent some time feeling the fit of the tubes. There is some looseness there on the second 
6V6 and the 5Y3 rectifier. I now have to figure out how to tighten up the tangs where the tube pins go in. I did clean them the other day with a piece of tight fitting braided copper wire and Deoxit. I used the wire as a brush.

I plugged in the speaker connection and plugged in the amp. The rectifier needed to be "fitted" a few times until the amp came to life. It is now much louder. Perhaps 6 to 8 watts worth on full, (maybe less).

I then tried the original 5Y3, and it took several "fitting" attempts to get the amp going. It sounded better than the tube from the back up box. I then tried a 5U4GB. It changed the speed or delay of notes some, as well as volume. It is a very big tube. It is nice to see what a tube can actually do at such a simple level of amp design.

I put the original 5Y3 back in and removed the middle 6V6. Yes, I answered my previous question, "can the amp run on only one 6V6?"

It sure can! It was even sweeter sounding than 2 6V6 tubes at only a slightly lower volume. I need to address how the tube pins fit.

I really like this amp with only one 6V6 in it.

I then grabbed my Kingsley Jester and plugged it in between the guitar and amp. The Boost now works, adding volume and flavor to the gritty sound. The overdrive and Jester tone stack made the sound very tasty, and louder. The Jester is hand wired and has a pair of Tung-Sol 12AX7 tubes in it.


So the original tubes do work. I just need to reset the female socket connections for the tube pins. I also have to investigate how to repair the speaker paper. I also need to know if this amp needs to get the tubes biased.

This can be considered a very good day with what I have learned.

- - - Updated - - -



gtone said:


> I'd venture that amp is closer to 10-12W of output with that circuit. WRT the speaker, you can convert from a field coil unit to a more modern, permanent magnet speaker, but you'll need a choke or a large capacity resistor to do the conversion. There's lots of stuff on the net about those conversions (I had to have it done for an old Valco I had that had a blown field coil speaker).
> 
> Good luck and enjoy that one!


Thanks gtone, I may have to go that route and am glad that it can be done.


----------



## jb welder (Sep 14, 2010)

Here is a link to info regarding socket re-tensioning. You don't have to use the exact tool, just something similar that does the job. I prefer to use something with an insulated handle just in case there is any voltage still present.
http://swartamps.com/tech/socket_retention/
The loose tube base is just glue that has let go, you can probably squeeze some super glue in there and it should hold. For the missing locater pin, you can put a scratch on the tube base in line with the key.
A low power amp like this is usually cathode biased, so there is no adjustement, although if it is way off, you can alter the value of the cathode resistor which will adjust the bias point.
Pulling one of the power tubes is the equivalent of a broken tube there. It's not going to do any damage, but you won't get a very good clean sound. For distorted sounds, it may sound better, as you have found.
There is plenty of info on the net regarding repair of ripped speaker cones.
If you can stay with the field coil speaker, it will be easier and probably sound better.


----------



## Tone Chaser (Mar 2, 2014)

Many months have gone by, and I have been patiently looking for a new handle for the amp while I have had it apart. Still no luck. I can't find anyone locally who has the leather to recreate the handle.

I googled how to repair the torn paper on speakers and gave repairing it a go. I was having no luck in finding someone who had a new cone.

The paper was very dusty and brittle in some places. Handling the cone material for the repair led to more repairs. Some areas went to dust. The paper cone is quite solid now with the repairs.

I tried to re-glue all the dried out loose wood in the cabinet.

I tightened up the pin sockets and cleaned up everything I could. 

I was getting tired of all the loose pieces everywhere and put it together tonight.

The speaker repair is working pretty good. It sounds pretty tight.

It sounds like a 5 watt or so amp with the tubes that came with the amp.

I am curious about putting new, or better used tubes in it. Will it get louder?

It takes pedals pretty good, and I have only tried the Fullerton Strat with it so far. I will give it a go with a Tele, Les Paul, and a few others over the next few days.

It sounds quite vintage.


----------



## greco (Jul 15, 2007)

Congrats on what you have achieved! Very, very impressive!

If you could bottle up some of your determination and perseverance, I'll buy at least a couple of gallons.

It would be great to see some pics of the amp (especially the miracle you performed on the speaker) but apparently pics are not uploading very well now.

There is a mennonite harness making/tack shop nearby. I bought tack oriented items from them when I was involved with horses. The staff are wonderful people and their prices are very fair. PM me if you want me to look into them making a copy of the handle for you.
OR.... You can contact them directly if you prefer: 
http://www.brubachersharness.ca/

Cheers

Dave


----------



## Tone Chaser (Mar 2, 2014)

Thanks Greco, for the lead on the leather work. I may take you up on the offer.

I am trying to leave this amp a vintage as possible; but that is not as easy as it sounds. The way they fastened everything on this amp was something like a rivet, instead of screws.

I knew that I should have taken pictures of the before, during and after, of the speaker repair. I just didn't do it for some dumb reason. There are many ideas on youtube on how to repair a hole in a speaker. This repair was originally a 5 inch long crack. It soon became 1/2 to 2/3 of the speaker needing repair. During the repair, my hands were covered with white carpenters glue. Both sides of the speaker cone needed repairs. As I worked the paper/glue into/onto the remnants of the existing paper, I got more daring, more competent; even though it was so fragile. Field coil speakers are quite hard to come by in good condition these days. This amp may have had an 8 or 10 inch speaker originally. It is hard to find evidence without removing the speaker cloth. I wasn't going to open that can of worms. The other 2 amps like this, that I have seen, had 8 inch speakers in them. I found that the upper bracing on the speaker baffle was somewhat whittled away to fit this 12 inch field coil speaker. The only holes that I could find were for mounting this speaker. 

I know a young local musician who records his own music with vintage instruments. When I find his number, I will ask him to record something with this amp, and post it for me. I don't know how to do that kind of stuff yet.


----------



## epis (Feb 25, 2012)

Hi Tone Chaser, you have a really cool amp !
As you can see it has 6C5 tube - single triode in preamp, gain factor of only 20. Regular preamp, even Champ has 12ax7, two triodes gain 100 X 100.
Your amp can't sound louder without some kind of mod, or without booster in front of the amp, it's normal for that configuration.
Here is a link to kijiji add for 12" field coil speaker here in Ottawa area, maybe you're interested :

http://www.kijiji.ca/v-electronics/...dio/583255647?enableSearchNavigationFlag=true

Best regards, Damir

P.S.

I can make the handle for your amp, PM me.


----------



## Tone Chaser (Mar 2, 2014)

Damir, that speaker in the kijji link looks massively bigger than the speaker I own. Mine just clears one of the transformers near the field coil. I sent him an email anyway to further investigate it.

I will PM you about the handle.


----------



## greco (Jul 15, 2007)

epis said:


> I can make the handle for your amp, PM me.


COOL! 

epis is such a talented fellow...meant in all sincerity.


----------



## toby2 (Dec 2, 2006)

Fab Audio in Toronto may be able to repair the speaker . He has repaired a couple of field coil speakers for me and they sound great . I would stick with the field coil type of speaker if possible.


----------



## epis (Feb 25, 2012)

Tone Chaser said:


> Damir, that speaker in the kijji link looks massively bigger than the speaker I own. Mine just clears one of the transformers near the field coil.


Yes, I see it now. It really looks to big for your amp.

About the handle, you may try as well to search for leather trunk handle on ebay and google, it shows a lots of results.

Cheers, Damir


----------



## epis (Feb 25, 2012)

greco said:


> COOL!
> 
> epis is such a talented fellow...meant in all sincerity.


Thanks for kind words Greco, I'm only a curious handy man, some time ago I acquired a few big pieces of thick leather, made a handle for my tweed 5E3 build and a handle for friends blues deluxe. If I had more time......


----------

