Hi David,
Check the data sheets. An EI transformer is normally taller with a smaller "footprint" than a Toroid type. An EI transformer tends to run cooler (because the core can get rid of heat easily) and is not as sensitive to a net "DC" flux in the core. They often have lower inrush currents as well.
If you order a transformer, make sure you have an electrostatic shield built in. It used to be normal practice for instrumentation and audio work.
-Chris
Check the data sheets. An EI transformer is normally taller with a smaller "footprint" than a Toroid type. An EI transformer tends to run cooler (because the core can get rid of heat easily) and is not as sensitive to a net "DC" flux in the core. They often have lower inrush currents as well.
If you order a transformer, make sure you have an electrostatic shield built in. It used to be normal practice for instrumentation and audio work.
-Chris
Hi Chris,
Sorry, I guess I didn't phrase the question correctly.
I was wondering more about magnetic field issues between the two, though size is a close second. (Amplifier of course! 😀 )
I've been looking to build a linear PSU.
Secondaries: say 4x (45V AC @16.67 A)
1x (20V AC @1A) (for Soft Start)
This should require ~3020VA.
Screened a must. I would like it potted and canned as well.
All of this would have to be a custom unit, unless I miraculously find one surplus somewhere. ( I can always hope, right? 😉 )
I was considering stacking two of the LoNo's @ 1500VA ea. and add a small third unit for soft start. Would this be the cheaper way to go? (Off the shelf units)? I'm really not sure for something of this size.
If an EI can do this without any field issues, and hopefully less $$$, I'm on it!
Thanks,
David.
Sorry, I guess I didn't phrase the question correctly.
I was wondering more about magnetic field issues between the two, though size is a close second. (Amplifier of course! 😀 )
I've been looking to build a linear PSU.
Secondaries: say 4x (45V AC @16.67 A)
1x (20V AC @1A) (for Soft Start)
This should require ~3020VA.
Screened a must. I would like it potted and canned as well.
All of this would have to be a custom unit, unless I miraculously find one surplus somewhere. ( I can always hope, right? 😉 )
I was considering stacking two of the LoNo's @ 1500VA ea. and add a small third unit for soft start. Would this be the cheaper way to go? (Off the shelf units)? I'm really not sure for something of this size.
If an EI can do this without any field issues, and hopefully less $$$, I'm on it!
Thanks,
David.
Haveing transformers made are cheaper than you'd think....
I can have about two EI 300W transformers made for the price of one 300VA torroidal form the RS catalog, useing a small transformer manufacturer in our local industrial area... places like these shoul dbe common all over the world where there are a few factories, as those places eat transformers...
My only negative comment about EI's is the size.... for anything over 200VA you are likely looking at a case height of at least 4 to 5 inches.. which ups the ante alot if you were going to buy a case.
I can have about two EI 300W transformers made for the price of one 300VA torroidal form the RS catalog, useing a small transformer manufacturer in our local industrial area... places like these shoul dbe common all over the world where there are a few factories, as those places eat transformers...
My only negative comment about EI's is the size.... for anything over 200VA you are likely looking at a case height of at least 4 to 5 inches.. which ups the ante alot if you were going to buy a case.
Hi Nordic,
What I would do is use two transformers, EI core. You will require two circuits to supply enough current anyway. Two power cords. I've owned amps like that. You are really talking about a pair of mono amplifiers in one case. Thinking about it, unless there is a compelling reason to use one case, I would use two. Each will be heavy in it's own right.
Potting will increase the core temperature of a toroid, concentrate on cooling. I would use an EI core for that very reason. Radiated hum is normally not too much of a problem either. Use a sub chassis for the EI core and have it double as a heat radiator. Use thermal compound between the sub chassis and the core. Now the stray flux is not in the chassis! 😀 Use a steel divider between the transformer and the rest of the primary circuitry and the audio circuitry. Any digital uPs can live with the primary circuit, or their own little island if you use any. Rotate the transformer to minimize flux before drilling and mounting it.
The quality of the transformer also plays a large part in radiated energy. A cheap toroid can be worse than an EI.
Your soft start can be powered from the existing secondary windings or directly from the mains. There are chips that are line operated and will provide 5V or so. You can use a small "housekeeping" transformer also. The more stock your transformer selections are, the less expensive they will normally be.
-Chris
Yup, completely agree on all points.
What I would do is use two transformers, EI core. You will require two circuits to supply enough current anyway. Two power cords. I've owned amps like that. You are really talking about a pair of mono amplifiers in one case. Thinking about it, unless there is a compelling reason to use one case, I would use two. Each will be heavy in it's own right.
Potting will increase the core temperature of a toroid, concentrate on cooling. I would use an EI core for that very reason. Radiated hum is normally not too much of a problem either. Use a sub chassis for the EI core and have it double as a heat radiator. Use thermal compound between the sub chassis and the core. Now the stray flux is not in the chassis! 😀 Use a steel divider between the transformer and the rest of the primary circuitry and the audio circuitry. Any digital uPs can live with the primary circuit, or their own little island if you use any. Rotate the transformer to minimize flux before drilling and mounting it.
The quality of the transformer also plays a large part in radiated energy. A cheap toroid can be worse than an EI.
Your soft start can be powered from the existing secondary windings or directly from the mains. There are chips that are line operated and will provide 5V or so. You can use a small "housekeeping" transformer also. The more stock your transformer selections are, the less expensive they will normally be.
-Chris
HI Chris & Nordic
Each transformer was meant for a monoblock. (I was thinking 4x secondaries for current distribution).
The case would be 10 in tall, min, and 20in deep, min. Attempting to keep width at 19 in. The heat sinks would leave me 9.5~10 in internal width. I was thinking I could fit everything into a single case, depending on the actual parts used.
The second PSU chassis is a possibility, but I thought I'd wait to acquire the parts at least before committing to a single or dual chassis configuration per monoblock.
The EI is sounding better every second! 😉 Especially at less money.
So far, email from Avel Lindberg didn't seem that interested in a small custom order, but will try again just to see. Plitron doesn't have a US distributor, so I'll have to see there as well via direct contact.
I also need to locate an EI source. (Will look up RS! Thanks Nordic! 😀 )
And No, I love stock. Easy to get.
Again, Thanks Guys!
David.
Each transformer was meant for a monoblock. (I was thinking 4x secondaries for current distribution).
The case would be 10 in tall, min, and 20in deep, min. Attempting to keep width at 19 in. The heat sinks would leave me 9.5~10 in internal width. I was thinking I could fit everything into a single case, depending on the actual parts used.
The second PSU chassis is a possibility, but I thought I'd wait to acquire the parts at least before committing to a single or dual chassis configuration per monoblock.
The EI is sounding better every second! 😉 Especially at less money.
So far, email from Avel Lindberg didn't seem that interested in a small custom order, but will try again just to see. Plitron doesn't have a US distributor, so I'll have to see there as well via direct contact.
I also need to locate an EI source. (Will look up RS! Thanks Nordic! 😀 )
And No, I love stock. Easy to get.
Again, Thanks Guys!
David.
btw
my package is gone 🙁
the seller stopped replying to mails , also wont answer the phone .
i opened a dispute , he didnt reply there also, filed a complaint to ebay , they said i'm too late .
i didnt file a complaint earlier because the seller was comunicating with me , he told me he will check it out , and the fleed.
1000$ gone 🙁
my package is gone 🙁
the seller stopped replying to mails , also wont answer the phone .
i opened a dispute , he didnt reply there also, filed a complaint to ebay , they said i'm too late .
i didnt file a complaint earlier because the seller was comunicating with me , he told me he will check it out , and the fleed.
1000$ gone 🙁
Hi sss,
Sorry to hear that. I've lost a small package in the mail once. Left the 'States but never made it into Canada.
-Chris
Sorry to hear that. I've lost a small package in the mail once. Left the 'States but never made it into Canada.
-Chris
Struck AGAIN!!!
I managed another sucking ebayer. I sold a old radio amplifier on ebay and was paid with Paypal. Upon entry to canada this ebayer contacted me asking me to de value the purchase price which was slightly more than $110.00 and threatened to send the item back and collect his money back if I didn't. This ebayer claimed he was going to have to pay a customs tax of $55 on this item.
Could it possibly run $55.00 tax on a $112.00 part?
Completely ticked off at this point after reading his response to me calling me a F***er I offered to send his emails to ebay and to the Canadian government. The toping on the cake is that the SOB will probably end up getting his money back and I will be out my money for conducting an honest transaction.
I managed another sucking ebayer. I sold a old radio amplifier on ebay and was paid with Paypal. Upon entry to canada this ebayer contacted me asking me to de value the purchase price which was slightly more than $110.00 and threatened to send the item back and collect his money back if I didn't. This ebayer claimed he was going to have to pay a customs tax of $55 on this item.
Could it possibly run $55.00 tax on a $112.00 part?
Completely ticked off at this point after reading his response to me calling me a F***er I offered to send his emails to ebay and to the Canadian government. The toping on the cake is that the SOB will probably end up getting his money back and I will be out my money for conducting an honest transaction.
Let me guess- did you use UPS? They (and some other carriers) will ding the recipient for an outrageous customs clearance fee.
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