I am the proud owner of this transformer.
I bought it by mistake for my ESP Project 101. It is too large for that project and now I am left wondering if there is a DIY project that can make use of this trannie. If you know of one, please let me know. Perhaps it will be my next project.
Thanks, Terry
I bought it by mistake for my ESP Project 101. It is too large for that project and now I am left wondering if there is a DIY project that can make use of this trannie. If you know of one, please let me know. Perhaps it will be my next project.
Thanks, Terry
Hi,
with this transformer (1000VA/2X56V) you can build a high power amplifier in Class AB (ca. 2X250W/8ohm). Normally, I would not see much point in building such a high-power amp for home use.
However, if you set primary winding to 230V, you'll get half the secondary voltage, which turns this transformer into a pretty good choice for, say, a Pass amp in Class A. Depending on power supply implementation (voltage losses), you could build A2, A5 or a high-power version of AlephX.
Before you decide to build a Class A amp, you should test the transformer for the intended purpose.
Detailed information and an overview of all the complexities involved in building such an amplifier can be found at www.passdiy.com (check out the gallery section).
I believe there are some PCBs circulating on the forum. Ask around. (I wouldn't know).
Regards,
Milan
with this transformer (1000VA/2X56V) you can build a high power amplifier in Class AB (ca. 2X250W/8ohm). Normally, I would not see much point in building such a high-power amp for home use.
However, if you set primary winding to 230V, you'll get half the secondary voltage, which turns this transformer into a pretty good choice for, say, a Pass amp in Class A. Depending on power supply implementation (voltage losses), you could build A2, A5 or a high-power version of AlephX.
Before you decide to build a Class A amp, you should test the transformer for the intended purpose.
Detailed information and an overview of all the complexities involved in building such an amplifier can be found at www.passdiy.com (check out the gallery section).
I believe there are some PCBs circulating on the forum. Ask around. (I wouldn't know).
Regards,
Milan
Hi still4given,
I think most of us use bridge rectifiers so the DC output voltage is greater the the AC secondary voltage, but if you use a full-wave rectification using just two diodes the DC output voltage is actually less than the AC seondary voltage. I can't remember the formula but I think it was .6 or .7 of the secondary. I have read some prefer full-wave over bridge rectification. So I think you could use this transformer for your original project and power a gainclone off the 17v secondaries.
I think most of us use bridge rectifiers so the DC output voltage is greater the the AC secondary voltage, but if you use a full-wave rectification using just two diodes the DC output voltage is actually less than the AC seondary voltage. I can't remember the formula but I think it was .6 or .7 of the secondary. I have read some prefer full-wave over bridge rectification. So I think you could use this transformer for your original project and power a gainclone off the 17v secondaries.
I´d go with moamps suggestions to wire the primaries in series leaving you with 28VAC which gives~40VDC+.
With that rail voltage you can simply build anything as it is quite a "standard" voltage. That includes P101 as well.
That said the transformer will be oversized for the purpose (unless you go class A) but it will also give great "regulation".
With that rail voltage you can simply build anything as it is quite a "standard" voltage. That includes P101 as well.
That said the transformer will be oversized for the purpose (unless you go class A) but it will also give great "regulation".
moamps said:
Hi moamps,
I am not very experienced with DIY amps but of the amps I own, Hafler DH200, Hafler P230, Soundcraftsmen PCR800 & Soundcraftsmen S860, the S860 is the best sounding and the most powerful. It's supposed to be 240wpc @ 8ohms.
I mainly use these in my studio for reference. Sometimes they are played fairly loudly. I drive JBL 4425's, 4412" and Yamaha NS1000's.
Anyway, perhaps the amps I have are not as efficient as the Aleph amps. They are in excess of 100wpc.
May I assume that if I run this trannie at lower voltage that I would have greater VA?
I'm not sure I'm experienced enough yet to tackle the Aleph X. Seems like most folks are tweaking them as they go. I would be better off with a design that is proven I think. I know that I don't have enough understanding to start tweaking someone's design.
Blessings, Terry
I am a bit surprised by the responses.
You may have noticed that transformers can get hot !
A 1000VA is designed for delivering that power for the rated voltage.
The core of the toroid has flux large enough to transform 1000VA.
Normal engineering means that primary and secondary windings are dimensioned in accordance with the voltage and power rating.
Meaning that the secondary windings are good for nearly 9 amps at 56 volts.
Derating the voltage by putting 110 volts on 230 volt primaries may lower the secondar output voltage, the secondary windings are still only good for 9 amps.
Reduce the input voltage by half, out comes half of the power, 500VA max !
And that does not make real sense, why buy a 1000VA transformer if you are going to use only half of that.
Transformer windings are isolated well enough for way beyond a thousand volts.
Putting 220 volts on 110 volt primaries is more realistic than the reverse strategy.
As the toroid is able to deliver 1000VA the output current is half of the design current for which the secondary cross sections are dimensioned.
56 Volts is good for at least 250 watts, place a small voltage transformer in series with the big one to feed the front stage of the amplifier and you are talking way beyond 300 watts.
Bridge the amps and you have a 500+ amp, strong enough to drive a serious subwoofer.
Overhere people have built 1000 watt amplifiers, plenty of designs available for those who feel the need.
If you decide to go for a smaller power amplifier, unwind the secondaries to whatever you need.
Put 110 on 220 primaries, extract a thousand watts and you might end up with an nice burning toroid by Christmas time !
You may have noticed that transformers can get hot !
A 1000VA is designed for delivering that power for the rated voltage.
The core of the toroid has flux large enough to transform 1000VA.
Normal engineering means that primary and secondary windings are dimensioned in accordance with the voltage and power rating.
Meaning that the secondary windings are good for nearly 9 amps at 56 volts.
Derating the voltage by putting 110 volts on 230 volt primaries may lower the secondar output voltage, the secondary windings are still only good for 9 amps.
Reduce the input voltage by half, out comes half of the power, 500VA max !
And that does not make real sense, why buy a 1000VA transformer if you are going to use only half of that.
Transformer windings are isolated well enough for way beyond a thousand volts.
Putting 220 volts on 110 volt primaries is more realistic than the reverse strategy.
As the toroid is able to deliver 1000VA the output current is half of the design current for which the secondary cross sections are dimensioned.
56 Volts is good for at least 250 watts, place a small voltage transformer in series with the big one to feed the front stage of the amplifier and you are talking way beyond 300 watts.
Bridge the amps and you have a 500+ amp, strong enough to drive a serious subwoofer.
Overhere people have built 1000 watt amplifiers, plenty of designs available for those who feel the need.
If you decide to go for a smaller power amplifier, unwind the secondaries to whatever you need.
Put 110 on 220 primaries, extract a thousand watts and you might end up with an nice burning toroid by Christmas time !
Hi,
Run your tranny at half volts if you want.
You cannot exceed the VA rating except for short term overloads.
With 1000va to play with, it will cover all except a large classA.
Are you able to confirm the current rating of all the windings?
It will give you more flexibility if you can series the 15vac onto the the high voltage. But if they are only low current then separately rectify & then stack on top of main output as a driver regulator feed.
regards Andrew T.
Run your tranny at half volts if you want.
You cannot exceed the VA rating except for short term overloads.
With 1000va to play with, it will cover all except a large classA.
Are you able to confirm the current rating of all the windings?
It will give you more flexibility if you can series the 15vac onto the the high voltage. But if they are only low current then separately rectify & then stack on top of main output as a driver regulator feed.
regards Andrew T.
Here's what it says in the add;
You are bidding on a new 1000VA toroidal transformer. It is precisely made for high-end power amp or equipment. It has very low power loss and magnetic leak. Labeled input 115 / 230 VAC 50/60 Hz (single coil with center tap), outputs 55VAC x 2 (dual coils), and 15VAC x 2 (dual coils)at 5A.
You would probably know if that meets the requirements better than me. What do you think?
Blessings, Terry
Hi Terry,still4given said:
If you wish to build a high-power amp for your recording studio, then the Leach Superamp might be just the thing. Pass amps work in Class A (which means that their efficiency is low), and they are intended mostly for home high-end setups.
Generally, no. In practice, you get 60-70 percent of nominal power.
Regards,
Milan
jacco vermeulen said:
Likewise.
You may have also noticed that Terry was advised to TEST the transformer before trying anything, which in itself means that this is not meant as the optimal solution but just an option worth exploring. I have connected 380V primary voltage transformers to the 230V network with no overheating problems. In modern transformers, core overload is of much greater concern than coil current overload, in my experience.
This is true only in case of permanent resistive load. In case of amp power supply, it is possible to achieve greater power without any significant overheating (or similar) problems.
For want of a more polite way to phrase it, I'll just say this must be one of the dumbest and most dangerous suggestions I have read recently. Here are the test results for the transformer's different primary volatages:
Voltage Test Result:
TEST CONDITION: Apply variable voltage to primary coil (115V terminals) from 100-180VAC. No load on secondary coils.
1. Primary V = 100VAC, Primary I = .04A
2. Primary V = 110VAC, Primary I = .05A
3. Primary V = 120VAC, Primary I = .06A
4. Primary V = 130VAC, Primary I = .07A
5. Primary V = 140VAC, Primary I = .10A
6. Primary V = 150VAC, Primary I = .13A
7. Primary V = 160VAC, Primary I = .30A
8. Primary V = 170VAC, Primary I = .95A
As you can see, increases in the primary voltage result in a significant increase in the "no-load" current (the core is getting saturated). For the primary voltage of 230V, the expected current is over 1.5A, which translates into a "no-load" dissipation of about 350-400W and, consequently, leads to transformer core overheating and meltdown. So much for burning toroids for Christmas.
Regards,
Milan
P.S. Moderators, S.O.S. - newbie overboard
Dear Milan,
NO transformer should be applied for a higher or lower voltage than it is intended for.
Applying 230 volts on 115 primaries will get you into trouble, it was mentioned for the arguement sake.
You might as well explain what the outcome will be for the transformer when your suggestion is applied.
It is quite common to unwind transformer secondaries instead of putting half the voltage on primary windings.
That way the primaries get the voltage originally intended for, and the secondary windings can handle the current that comes with it.
You may wish to advise transformer manufacturers to wire their transformers with half diameter secondaries, that should be good for quite a big cost reduction.
NO transformer should be applied for a higher or lower voltage than it is intended for.
Applying 230 volts on 115 primaries will get you into trouble, it was mentioned for the arguement sake.
You might as well explain what the outcome will be for the transformer when your suggestion is applied.
It is quite common to unwind transformer secondaries instead of putting half the voltage on primary windings.
That way the primaries get the voltage originally intended for, and the secondary windings can handle the current that comes with it.
You may wish to advise transformer manufacturers to wire their transformers with half diameter secondaries, that should be good for quite a big cost reduction.
Overhere, toroid transformer manufacturers advise to unwind secondaries.
Of course 115 volts can be put on 230 primaries, and it may even be possible to get 600 to 700VA out of it without any trouble for the core or the windings.
Follow manufacturer layout and stick to 500VA.
Overhere it is dead easy to find a new 500-600VA toroid on the web for les than $30.
Here MSRP for toroids are a lot higher than in the US, i can imagine finding one in the USA for less than $69 is certain.
If Terry wants to build a 600VA amplifier he would do better to sell the 1000VA to someone who needs it, buy a 600VA toroid and get a return from the money paid on Ebay.
I can also imagine that Terry can think of building a Nelson Pass amplifier himself, build a Pass amp seems to be the standard advise from not-newbees.
How i read Terry's question was that he bought a 1000VA toroid and is looking for a design to use a 1000VA toroid, not 500VA, 600 or 700VA.
Advising to operate a transformer at 70% of its capability with 115volts on 230 volt primaries and exceeding the secondary current rating by 60%, instead of looking for the right toroid is not sound advise.
Of course 115 volts can be put on 230 primaries, and it may even be possible to get 600 to 700VA out of it without any trouble for the core or the windings.
Follow manufacturer layout and stick to 500VA.
Overhere it is dead easy to find a new 500-600VA toroid on the web for les than $30.
Here MSRP for toroids are a lot higher than in the US, i can imagine finding one in the USA for less than $69 is certain.
If Terry wants to build a 600VA amplifier he would do better to sell the 1000VA to someone who needs it, buy a 600VA toroid and get a return from the money paid on Ebay.
I can also imagine that Terry can think of building a Nelson Pass amplifier himself, build a Pass amp seems to be the standard advise from not-newbees.
How i read Terry's question was that he bought a 1000VA toroid and is looking for a design to use a 1000VA toroid, not 500VA, 600 or 700VA.
Advising to operate a transformer at 70% of its capability with 115volts on 230 volt primaries and exceeding the secondary current rating by 60%, instead of looking for the right toroid is not sound advise.
Suppose Terry would want to build a Pass amplifier, say the Aleph 4.
With a CLC powersupply the transformer would need 40Vac secondary windings.
Unwinding the secondaries from 56 to 40 volts would be a reduction of 28.6 % in voltage.
In accordance with the toroid design, with 28.6 % of the secondary winding taken off, the secondary current can be
18.3 % higher.
The rating for the 56volt secondaries would be 850VA, 150VA is for the 15 volt secondaries.
With 28.6% lower voltage and 18.3% higher current the 850VA reduces to 718VA.
That is more than the maximum expected rating for putting 115 volts on 230 volts primaries.
And, there is no need to exceed manufacturers guidelines.
In reality, the secondary windings are usually already dimensioned for the possibillity of unwinding to a lower secondary voltage.
At 56 volts the secondaries would be good for 7.59 amps for 850VA.
Unwinded to 40Vac the current in the toroid's secondaries for 700VA would be 8.75 amps.
With 28.6% of the secondary windings taken off, the load on the secondaries would be 5% lower than originally at 56 volts.
With 115 volts on 230volt primaries, secondary voltage would be 28Vac, the secondary windings current 12.5 amps at 700VA.
Compared to the 56 volt layout the load on the secondary windings is exceeding the load of the 850VA/56Volt appliance
by 171%.
With a CLC powersupply the transformer would need 40Vac secondary windings.
Unwinding the secondaries from 56 to 40 volts would be a reduction of 28.6 % in voltage.
In accordance with the toroid design, with 28.6 % of the secondary winding taken off, the secondary current can be
18.3 % higher.
The rating for the 56volt secondaries would be 850VA, 150VA is for the 15 volt secondaries.
With 28.6% lower voltage and 18.3% higher current the 850VA reduces to 718VA.
That is more than the maximum expected rating for putting 115 volts on 230 volts primaries.
And, there is no need to exceed manufacturers guidelines.
In reality, the secondary windings are usually already dimensioned for the possibillity of unwinding to a lower secondary voltage.
At 56 volts the secondaries would be good for 7.59 amps for 850VA.
Unwinded to 40Vac the current in the toroid's secondaries for 700VA would be 8.75 amps.
With 28.6% of the secondary windings taken off, the load on the secondaries would be 5% lower than originally at 56 volts.
With 115 volts on 230volt primaries, secondary voltage would be 28Vac, the secondary windings current 12.5 amps at 700VA.
Compared to the 56 volt layout the load on the secondary windings is exceeding the load of the 850VA/56Volt appliance
by 171%.
First, I want to say how thankful I am that each of you have given your time to make suggestions here. I have already learned some more about the operation of a toroid.
I want to be in this DIY hobby for the long haul and I know I need to learn all of this stuff to really be successful at it.
I certainly do plan to build a Pass amp some day, but I don't really want to modify this particular toroid for that purpose.
As jacco suggested, I really am interested in an amp design that can make use to this transformer as is. If there isn't one around right now, I'll set it aside and wait until I can find one. I'm not nearly sharp enough right now to start unwinding this thing.
I already have two new E-I trannies in the 40-0-40 category that I bought for my Haflers and didn't need. I was really looking for an amp kit or design that could use this tranny.
It doesn't have to be for use in my studio. I also have a PA system that I could use it in. Maybe even a sub amp?
I was just hoping that someone knew of such an amp design.
Blessings, Terry
I want to be in this DIY hobby for the long haul and I know I need to learn all of this stuff to really be successful at it.
I certainly do plan to build a Pass amp some day, but I don't really want to modify this particular toroid for that purpose.
As jacco suggested, I really am interested in an amp design that can make use to this transformer as is. If there isn't one around right now, I'll set it aside and wait until I can find one. I'm not nearly sharp enough right now to start unwinding this thing.
I already have two new E-I trannies in the 40-0-40 category that I bought for my Haflers and didn't need. I was really looking for an amp kit or design that could use this tranny.
It doesn't have to be for use in my studio. I also have a PA system that I could use it in. Maybe even a sub amp?
I was just hoping that someone knew of such an amp design.
Blessings, Terry
Here is one you may like to take a peek at :
http://www.a-and-t-labs.com/K6_Sw_Amp
It uses the familiar irfp9240/240.
I am building Susan Parker's subwoofer with double 16" speakers.
When it is finished i am thinking of building this amp to power it.
With a regular powersupply of course.
Interesting about the design is its flexibility i think.
Have a really peacefull Christmas, Terry.
jacco.
http://www.a-and-t-labs.com/K6_Sw_Amp
It uses the familiar irfp9240/240.
I am building Susan Parker's subwoofer with double 16" speakers.
When it is finished i am thinking of building this amp to power it.
With a regular powersupply of course.
Interesting about the design is its flexibility i think.
Have a really peacefull Christmas, Terry.
jacco.
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