This is kind of an interesting find I acquired over the weekend. A guitarist I used to play in a band with wanted a distortion pedal for his current project (he sold his old gear when our band broke up) but didn't have any money, so he offered me this. It didn't work at first (one of the connections to ground had come unsoldered, piece of cake), but is a great sounding amp.
The story he was told and that he passed on to me was that in the early 50's the Japanese had been making fake (not clones, just straight up counterfeit) Fender guitars and amps, and some of the US soldiers that were stationed over there picked them up cheap and brought them home. He assured me that it was super rare, but I'm not really sure one way or the other.
What I am sure about is that the tubes that were in it looked very old and were Japanese, and many of the components say made in Japan. It looks like the circuit is relatively well-designed, the enclosure and hardware not so much. The circuit is point to point with a couple tag boards here and there for structural integrity and convenience. It uses a pair of 12AX7s in the preamp and a single EL84 for the power section. The controls are volume, bass, treble, and tremolo. The output is comparable to many 5 watt tube amps I have played so that's about what I assume it to be. The strangest thing to me so far is that the box is relatively large but they only put a single 8" speaker in it, which will break up right about the same point the amp does. Another odd point was that in place of an independent power switch the on/off was connected to a switch on the tremolo pot. Not volume, as is sometimes found, but for some reason on the tremolo.
I had to replace all of the pots as they were past the point of cleaning, and I took the chance to install a proper on/off switch. The faceplate is so worn it's unreadable, so I re-labelled it with sharpie until I am able to get a replacement on it. I replaced the speaker with another 8" I had lying around because it was pretty well shot and frankly it sounds very good. The clean is very rich and balanced and I can get a gentle breakup before the speaker starts to disagree. I tried disconnecting the speaker and running it through a 2x10 cab and a 1x12, and I liked the 12 better so I ordered a 12" Celestion for it. Through the larger speaker I can crank it to hear the full gain sound, and it is sweet! I don't think it will replace my main gigging amp, but it will definitely be one I keep around for a different flavor in recording.
Sorry to write so much before even posting pictures :P Here ya go (click for full-size):
(http://s16.postimg.org/aqnpl3701/image.jpg) (http://postimg.org/image/aqnpl3701/)
Get a load of that super convincing logo!
(http://s16.postimg.org/9xb3sh0z5/image.jpg) (http://postimg.org/image/9xb3sh0z5/)
(http://s16.postimg.org/dfmlhy8fl/image.jpg) (http://postimg.org/image/dfmlhy8fl/)
(http://s16.postimg.org/z5vxm55wx/image.jpg) (http://postimg.org/image/z5vxm55wx/)
The orange drops look a little out of place, so either this was repaired/modded or orange drops just last forever :P Also, the fuse holder was top-mounted, I moved it to the inside temporarily to accommodate the power switch. I plan to put it back on top when I re-do the chassis.
(http://s16.postimg.org/t2duvbm7l/image.jpg) (http://postimg.org/image/t2duvbm7l/)
(http://s16.postimg.org/oujkthe7l/image.jpg) (http://postimg.org/image/oujkthe7l/)
So anyway, I promise this will not be my only post on this because I will be doing A LOT of work on this thing. I plan on doing the following (and have already ordered parts):
- Replace tubes, Sovteks all around
- Replace speaker, Celestion Rocket 50 (it was the cheapest one I could find and I'm on a budget :P )
- Replace chassis; this is a big deal as the way it's currently mounted is already starting to fall apart. Mounting everything (especially transformers) to the back of a vertical thin sheet of metal was not the best idea!
- Replace super sketchy 2-prong power cord with a 3-prong cord (I'm a player, not a collector, so I view this as essential for vintage amps)
- Replace pilot light; it works, but the jewel is missing and I can't find one that matches the threading
- Replace logo with actual Fender logo; obviously not a big deal, but it makes me happy ;D
- Replace knobs with vintage style Fender knobs; same as above ;D
- Replace power switch with one that actually looks nice, not just whatever was in the parts bin :o
I thought briefly about stripping it completely down and re-doing the tolex, maybe with a nice tweed covering, and also replacing the grill cloth, but since I have never done either of these before and I hear they can be tricky I decided against it.
So the big question is does anybody out there *cough* *Paul* *cough* know anything about these other than what I was told?
Less important question, is there anyone out there that is comfortable working tolex and/or grill cloth that could help me out if I can get this to you? ;D
That's a cool find! Looking forward to see what you discover.
If your friend is to be believed, the Japanese would have had to be ahead of Fender by about a decade as far as looks. It wasn't until the mid 60's (63 I think) that fender started making amps with black tolex, the black face amps. Silverface, black tolex even later, mid to late 60's. From the late 40's to the end of the 50's it was all tweed. TV fronts at first, then the wide pannels. The turn of the decade (into the 60's) was when things started to blend, blondes and brown faces that bridged the gab between tweed and blackface.
I may have missed the part where you said the amp was refinished, but I'd guess the amp was made much later than what your friend reckons.
Quote from: mth5044 on January 19, 2016, 08:52:32 AM
If your friend is to be believed, the Japanese would have had to be ahead of Fender by about a decade as far as looks. It wasn't until the mid 60's (63 I think) that fender started making amps with black tolex, the black face amps. Silverface, black tolex even later, mid to late 60's. From the late 40's to the end of the 50's it was all tweed. TV fronts at first, then the wide pannels. The turn of the decade (into the 60's) was when things started to blend, blondes and brown faces that bridged the gab between tweed and blackface.
I may have missed the part where you said the amp was refinished, but I'd guess the amp was made much later than what your friend reckons.
Good to know :) It doesn't look like the amp has been refinished, so it seems safe to assume it's nowhere near as old as he said it is. I guess the main thing that made me want to think it was that old was the circuit; the oldest actual Fender amp I've worked on was a 1959 tweed deluxe, and even on a 1959 they were using eyelet board for the circuit. In my mind it just made sense that point-to-point was an older layout than turret or eyelet boards, but obviously there was nothing stopping people from doing it in the 60's or 70's or even today.
As a side note, one of the main reasons I want to refinish it is that the tolex doesn't look anything like the tolex found on Fender amps or frankly any others, more like a thin vinyl covering you might see on an ugly old couch :P
Some manufacturers used either a tremolo or tone control for the ON/OFF switch because the volume control was where small signal levels were found and AC hum could be picked up. A tremolo is an oscillator with a relatively high signal level and tone controls usually came after an amplifier stage so they were relatively immune to AC pickup as well. Of course a separate switch was even better.
Quote from: vigilante397 on January 19, 2016, 02:48:39 AM
This is kind of an interesting find I acquired over the weekend.
Eek! :icon_eek:
Quote
- Replace tubes, Sovteks all around
- Replace speaker, Celestion Rocket 50 (it was the cheapest one I could find and I'm on a budget :P )
- Replace chassis; this is a big deal as the way it's currently mounted is already starting to fall apart. Mounting everything (especially transformers) to the back of a vertical thin sheet of metal was not the best idea!
- Replace super sketchy 2-prong power cord with a 3-prong cord (I'm a player, not a collector, so I view this as essential for vintage amps)
- Replace pilot light; it works, but the jewel is missing and I can't find one that matches the threading
- Replace logo with actual Fender logo; obviously not a big deal, but it makes me happy ;D
- Replace knobs with vintage style Fender knobs; same as above ;D
- Replace power switch with one that actually looks nice, not just whatever was in the parts bin :o
Soooo... pretty much everything. ;)
I guess you could keep the wood? ;D
Quote from: bluebunny on January 19, 2016, 01:14:05 PM
Quote from: vigilante397 on January 19, 2016, 02:48:39 AM
This is kind of an interesting find I acquired over the weekend.
Eek! :icon_eek:
Quote
- Replace tubes, Sovteks all around
- Replace speaker, Celestion Rocket 50 (it was the cheapest one I could find and I'm on a budget :P )
- Replace chassis; this is a big deal as the way it's currently mounted is already starting to fall apart. Mounting everything (especially transformers) to the back of a vertical thin sheet of metal was not the best idea!
- Replace super sketchy 2-prong power cord with a 3-prong cord (I'm a player, not a collector, so I view this as essential for vintage amps)
- Replace pilot light; it works, but the jewel is missing and I can't find one that matches the threading
- Replace logo with actual Fender logo; obviously not a big deal, but it makes me happy ;D
- Replace knobs with vintage style Fender knobs; same as above ;D
- Replace power switch with one that actually looks nice, not just whatever was in the parts bin :o
Soooo... pretty much everything. ;)
I guess you could keep the wood? ;D
And some transformers! ... hopefully
http://svvintageamps.com/dating.php
Does it smell old?
Quote from: J0K3RX on January 19, 2016, 01:33:41 PM
http://svvintageamps.com/dating.php
Does it smell old?
It doesn't have a serial number, and none of the pot or transformer codes match any of the ones on that site :P
I guess I would say it smells old, but my friend and his father are both chain smokers, so it smells more like stale smoke than anything ::)
Quote from: vigilante397 on January 19, 2016, 06:00:35 PM
it smells more like stale smoke than anything ::)
Ah, "mojo". 8) You can tell people it's been gigged in smoky blues clubs since the dawn of time... ;)
so those two have found a way of getting the smoke in?
Quote from: duck_arse on January 20, 2016, 09:24:22 AM
so those two have found a way of getting the smoke in?
Mind you this is just regular smoke, not magic smoke. Once the magic smoke has been released it's impossible to get back in ;D
Quote from: vigilante397 on January 20, 2016, 10:28:15 AM
Quote from: duck_arse on January 20, 2016, 09:24:22 AM
so those two have found a way of getting the smoke in?
Mind you this is just regular smoke, not magic smoke. Once the magic smoke has been released it's impossible to get back in ;D
Hey, don't knock magic smoke till you've smoked it! ;)
Nice amp. Quirky, in the best possible way. I have a old Carlsbro amp from the early seventies (the last valve amps they made) with a similarly chequered past!
T.
Quote from: vigilante397 on January 19, 2016, 02:48:39 AMI plan on doing the following (and have already ordered parts):
- Replace tubes, Sovteks all around
- Replace speaker, Celestion Rocket 50 (it was the cheapest one I could find and I'm on a budget :P )
- Replace chassis; this is a big deal as the way it's currently mounted is already starting to fall apart. Mounting everything (especially transformers) to the back of a vertical thin sheet of metal was not the best idea!
- Replace super sketchy 2-prong power cord with a 3-prong cord (I'm a player, not a collector, so I view this as essential for vintage amps)
- Replace pilot light; it works, but the jewel is missing and I can't find one that matches the threading
- Replace logo with actual Fender logo; obviously not a big deal, but it makes me happy ;D
- Replace knobs with vintage style Fender knobs; same as above ;D
- Replace power switch with one that actually looks nice, not just whatever was in the parts bin :o
I thought briefly about stripping it completely down and re-doing the tolex, maybe with a nice tweed covering, and also replacing the grill cloth...
BUT BUT BUT BUT BUT BUT BUT....
You are changing EVERYTHING. What's the point? Maybe it's better to keep it this way and spend the SAME AMOUNT OF MONEY in parts to build another one.
Look at the fun side of things. You bring this old, beat-up, obviously fake amp with a fake Fender logo to a gig, and knock everyone out with the American Soldiers in Japan story. If you say it sounds sweet, why remake it? It's not a collector's point of view, it's just that you're not just changing one of two things, you will actually build something else without recycling anything and throwing almost every part in the trash can. So build something else and keep the Japanese alive. You'll have two amps for the price of one :)
Quote from: Hatredman on January 20, 2016, 04:33:18 PM
BUT BUT BUT BUT BUT BUT BUT....
You are changing EVERYTHING. What's the point? Maybe it's better to keep it this way and spend the SAME AMOUNT OF MONEY in parts to build another one.
Look at the fun side of things. You bring this old, beat-up, obviously fake amp with a fake Fender logo to a gig, and knock everyone out with the American Soldiers in Japan story. If you say it sounds sweet, why remake it? It's not a collector's point of view, it's just that you're not just changing one of two things, you will actually build something else without recycling anything and throwing almost every part in the trash can. So build something else and keep the Japanese alive. You'll have two amps for the price of one :)
I'm not changing everything :P I'm leaving the circuit untouched, just moving it to a more sturdy chassis. I'm still keeping the original transformers as I see nothing wrong with them. The only tone-affecting changes will be tubes and speaker. As I mentioned the existing speaker was pretty shot, and I don't think an 8" was an appropriate choice. The tubes are more of a testing thing. I stil believe "if it's not broke don't fix it," and the existing tubes sound good I just want to see if the Sovteks sound better.
So to clarify, I'm really just changing tubes, speaker (which I do to almost every amp :P ), and switch, and everything else is purely cosmetic, except of course for the chassis which I view as essential because this one is hanging by two screws and is only a matter of time before it falls altogether.
Also as a brief update, speaker showed up today, chassis should be here tomorrow, and tubes Friday. ;D
And as for the building, the total spent on parts was less than $100, which is way less than any amp I've ever built :)
Anyway, leave the old fake tolex, grill cloth and fake Fender plate. For Frodo. I mean, for Mojo.
Kind of forgot to update this as I made progress on the amp. The hardest and most time-consuming part was moving everything over to the new chassis without completely taking apart the circuit. So I kept the circuit completely intact and kept the stock transformers, but changed just about everything else :P Pretty sure I did everything I listed above, but to reiterate:
New tubes (matched Sovteks, HUGE tonal improvement)
New speaker (12" Celestion Rocket 50, again HUGE improvement in sound)
New chassis (Hammond enclosure from Tubes and More, huge improvement in stability)
3-prong cord (grounding it completely got rid of background noise 8) )
New handle (went with a vintage Fender style, much more comfortable)
Rubber feet (apparently whoever designed it decided it didn't need feet)
And some cosmetic stuff: Fender knobs, Fender pilot light, real Fender logo (sorry Hatredman :P )
I was thinking about a faceplate, but I think I'll probably just paint the top of the box silver and throw a waterslide on it ;D Click on pictures for full image.
(http://s8.postimg.org/9euyk1csx/IMG_2520.jpg) (http://postimg.org/image/9euyk1csx/)
(http://s8.postimg.org/jfzstcpw1/IMG_2526.jpg) (http://postimg.org/image/jfzstcpw1/)
(http://s8.postimg.org/zcykq2ia9/IMG_2527.jpg) (http://postimg.org/image/zcykq2ia9/)
(http://s8.postimg.org/6pvkg9hxt/IMG_2528.jpg) (http://postimg.org/image/6pvkg9hxt/)
(http://s8.postimg.org/xp40p5tsh/IMG_2529.jpg) (http://postimg.org/image/xp40p5tsh/)
(http://s8.postimg.org/gedlx524x/IMG_2531.jpg) (http://postimg.org/image/gedlx524x/)
Damn the naysayers, I think you did yourself and that amp a huge service buy making better than 'new', whatever 'new' was when it was made. Looks nice! Trace the circuit yet?
That looks awesome, I did like the old "Femder" logo though, perhaps you should save it an put it on a pedal or something.
Quote from: mth5044 on February 08, 2016, 01:29:07 PM
Damn the naysayers, I think you did yourself and that amp a huge service buy making better than 'new', whatever 'new' was when it was made. Looks nice! Trace the circuit yet?
Thanks! ;D I haven't traced it yet, though I do have plans to do so.
Quote from: wavley on February 08, 2016, 01:39:37 PM
That looks awesome, I did like the old "Femder" logo though, perhaps you should save it an put it on a pedal or something.
I liked the logo too, but not enough to leave it on the amp :P I still kept it and was trying to decide what to do with it. Maybe do a cab sim, cover it in tweed and throw it on there? 8)
Or you can send it to me, I'd love to put it on my cabinet :D
I have a friend in town that runs a recording studio and I brought the amp by tonight to show it off as he's a huge gear head (that's pretty much the basis of our friendship :P ) and he fell in love. He says it sounds a lot like he would imagine a Fender Supro would sound like if it was EL84 powered. He just played with it through a strat for a bit and loved it, but I assured him it really sings with humbuckers. So I'm letting him hold onto it for a couple days so he can try it with his Custom Shop ES-335 (trying to talk him into trading me that one :P ). But he's already assured me that "If you sell this thing, I will buy it."
I'm still having a musical identity crisis deciding if I'm a drummer that also plays guitar or a guitarist that also plays drums, but if I decide I'm a drummer that also plays guitar (most likely, as I'm nowhere near as comfortable on guitar; I can jump into any jam session on drums, but guitar you need to tell me the key, all the changes, and give me two weeks to practice) then I will do a recording so I can show you all how it sounds, trace the schematic for future reference, then let go of it for a profit ;D
I can see your boutique amp business coming in to fruition.
Yes, and you can even base your logo on the fake Fender onde ;)
Quote from: Hatredman on February 10, 2016, 08:48:57 AM
Yes, and you can even base your logo on the fake Fender onde ;)
Would I get sued if I call it a "Femder"? :P
Quote from: vigilante397 on February 10, 2016, 09:31:45 AM
Would I get sued if I call it a "Femder"? :P
Ignorance is bliss. Stick with the old G.I. Joe story and tell people the original logo fell off during transport on a military helicopter.
My motto: if the real story is boring, make up a better one.
Remember that time a million years ago I said I would trace the schematic? Well I did it. While I was tracing it, however, I was checking out the EQ and it looked so close to a Baxandall that I'm pretty sure I actually just hooked it back up wrong when I re-housed it, so I fixed it to be a true Baxandall and I LOVE what it did to the tone. Actually takes dirt pedals pretty well now. And sorry if the schematic looks a little weird, I'm trying to force myself to use Altium more :P Oh, and I forgot to mark on there: V1 and V2 are 12AX7, V3 is an EL84.
Too small image taken from a screenshot:
(http://i.imgur.com/cfduqsR.jpg)
And a PDF so you can actually see things :P https://www.dropbox.com/s/jiayumqqnjntyho/Schematic%20Prints.pdf?dl=0 (https://www.dropbox.com/s/jiayumqqnjntyho/Schematic%20Prints.pdf?dl=0)
As is I estimate it to be about 5W, and through a 12" speaker it sounds incredible. I'm thinking about using this to start my new boutique amp company :P I'll still keep this exact configuration, but I also want to try adding another EL84 in push-pull to get closer to 15W or so for a more practical gigging amp. More on that later in the summer when my life has calmed down a little more :P
nathan - did we ask, or did you tell us - is the "tremolo" a rate pot or a depth pot? I was going to say "yr circuit looks to be missing a pot in series w/ R24", but now I'm not going to.
Quote from: duck_arse on April 30, 2016, 10:53:31 AM
nathan - did we ask, or did you tell us - is the "tremolo" a rate pot or a depth pot? I was going to say "yr circuit looks to be missing a pot in series w/ R24", but now I'm not going to.
It's a depth pot. Really good sounding tremolo BTW.
QuoteLess important question, is there anyone out there that is comfortable working tolex and/or grill cloth that could help me out if I can get this to you? ;D
I could help you if you were located near my home... In France... :icon_confused:
(http://img15.hostingpics.net/pics/116883IMG0841red2.jpg)
(http://img11.hostingpics.net/pics/332096IMG0046red.jpg)
(http://img15.hostingpics.net/pics/821737IMG1875.jpg)
(http://img15.hostingpics.net/pics/703657IMG1876.jpg)
(http://img15.hostingpics.net/pics/194645IMG3443red2.jpg)
(http://img15.hostingpics.net/pics/194842IMG1463.jpg)
(http://img15.hostingpics.net/pics/524442IMG1465.jpg)
(http://img15.hostingpics.net/pics/562553IMG1469.jpg)
Let me tell you that it is not so difficult to achieve by yourself, if you are used to build, paint and etch stompboxes !
For sure, you can find many tutorials on the web to explain you how to proceed. It is somewhat similar to wallpaper putting, in a more accurate way and less surface ;D.
First, you need to practice a bit on dummy material in order to understand the basics : how to realize joints, seams, angles, rounded junctions, how and where to cut the tolex to obtain the right size without wasting it, etc...
A
real key point is the
glue. You need to choose the appropriate glue, not the all-aroung neoprene, universal or so. Without that, you job will be not be neat, nor presentable and durable, if you arrive at end...
The glue that I used on the pictured amps above is : http://www.tube-town.net/ttstore/Tolex-entoilage/Tolex/Tolex-Glue-SG5-500-ml::4756.html (http://www.tube-town.net/ttstore/Tolex-entoilage/Tolex/Tolex-Glue-SG5-500-ml::4756.html). It is very friendly to use, allowing you to position / reposition the Tolex for a moment when putting it.
But I am in Europe, nonetheless you can surely find the equivalent glue at MojoTone or any amp parts dealer in the USA, that by the way can sell you along some Tolex leftover sheets of different colors for practice.
A+!
Quote from: tubelectron on May 01, 2016, 06:48:11 AM
QuoteLess important question, is there anyone out there that is comfortable working tolex and/or grill cloth that could help me out if I can get this to you? ;D
I could help you if you were located near my home... In France... :icon_confused:
You, sir, have MAD skills. Wow...nice looking amps.
Quote from: tubelectron on May 01, 2016, 06:48:11 AM
I could help you if you were located near my home... In France... :icon_confused:
One of these days I hope to get out to that part of the world, but alas it will not be any time soon :P Thanks for the tips though, I'll definitely look into it. Also I've seen your amps in a few different places and I'm a huge fan 8)
Thank you Guys !
I looked again to your little "Fender Fake" amplifier, vigilante397 :
- You shouldn't encounter much issues for retolexing the cab : it is straight and square angles. One strip for the cab, one cut for the back. I think that you can even preserve the grillcloth that appears to be still in good shape : a good cleaning, maybe a bit of gentle stretching with an hair-dryer (if it's plastic-made).
- You mention that it was probably made in Japan in the 50's, if I recall well. But personally, I am akeen to think that it could possibly be European-made, and probably Italian-made, from the 60's, looking to the components inside (with the exception of the orange drops caps).
A+!
+1 on using the right tolex glue. The 3M spray adhesive stuff will NOT yield good results. Use a dropcloth if doing indoors, and wear clothes you don't care much about, tolex glue will not wash out. It is water-based, but not water-soluable once dry.
I use a paint roller to apply to the back of the tolex and the cabinet. Don't get the foam type, it will dissolve. Do get extra rollers, the one you start with will be gummed up before you're done. Spread the glue thin but completely. Once it turns from milky to clear, the pieces are ready to apply. Drying time can be sped up with a heat gun or hair dryer.
I tend to stick on slightly oversized pieces, then trim with a straightedge and exacto. Pretty quick. If you need to pre-cut a piece, remember that the tolex will stretch some, so slightly undersize it. Don't worry about getting glue on the outside of the tolex, it will rub right off with your thumb even after it's dry.
After a few days, I like to tack down any loose edges with super glue. Particularly where tolex overlaps.
Practice on scrap like Bruno says. The corners are a bit tricky to make look neat. Once you've done it a couple times, you'll have it down.
Quote from: thermionix on May 01, 2016, 06:56:01 PM
+1 on using the right tolex glue. The 3M spray adhesive stuff will NOT yield good results. Use a dropcloth if doing indoors, and wear clothes you don't care much about, tolex glue will not wash out. It is water-based, but not water-soluable once dry.
I use a paint roller to apply to the back of the tolex and the cabinet. Don't get the foam type, it will dissolve. Do get extra rollers, the one you start with will be gummed up before you're done. Spread the glue thin but completely. Once it turns from milky to clear, the pieces are ready to apply. Drying time can be sped up with a heat gun or hair dryer.
I tend to stick on slightly oversized pieces, then trim with a straightedge and exacto. Pretty quick. If you need to pre-cut a piece, remember that the tolex will stretch some, so slightly undersize it. Don't worry about getting glue on the outside of the tolex, it will rub right off with your thumb even after it's dry.
After a few days, I like to tack down any loose edges with super glue. Particularly where tolex overlaps.
Practice on scrap like Bruno says. The corners are a bit tricky to make look neat. Once you've done it a couple times, you'll have it down.
Exact complementary description to what I wrote before :icon_cool:
Good tip, thermionix : I didn't thought of using a paint roller, solely a flat brush :icon_rolleyes:... But I will come to it for larger surfaces I think !
A+!
Quote from: tubelectron on May 01, 2016, 06:23:30 PM
- You mention that it was probably made in Japan in the 50's, if I recall well. But personally, I am akeen to think that it could possibly be European-made, and probably Italian-made, from the 60's, looking to the components inside (with the exception of the orange drops caps).
A+!
I don't think it was made in the 50s anymore, but I believed it was Japanese made because all the caps (excepting orange drops of course) are Japanese and the tubes and speaker it had when I got it were Japanese made. Out of curiosity, what about the components makes you think it's Italian made?
Quote from: vigilante397 on May 02, 2016, 05:18:01 PM
I don't think it was made in the 50s anymore, but I believed it was Japanese made because all the caps (excepting orange drops of course) are Japanese and the tubes and speaker it had when I got it were Japanese made. Out of curiosity, what about the components makes you think it's Italian made?
Those greenish caps are Mullard/Philips "mustard" caps, made in England and Europe. Serious Mojo parts! Old Marshall, Vox, and Traynor amps were made with them, along with some classic recording gear, and a few pedals. Jap tubes and speaker may not be original to the amp.
Can't quite make it out in the pics, but that multi-section can cap looks like maybe a US-made Mallory. Wouldn't be a bad idea to replace that, btw. Decades-old electros might fly in a low-voltage pedal, but when they fail or leak current in a tube amp, they can take out power transformers.
Hi Nathan, Are you sure about R2 being 1k? Usually see 100k/1k5 plate/cathode combo, like the first triode.
dave
Quote from: davent on May 03, 2016, 01:40:28 PM
Hi Nathan, Are you sure about R2 being 1k? Usually see 100k/1k5 plate/cathode combo, like the first triode.
dave
You are definitely correct, you can see the two 100K plate resistors in the photos. Also, the schematic is incomplete at the HV secondary of the PT. Surely it's supposed to be a full-wave rectifier.
Quote from: thermionix on May 03, 2016, 03:41:07 PM
Quote from: davent on May 03, 2016, 01:40:28 PM
Hi Nathan, Are you sure about R2 being 1k? Usually see 100k/1k5 plate/cathode combo, like the first triode.
dave
You are definitely correct, you can see the two 100K plate resistors in the photos. Also, the schematic is incomplete at the HV secondary of the PT. Surely it's supposed to be a full-wave rectifier.
Good catch, it definitely is a 100k on the plate. Altium defaults every resistor to 1k until you change it and I apparently missed that one.
It seems weird, but I promise the schematic shows exactly how the power supply is. One of the HV secondaries is attached to nothing and the other is set up as a half-wave rectifier with the center tap.
I haven't tested any of the caps for leaking (mostly because it sounds really good as is), but I'll do it when I get home Sunday. I'll also double-check labels on all the caps for where they were made.
You'd know if the coupling caps were leaking because it sounds like a scratchy pot (Crackle Okay on an SHO).
I'd do any electrolytic caps for sure, and any coupling caps that cause a scratchy pot, otherwise I'd leave orange drops and mustards alone. Maybe replace the ceramic discs.
I'm messing around with my Harmony 525, maybe going to use the unused half of the input 12AX7 in parallel with the input stage because I love the sound of parallel input triodes and I noticed yesterday that the schematic has .005uF input cap with what I consider to be pretty low grid to ground of 270k and you pretty much have the same thing going on. Except you don't have any grid stoppers. I have three channels: 47k and two 470k, thinking about switching one of the 470k's to 68k for a more normal value and just bypassing the input cap. When I parallel the input triodes I might have to play around with that 270k to ground, we'll see.
Push-Pull requires a different output transformer right? And your driver tube will have to be rewired as a paraphrase phase inverter if you want to be push-pull. If your current transformer can handle it maybe you could try just a second EL84 in parallel single ended for a bit more. Or, I build an amp recently and used the quite reasonably priced 25 watt single ended output transformer from Weber with a single KT66 (well any octal actually, but I like the 66 best) It's huge, but I think the amp is really fantastic sounding, all the rawness of a no feedback single ended amp, but with a more open sound than the 15 watt transformer that a lot folks would use in the same situation.
The mustards and orange drops won't be leaky. It was the filters I was concerned about. Also, half wave rectified B+ is possible, but highly unusual and downright silly.
Quote from: wavley on May 04, 2016, 12:53:55 PM
the schematic has .005uF input cap with what I consider to be pretty low grid to ground of 270k and you pretty much have the same thing going on. Except you don't have any grid stoppers. I have three channels: 47k and two 470k, thinking about switching one of the 470k's to 68k for a more normal value and just bypassing the input cap.
It's not grid leak biased, is it? Is there a cathode resistor or straight to ground?
Quote from: thermionix on May 04, 2016, 04:55:01 PM
The mustards and orange drops won't be leaky. It was the filters I was concerned about. Also, half wave rectified B+ is possible, but highly unusual and downright silly.
Quote from: wavley on May 04, 2016, 12:53:55 PM
the schematic has .005uF input cap with what I consider to be pretty low grid to ground of 270k and you pretty much have the same thing going on. Except you don't have any grid stoppers. I have three channels: 47k and two 470k, thinking about switching one of the 470k's to 68k for a more normal value and just bypassing the input cap.
It's not grid leak biased, is it? Is there a cathode resistor or straight to ground?
It's not grid leak biased, it's got a bypassed cathode, and 270k would be an awfully small grid leak resistor. My input stage looks exactly like has drawn, but mine has grid stoppers. The 525 is just a supro thunderbolt with a different tone stack, I'm going to make a few tweaks and live with the tone stack a little longer because it is so different than everything else I have, but will probably end up switching to a thunderbolt tone control and maybe using the unused control as a master volume or something.
That's why I thought it was funny that I was staring at the schematic for my amp when he posted the schem for his Femder it had very close to the same input topology. Where they differ is while the Femder doesn't have any grid stoppers, I have 470k on two of the three inputs and 47k on the outputs, which is a bit excessive in my opinion. I'm going to switch one of the 470k to 68k and parallel the unused input triode before I make a decision about tweaking the outputs.
Quote from: wavley on May 04, 2016, 12:53:55 PM
Push-Pull requires a different output transformer right? And your driver tube will have to be rewired as a paraphrase phase inverter if you want to be push-pull. If your current transformer can handle it maybe you could try just a second EL84 in parallel single ended for a bit more.
Correct and correct. I'm not positive the current power transformer could handle another tube, but I wasn't really planning on modding this amp to be push-pull, I want to keep this one as-is as much as possible (I probably will swap the ceramics and check everything else for leaking just for fun, and replace if necessary), but I like the design and I want to experiment with building based on this design. I found a pretty cheap American supplier for transformers so I'll probably get a single ended and push-pull and experiment with configurations until I find the sound I like at a power level I can use ;D
Quote from: vigilante397 on May 05, 2016, 04:00:14 PM
Quote from: wavley on May 04, 2016, 12:53:55 PM
Push-Pull requires a different output transformer right? And your driver tube will have to be rewired as a paraphrase phase inverter if you want to be push-pull. If your current transformer can handle it maybe you could try just a second EL84 in parallel single ended for a bit more.
Correct and correct. I'm not positive the current power transformer could handle another tube, but I wasn't really planning on modding this amp to be push-pull, I want to keep this one as-is as much as possible (I probably will swap the ceramics and check everything else for leaking just for fun, and replace if necessary), but I like the design and I want to experiment with building based on this design. I found a pretty cheap American supplier for transformers so I'll probably get a single ended and push-pull and experiment with configurations until I find the sound I like at a power level I can use ;D
I just built a single ended, wired the output universal, and put a 470R cathode resistor in so everything will bias up (sure bigger tubes are biased a bit cold, but I played with it and the ability to swap to any tube trumped the marginal difference it made in this amp). I used the 25 watt OT from Weber and it sounds really fantastic and loud enough to use with a reasonable volume band. I'm really enjoying the elegance of simple amps that have all the parts balanced. For me it was a two tube amp with a tweed tone control and a post driver master volume, it's really the first master volume that I haven't just put on 10 to pretty much take out of the circuit. I was thinking about building the same amp with parallel single ended output tubes for more omph, we'll see if I get the time.
That's why I'm revisiting my Harmony 525, I've just been using it as a low volume studio bass amp (my 70's Japanese Hofner copy sounds really great through it) but I think I can heat it up into being a great guitar amp and it will still make a good studio bass amp. Like I said, our input stages are fairly similar so I'm following this pretty closely to see your results. I actually really like cheap tube amps from the 50's, 60's, and 70's... sure most of them are kinda one trick ponies, but that trick is so different than the classic Fender and Marshall tones. The other little amp I really love is the Kalamazoo Model One and Two. I had a One, sold it to a guy and kinda regretted it, got a Two at the shop, made the right business decision, modded it and sold it, now that guy bought my old one and has both now! Just to tease me he brought it up yesterday so I could order a Weber speaker for it and so it's sitting next to my bench.
I hate to necro-bump this thread after it's been dead over a year, but I still get to thinking about this amp sometimes when my mind wanders. I've made a couple mods recently as well. It now has a Tone Tubby Red Alnico speaker (LOVE LOVE LOVE this tone), I swapped one of the resistors in the tremolo circuit for a pot so I can control the tremolo speed as well as the depth, and I made a faceplate for it with my new laser engraver.
But I'm still puzzled as to the origins and age of the thing. I said over a year ago that I would double check the origins of the components and never did, until tonight, when I verified that everything with a label on it is Sprague. All the electrolytics inside, the orange drops, and the multi-section can are all Sprague. I was able to get the model number off the can, a Sprague TVL 4773, and it looks like there might be a date code on the bottom (7839L), but I'm not positive that's what it is. The output transformer says "LION" 5K REG. PHIL PAT. OFF, but I can't figure anything out there. Power transformer is stamped with GENERAL TRANSOFMER, no label or anything. I'm really kicking myself for throwing away the original pots, they may have had some secrets to tell ::) But that was 4 years ago, what can you do now.
Anyway, here are some pictures of the cap and the transformers, do any of these mean anything to anyone?
(http://i.imgur.com/mxOhTWX.jpg)
(http://i.imgur.com/ytgeGNB.jpg)
(http://i.imgur.com/SsfsINu.jpg)
(http://i.imgur.com/WeuulrK.jpg)
Small update (in case anyone is still following this), a quick Google search shows that REG PHIL PAT OFF means registered in the Phillippines patent office. So American caps, Japanese tubes and speaker, Phillippine output transformer? ???
Quote from: vigilante397 on August 15, 2017, 01:05:07 PM
...Phillippine output transformer? ???
... mmh did the builder take home some souvenir from his sex tour?
Quote from: vigilante397 on August 15, 2017, 01:05:07 PM
So American caps, Japanese tubes and speaker, Phillippine output transformer?
Don't forget the mustard caps (Mullard/Philips) which are European. To my knowledge those were made in England and Spain. I think you have somebody's homemade amp. There is probably no way to tell where it was made. 7839 is quite possibly a date code, 39th week of 1978. That's well after the Vietnam War, so it wasn't a Filipino trying to sell a cheap "Fender" to some GI (that kind of stuff happened a lot back then).
Quote from: thermionix on August 15, 2017, 02:54:29 PM
I think you have somebody's homemade amp.
I agree, it definitely seems that way. But I just wish I could get some answers :P the guy I got it from has been on a LOOOOOT of drugs as long as I've known him so I doubt he would be any help. Again none of this is crucial information for me to have, I'll he keeping the amp regardless, I just get so darn curious!
On the other hand, having the answers would draw a line under it. There's something romantic in the mystery - it just might have been used by......
Quote from: stallik on August 15, 2017, 06:30:21 PM
On the other hand, having the answers would draw a line under it. There's something romantic in the mystery - it just might have been used by......
What about the Femder logo, did you do something with it?
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Scarlett Johansson uses a Burst Box with her Telecaster.
What about the Femder logo, did you do something with it?
[/quote]
Not yet, it's still just sitting on my workbench. I was thinking about cleaning it up and re-doing the paint, bring it back to its former glory 8)