Toroidal Transformer
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rhequiem
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"Toroidal Transformer" sure is a cool band name, though 
StratmanR2S
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I always liked the Deceptigones. I cant remember what planet their from.
JKMV12
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i'm not a complete expert on this, but being toroidal has nothing to do with the core it has. it has to do with how the wire is wound and in this case it is wound around a torus shaped core. basically it is a different geometric shape and a different winding pattern (i.e. toroid/circle instead of solenoid/square). Again i'm not an expert, but from what i already know about transformers and toroids and what i have read, being toroidal has nothing to do with the type of core it has.Vince said:
JKMV12
Well-known member
i see what you are saying, but it can still be an iron core, just a smaller one. i have been reading a bit on them, and they do offer some advantages. We have already established that they are smaller and weigh less than laminated transformers, but they also eliminate or greatly reduce stray magnetic fields. It also can reduce the noise/hum. again, not an expert, but it seems that toroidal transformers are not as bad as you say they are.Vince said:
Think about this.... If they are not as bad as what I say they are.... why are highend amp companies not using them? I mean they save weight which would reduce their shipping costs and customers complaints about heads being end heavy, They are much cheaper to make which would reduce their bottom line...
They are just not up to quality standards ....
They are just not up to quality standards ....
JKMV12
Well-known member
idk why they don't use them...maybe they are more expensive to produce. i guess the labor costs are high b/c of the windings. maybe they are more ideal for other applications. all i know is there is a reason someone developed it..and there is a reason that people use them.Vince said:
JKMV12
Well-known member
have you had a personal experience that tells you that toroidal transformers are inferior to standard transformers?Vince said:
kc2eeb
Well-known member
Toroidal transformers are used in a wide variety of electronic equipment
and not because they're "cheap" to make.
The magnetic field of a toroid is contained within it, so hum and noise are extremely low. So, for a power transformer, there's a lot to like.
There are a few all tube audio power amps using toroidals for both power and output. Give 'em a listen and make your choices.
For a guitar amp, it's a different story.
To be brief, it's the sound of tubes and transformers being pushed past
their "clean, undistorted" threshold that makes and old Deluxe or AC30
sound they way they do.
Putting a really good output transformer in some amps literally kills their tone.
You've got to use your ears and pick what's right for YOU.
and not because they're "cheap" to make.
The magnetic field of a toroid is contained within it, so hum and noise are extremely low. So, for a power transformer, there's a lot to like.
There are a few all tube audio power amps using toroidals for both power and output. Give 'em a listen and make your choices.
For a guitar amp, it's a different story.
To be brief, it's the sound of tubes and transformers being pushed past
their "clean, undistorted" threshold that makes and old Deluxe or AC30
sound they way they do.
Putting a really good output transformer in some amps literally kills their tone.
You've got to use your ears and pick what's right for YOU.
Rod
Well-known member
The Tourmaster Has a toroidal power transformer...and it sounds great...HUGE sounding in the 100 watt mode
I do wish my Lynchbox 100 wasn't as heavy...That things a beast
I do wish my Lynchbox 100 wasn't as heavy...That things a beast
using one as a for a power transformer just make sense weight wise. the 12 unit rack amp has one. I think sourcing them maybe a little harder. as far as for an OT they have a different sound more hifi, not necessarily good for guitar amps. Rm100 not only heavy but balanced horribly for carrying.
could be that the off shore places are not tooled right to make them so they cost more.
could be that the off shore places are not tooled right to make them so they cost more.
bruce egnater
Well-known member
Fun reading.
Advantages of Toroidal Power Transformers
Toroidal transformers offer many advantages over standard laminated power transformers. Toroidals provide quiet, efficient operation with very low stray magnetic fields. Their small size and weight support a package that is easy to design into any application.
The Toroidal Core
At the heart of the toroidal is a highly efficient donut shaped core. To construct the core, grain-oriented silicon-iron is slit to form a ribbon of steel which is then wound, like a very tight clock spring. The result is a core in which all of the molecules are aligned with the direction of flux. Molecules not aligned with the flux direction increase a core's reluctance (the capacity for opposing magnetic induction), degrading performance to the level of common steel when the molecules are 90 degrees out of phase. EI laminated cores, which are stamped from grain-oriented Si-Fe, may have as much as 40% of the total core area perpendicular to the ideal grain direction, with another 40% acting only as a return flux path. This more efficient use of the core material in a toroidal can result in a size and weight reduction of up to 50% (depending on power rating), allowing the design engineer to innovate by exploiting the toroidal's small size, low weight, ease of mounting, and flexible dimensions.
Efficiency
Since toroidal cores are constructed of a continuously wound ribbon, there is virtually no air gap. The windings are evenly wrapped over the entire core allowing the transformer to operate at a higher flux density than in standard transformers. Toroidal transformers can operate at 1.6 to 1.8 Tesla (16,000 to 18,000 Gauss) while EI cores are limited to 1.2 to 1.4 Tesla (12,000 to 14,000 Gauss). The magnetic flux of the windings is oriented in the same direction as the grain-oriented core, thus achieving very high electrical efficiencies. Efficiency is a measure of a transformer's ability to deliver the input power to the load. Efficiency is expressed as a percent by:
% = ( PO / PI ) x 100
where; PO = Output power, PI = Input power, % = Efficiency
Also, standby losses are greatly reduced under no-load operation due to the lower magnetizing currents required by the toroidal core.
Stray Magnetic Fields
The primary cause of leakage flux from any transformer is the air gap. Ideally, a magnetic circuit should have no air gap. In traditional transformers with EI laminations stacked to form the core, the air gap at the junction of the I and the E is the source of most of the leakage flux. This flux strays into the surroundings due to the high reluctance of the air and the concentration of flux in the laminations. For the same reasons, mounting holes and grooves in the laminations also cause a small amount of leakage flux. The tape wound cut-C core is an improvement; but there is still an large air gap causing unwanted stray flux. Since toroidal cores are wound from a continuous ribbon of steel, stray fields from air gaps are eliminated.
In addition, the windings of the toroidal transformer uniformly encase the core in copper. This results in a natural magnetic screening effect which, in combination with the elimination of the air gap, results in an 8:1 reduction of radiated magnetic field over an equivalent rated EI transformer. The windings covering the solid ring core also help reduce magnetostriction -- the main source of acoustic "hum" in standard transformers. Audible noise can be reduced even further by varnish impregnating the toroidal core and/or the copper windings.
Duty Cycle
Significant reductions in transformer size and weight may be realized in many cases where the transformer is loaded intermittently. In such cases, the load is on (tON) for only a small portion of the total period (tCYCLE). The period is much shorter than the thermal time constant of the transformer. To calculate the nominal power rating (VA) of the transformer use the following equation:
PNOM = PLOAD tON / tCYCLE
where; tCYCLE = tON + tOFF
Regulation
The regulation (percentage of voltage drop) may be expressed with the following equation:
% Regulation = [( VNL - VFL ) / VFL ] x 100
VNL = Open circuit, no load voltage
VFL = Full load voltage
Common values for regulation are around 5%. However, regulation can be adjusted to conform to most requirements. Regulation is inversely proportional to efficiency, physical size, and cost, and is directly proportional to temperature rise. All these factors should be taken into consideration when the regulation spec is determined.
Size Considerations
While the cross-sectional area of the toroidal core must be held constant, the height and diameter may be varied to meet package constraints. The functional optimum ratio of diameter to height is 2:1. A 3:1 ratio may be used in applications where a very low profile is required. And if a minimum footprint is required an aspect ratio of 1.5:1 could be considered. The only physical restrictions on the size of a toroidal transformer are the limitations of the winding machinery. A minimum center hole must be maintained in order to permit the insertion of the winding magazine, for application of the wire and insulation.
Temperature Considerations
Operating temperature is an important safety factor which must be considered. It is common to see a 60C to 70C rise above ambient at rated power. Heat generated by the power transformer is due to the sum of the copper and, to a lesser extent, the core losses. Since copper has a positive temperature coefficient, its resistance increases with temperature. As the temperature of the coil rises, the DC resistance of the windings also increases, resulting in a self heating cycle. Temperature rise can be reduced by increasing both the diameter of the winding wire and the size of the transformer. However this is at the expense of increased costs. Tabtronics transformers utilize UL recognized insulation systems for Class B (130C) operation. Temperature rise will also depend on where and how the transformer is mounted and how well it is cooled. When higher temperature ratings are needed, we offer UL recognized systems to Class F (155C) and Class H(180C).
--------------------------------------------------------------------------------
Advantages of Toroidal Power Transformers
Toroidal transformers offer many advantages over standard laminated power transformers. Toroidals provide quiet, efficient operation with very low stray magnetic fields. Their small size and weight support a package that is easy to design into any application.
The Toroidal Core
At the heart of the toroidal is a highly efficient donut shaped core. To construct the core, grain-oriented silicon-iron is slit to form a ribbon of steel which is then wound, like a very tight clock spring. The result is a core in which all of the molecules are aligned with the direction of flux. Molecules not aligned with the flux direction increase a core's reluctance (the capacity for opposing magnetic induction), degrading performance to the level of common steel when the molecules are 90 degrees out of phase. EI laminated cores, which are stamped from grain-oriented Si-Fe, may have as much as 40% of the total core area perpendicular to the ideal grain direction, with another 40% acting only as a return flux path. This more efficient use of the core material in a toroidal can result in a size and weight reduction of up to 50% (depending on power rating), allowing the design engineer to innovate by exploiting the toroidal's small size, low weight, ease of mounting, and flexible dimensions.
Efficiency
Since toroidal cores are constructed of a continuously wound ribbon, there is virtually no air gap. The windings are evenly wrapped over the entire core allowing the transformer to operate at a higher flux density than in standard transformers. Toroidal transformers can operate at 1.6 to 1.8 Tesla (16,000 to 18,000 Gauss) while EI cores are limited to 1.2 to 1.4 Tesla (12,000 to 14,000 Gauss). The magnetic flux of the windings is oriented in the same direction as the grain-oriented core, thus achieving very high electrical efficiencies. Efficiency is a measure of a transformer's ability to deliver the input power to the load. Efficiency is expressed as a percent by:
% = ( PO / PI ) x 100
where; PO = Output power, PI = Input power, % = Efficiency
Also, standby losses are greatly reduced under no-load operation due to the lower magnetizing currents required by the toroidal core.
Stray Magnetic Fields
The primary cause of leakage flux from any transformer is the air gap. Ideally, a magnetic circuit should have no air gap. In traditional transformers with EI laminations stacked to form the core, the air gap at the junction of the I and the E is the source of most of the leakage flux. This flux strays into the surroundings due to the high reluctance of the air and the concentration of flux in the laminations. For the same reasons, mounting holes and grooves in the laminations also cause a small amount of leakage flux. The tape wound cut-C core is an improvement; but there is still an large air gap causing unwanted stray flux. Since toroidal cores are wound from a continuous ribbon of steel, stray fields from air gaps are eliminated.
In addition, the windings of the toroidal transformer uniformly encase the core in copper. This results in a natural magnetic screening effect which, in combination with the elimination of the air gap, results in an 8:1 reduction of radiated magnetic field over an equivalent rated EI transformer. The windings covering the solid ring core also help reduce magnetostriction -- the main source of acoustic "hum" in standard transformers. Audible noise can be reduced even further by varnish impregnating the toroidal core and/or the copper windings.
Duty Cycle
Significant reductions in transformer size and weight may be realized in many cases where the transformer is loaded intermittently. In such cases, the load is on (tON) for only a small portion of the total period (tCYCLE). The period is much shorter than the thermal time constant of the transformer. To calculate the nominal power rating (VA) of the transformer use the following equation:
PNOM = PLOAD tON / tCYCLE
where; tCYCLE = tON + tOFF
Regulation
The regulation (percentage of voltage drop) may be expressed with the following equation:
% Regulation = [( VNL - VFL ) / VFL ] x 100
VNL = Open circuit, no load voltage
VFL = Full load voltage
Common values for regulation are around 5%. However, regulation can be adjusted to conform to most requirements. Regulation is inversely proportional to efficiency, physical size, and cost, and is directly proportional to temperature rise. All these factors should be taken into consideration when the regulation spec is determined.
Size Considerations
While the cross-sectional area of the toroidal core must be held constant, the height and diameter may be varied to meet package constraints. The functional optimum ratio of diameter to height is 2:1. A 3:1 ratio may be used in applications where a very low profile is required. And if a minimum footprint is required an aspect ratio of 1.5:1 could be considered. The only physical restrictions on the size of a toroidal transformer are the limitations of the winding machinery. A minimum center hole must be maintained in order to permit the insertion of the winding magazine, for application of the wire and insulation.
Temperature Considerations
Operating temperature is an important safety factor which must be considered. It is common to see a 60C to 70C rise above ambient at rated power. Heat generated by the power transformer is due to the sum of the copper and, to a lesser extent, the core losses. Since copper has a positive temperature coefficient, its resistance increases with temperature. As the temperature of the coil rises, the DC resistance of the windings also increases, resulting in a self heating cycle. Temperature rise can be reduced by increasing both the diameter of the winding wire and the size of the transformer. However this is at the expense of increased costs. Tabtronics transformers utilize UL recognized insulation systems for Class B (130C) operation. Temperature rise will also depend on where and how the transformer is mounted and how well it is cooled. When higher temperature ratings are needed, we offer UL recognized systems to Class F (155C) and Class H(180C).
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Interesting... you learn something new every day!
All the Chinese amplifier manufacturers use these type transformers (as in not making them for a non-Chinese maker). I have yet to see one as a replacement for traditional transformers...
All the Chinese amplifier manufacturers use these type transformers (as in not making them for a non-Chinese maker). I have yet to see one as a replacement for traditional transformers...
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