I sent a request for information to Rockna about a toroid with the same specs. There may be too many unknowns about them regarding how much time, and delivery reliability, but I thought that we should find out the basics at least. I have heard other rumors about very reasonably priced toroids from that area....
Mark
Mind you guys, this is a Class A circuit, and the regulation of the trafo is quite important. Don't skimp on that part.
Better up the VA rating a bit, for this fine preamp. I am going for 2 160VA trafos with 2x55V and 2x12V, one of each. They will power a dual mono configuration. For the original BosoZ, NP recommended 2 pcs. 30VA trafos. Mayby this circuit needs a bit more.
Just my 2 cents
Steen
steenoe said:Mind you guys, this is a Class A circuit, and the regulation of the trafo is quite important. Don't skimp on that part.
Better up the VA rating a bit, for this fine preamp. I am going for 2 160VA trafos with 2x55V and 2x12V, one of each. They will power a dual mono configuration. For the original BosoZ, NP recommended 2 pcs. 30VA trafos. Mayby this circuit needs a bit more.
Just my 2 cents
Steen
Hah, what does 2 cents buy nowadays!
Steen the members buying kits will be getting a 50VA transformer with each PSU. For most setups that will will mean 2 transformers for stereo operation.
As far as a 160VA Dual 55 secondary, I assume you will run the secondaries in parallel for more current as 50-0-50 is not needed for Kari's boards.
BTW I have a Plitron 300VA dual 55AC secondaries I will likely be selling, just think of how many boards you could power with those secondaries in parallel!
Regards
Anthony
I intend to use one secondary for each psu board. As I said Dual mono setup, well not really anyway, guess I would need 4 trafos for that
But 4 seperate secondaries, kind of cut it for me 2 PSU boards, with their own dedicated secondaries.I was just hinting that a bigger then needed trafo, might be a good thing
I will surely go for that Steen.
Edit.
Not much, except for a good idea now and then
But they mostly comes for free
Coulomb said:
BTW I have a Plitron 300VA dual 55AC secondaries I will likely be selling, just think of how many boards you could power with those secondaries in parallel!
Regards
Anthony
I would be very much interested in that transformer since I need to power up 6 kits. If you do not have bayer on your mind, I would be interested in adding that to my kits.
AR2
Oops! Found my invoice in my deleted items folder. 
Parts Express has a transformer P/N 129-080 http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-080 for $5.
It's described as a 28 VCT transformer, but in reality it has two independent 14V windings. They don't give a VA rating, but it should be somewhere around 100VA given its size. A pair could provide -9V and ~50V rails.
Parts Express has a transformer P/N 129-080 http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-080 for $5.
It's described as a 28 VCT transformer, but in reality it has two independent 14V windings. They don't give a VA rating, but it should be somewhere around 100VA given its size. A pair could provide -9V and ~50V rails.
Here's the response from Romania....just to add more confusion...
Hello,
thank you for your inquiry.
I can complete your order in the requested time (it will take 2-3 weeks). The price per toroid is about 7.7 euro.
We have a total of 50 kg to ship.
The shipping via EMS is about 215 euro for a max. 30 kg package.
The second package of 20 kg is 150 euro.
So total shipping : 365 euro.
Total toroids : 539 euro.
If I can find a cheaper alternative for shipping I'll let you know.
Kind Regards,
Nicolae Jitariu
Rockna Electronics
www.rockna-line.com
----- Original Message -----
From: Mark *********
To: office@rockna-line.com
Sent: Thursday, May 19, 2005 7:55 PM
Subject: Toroid transformers needed
To Whom It May Concern:
Hello, we are building a group project for the DIYAudio.com web forum. It is the largest forum on line for people that want to make their own audio equipment, with over 30,000 members. You company was mentioned to me because some people noticed that you can supply toroid transformers. (there is some interest in your PC CD control card by people in our group too)
Often we will combine our efforts to purchase what we need.
In this case it is a :
0-55(750mA) and 0-12(750mA) toroid with 110v primeries. Total of 50 VA
We would need about 70 of them. Would you be able to get this quantity in a reasonable time, (1 month) considering that they will probably have to be custom made? What would you estimate that the price would be, and how would we pay you? Also could you estimate shipping to Canada or the USA?
Thank you,
Mark *********
Moderator, DIYAudio.com
Hello,
thank you for your inquiry.
I can complete your order in the requested time (it will take 2-3 weeks). The price per toroid is about 7.7 euro.
We have a total of 50 kg to ship.
The shipping via EMS is about 215 euro for a max. 30 kg package.
The second package of 20 kg is 150 euro.
So total shipping : 365 euro.
Total toroids : 539 euro.
If I can find a cheaper alternative for shipping I'll let you know.
Kind Regards,
Nicolae Jitariu
Rockna Electronics
www.rockna-line.com
----- Original Message -----
From: Mark *********
To: office@rockna-line.com
Sent: Thursday, May 19, 2005 7:55 PM
Subject: Toroid transformers needed
To Whom It May Concern:
Hello, we are building a group project for the DIYAudio.com web forum. It is the largest forum on line for people that want to make their own audio equipment, with over 30,000 members. You company was mentioned to me because some people noticed that you can supply toroid transformers. (there is some interest in your PC CD control card by people in our group too)
Often we will combine our efforts to purchase what we need.
In this case it is a :
0-55(750mA) and 0-12(750mA) toroid with 110v primeries. Total of 50 VA
We would need about 70 of them. Would you be able to get this quantity in a reasonable time, (1 month) considering that they will probably have to be custom made? What would you estimate that the price would be, and how would we pay you? Also could you estimate shipping to Canada or the USA?
Thank you,
Mark *********
Moderator, DIYAudio.com
I am leaning towards a 50VA R-CORE transformer from DIYCLUB Biz that is off the shelf 4 x 0-18VA. That is an even split of 4 x 694 mA secondaries which would provide 0-54VAC @ 694 mA and 0-18 @ 694 mA. This would be plenty for a Kari's BOSOZ power supply and two preamps from what I have read.
These R-CORE transformers wiegh 0.7 Kilograms each, 454gm equals 1 pound for our non metric friends. This makes these transformers a hefty product to be sure, which at least to me indicates that are not some cheap trinket.
I do not reccomend EI transformers for preamps Due to the Magnetic field they generate and Toroids generally have too much bandwidth to be inherently quite. I think an R-CORE is the best choice for this application. I have attached a Photo, they look to be of good quality and have the rough dimensions of 3.5" square and 2" in hieght.
I would ask that the members that have not submitted thier Pre payments as yet do so soon. These will have to be shipped to me surface mail and will take at least 4 to 6 weeks to arrive.
Regards
Anthony
These R-CORE transformers wiegh 0.7 Kilograms each, 454gm equals 1 pound for our non metric friends. This makes these transformers a hefty product to be sure, which at least to me indicates that are not some cheap trinket.
I do not reccomend EI transformers for preamps Due to the Magnetic field they generate and Toroids generally have too much bandwidth to be inherently quite. I think an R-CORE is the best choice for this application. I have attached a Photo, they look to be of good quality and have the rough dimensions of 3.5" square and 2" in hieght.
I would ask that the members that have not submitted thier Pre payments as yet do so soon. These will have to be shipped to me surface mail and will take at least 4 to 6 weeks to arrive.
Regards
Anthony
Attachments
Illusus said:
Doh! I must have posted it half a dozen times!
Here it is again, it's actually an extension of Kari's Wikki.
Kari's Wikki, scroll down to second list for Parts GB section.
Regards
Anthony
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.