Hi friends,
First of all, sorry about my poor english language.
I'm new on the forum and hope to learn a lot here.
I'm starting study the output transformers, have
some experience with solid state amps and effects
but still a newbie with tubes.
I'm using the OPT Design Assistante, great program,
but I have a lot of doubts about the real and correct
way to use it. I plan to start with a EL84 PP amp.
The specs Iam using with opt_da are:
Freq(hz): 40 -> Think its the lowest frequency of transformer
Watts: 20 -> EL84 PP about 18 to 20 watts
SE option not checked -> PP opt
Rp(Ohms): ?? -> not sure about this value
Primary (Z): 8000 -> EL84 PP impedance
Ip (0): 0.140 -> not sure about this value
So, any info about this program and values
will be very important to me. Thanks a lot,
sorry about the idiot questions.
Blindsjc
First of all, sorry about my poor english language.
I'm new on the forum and hope to learn a lot here.
I'm starting study the output transformers, have
some experience with solid state amps and effects
but still a newbie with tubes.
I'm using the OPT Design Assistante, great program,
but I have a lot of doubts about the real and correct
way to use it. I plan to start with a EL84 PP amp.
The specs Iam using with opt_da are:
Freq(hz): 40 -> Think its the lowest frequency of transformer
Watts: 20 -> EL84 PP about 18 to 20 watts
SE option not checked -> PP opt
Rp(Ohms): ?? -> not sure about this value
Primary (Z): 8000 -> EL84 PP impedance
Ip (0): 0.140 -> not sure about this value
So, any info about this program and values
will be very important to me. Thanks a lot,
sorry about the idiot questions.
Blindsjc
blindsjc,
Welcome, lot's of people here struggle with English so do not feel embarrassed about that.
The Rp is plate impedance in mhos, often called transconductance it it the actual plate impedance, as opposed to the load impedance. The program is going to add these two numbers Rp & Rl in parallel ie. (1/Rp + 1/Rl) + primary winding DCR. This equals the reactive load resistance of the tubes. This reactive resistance is then divided by the frequency of interest and 2 X pi to find the inductance the full primary of the PP OPT must have, for - 3 dB at the frequency of interest, 40 Hz. Having this value at 1 volt 120 Hz guarantees that you will have at least three times this value of inductance, once power is actually applied. Three times the needed inductance means you will be about -.75 dB at 40 Hz for most listening levels. Very quiet will be about - 2 dB and so will very loud.
The Ip is an indicator of what currents are flowing through the primary wires for ohmic heating, just to make sure that you do not run too hot. This is not usually a factor because you really do not want much more than 100 ohms of DC resistance in each half of the primary winding and here, less is better, all the way down to about 20 ohms per side, beyond that no benefit is derived.
Post the design results when you think you are getting somewhere, there are lots of very competent folks here who will help.
There are NO stupid questions.
Bud
Welcome, lot's of people here struggle with English so do not feel embarrassed about that.
The Rp is plate impedance in mhos, often called transconductance it it the actual plate impedance, as opposed to the load impedance. The program is going to add these two numbers Rp & Rl in parallel ie. (1/Rp + 1/Rl) + primary winding DCR. This equals the reactive load resistance of the tubes. This reactive resistance is then divided by the frequency of interest and 2 X pi to find the inductance the full primary of the PP OPT must have, for - 3 dB at the frequency of interest, 40 Hz. Having this value at 1 volt 120 Hz guarantees that you will have at least three times this value of inductance, once power is actually applied. Three times the needed inductance means you will be about -.75 dB at 40 Hz for most listening levels. Very quiet will be about - 2 dB and so will very loud.
The Ip is an indicator of what currents are flowing through the primary wires for ohmic heating, just to make sure that you do not run too hot. This is not usually a factor because you really do not want much more than 100 ohms of DC resistance in each half of the primary winding and here, less is better, all the way down to about 20 ohms per side, beyond that no benefit is derived.
Post the design results when you think you are getting somewhere, there are lots of very competent folks here who will help.
There are NO stupid questions.
Bud
blindsjc said:
Hi Blindsjc
Thanks for apreciations about the program !
For penthode PP, use Rp = Zp, here 8000.
It will be lower in the real amp if some feedback is used around the outpt stage.
Try a simulation with 2000 to have an idea on how this affects frequency response.
Ip is for each tube, so 0.05 is good for each EL84 (with 250V on plates, Ip is limited to 12 / 250 = 0.048 by the maximum allowed plate dissipation).
This parameter affects the diameter of the primary wire.
Check for TOTAL and AC copper losses to see its effect
Remember to set the gap to 0 mm.
Yves.
Thanks a lot friends,
Things are a lot clear now...hahaha...thanks.
and Yves, this programa is really good.
Another question is about the iron cores,
my supplier dont have the model specified
by the program (EI84B), they have a EI85
like this pdf info.
http://www.mgsel.com.br/biblioteca_download.php/29/EI85_ST_CAN.PDF
There are some place where I can find a
complete reference about this core standards?
I think that this supplier codes haves
nothing to do with the standards which
appears on the program and I will need
to use the mm values from the "core data"
window.
Thnaks again.
Blindsjc
Things are a lot clear now...hahaha...thanks.
and Yves, this programa is really good.
Another question is about the iron cores,
my supplier dont have the model specified
by the program (EI84B), they have a EI85
like this pdf info.
http://www.mgsel.com.br/biblioteca_download.php/29/EI85_ST_CAN.PDF
There are some place where I can find a
complete reference about this core standards?
I think that this supplier codes haves
nothing to do with the standards which
appears on the program and I will need
to use the mm values from the "core data"
window.
Thnaks again.
Blindsjc
blindsjc said:
They look very similar.
"EI" stands for the mecanical aspect of lams looking as the letters E and I parts that will be packed (stacked) to obtain the core.
The number "84" in european standards is the lenght of the "I" part of the lams. Its width - as long as the width of the lateral legs of the "E" part - is always 1/6th of this value (here 14mm).
The width of the center leg of the "E" part (also named tongue) is always 1/3rd (here 28mm).
Theses relations apply to all "scrapless" laminations.
In your drawing lenght of the "I" part is called "A" (86mm) wich however includes the mounting brackets thickness.
From this value, you may compute all others from relations above.
The "B" value being equal to A * 5 / 6 .
But the height of the stack is missing.
Look at
http://www.elettronicanovarria.com/rocchettilamierinonuclei.html
(sorry for not having found in english)
The leftmost table is for bobins, the right ones are for lams/core in various grades.
The lams size we need is 84 x 70 mm (note that 70 is 84 * 5 / 6 as stated above)
This means a thongue width (colonna in italiano) of (84/3) = 28mm.
The B suffix stands for a 45 mm stack (paco)
Does that help ?
Yves.
Great !
Show me what you plan to do when ready.
Over all, your first specifications seem a bit optimistic regarding the max output power from 2 x EL84, probably near to 15 than to 20W.
But you are slighty pessimistic about lowest frequency, I would have targeted 30Hz rather than 40 !
BTW one somewhat compensates the other.
Yves.
Show me what you plan to do when ready.
Over all, your first specifications seem a bit optimistic regarding the max output power from 2 x EL84, probably near to 15 than to 20W.
But you are slighty pessimistic about lowest frequency, I would have targeted 30Hz rather than 40 !
BTW one somewhat compensates the other.
Yves.
Hi Ashok
Software is written by Yves.
His website link is.
http://www.dissident-audio.com/OPT_da/Page.html
very good software.
regards
Software is written by Yves.
His website link is.
http://www.dissident-audio.com/OPT_da/Page.html
very good software.
regards
Friends,
I think I have something to show with OPT_DA,
so take a look. Thanks for all comments.
http://server6.pictiger.com/img/675068/picture-hosting/opt-yves-.gif
diegot
Fala Diegão!
I will use it on a guitar amplifier, the output transformers
here in Brasil, like you know, are soooo expensive.
Yves
I was just think about the primary and secondary
windings in different layers like: P1|S1|P2....
How do you make this? We need to cut and to
solder the copper all the time between those
layers? I dont think I will use a lot of layers but
better to ask before no? Thanks.
Edit: Just to make it clear, I mean to cut in the middle
of primary to insert the secondary layer, and after that
to solder the first part of primary to copper and continue
with primary. This is ok, but how to make it with a primary
in 15 parts? Same way?
Thanks
I think I have something to show with OPT_DA,
so take a look. Thanks for all comments.
http://server6.pictiger.com/img/675068/picture-hosting/opt-yves-.gif
diegot
Fala Diegão!
I will use it on a guitar amplifier, the output transformers
here in Brasil, like you know, are soooo expensive.
Yves
I was just think about the primary and secondary
windings in different layers like: P1|S1|P2....
How do you make this? We need to cut and to
solder the copper all the time between those
layers? I dont think I will use a lot of layers but
better to ask before no? Thanks.
Edit: Just to make it clear, I mean to cut in the middle
of primary to insert the secondary layer, and after that
to solder the first part of primary to copper and continue
with primary. This is ok, but how to make it with a primary
in 15 parts? Same way?
Thanks
blindsjc, transformers in Brazil are toooo much expensive, you are right. Guitar amps make the things much more easyer. You are in the right path spliting the primary in two and putting the secundary in the middle. For hifi you need more layers.
Where you from? I now a guy who wind transformers for a decent price.
Diego
Where you from? I now a guy who wind transformers for a decent price.
Diego
Yes Diego,
Very weird two Brazilians speaking in english,
but is a way to respect all the other members
who help us a lot...
In the truth I really want to learn how to wind
my own transformers, here we have some good
winders but I want to learn. I'm from São José
dos Campos - SP, are you near?
About the transformers, I just realized that the center
tap in this case will be used for a B+ connection, but
I think about a transformer with a lot of layers, I will
have a lot of solder connections, or will need a way to
put the copper reel of primary twirling while a make the
winding of secondary. Man, It's hard to explain it in
english but I think you can understand.
Thanks
Very weird two Brazilians speaking in english,
but is a way to respect all the other members
who help us a lot...
In the truth I really want to learn how to wind
my own transformers, here we have some good
winders but I want to learn. I'm from São José
dos Campos - SP, are you near?
About the transformers, I just realized that the center
tap in this case will be used for a B+ connection, but
I think about a transformer with a lot of layers, I will
have a lot of solder connections, or will need a way to
put the copper reel of primary twirling while a make the
winding of secondary. Man, It's hard to explain it in
english but I think you can understand.
Thanks
Hi Diego
I have been saving a set of EL84's for many years with the idea of building an amp with it. It's a well regarded tube and I wanted to have my own 84 amp.
Could you share the winding information for hi-fi use ? I have an old manual winder and so I can wind it myself. We do get CRGO laminations but I'm not sure how good they really are.
I'm not sure if you can post it here or if you would only email it.
If it's only by email you can send it to ashok(at)sify(dot)com .
Thanks,
Cheers,
Ashok.
I have been saving a set of EL84's for many years with the idea of building an amp with it. It's a well regarded tube and I wanted to have my own 84 amp.
Could you share the winding information for hi-fi use ? I have an old manual winder and so I can wind it myself. We do get CRGO laminations but I'm not sure how good they really are.
I'm not sure if you can post it here or if you would only email it.
If it's only by email you can send it to ashok(at)sify(dot)com .
Thanks,
Cheers,
Ashok.
Hi ashok,
Sure Diego haves a lot of experience and will
add a lot of info to this reply, but just to share what
I have studied, some hi-fi OPTs haves a lot of layers,
one for each complete line of winding in the reel,
all they isolated by thin paper. This will increase
a lot the response to high frequencies.
Some info about a diy opt here:
http://www.audiohobbyist.com/projects/diyopt.htm
PS: looking at these images again I see the wires
cut at the winder side, so I think that they are really
soldered at each layer end.
Thanks
Blindsjc
Sure Diego haves a lot of experience and will
add a lot of info to this reply, but just to share what
I have studied, some hi-fi OPTs haves a lot of layers,
one for each complete line of winding in the reel,
all they isolated by thin paper. This will increase
a lot the response to high frequencies.
Some info about a diy opt here:
http://www.audiohobbyist.com/projects/diyopt.htm
PS: looking at these images again I see the wires
cut at the winder side, so I think that they are really
soldered at each layer end.
Thanks
Blindsjc
Hi Guys,
If you do not have vacumn varnish and bake out capabilities you must use a "paper section" coil. This means a layer of paper for every layer of High Voltage winding wire.
The most common guitar amp winding style is as follow. If you consider the primary as two halves of the total winding, part A and part B. Then you should wind 1/2 of the primary part A turns first, using a layer of paper at least 1.75mm wider than the winding width for each layer. This means that the winding width must be 3.5mm narrower than the length of the center tongue of the E.
Then put two wraps of a high voltage dielectric plastic (Nomex 410 0.075mm thick minimumX2 layers) over the 1/2 of primary winding A. Then wind the 4 ohm secondary, probably best to split the wire size and make two windings of it here. Then two more wraps of the dielectric plastic.
Then wind all of the B winding, again using the layer paper. When done wind two layers of dielectric plastic.
Then wind the remaining turns needed for the 8 ohm and 16 ohm winding, using correct wire sizes for both load currents.
Then two more wraps of dielectric plastic.
Then the final 1/2 of the primary A winding, again using the layer papers. Then a final two layer wrap of the dielectric paper.
Now, you do not cut the wires for every layer. Instead when you have reached the end of the first primary A wire layer, you insert the paper under the wire and angle the wire slightly back across the winding. The wire will climb up on the paper and travel back across, using the layer below it as a position guide.
You can also tape the paper layer in place, across the end, onto the coil wire. You must figure out your start position and finish position for each winding and make a drawing that reminds you where to start and stop. You can use tape to fix these starts and stops in place.
You want to be careful not to pull the wire tight, just snug and you will be guiding it with your fingers so you might want some cotton finger tips or cotton glove to keep the wire from burning your skin with friction heat.
This is a VERY brief description of a VERY simple coil that will work very well for guitar amplifiers. I know this because we build OPT's for THD, Soldano, Gibson, Triad and many small boutique guitar amp builders. We also supply the DIY market with some very musical devices.
Once you have wound a few coils, to learn how to trick coated magnet wire into doing what you want it to, instead of what it wants to do, I can give you some detailed descriptions of how to handle safety issues and how to connect lead wires securely. But first you must struggle with the basics of how to control the wire, what kind of winding fixture to use and how to keep track of the number of turns.
By the way, winding the primary in this fashion will exactly balance the DC resistance of the two halves of the winding. This is an important point as unbalanced DCR can shorten tube life and ruin tone.
This is a very skilled business you are attempting and there is a lot of information you will need as you learn it. Be brave, you can do it.
Bud
If you do not have vacumn varnish and bake out capabilities you must use a "paper section" coil. This means a layer of paper for every layer of High Voltage winding wire.
The most common guitar amp winding style is as follow. If you consider the primary as two halves of the total winding, part A and part B. Then you should wind 1/2 of the primary part A turns first, using a layer of paper at least 1.75mm wider than the winding width for each layer. This means that the winding width must be 3.5mm narrower than the length of the center tongue of the E.
Then put two wraps of a high voltage dielectric plastic (Nomex 410 0.075mm thick minimumX2 layers) over the 1/2 of primary winding A. Then wind the 4 ohm secondary, probably best to split the wire size and make two windings of it here. Then two more wraps of the dielectric plastic.
Then wind all of the B winding, again using the layer paper. When done wind two layers of dielectric plastic.
Then wind the remaining turns needed for the 8 ohm and 16 ohm winding, using correct wire sizes for both load currents.
Then two more wraps of dielectric plastic.
Then the final 1/2 of the primary A winding, again using the layer papers. Then a final two layer wrap of the dielectric paper.
Now, you do not cut the wires for every layer. Instead when you have reached the end of the first primary A wire layer, you insert the paper under the wire and angle the wire slightly back across the winding. The wire will climb up on the paper and travel back across, using the layer below it as a position guide.
You can also tape the paper layer in place, across the end, onto the coil wire. You must figure out your start position and finish position for each winding and make a drawing that reminds you where to start and stop. You can use tape to fix these starts and stops in place.
You want to be careful not to pull the wire tight, just snug and you will be guiding it with your fingers so you might want some cotton finger tips or cotton glove to keep the wire from burning your skin with friction heat.
This is a VERY brief description of a VERY simple coil that will work very well for guitar amplifiers. I know this because we build OPT's for THD, Soldano, Gibson, Triad and many small boutique guitar amp builders. We also supply the DIY market with some very musical devices.
Once you have wound a few coils, to learn how to trick coated magnet wire into doing what you want it to, instead of what it wants to do, I can give you some detailed descriptions of how to handle safety issues and how to connect lead wires securely. But first you must struggle with the basics of how to control the wire, what kind of winding fixture to use and how to keep track of the number of turns.
By the way, winding the primary in this fashion will exactly balance the DC resistance of the two halves of the winding. This is an important point as unbalanced DCR can shorten tube life and ruin tone.
This is a very skilled business you are attempting and there is a lot of information you will need as you learn it. Be brave, you can do it.
Bud
Thanks Bud,
I remember my first attempt with a tube screamer project,
man, I was almost crying when it comes to live first time.
Today I use my delay, my own distortions and my amps
of 30 and 60watts, with mid shift to alternate mids and
everything else. Like you said, we need some time, fails
and victories to make something part of your knowhow.
Just finished to read the transformer chapter of RH4
and things are getting clear with the help of all of you
good people.
Sorry, but my english language doen't allow me understand
about the way to keep the wire of primary withou cuts when
winding the secondary, sorry.
So, some comments about the project made with the OPTda?
http://server6.pictiger.com/img/675068/picture-hosting/opt-yves-.php
Thanks
I remember my first attempt with a tube screamer project,
man, I was almost crying when it comes to live first time.
Today I use my delay, my own distortions and my amps
of 30 and 60watts, with mid shift to alternate mids and
everything else. Like you said, we need some time, fails
and victories to make something part of your knowhow.
Just finished to read the transformer chapter of RH4
and things are getting clear with the help of all of you
good people.
Sorry, but my english language doen't allow me understand
about the way to keep the wire of primary withou cuts when
winding the secondary, sorry.
So, some comments about the project made with the OPTda?
http://server6.pictiger.com/img/675068/picture-hosting/opt-yves-.php
Thanks
blindsjc,
Actually your English is quite good, I am at fault.
Let us assume that when winding secondaries, you want to have 4 ohm, 8 ohm and 16 ohm speaker impedance matching taps. This makes the amplifier very useful for many different situations.
In the first space for secondaries, you find that you need a particular wire size for heat requirements and it is large enough to fill 1 1/2 layers, but not two full layers, this will make all following layers hard to keep even and level. Also it will cause poor coupling with the primary windings.
Then, the thing to do is to split one winding into two. Usually, if you split the wire size by dividing the circular mils per amp by 2, you can get the turns into two windings, of one layer each. These wires will start and finish on opposite sides of the coil. This is fine, not a problem. It also gives the very best coupling possible, with the primaries and allows easy winding later.
Then you come to the second space to wind secondaries. Let us say you needed 44 turns for 4 ohms. You will then need 63 turns for 8 ohms and 88 turns for 16 ohms. Since you already have 44 turns wound for 4 ohms, just add 19 turns of a proper wire size for 8 ohms. This will again be in just one layer.
Then add another winding of 25 turns, using only one of the wires you used for the 4 ohm winding, and you have all three secondaries.
All secondaries will have maximum coupling and if you are clever with where you start and stop each winding, you can bring the coil start and finish wires up the winding sides and out onto the outer surface of the finished coil in the best place for lead connection.
Ask more questions please, if this is still not clear. Trust me, it will soon make perfect sense.
Bud
Actually your English is quite good, I am at fault.
Let us assume that when winding secondaries, you want to have 4 ohm, 8 ohm and 16 ohm speaker impedance matching taps. This makes the amplifier very useful for many different situations.
In the first space for secondaries, you find that you need a particular wire size for heat requirements and it is large enough to fill 1 1/2 layers, but not two full layers, this will make all following layers hard to keep even and level. Also it will cause poor coupling with the primary windings.
Then, the thing to do is to split one winding into two. Usually, if you split the wire size by dividing the circular mils per amp by 2, you can get the turns into two windings, of one layer each. These wires will start and finish on opposite sides of the coil. This is fine, not a problem. It also gives the very best coupling possible, with the primaries and allows easy winding later.
Then you come to the second space to wind secondaries. Let us say you needed 44 turns for 4 ohms. You will then need 63 turns for 8 ohms and 88 turns for 16 ohms. Since you already have 44 turns wound for 4 ohms, just add 19 turns of a proper wire size for 8 ohms. This will again be in just one layer.
Then add another winding of 25 turns, using only one of the wires you used for the 4 ohm winding, and you have all three secondaries.
All secondaries will have maximum coupling and if you are clever with where you start and stop each winding, you can bring the coil start and finish wires up the winding sides and out onto the outer surface of the finished coil in the best place for lead connection.
Ask more questions please, if this is still not clear. Trust me, it will soon make perfect sense.
Bud
blindsjc,
For the primary windings. Let us say you must wind 2000 turns total. That means your B+ CT will be at 1000 turns. For a very good guitar amplifier coil you can use the very first coil winding configuration shown in the RDH4 section on coil interleave.
In this case you would wind 500 turns, using wire positions 1 & 2.
Then you wind two secondaries with 44 turns, using wire positions 5 & 6..
Then you wind 1000 turns using wire positions 3 & 4.
Then you wind 19 turns using wire positions 6 & 7.
Then you wind 25 turns using wire positions 7 & 8.
Then you wind 500 turns using wire positions 2 & 3.
These wire positions are start and stop positions along the top surface of the finished bobbin. They are imaginary, something you make up on your own. If you wind with a plastic coil former with slots already cut into the walls, each slot would be one of the wire positions.
If you draw a 3D view of a finished coil and pick the front right corner, on top, as position one, then position 2 is on that edge of the coil face also but a little farther down the side.
Position 3 is on the same side as position 1 but mid way down the coil face and position 4 is in the back right corner.
Then rotate the coil as if you were winding it, to the opposite coil face. position 5 is in the front right corner, position 6 finish is across on the left side, a little way down the side.
Position 6 start is on the same side as position 5 and position 7 finish is on the opposite side of the coil face with, 6 finish.
Position 7 start is on the same side as 5 start and position 7 finish is on the left side again, with position 7 back on the start on the right. Position 8 finish is then on the left side with 6 & 7 finish. So, starts on the right and finishes on the left, for the secondaries.
You cut these wires when you finish each winding, leaving a long enough length to bend up the coil wall and over the eventual top of the coil to the opposite edge. This will leave enough coil wire to allow you to combine starts and finishes, with the same number, to the same colored lead wire.
So, no connecting of wires in the windings. This a very unsafe thing to do. If you draw this out in a 3D drawing on paper and think your way through, it will become clear. I promise.
Bud
For the primary windings. Let us say you must wind 2000 turns total. That means your B+ CT will be at 1000 turns. For a very good guitar amplifier coil you can use the very first coil winding configuration shown in the RDH4 section on coil interleave.
In this case you would wind 500 turns, using wire positions 1 & 2.
Then you wind two secondaries with 44 turns, using wire positions 5 & 6..
Then you wind 1000 turns using wire positions 3 & 4.
Then you wind 19 turns using wire positions 6 & 7.
Then you wind 25 turns using wire positions 7 & 8.
Then you wind 500 turns using wire positions 2 & 3.
These wire positions are start and stop positions along the top surface of the finished bobbin. They are imaginary, something you make up on your own. If you wind with a plastic coil former with slots already cut into the walls, each slot would be one of the wire positions.
If you draw a 3D view of a finished coil and pick the front right corner, on top, as position one, then position 2 is on that edge of the coil face also but a little farther down the side.
Position 3 is on the same side as position 1 but mid way down the coil face and position 4 is in the back right corner.
Then rotate the coil as if you were winding it, to the opposite coil face. position 5 is in the front right corner, position 6 finish is across on the left side, a little way down the side.
Position 6 start is on the same side as position 5 and position 7 finish is on the opposite side of the coil face with, 6 finish.
Position 7 start is on the same side as 5 start and position 7 finish is on the left side again, with position 7 back on the start on the right. Position 8 finish is then on the left side with 6 & 7 finish. So, starts on the right and finishes on the left, for the secondaries.
You cut these wires when you finish each winding, leaving a long enough length to bend up the coil wall and over the eventual top of the coil to the opposite edge. This will leave enough coil wire to allow you to combine starts and finishes, with the same number, to the same colored lead wire.
So, no connecting of wires in the windings. This a very unsafe thing to do. If you draw this out in a 3D drawing on paper and think your way through, it will become clear. I promise.
Bud
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