Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
- Thread starter crusty philtrum
- Start date
Chickenwings
Alnico 6/8
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
crusty for PM.
crusty for PM.
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crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
With the original s/s rectifier, in conjunction with some CBS-period resistor values, the amp had a wonderful s/f Fender clean sound, but it had that sound almost all the way up, like a Twin Reverb. I wouldn't have called the response 'stiff', but it was kind of 'uptight' compared to the tube rectifier. The tube (I used a GZ34, but i could also use a 5U4) has made the response a little softer and more reactive to playing touch. It's a little more 'organic', it just feels more like the amp interacts with you more. It's subtle but definitely noticeable and an improvement. If i used a 5U4 rectifier tube, the bounce and sag would be more noticeable, and that's always an option, but so far I'm liking it with the GZ34.
Changing the CBS era resistors in a couple of places allowed the amp to be a little more gainy ... not dirty, but the sound changes as the volume is increased, going from warm to fatter to the start of break-up to a nice gentle overdriven sound that is very musical and enjoyable to listen to. I guess changing a couple of resistor values changed the sound, and the rectifier swap affected the response, although no doubt the two things overlap in some aspects.
Some players might prefer the 'clean all the way up' version of the sound, others would prefer the way it is now. Depends on a player's application(s) i suppose. I was looking to get a vintage-style response, a little sag but maintaining the lovely warm but sparkly cleans at lower levels and gently evolving into a good bluesy sort of tone that could then be knocked 'over the edge' with an overdrive pedal. I didn't want to push it into full-blown, over-the-top SRV hot-rodded territory because i wanted to keep it versatile and not too orientated towards one specific purpose. Also i wanted it to work well with single-coils and humbuckers, and it seems to be sitting in a place that lets both types of pickups/guitars perform well without compromising how the other type would work.
So basically it's the kind of amp that i would have used as a teenager back in the early '70s. Just a nice core tone with some dynamic response that can easily be boosted with a pedal for rock tones. The tube rectifier has definitely contributed a lot to getting it to that place, it's given the amp a lot more character and life. I'm very happy with the outcome, and consider it well worth the time, effort and money.
With the original s/s rectifier, in conjunction with some CBS-period resistor values, the amp had a wonderful s/f Fender clean sound, but it had that sound almost all the way up, like a Twin Reverb. I wouldn't have called the response 'stiff', but it was kind of 'uptight' compared to the tube rectifier. The tube (I used a GZ34, but i could also use a 5U4) has made the response a little softer and more reactive to playing touch. It's a little more 'organic', it just feels more like the amp interacts with you more. It's subtle but definitely noticeable and an improvement. If i used a 5U4 rectifier tube, the bounce and sag would be more noticeable, and that's always an option, but so far I'm liking it with the GZ34.
Changing the CBS era resistors in a couple of places allowed the amp to be a little more gainy ... not dirty, but the sound changes as the volume is increased, going from warm to fatter to the start of break-up to a nice gentle overdriven sound that is very musical and enjoyable to listen to. I guess changing a couple of resistor values changed the sound, and the rectifier swap affected the response, although no doubt the two things overlap in some aspects.
Some players might prefer the 'clean all the way up' version of the sound, others would prefer the way it is now. Depends on a player's application(s) i suppose. I was looking to get a vintage-style response, a little sag but maintaining the lovely warm but sparkly cleans at lower levels and gently evolving into a good bluesy sort of tone that could then be knocked 'over the edge' with an overdrive pedal. I didn't want to push it into full-blown, over-the-top SRV hot-rodded territory because i wanted to keep it versatile and not too orientated towards one specific purpose. Also i wanted it to work well with single-coils and humbuckers, and it seems to be sitting in a place that lets both types of pickups/guitars perform well without compromising how the other type would work.
So basically it's the kind of amp that i would have used as a teenager back in the early '70s. Just a nice core tone with some dynamic response that can easily be boosted with a pedal for rock tones. The tube rectifier has definitely contributed a lot to getting it to that place, it's given the amp a lot more character and life. I'm very happy with the outcome, and consider it well worth the time, effort and money.
glassman
Electron Herder
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Hey Crusty...for future reference, I've used 5V 3A transformers as an add on so the original PT can still be used. The 5V transformer needs to be HiPot tested at at least 1500V to be safe...the ones I sourced were HiPotted at 2500V. They work really well and fit inside most chassis. I've done quite a few of these over the years. Being the kind of guy that won't do something to someone else's amp that I wouldn't do to my own, I added one to my Laney AOR50 some time back and made it switchable. The tube rectifier (5U4) has considerably less filtering than the SS rectifier and the two sound quite different when the volume gets up there. I used a DPDT switch; the other side of it knocks a few volts off the bias to keep the current comparable in either rectifier. Give it a shot next time!
Hey Crusty...for future reference, I've used 5V 3A transformers as an add on so the original PT can still be used. The 5V transformer needs to be HiPot tested at at least 1500V to be safe...the ones I sourced were HiPotted at 2500V. They work really well and fit inside most chassis. I've done quite a few of these over the years. Being the kind of guy that won't do something to someone else's amp that I wouldn't do to my own, I added one to my Laney AOR50 some time back and made it switchable. The tube rectifier (5U4) has considerably less filtering than the SS rectifier and the two sound quite different when the volume gets up there. I used a DPDT switch; the other side of it knocks a few volts off the bias to keep the current comparable in either rectifier. Give it a shot next time!
Lake Placid Blues
New member
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Great work.
Great work.
crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
My first thoughts about changing to a valve rectifier went along the lines of installing a 5V/3A filament transformer but I simply couldn't see where I could physically mount one. I couldn't find one locally and would probably have had to get one from overseas (I'm in Australia). The chasis layout is identical to that of most Fender amps although i think the B+ rectifier diodes/ bias supply parts board is in a different location in the Guyatone, which may explain why I couldn't find any useable chasis real estate for an extra transformer.
However i was always prepared for the extra expense if the original transformer didn't have the 5 Volt winding, and if i couldn't fit a filament transformer in there; the original transformer will not be wasted, it will be used in another build. I might try to get a suitable filament transformer to keep on hand anyway for future projects, and at least then i could use it to see where it might fit before needing to swap a power transformer.
But the end result, for my tastes, has been very worthwhile even having taken the more expensive path. I think i spent a total of about $300 to do all the upgrades i've tried to outline here, including the new power transformer, grill cloth, knobs, components, rectifier tube and socket, etc. Obviously i would have saved a good chunk of that if i'd only needed to buy a filament transformer instead of the full power unit, but either way it has been a very worthwhile upgrade that i would have no hesitation in doing again.
My first thoughts about changing to a valve rectifier went along the lines of installing a 5V/3A filament transformer but I simply couldn't see where I could physically mount one. I couldn't find one locally and would probably have had to get one from overseas (I'm in Australia). The chasis layout is identical to that of most Fender amps although i think the B+ rectifier diodes/ bias supply parts board is in a different location in the Guyatone, which may explain why I couldn't find any useable chasis real estate for an extra transformer.
However i was always prepared for the extra expense if the original transformer didn't have the 5 Volt winding, and if i couldn't fit a filament transformer in there; the original transformer will not be wasted, it will be used in another build. I might try to get a suitable filament transformer to keep on hand anyway for future projects, and at least then i could use it to see where it might fit before needing to swap a power transformer.
But the end result, for my tastes, has been very worthwhile even having taken the more expensive path. I think i spent a total of about $300 to do all the upgrades i've tried to outline here, including the new power transformer, grill cloth, knobs, components, rectifier tube and socket, etc. Obviously i would have saved a good chunk of that if i'd only needed to buy a filament transformer instead of the full power unit, but either way it has been a very worthwhile upgrade that i would have no hesitation in doing again.
crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
I don't know what one of those is, so ... no.
Edit : I just looked them up. The voltage drop doesn't seem big enough for the GZ34 version. But I'm happier with glass anyway, that's what the whole project was about.
Just in the process now of installing the effects loop. I'm very much looking forward to discovering how it works and sounds.
I don't know what one of those is, so ... no.
Edit : I just looked them up. The voltage drop doesn't seem big enough for the GZ34 version. But I'm happier with glass anyway, that's what the whole project was about.
Just in the process now of installing the effects loop. I'm very much looking forward to discovering how it works and sounds.
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Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
That is pretty standard voltage drop for a Z34.
Even the linear drop of sag resistors would be hard to detect.
Then you do not need a 5 volt supply.
I never saw any magic in tube diodes.....but then again I am not playing with your fingers and ears.
Good Luck
That is pretty standard voltage drop for a Z34.
Even the linear drop of sag resistors would be hard to detect.
Then you do not need a 5 volt supply.
I never saw any magic in tube diodes.....but then again I am not playing with your fingers and ears.
Good Luck
jimijames
New member
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
I do have a question - what are your thoughts on a tube rectifier vs. a 'sag' resistor on the front end of the amp?
Having never played (I think) an amp with a tube rectifier I'm curious. From what I've read, it's more of a 'feel' thing - but that being said I've never found any of the tube amps I've played through lacking in feel. I'd like to try one sometime. For some reason, I feel like rectifier tubes are less common but I know there's no way that's the case because so many amps have them.
I do have a question - what are your thoughts on a tube rectifier vs. a 'sag' resistor on the front end of the amp?
Having never played (I think) an amp with a tube rectifier I'm curious. From what I've read, it's more of a 'feel' thing - but that being said I've never found any of the tube amps I've played through lacking in feel. I'd like to try one sometime. For some reason, I feel like rectifier tubes are less common but I know there's no way that's the case because so many amps have them.
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crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
I have used sag resistors both on the entire power line (affecting power and preamp stages) and also just on the power tube feed in various builds. They work to some degree, depending on the resistor values, but i dunno ..... on this project i wanted to turn it into a Fender Pro Reverb and it was an ideal candidate for a tube. I like old amps so there was never any doubt for me on this project ... a glass tube was what i wanted, so that's what i did. Not once have i ever complained about the cost of getting a suitable new power tansformer, i would do it over again exactly the same in a heartbeat, and i am not a wealthy person.
It's kind of like how you can now get s/s preamp tube replacements. No doubt very cool for some people, which is great. But i kinda like going to the source on some projects ... why imitate something when you can use the real thing ? For me, it's not just about the sound, but the old school technology .... if i had my way, pots would still be called rheostats, capacitors would still be called condensers, EQ would still be 'tone controls', and 'gain' would not be a word in the musician's vocabulary. This stuff is my hobby, i like working at this stuff and i love playing guitar with the results. I don't have a partner or family, and after i pay my rent and bills, i put what's left of my money into my gear (albeit with a lot of careful research and planning beforehand, I can't afford costly mistakes).
Plus i guess a lot of the music i love was made with the old stuff.
I too have played, owned and built many valve amps with s/s rectification and they've all been great, but i suppose the tube rectifier just adds more to the responsiveness. What can happen is that such amps can sag nicely with vintage-ouput pickups but get too mushy with high-output pickups. That's not really a problem for me because i don't use high-output pickups. For some people, it could be a problem. Plus i don't slam the front of amps too hard with pedals, I use overdrive rather than distortion and usually the drive is kept pretty low, and the level is boosting the original signal but only just to the point where the amp is giving up more edge and hair, not to the point where it sounds like the amp is about to cough out it's speaker cones and then collapse in a heap.
In this particular project, the original 'Twin' performance of the Guyatone appeared to need a double-headed approach to getting it to be a Pro Reverb ... changing the CBS-era resistor values back to the values of the original Pro Reverb circuit to get the gain structure throughout the amp right, and the rectification. I don't know for certain because i did all the work in one hit, but i suspect that doing either one of those two main changes would have made noticeable improvements for my tastes, but doing both just nailed it.
I dunno, maybe it seems strange to some people, but the old school stuff (parts) are still available and this was one project where i wanted to stay old school (or, given the donor amp ... make it more old school). I'll see how it goes over time ... it's good to know there are alternatives like the Copper Cap and sag resistors i can try if this version somehow disappoints me, but I don't think that's likely. The way it is, I've gone to the source as far as the Pro Reverb circuit (ok, different transformer and component types, but many original parts from the original amps would have been replaced by now anyway).
Besdies, if ya dig tubes, why wouldn't you want to add another one ? hehe.
Lil update ... I've got half of the effects loop built, another couple of hours and i should have it ready for testing.
I have used sag resistors both on the entire power line (affecting power and preamp stages) and also just on the power tube feed in various builds. They work to some degree, depending on the resistor values, but i dunno ..... on this project i wanted to turn it into a Fender Pro Reverb and it was an ideal candidate for a tube. I like old amps so there was never any doubt for me on this project ... a glass tube was what i wanted, so that's what i did. Not once have i ever complained about the cost of getting a suitable new power tansformer, i would do it over again exactly the same in a heartbeat, and i am not a wealthy person.
It's kind of like how you can now get s/s preamp tube replacements. No doubt very cool for some people, which is great. But i kinda like going to the source on some projects ... why imitate something when you can use the real thing ? For me, it's not just about the sound, but the old school technology .... if i had my way, pots would still be called rheostats, capacitors would still be called condensers, EQ would still be 'tone controls', and 'gain' would not be a word in the musician's vocabulary. This stuff is my hobby, i like working at this stuff and i love playing guitar with the results. I don't have a partner or family, and after i pay my rent and bills, i put what's left of my money into my gear (albeit with a lot of careful research and planning beforehand, I can't afford costly mistakes).
Plus i guess a lot of the music i love was made with the old stuff.
I too have played, owned and built many valve amps with s/s rectification and they've all been great, but i suppose the tube rectifier just adds more to the responsiveness. What can happen is that such amps can sag nicely with vintage-ouput pickups but get too mushy with high-output pickups. That's not really a problem for me because i don't use high-output pickups. For some people, it could be a problem. Plus i don't slam the front of amps too hard with pedals, I use overdrive rather than distortion and usually the drive is kept pretty low, and the level is boosting the original signal but only just to the point where the amp is giving up more edge and hair, not to the point where it sounds like the amp is about to cough out it's speaker cones and then collapse in a heap.
In this particular project, the original 'Twin' performance of the Guyatone appeared to need a double-headed approach to getting it to be a Pro Reverb ... changing the CBS-era resistor values back to the values of the original Pro Reverb circuit to get the gain structure throughout the amp right, and the rectification. I don't know for certain because i did all the work in one hit, but i suspect that doing either one of those two main changes would have made noticeable improvements for my tastes, but doing both just nailed it.
I dunno, maybe it seems strange to some people, but the old school stuff (parts) are still available and this was one project where i wanted to stay old school (or, given the donor amp ... make it more old school). I'll see how it goes over time ... it's good to know there are alternatives like the Copper Cap and sag resistors i can try if this version somehow disappoints me, but I don't think that's likely. The way it is, I've gone to the source as far as the Pro Reverb circuit (ok, different transformer and component types, but many original parts from the original amps would have been replaced by now anyway).
Besdies, if ya dig tubes, why wouldn't you want to add another one ? hehe.
Lil update ... I've got half of the effects loop built, another couple of hours and i should have it ready for testing.
Chickenwings
Alnico 6/8
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
tell me about sag resistors crusty. I've not heard of them before but i think i want one.
I found this info:
http://www.justinholton.com/hotrod/sag.html
It all looks really cool in theory, but is it any relevance for the twin?
perhaps this one?
http://au.element14.com/vishay-dale...und-150-ohm-25w/dp/1154967?Ntt=RH025150R0FE02
http://au.element14.com/vishay-dale...w/dp/1369551?Ntt=VISHAY+DALE+-+RH050200R0FE02
i guess i'd need to do something to get the bias back up to compensate too.
wiring diagram
http://www.tone-lizard.com/Mods_and_Odds.htm
any good?
or dis one? .....i emailed weber and they reckon either the WZ34 or WZ68 modules
http://www.webervst.com/ccap.html
this is a pic of an installed one in a different amp:
tell me about sag resistors crusty. I've not heard of them before but i think i want one.
I found this info:
http://www.justinholton.com/hotrod/sag.html
It all looks really cool in theory, but is it any relevance for the twin?
perhaps this one?
http://au.element14.com/vishay-dale...und-150-ohm-25w/dp/1154967?Ntt=RH025150R0FE02
http://au.element14.com/vishay-dale...w/dp/1369551?Ntt=VISHAY+DALE+-+RH050200R0FE02
i guess i'd need to do something to get the bias back up to compensate too.
wiring diagram
http://www.tone-lizard.com/Mods_and_Odds.htm
any good?
or dis one? .....i emailed weber and they reckon either the WZ34 or WZ68 modules
http://www.webervst.com/ccap.html
this is a pic of an installed one in a different amp:
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kramersteen
PowerMetalRaph
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Great work mate. All the pics remind me of growing up with my brother. He was/is right into audio engineering.
Great work mate. All the pics remind me of growing up with my brother. He was/is right into audio engineering.
Little Jay
New member
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Hi there. Great project! I own and play two Guyatones, an old GA-1100 (100% AB763 Twin Reverb specs!) and a somewhat newer GA-1100D (I 'Blackfaced' that to almost AB763). They are great amps, perfect alternatives for a Twin Reverb. I love those big clean tones for my playing, but I am wanting a Pro Reverb as well (the GAS you know...), preferebly Blackface, but man, those prices..... So I have actually been thinking of converting a GA-1050 to Pro Reverb specs quite some time now. And now I just happen to stumble upon your post... can't be a coincidence....gotta find me that GA1050 and use your post as a guideline! You obviously know your way around in amps, I'm less experienced, so your topic is just what I need.
By the way, there is a nice Guyatone Vintage Amp Group on facebook to check out if you like. I will put a link to this topic there, I'm sure they will love it.
Hi there. Great project! I own and play two Guyatones, an old GA-1100 (100% AB763 Twin Reverb specs!) and a somewhat newer GA-1100D (I 'Blackfaced' that to almost AB763). They are great amps, perfect alternatives for a Twin Reverb. I love those big clean tones for my playing, but I am wanting a Pro Reverb as well (the GAS you know...), preferebly Blackface, but man, those prices..... So I have actually been thinking of converting a GA-1050 to Pro Reverb specs quite some time now. And now I just happen to stumble upon your post... can't be a coincidence....gotta find me that GA1050 and use your post as a guideline! You obviously know your way around in amps, I'm less experienced, so your topic is just what I need.
By the way, there is a nice Guyatone Vintage Amp Group on facebook to check out if you like. I will put a link to this topic there, I'm sure they will love it.
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
OMG!! What a great job. Beautiful finished product. The cream tolex couldn't have been a better choice. Looks amazing. From what you describe it seems like it would sound as good as it looks as well.
We all thank you for such a great post.
Now if I could only convince you to move to California.....
OMG!! What a great job. Beautiful finished product. The cream tolex couldn't have been a better choice. Looks amazing. From what you describe it seems like it would sound as good as it looks as well.
We all thank you for such a great post.
Now if I could only convince you to move to California.....
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
post #1
Monday, January 05, 2015 20:38 EST
Happy New Year, folks.
I'm trying to repair a Guyatone GA-1050 Reverb Jazz and, with a little help from members here, might succeed.
The regular channel works, Tremolo works, but Reverb does not work. All the tubes glow and look okay.
I removed the reverb tank to have a look. I discovered that it's missing one of its two springs, and also that one of the four magnets has broken free from its mooring. So, I thought I might start with replacing the reverb tank.
The reverb tank is an Accutronics 4BB1D1B. This code means:
4 - Long (16¾") 2 spring unit
B - input impedance = 150 Ohms
B - output impedance = 2,250 Ohms
1 - decay time = Short (1.2 to 2.0 sec.)
D - connectors = Input and Output Insulated
1 - locking devices = No Lock
B - mounting plane = Horizontal, Open Side Down
(source: http://home.comcast.net/~machrone/bjr/reverbcodes.htm)
My first question is:
Is the above-described reverb tank what was originally installed on the Guyatone GA-1050?
post #1
Monday, January 05, 2015 20:38 EST
Happy New Year, folks.
I'm trying to repair a Guyatone GA-1050 Reverb Jazz and, with a little help from members here, might succeed.
The regular channel works, Tremolo works, but Reverb does not work. All the tubes glow and look okay.
I removed the reverb tank to have a look. I discovered that it's missing one of its two springs, and also that one of the four magnets has broken free from its mooring. So, I thought I might start with replacing the reverb tank.
The reverb tank is an Accutronics 4BB1D1B. This code means:
4 - Long (16¾") 2 spring unit
B - input impedance = 150 Ohms
B - output impedance = 2,250 Ohms
1 - decay time = Short (1.2 to 2.0 sec.)
D - connectors = Input and Output Insulated
1 - locking devices = No Lock
B - mounting plane = Horizontal, Open Side Down
(source: http://home.comcast.net/~machrone/bjr/reverbcodes.htm)
My first question is:
Is the above-described reverb tank what was originally installed on the Guyatone GA-1050?
crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
The Guyatone reverb circuitry is almost exactly the same as the Fender version, The best spring to use would be the 4AB3C1B.
I'm not sure what Guyatone originally used, but the one i mention is the standard two-spring version usually used in most Fender amps. When i did this re-vamp, i did try a three-spring version (9AB3C1B) but it was a little 'too much' for general use.
An important difference is that the Fender circuit has a 1 Meg resistor to ground at the input to the reverb driver valve (12AT7), the Guyatone uses a 470K. Change it to 1 Meg to get closer to the true Fender circuit.
Do you have a schematic for the Guyatone ?
The Guyatone reverb circuitry is almost exactly the same as the Fender version, The best spring to use would be the 4AB3C1B.
I'm not sure what Guyatone originally used, but the one i mention is the standard two-spring version usually used in most Fender amps. When i did this re-vamp, i did try a three-spring version (9AB3C1B) but it was a little 'too much' for general use.
An important difference is that the Fender circuit has a 1 Meg resistor to ground at the input to the reverb driver valve (12AT7), the Guyatone uses a 470K. Change it to 1 Meg to get closer to the true Fender circuit.
Do you have a schematic for the Guyatone ?
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Mon. 15/01/05 21:42 EST
.post #2
Although the two rear panels (and hence, I assume, the supplied schematic) are missing, I found this :
http://gribskovcomputer.dk/wp-content/uploads/2013/07/GA-1050.jpg
Could I install the 4AB3C1B (whose input impedance is considerably lower than the 4BB3C1B) and keep the existing 470K resistor, without risk of harming the rest of the circuit?
I ask this because my goal is not necessarily to bring the amp closer to a Fender Pro Reverb. My goal (at least, initially) is to restore full functionality, even if that is merely original functionality. If I can do that, I'll then consider changing the specs.
Mon. 15/01/05 21:42 EST
.post #2
Although the two rear panels (and hence, I assume, the supplied schematic) are missing, I found this :
http://gribskovcomputer.dk/wp-content/uploads/2013/07/GA-1050.jpg
Could I install the 4AB3C1B (whose input impedance is considerably lower than the 4BB3C1B) and keep the existing 470K resistor, without risk of harming the rest of the circuit?
I ask this because my goal is not necessarily to bring the amp closer to a Fender Pro Reverb. My goal (at least, initially) is to restore full functionality, even if that is merely original functionality. If I can do that, I'll then consider changing the specs.
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crusty philtrum
Vintageologist
Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Ok, that's the same schematic i have here (the amps usually had a paper copy in the back somewhere, sometimes in the reverb spring bag). Gotta love the 'Tremoro Pedal' at V9, hehe.
Indeed you could start by just replacing the spring without changing any resistors. The resistor changes (there are two) are about gain levels, the circuit will work fine as it is, and provide more reverb if you swap the resistor i mentioned). There is another resistor on the output of the reverb recovery/ input of recovery tube that will affect the gain of the whole amp, and improve the sound. The way the reverb circuit is stock, you'll get the same sound but the reverb level will be set higher than it would be with the true Fender component values.
There is a quick, rough-and ready way to test the reverb circuit. You could take the output that normally feeds the spring's input, and connect it to a very small speaker instead (or even a litttle practice amp), turn up the reverb knob and play. If the reverb drive circuitry is working, you should hear guitar in the little speaker. You can also connect the headphone output of a small battery-powered radio or iPod-type device to the amp's reverb return input, turn the reverb level knob up, and hear the radio coming through the amp if the return/ recovery stage is working properly.
Ok, that's the same schematic i have here (the amps usually had a paper copy in the back somewhere, sometimes in the reverb spring bag). Gotta love the 'Tremoro Pedal' at V9, hehe.
Indeed you could start by just replacing the spring without changing any resistors. The resistor changes (there are two) are about gain levels, the circuit will work fine as it is, and provide more reverb if you swap the resistor i mentioned). There is another resistor on the output of the reverb recovery/ input of recovery tube that will affect the gain of the whole amp, and improve the sound. The way the reverb circuit is stock, you'll get the same sound but the reverb level will be set higher than it would be with the true Fender component values.
There is a quick, rough-and ready way to test the reverb circuit. You could take the output that normally feeds the spring's input, and connect it to a very small speaker instead (or even a litttle practice amp), turn up the reverb knob and play. If the reverb drive circuitry is working, you should hear guitar in the little speaker. You can also connect the headphone output of a small battery-powered radio or iPod-type device to the amp's reverb return input, turn the reverb level knob up, and hear the radio coming through the amp if the return/ recovery stage is working properly.
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Re: Adding A Tube Rectifier To A Guyatone S/F Fender Clone (and other upgrades)
Mon. 15/01/05 23:24 EST
.post #3
Found this:
Am I correct in assuming that the reverb tank will still work with one spring removed? Regardless, if I want full reverb, I must replace this defective reverb tank. I'm still not sure which tank to install: 4AB3C1B or 4BB3C1B. I'm still curious to know with which tank the GA-1050 was originally equipped.
Time to sleep now, but I will return to this thread. Thank you for the prompt and informative responses.
Mon. 15/01/05 23:24 EST
.post #3
Found this:
Am I correct in assuming that the reverb tank will still work with one spring removed? Regardless, if I want full reverb, I must replace this defective reverb tank. I'm still not sure which tank to install: 4AB3C1B or 4BB3C1B. I'm still curious to know with which tank the GA-1050 was originally equipped.
Time to sleep now, but I will return to this thread. Thank you for the prompt and informative responses.
