first amp build 6g3

Hi guys burninwordz I've decided to build a 6g3 amp using a filmosound amp . well I'm no expert in amp building I could use your knowledge. i've built a couple of pedals; foxxtone,fenderblender,bazz fuzz,axis silicon and modded my wah-wah. so i have general electronic skills, but this amp thing is a whole new world for me i'm kinda lost and I need your guidence Through this build. I love the idea of building my own guitar gear so now its time for the amp. first question Could i use the trannies from the filmo for this build? i have chassis so thats no problem here's some pixs of the filmosound thanks your advice will be appreciated :confused:

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What tubes has it got ?

I have built a bunch of amps from that chassis particularly the 6v6 powered ones, this one has EL 84 power tubes and a 5879 or a Ef86. I would suggest building a Spitfire\AC15 type ,using the el84 tubes.The transformers are great for that setup.It isn't easy though, that is a really small chassisto work in, and you really have to gut the whole thing.

http://www.turretboards.com/layouts_schematics/kits/msf.pdf Here's a good layout to try.

hi BOBBY-Z the tubes it have are 6a75, 6ca4,62q5,65q5,6267,and two 12ax7 i don't know there function ,the only ones i reconize are the two 12ax7 thanks. any suggestions welcome!!

hi G-LOG thanks for the suggestion just checked out the SpitFire/AC15 layout not a bad idea for a build ,i happend to have another filmo amp around .my plans were to swap the original chassis and build a new one as i had read in your thread that you built a 6g3 lite, but it wasn't clear if you used the stock trannies for the build . thanks ,any suggestions welcomed !!

Yep, I used the stock trannies for it.The 6267 is like a EF86 and are you sure those tubes don't say 6bq5? That is an el84 variant.

Hi G-log I found the schematic for this filmosound amp model 8399 and yes you are right some model use 6bq5,el84,65q5 it all depends were they where built. Some models were built in canada,british and japan and thanks for the info on the tubes and the trannies. now it's time to start collecting parts for my build.As allways suggestions welcome !!! my model uses 65q5

Hi G-log I found the schematic for this filmosound amp model 8399 and yes you are right some model use 6bq5,el84,65q5 it all depends were they where built. Some models were built in canada,british and japan and thanks for the info on the tubes and the trannies. now it's time to start collecting parts for my build.As allways suggestions welcome !!! my model uses 65q5

Might be a smudged schematic or something, 65Q5 does not sound like a numbering found on a common tube. Maybe the 5 was actually a B.

That's what I was thinking.I don't think a 65q5 exists.

hi G-log and printer2 I took a look at the numbers on the top of the filmo amp and it's hard to distinguished the b or 5 so I googled up the schematic and yes it's a 6bq5 and i took a good look at the tube which i didn't do at the moment and to my surprise it;s a 6bq5 (felt so dumb)ha ha:oops: .thanks for clearing that out for me it's all a learning process which i'm willing to learn thanks again as allways suggestion welcomed:lol:

HI today i'll cut out the chassis using a piece of galvalum i purchased, does galvalum work well for this type of build?due to high voltage. as allways suggestions welcomed!!!

I know this is a diversion
So you have ef86, 2 12ax7, 2 el84s, and rectifier?
That sounds like a good candidate for a ceriatone creme brulée!!!

Hi andyfromdenver a ceriatone creme brulée ? sounds deliciuos but what is it?

Hi guys just finished building the chassis for the 6g3 ,I made out of galvalum hard to bend but got the job done. here are some pix of the process, just needs a paint job and it's ready.thanks as allways suggestions welcomed!!!
gotta change the date on my camera!!!!:mad:
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the chassis dimensions are 18x6x2 1/2 THANKS:grin:
don't pay no mind to tha dates, camera is traveling in time:lol:
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Hi andyfromdenver a ceriatone creme brulée ? sounds deliciuos but what is it?
I've never heard one, but it looks cool.
Sorry for the interruption, I thought you were recycling that chassis, I see you're getting super handy and building from scratch. Awesome!!!!!!

Looks an awful lot like an ac15

Yeah Andyfromdenver trying save on my first build I think a chassis that size are about $35 to $45 dollars with out the shipping to puerto rico, so I built it , I bought a 5feet galvalum beam for $15 and I have enough for my next build,I got the filmo amp for $20 and as always staying true to the DIY religion and save as much as we can !!!! awesome schematic and it does look like AC15 REvv23 thanks for dropping by as allways sugguestions Welcomed

hi guys I need a capacitor kit for my 6g3 build any recommendations from good vendor?

http://www.hoffmanamps.com/

the chassis dimensions are 18x6x2 1/2 THANKS:grin:
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Man, that must have made a racket!! Great job on that chassis. I envy the space, the tools, and the FUN!! :grin:

Man, that must have made a racket!! Great job on that chassis. I envy the space, the tools, and the FUN!!
Hi charisjapan It's the old banging and shaping to get things done!!!thanks

Hi guys thanks for viewing my build, been busy working here's 'some pics of the 6g3 ,thats me trying to learn how to use my clausing mill machine, I put the trannies,tube sockets, two pots ,just to get the feeling of the build. thanks will be posting soon with more updates !!!! :grin:
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It has a cool "distressed" look! Guitar makers charge big $ for that... I see a business model :)

HI guys i'm a bit confused here, on the 6g3 schematic the voltage going to the 6v6gt reads 365v but the filmosound tranny says 240 v does this mean that i'll have to change the pt for this build ,G-LOG used the filmo trannys for his build but with some mods will i have to do the same , HELP NEEDED !!!!!! thanks

Using a solid state bridge rectifier you will get 335Vdc (240V X 1.4 = 336V) minus losses in the circuit, maybe 320-325V. The Tweed Vibrolux and Harvard ran in this range, you are a little low to be 100% correct but not enough to worry about. You might put out 12W rather than 14W.

Hope you do not mind my asking, but I am a little confused. Are you using 6V6's or 6bq5's?

the two amps use different rectifiers. Even if the transformers were identical the rectified DC voltages might not be the same.

The big problem you have is that a 6g3 uses a 5 volt rectifier tube - a 5ar4 (aka GZ34.)

It is hard to tell from the pictures, but judging from the tube complement it looks like your power transformer does not have a 5 volt filament tap.

In which case you will have to deviate from the actual 6g3 schematic. You can stay with the 6ca4 rectifier, or maybe switch to solid state rectification. I'd try the tube rectifier first.

It looks like you have what Keyser says. It its an oddball model, for sure. I did notice that you do have 6Aq5 tubes in there. I didn't know there was a model using those tubes.Bell & Howell made so many different ones.There are a ton of schematics in this file to help you out .
http://www.film-tech.com/warehouse/manuals/AMPS.pdf

6AQ5's or 6BQ5's? Is it a 7-pin tube or a 9-pin, hard to tell by the pictures. A tube rectifier is doable but it would use up more precious volts. Would make sense with the transformer voltage and them being 6AQ5's. Then the question is what output tube do you want to run? Get new sockets or use what you have? May not end up 100% 6G3 but depends how close you want to get.

hi guys I'll start by answering PRINTER2 question:I wasn't sure if the original tubes work,when I plug the filmo some smoke started to come out of one the resistors next to the filters ,and the 6CA4 looks burned out.so I decided to use new ones ,avoiding future headaches, and the 6bq5''s are 9 pins I ordered new sockets for 6v6's and kept the 12ax7 sockets and build it as close to the 6g3, here's a pics of the 8399 model transformer schematic.

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Do I need to build a bridge rectifier or am i good with to go ahead ?

Another question: Using a bridge rectifier does it change the sound ?or it does not affect it at all ,thanks guys for the help well appreciated ,another question:How can i tell if my transformer has a 5 volt filament tap ? remember all this tube building is new to me and i'm building it from scratch not having any instructions on how to build it and i'm following all your feedback,thanks, as allways comments welcomed!!!

No you do not need a bridge rectifier. When you gave the transformer voltage I thought you were measuring across the secondary terminals and not from one to the center tap. You can go with a tube rectifier or a couple of SS diodes if you want.

The schematic above shows a 110V tap on the primary, do you have one? If you hook up 120V to this your secondary voltage will be about 10% higher. The heater windings will also be 10% higher but you could put a couple of resistors on either side of the winding to knock it down.

Was the 240V you mentioned written on the transformer or did you measure it? If you could measure the voltage on the transformer with no load and then measure the resistance of the secondary we could throw the numbers in Duncan's PSU Designer (a power supply simulator) and tell you what you will get for different options.

THANKS PRINTER2 that's the exact schematic for my filmo model,I've been reading filmosound mods in different site's and not having no info about the amp,after reading a mod were that person 's concern was his tranny voltage was 240v's .I'm assuming that all of the filmo amps run on the same voltage so I was worried if it was o k to build it with that voltage level and after you guy's started feeding me with info I went looking to find out the voltage level in the schematic and was relieved to realize there won't be a problem for now with the voltage thank you guys push us noob's to learn and do our homework so we could get it right!!!!!:grin:

Cool project, good luck.

Thanks telex76, that's appreciated :grin: :grin:

Just got this in the mail :grin: ordered from AES,and I grab my chassis and started putting parts on it, (ouch something just fell in my eye) seriously guys allways wear protective sunglasses when drilling or cutting any type of material (it a bugger)so here are some more pics of the 6g3 with finally new parts!!!!!:grin: thanks as always comments welcomed.

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Hi guys a tech question about capacitors. In the 6g3 schematic it reads .01UF@ 400v ,can i use a .01uf@630v, Does this in any way affect the amp thanks .????

Nope!

That "nope" means that it won't affect the amp. When you go higher in voltage than the specs its alright as it just adds a safety factor. You normally don't want to go lower in voltage value unless you know for sure that the cap used was only used due to ease of availability and not due to the voltages present (like in a guitar's tone control).

Capacitors are rated in terms of their capacitance (amount of charge they can hold) and the maximum voltage they can safely withstand. You should always use a capacitor that can handle the peak voltage it might see (peak voltages, such as at start up are often substantially higher than operating voltages.)

So, for any given application going with a higher than specified voltage rating in never a functional problem. It might be an added expense, or physically larger than the original item, but sometimes a higher rated part might even be cheaper (due to wide availability/economy of scale issues.)

'Mallory' 150s are often cheaper in the 630V rating.

About the only exception to this rule is electrolytic cathode bypass caps, in that instance it is best to find caps with a voltage rating as close to (but not below) the anticipated bias voltage.

Thanks guys another tech question ,Is there any difference between .02uf and .022uf ? ,I've been shopping for parts and the majority of companys don't seem to have .02uf but .022 and they don't specify if there's any difference between the two thanks. andif it changes the quality of the sound. I know that these might be silly questions, But I rather ask so I could build the amp the right way thanks :grin:

Yes theres a difference, but it wont matter very much. Imo. Depends where you are using it as well. As well as looking at cap specs different types have slightly different effects on sound as well. Ill let someone more knowledgeable than me explain my answer. Sorry i cant be much help!

Sent from my iPhone using TDPRI

Thanks guys another tech question ,Is there any difference between .02uf and .022uf ?
No.
As you'll find most of us just get as close as we can to the original schem specs. (unless you're doing intentional mods

Every electronic component has a tolerance rating as provided by the manufacturer. So the actual value of the specific part in your solder flecked hands may vary from the stated value by plus or minus that amount.

Back in the day pretty much everything used to build a Fender amp was +/- 20%. So while the schematic says 0.2 uf the ones actually in the amps might be anywhere from 0.016 to 0.24 uf.

In which case your 0.022 uf cap is just fine (being more modern construction it probably has either a 10% or 5% tolerance rating.) But, if having built the amp you find the tone not to your liking, you certainly can adjust that value to suit your tastes.

Hi guys here's an update did the head cab using 1/2 inch plywood,it's not great if your gonna box joint it ,splinters all over the place,wasn't to proud of it but manage to save it ,here's some pics.

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Here's some more pics with the 6g3 head

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Hi guys thanks for answering my tech questions[keyser Soze ,andyfromdenver,Revv23and all the good guys from the shock bro forum, yesterday caps and resistors came in from tubesandmore and newoldsound these guys are very diligent in there service . here's some more pics with the board and caps. Will keep you's updated:grin:

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Burnin, call me crazy, but I kinda wish you'd slap a handle, knobs, and logo on it as is and call it done. It looks really cool to me! One of my favorite restaurants here in Athens, The Grit has old sandblasted walls that reveal years of paint coats in weird patterns and layers, I kind of want to make combo cabs like that! I don't think anyone has done that yet.

*edit* oh yeah, and you can tell from my build threads, I like old label maker info too. DIY class.

Burnin, call me crazy, but I kinda wish you'd slap a handle, knobs, and logo on it as is and call it done. It looks really cool to me! One of my favorite restaurants here in Athens, The Grit has old sandblasted walls that reveal years of paint coats in weird patterns and layers, I kind of want to make combo cabs like that! I don't think anyone has done that yet.

*edit* oh yeah, and you can tell from my build threads, I like old label maker info too. DIY class.

+1

Sent from my iPhone using TDPRI

Burnin, call me crazy, but I kinda wish you'd slap a handle, knobs, and logo on it as is and call it done. It looks really cool to me! One of my favorite restaurants here in Athens, The Grit has old sandblasted walls that reveal years of paint coats in weird patterns and layers, I kind of want to make combo cabs like that! I don't think anyone has done that yet.

*edit* oh yeah, and you can tell from my build threads, I like old label maker info too. DIY class.

I really loved the amp my self and wanted to keep it the way it was but my wife wasn't to into it ,so to please her i'll be painting it candy apple red with white stripes ,but on my next build i'll be giving it that "distress look"thanks for suggestions, here's some more pics :grin:
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I really loved the amp my self and wanted to keep it the way it was but my wife wasn't to into it ,so to please her i'll be painting it candy apple red with white stripes...

Candy Cane! Thumbs up!!

I can understand the "distressed/cast-off/relic-ed" look, but my OCD side wouldn't allow it. I even have a 15 year-old cab I picked up at an auction for next to nothing, which only has about 3 little tears in the tolex, and I can't wait to re-cover it. Strangely enough, I have absolutely no problem with blemishes that I caused accidentally. Go figure, Freud... :neutral:

Tip of the day... Make wife happy! :grin:

charisjapan

I really loved the amp my self and wanted to keep it the way it was but my wife wasn't to into it ,so to please her i'll be painting it candy apple red with white stripes ,but on my next build i'll be giving it that "distress look"thanks for suggestions, here's some more pics :grin:



Lol "distressed" thank you, it took me about fifteen words to get there :). Exactly!
Red and white strips sounds pretty friggin cool too! Can't wait.

Hi guys here's an update soldered some caps, resistors and cables. everythings running smooth ,here's a pic of the board and of the layout .In the layout photo there's two Y's and two X's ,I was looking at the shematic and they connect. Y cap .01uf connects to resistors Y 100K and 15k and X 100k and15k resistors connects to X 220k,.003uf cap, Am i going the right way ? if there's anything wrong just let me know thanks . .136034

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I'm not completely clear on what you're describing as to those X's and Y's connecting together. If you print out the schematic (not just the layout) I believe that there will be an X and Y tap from the power supply caps (doghouse under the chassis) that is where those X and Y taps/wires originate from. Its how you get your voltage from the power transformer/rectifier to your preamp tubes.

Maybe that's what you were trying to describe, but it sounded to me like you may be trying to connect a wire between the two X's and the two Y's in the layout on your board.

I think he's just saying the 2 X's connect on back of the board, and the 2 Y's connect on back of the board.
As far as I know, that's correct.

Thanks guys, your both right here's the schematic of the 6g3

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Hi guys busy working ,here's some pics update:

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More pics:

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Here's some more pics,those caps are f&t made in germany ,another tech question ,should I solder a bus line wire across the pots for the ground? or it's just fine.thanks for all the help :grin:

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Grounding is skin-the-cat (meaning there are any number of methods that might work.) The proof of any approach is when the amp functions properly and hum is at or below an acceptable level.

You can try the bus bar approach, or you can use separate wires and pull all those grounds together at one star point attached to the chassis.

Or you can mix the two - localized grounds eventually tied together at one star, etc.

Here are three of the best discussions on the topic.

http://www.geofex.com/Article_Folders/stargnd/stargnd.htm
http://www.aikenamps.com/StarGround.html
http://www.freewebs.com/valvewizard2/Grounding.html

The Valve Wizard one is probably the most detailed, and from a theoretical standpoint I think the best, but also the most technically challenging when it comes to putting the knowledge to practical use. Start with the one from Aiken, he includes a good discussion of the buss approach, and go from there.

Looking good. I'm building this circuit myself.
Good to have some of my questions answered on your thread.

Thanks keyser I'l be reading that info and telex76 glad to be of any help in your 6g3 build ,HERE I GO AGAIN!!!!another tech question; Do i connect the heater wires starting from the Gz34 socket or the 6v6gt socket ,the thing is that my build layout is quite different from the original layout my pilot is on my far rightside and on the original layout it's on the far left side ,so im thinking that i'll need to connect the 6.3v cables to one of these's to sockets and work my way up to the pilot light,from left to right gz34 to 6v6gt to 6v6gt to 12ax7 to 12ax7 to the 7025 socket to pilot light is this the right way to go:?: .thanks for all the help very appreciated,:wink: the heater wires do they go on the 7 and 2 pins?, my layout doesn't have them, thanks again :grin:

Wait unitl someone else smarter than me replies, but iirc is that heaters dont go on the rectifier, and on preamp tubes they should be negative on 5&4, and positive on 9. And on power tubes they go on 2 neg 7 pos... No heater for the rectifier.

The rectifier should have separate heaters.
Pins 2 & 7 on 6v6s and 4+5 (together) & 9 on 12ax7s. So I'm confused, the pilot light is over by input jacks? Interesting. Can't confidently comment on hitting them last in heater chain, but don't see why not. You're going to have your heaters very near your vulnerable input jacks if that's the case. Maybe a no-no, but the proof will be in operation :)
Hope you have shortest possible path from input jacks to first preamp tube.

*disclaimer: I'm no expert*

No problem hitting the pilot light last in the chain, but noise could be picked up by the inputs if the pilot light (heater wires, really) is in close proximity.

As Andy suggested, just have to wait and see.

Thanks for the input guys,so it's o.k that the pilot light is last on the chain, I guess I wasn't clear on were the pilot light will be so I'll post a pic. so now I'm confused .the heater wires on the power tubes don't connect with the heater wires that connect to the preamp pins?:confused:

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that ugly hole next to the speed and intensity pot is for the pilot light ,thanks

Yes the heaters connect to the preamp tubes, the power tubes and the pilot light.

The heater wires, generally, do not connect to the rectifier tube.

Typically, the rectifier tube has its own 5V heater. Usually the two yellow wires from a separate PT winding are for the rectifier tube heater.

Yes the heaters connect to the preamp tubes, the power tubes and the pilot light.

The heater wires, generally, do not connect to the rectifier tube.

Typically, the rectifier tube has its own 5V heater. Usually the two yellow wires from a separate PT winding are for the rectifier tube heater.

Thanks hackworth for clearing that out for me and thanks to the guys on the forum ,wil be posting soon:lol:

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that ugly hole next to the speed and intensity pot is for the pilot light ,thanks

ok, cool. Not ugly! This'll be interesting :) Good luck with rest of build, you're pretty close!

Ok now I'm confused.

Your original amp had a 6ca4 rectifier. Does your power transformer even have a 5 volt tap? If so, then that is what you attach to the heaters of a GZ34. If you don't have a 5 volt tap then you need to rethink that GZ34, and based on the schematic snippets posted I don't think you have a 5v tap, just two 6.3 volts.

In which case you are back to a 6ca4 (aka ez81) or solid state rectification. You could also try a copper cap type insert for the octal socket you already have. They are solid state designed to mimic the performance of a tube rectifier (but require no heater current.)

Everything else is powered by the 6.3 volt heater wires with the indicated hum balance pot. Since all of those are being wired in parallel you do not necessarily need to chain them all together. You could feed the lamp from it's own pair of wires, so long as it all stays in parallel everything is good.

Heater wires are AC and high current, so can be a major source of noise in an amplifier. routing them in a way that keeps them as far as possible from signal wires (anything coming from a plate, or going to a grid) is always good.

[QUOTE=Keyser Soze;4351943]Ok now I'm confused.

Your original amp had a 6ca4 rectifier. Does your power transformer even have a 5 volt tap? If so, then that is what you attach to the heaters of a GZ34. If you don't have a 5 volt tap then you need to rethink that GZ34, and based on the schematic snippets posted I don't think you have a 5v tap, just two 6.3 volts.

In which case you are back to a 6ca4 (aka ez81) or solid state rectification. You could also try a copper cap type insert for the octal socket you already have. They are solid state designed to mimic the performance of a tube rectifier (but require no heater current.)

O.K now I'm confused,:mrgreen: the filmosound schematic doesn't indicate the 5volt tap so I'll measure the volts on the tranny and get back to on this matter .I also look up the copper cap type insert you suggested and if it's needed i'll go that route ,weber has then for $22 not bad and tubesandmore for$15,I think that the difference between then is that webers look like a tube and tubesandmore are the yellowjacket type so thats not bad, thanks for the help keyser. I also read G-LOGS 6g3 build using a filmosound amp but not sure if he did that convertion. to all the noobs BBUUUYYYYY A KIT !!!!!! it's much easier and less headaches the build from scratch leave it to the pros :lol:

The tubesandmore SS plug in rectifier is fine. But if you have an extra 6.3V tap, use it for the heater on your rectifier tube socket. Buy an EZ81 (aka 6ca4) and the SS Rectifier. As Keyser said, the SS Rectifier will not use the heater, but it will be there in case you want tube rectification. If you can get both the tube and the SS plug in rectifier, I would do that.

All the Filmosound conversions I have done used a 5Y3 rectifier so I had no issues with this. You should stick with a layout that used an EZ81/6CA4

The tubesandmore SS plug in rectifier is fine. But if you have an extra 6.3V tap, use it for the heater on your rectifier tube socket. Buy an EZ81 (aka 6ca4) and the SS Rectifier. As Keyser said, the SS Rectifier will not use the heater, but it will be there in case you want tube rectification. If you can get both the tube and the SS plug in rectifier, I would do that.

Hackworth: Would I have to change the whole build with this conversion if I buy both EZ81 and the ss plug in rectifier, do to the fact it's almost finished? Isn't it easier to just buy a new pt? even though I have the (6ca4)tube socket and also the gz34 tube socket, and the filmo tranny, so what needs to be changed:confused:I could get the ez81 locally thats no problem. Do i scratch this build and start all over again? that would be pure madness? wouldn't it. thanks hackworth I appreciate all the help I can get and for taking out of your time to help me.
G-LOG thanks you did advice me to stick with a EZ81/6CA4 layout but now I have to finish it so WHAT THE HELL AM I BUILDING HERE!!!!!!!!:grin:

I would go for the 6CA4 and be done with it.

I concur with printer. Buy the local EZ81.

I would go for the 6CA4 and be done with it.

O.K PRINTER and HACKWORTH lets say I do the swap and use the ez81(6ca4)TUBE what changes do I need to do? And isn't it no longer a 6g3 and then what would it be ? and whats the difference between both tubes? Do I connect the EZ81 according to the filmosound layout or the 6g3 layout?Does this change the amp sound? Will it be a british sound or fender? I know I'll have to change the tube socket so that alone is something I"ll have to think about , Can I connect both SS cap rectifier and EZ81 and just switch them with a pushbotton or is there a tube adapter that goes on top of the gz34 socket and convert it to a EZ81 . I know a lot of questions but if you don't ask you don't learn. thanks

Rectifier Tube:
Converts HT AC voltage from your transformer to HT DC voltage that your amp can use. A tube rectifier has a filament - it needs a heater voltage to function (usually low voltage with relatively high amperage). Your transformer we hope is good.

Transformers are expensive. So it is a good idea with your project to use the power transformer (PT) you have if it is functional. If you have to revise your rectifier connections, this is not a major deal.

It has been surmised that your PT is not fitted with the typical 5 volt winding for typical rectifiers such as the 5Y3 or GZ34 for example. BUT you do have an extra 6.3v winding that should be used with an EZ81.

As I said, a rectifier tube converts AC current to DC current. As it does this, it typically increases the current by a considerable measure.

The rectifier you use will have little bearing on the performance of your amp.

It is now a matter of studying the pin out on the EZ81 and making the appropriate connections.

Of course the Tube Socket is a smaller 9 pin b/c the EZ81 is a noval tube. Here is a diagram which shows the pin out

http://www.ceriatone.com/images/layoutPic/marshallLayout/18wattTMBceriatone.jpg

Here's one without the back up protection diodes which may add confusion.
http://www.trinityamps.com/ForumGallery/trinity/Doc_Files/Trinity_TMB_layout_21Dec.jpg

Sorry, I have not really been following the discussion all that closely, the pictures are just too darn engaging, also I have been working on my builds. Now that I looked back and am sort of back up to speed I may have another option.

Seeing that you already have the hole drilled for an 8 pin socket the only real problem is that the transformer has a 6.3V winding for the rectifier tube rather than a 5V winding. So we have to loose 1.3V. You know what I do when I want to loose some voltage? I stick in a resistor.

The GZ34 uses 1.9A for the heater. Good old Ohms Law says 1.3V / 1.9A = 0.68 ohms. Not too common. How about if we parallel a 1.0 ohm resistors with a 2.0 ohm? That will give us 0.67 ohms, sounds perfect. Maybe a 5W for the 1 ohm and 2W for the 2 ohm.

So what do you think?

If you want to be able to switch to SS diodes, check out the Prosonic.

http://ampwares.com/schematics/prosonic.pdf

Sorry, I have not really been following the discussion all that closely, the pictures are just too darn engaging, also I have been working on my builds. Now that I looked back and am sort of back up to speed I may have another option.

Seeing that you already have the hole drilled for an 8 pin socket the only real problem is that the transformer has a 6.3V winding for the rectifier tube rather than a 5V winding. So we have to loose 1.3V. You know what I do when I want to loose some voltage? I stick in a resistor.

The GZ34 uses 1.9A for the heater. Good old Ohms Law says 1.3V / 1.9A = 0.68 ohms. Not too common. How about if we parallel a 1.0 ohm resistors with a 2.0 ohm? That will give us 0.67 ohms, sounds perfect. Maybe a 5W for the 1 ohm and 2W for the 2 ohm.

So what do you think?

Nothing wrong with that approach, but since this is AC you might want to half those values and apply it to both sides of the heater to maintain better balance and reduce the possibility of excessive noise. 0.33 ohm 5 watt Xicons are dirt cheap and close enough.

So what do I think? qoute PRINTER , not a bad idea it's an easier way and cheaper ,all I have to do now is solder like Keyser sugguested a .33ohm 5w resister to the 6.3 heater wire and another .33 ohm 5w to the other wire and problem solved or Do I need to get 4 resistors 2 connected in parallel to each 6.3 heater wire? the good thing about all this is that I have options and thats good. I could put the resistors or a copper cap type insert which is not bad either and not have to drill another hole in the chassis for the 6ca4 tube rectifier and I wasn't sure if I'd have to make changes in the 6g3, like resistors or caps. so thanks to all and I'll get back to you's on this matter.

Nothing wrong with that approach, but since this is AC you might want to half those values and apply it to both sides of the heater to maintain better balance and reduce the possibility of excessive noise. 0.33 ohm 5 watt Xicons are dirt cheap and close enough.

I am assuming the transformer winding will only be used for the rectifier. And if that is so the minimal unbalance in the rectifier heater will be of no consequence. After all, the rectifier is putting out hundreds of volts of AC, a volt or two from the heaters will will not add to the noise. Mind you a couple of 0.33's would do just fine.

So what do I think? qoute PRINTER , not a bad idea it's an easier way and cheaper ,all I have to do now is solder like Keyser sugguested a .33ohm 5w resister to the 6.3 heater wire and another .33 ohm 5w to the other wire and problem solved or Do I need to get 4 resistors 2 connected in parallel to each 6.3 heater wire? the good thing about all this is that I have options and thats good. I could put the resistors or a copper cap type insert which is not bad either and not have to drill another hole in the chassis for the 6ca4 tube rectifier and I wasn't sure if I'd have to make changes in the 6g3, like resistors or caps. so thanks to all and I'll get back to you's on this matter.

No, I just gave one example of how to get the right value. Sad to say but a lot of places you can not get much out of the ordinary in parts. If you can get the two 0.33 5W resisters you should be in the ballpark.

Thanks PRINTER,parts express in Ohio has them for $o.42cents and they ship to P.R so I guess I'm in the ballpark.:wink: So there shouldn't be any mayor issues with the volt drop in the heater wires.thanks. I was worried about changin the whole build .thanks Keyser for the resistors:lol:

Yeah, the balanced recommendation is purely theoretical, I've never tried wiring dropping resistors on a rectifier.

But the 'danger' isn't noise showing up on the actual heater inside the rectifier, it's that, because all of the secondary windings are in common, the noise (just like diode noise) would tend to show up on all of the other windings as well.

Also because '330' is a number common to all E series resistors, so should be cheap and readily available. Total power dissipation calculates out to 2.47 watts (1.3 volts * 1.9 amps) so a pair of 3 or 5 watt resistors should be more than adequate.

edit: There is a Radio Shack in Isabela, they might have what you need. Not all Rat Shack components are decent quality but power resistors are about as foolproof as an item gets.

thanks for the tip keyser the shack didn't have them, but i found them at a local electronic store no need to pay shipping fees:grin: thanks, waiting one the tubes to fire her up lets cross our fingers:neutral::?::?::?:

Excellent!

Let us know how it sounds as soon as you get it working.

One thing you will need to watch is your power transformer's temperature.

A 6ca4 rectifier only draws 1 amp of heater current. The 5y3 will draw 2 amps. Ordinarily you would assume the rectifier heater wiring was only rated for 1 amp, but that's a rather low value for an otherwise robust transformer. And transformers were often designed with multiple intended uses. So it is probably not enough to be a problem, but it may cause your PT to get warmer than it otherwise might.

Unfortunately there is no 'absolute' in terms of how hot is too hot. But if it is painful to touch that is too hot.

Even if that problem arises all is not lost, you'd simply have to use a copper cap type replacement device. Or, if you were dead set on using a tube recto you could install a dedicated 5 v transformer.