| roadkill |
Hello Bangalorean DIYers,
I posted some time ago asking where I can pick up a toroid core transformer in bangalore. Well, now I know. Miracle transformers will supply them in single-piece quantities, and even courier them to your home (for just Rs. 30!). I ordered a 225VA 25Vx2 toroid (model no M225 50) from them, it cost me Rs. 915 (MRP). Total charge including shipping was Rs. 1225.
Website: www.toroidal.com
Since then, they updated their site, they also offer encapsulated transformers, good for preamp supplies and such (small, starts at just 2VA!!!).
I've only unpacked the toroid, will check it out tomorrow (spent the day at URock :)). It will end up feeding five gainclones (LM3886). Yes I know it's underpowered, but I wont be using it near full amplitude. Besides, I will be using a powered sub.
Hope this post helped! |
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| ashwin |
roadkill,
thanks for that info! I see that they also offer audio output transformers for tube amps. I didn't know that kind of thing was still being manufactured! So now I can play around with tubes for a while :)
Any particular reason (apart from size) you're using torroidals instead of EI?
- Ashwin |
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| tcpip |
| quote: | Originally posted by roadkill
Miracle transformers will supply them in single-piece quantities, and even courier them to your home (for just Rs. 30!). |
This is fantastic news! I presume they'll ship anywhere in India. I don't even know of any toroidal tranny guys with ready-made list of models in Bombay, let alone B'lore. I keep hearing that there are guys who make toroids in Bombay, but I've yet to meet anyone who can (i) sell retail, (ii) has a range of standard specs. And the fact that these chaps have a Website is an added blessing. Bolton doesn't yet have a Website, and probably never will, for instance.
Great news! Thanks.
The price premium is interesting, though. I bought a 26-0-26V, 5A (that makes it a mite more than 250VA?) E+I transformer through Angshu's good offices from a guy called "Guru" in Delhi, and that cost me Rs.550. (I too plan to power some gainclones or P3As with it.) Your toroid is twice as expensive. But I guess I can now make my chassis slimmer.
Toroids should be ideal for low-current ratings (500mA or less?) for preamps, where I can really cram things tight and not worry about EMI. For poweramps, I'm quite often more open to E+I, specially if toroids cost this much extra.
Tarun |
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| roadkill |
ashwin, I used a toroid mostly for the size reduction. I am planning to try a cabinet design featured in Elektor, where they bolt on aluminium sheets to a pair of heatsinks. The heatsinks form the side walls, and the sheets form the top, bottom, rear and front panels. The largest heatsink extrusions I could find did not have enough height to fit an E-I of 225VA. Then there are other issues, like less EMI, simple means of mounting, etc.
tarun, the rumours must be true :) I've been to Lamington rd only thrice, there's this very dank-looking bridge you have to pass under if you're getting off at the local station, there was a hole-in-the-wall shop which had toroids. I didnt have enough money to buy them at the time (it was the last time I was there, on my way out... argh!) He also had C-core trannys, which apparently can be made smaller than a regular E-I, tho not as slim as a toroid. EMI is less, too, and there won't be a problem with inrush current like toroids have. Freight to mumbai would probably cost a bit more than just Rs. 30, it weighed about 3 kgs in all. |
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| ashwin |
| quote: | Originally posted by roadkill
The largest heatsink extrusions I could find did not have enough height to fit an E-I of 225VA. Then there are other issues, like less EMI, simple means of mounting, etc.
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Hmm, I have the same problem, my 15-0-15V/5A is about 5" high. But the place where I bought the heatsink did have some tall extrusions (6-7" IIRC) which I intend to try. Where did you get your heatsinks from? I got mine from an Al shop at the entrance to SP road (from the town hall side).
- Ashwin |
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| roadkill |
ashwin,
I got my heatsinks from Cee Pee electronics (near Vishal). They're fairly expensive, too, so I guess I could try the place you mentioned. What's it called? Hope they're anodized ones... |
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| ashok |
Ashwin,
Where did you find the audio transformers for tubes on the Miracle web site ? I checked and seem to have missed them.
I have had a few dealings lately with them and they did not have any transformers for tubes. However they do have line level ( 70 V and 100V ) audio transformers for audio distribution purposes. I am not sure if you can use these with tubes . Their specs may not be suitable. On the other hand have you discovered that they can be used as tube OPT's ? If so that's great. Let us know.
Cheers. |
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| ashwin |
| quote: | Originally posted by roadkill
ashwin,
I got my heatsinks from Cee Pee electronics (near Vishal). They're fairly expensive, too, so I guess I could try the place you mentioned. What's it called? Hope they're anodized ones... |
My place was called Maruti Metals. Not an electronics shop, more an Al extrusions shop. But the Al was expensive.
| quote: | Originally posted by ashok
Ashwin,
Where did you find the audio transformers for tubes on the Miracle web site ? I checked and seem to have missed them.
I have had a few dealings lately with them and they did not have any transformers for tubes. However they do have line level ( 70 V and 100V ) audio transformers for audio distribution purposes. I am not sure if you can use these with tubes . Their specs may not be suitable. On the other hand have you discovered that they can be used as tube OPT's ? If so that's great. Let us know.
Cheers. |
Well, I'm not a tube expert, so you may be right. I assumed that they were OPTs because of the following quote on their page:
"Audio Line Matching Transformers 40
EDIT: dunno how this incomplete post happened... |
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| ashwin |
| quote: | Originally posted by roadkill
ashwin,
I got my heatsinks from Cee Pee electronics (near Vishal). They're fairly expensive, too, so I guess I could try the place you mentioned. What's it called? Hope they're anodized ones... |
roadkill, my place was called Maruti Metals. Not an electronics shop, more an Al extrusions shop. But the Al was expensive.
| quote: | Originally posted by ashok
Ashwin,
Where did you find the audio transformers for tubes on the Miracle web site ? I checked and seem to have missed them.
I have had a few dealings lately with them and they did not have any transformers for tubes. However they do have line level ( 70 V and 100V ) audio transformers for audio distribution purposes. I am not sure if you can use these with tubes . Their specs may not be suitable. On the other hand have you discovered that they can be used as tube OPT's ? If so that's great. Let us know.
Cheers. |
Well, I'm not a tube expert, so you may be right. I assumed that they were OPTs because of the following quote on their page:
"Audio Line Matching Transformers 40 HZ TO 20,000 HZ
The purpose of this Transformer is to match the Impedance of the loudspeaker or a number of loudspeakers to the optimum load of the tube or transistor. In other words, the transformer transforms the Impedance of the speaker, so that the impedance which it presents to the primary winding is equal to the load of the Output stage active element (tube to transistor)."
On their home page, click products -> transformers -> Audio Line Matching Transformers.
So what's the deal? Are they OPTs or not?
Why would you need a 70/100V rated transformer for audio distribution? I thought the 70/100V was for the high anode voltage of a tube stage.
- Ashwin |
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| ashok |
| quote: | | Why would you need a 70/100V rated transformer for audio distribution |
Same reason as High Voltage power transmission. It cuts down on losses in the interconnecting wire. Higher voltage means lower current . So IxR loss drops.
70 and 100 volts distribution transformers are used universally .
I have been quite blind to the fact that if they made those transformers , I could get them to make units to our specs.
There is however a difference between OK transformers and superb transformers. We need to explore that possibility.
I did not read the blurb that followed it on the web page. I will follow up on this and let you know what transpires. If we can get some modified units I will test them out and see what we get.
Cheers. |
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| brokenbinil |
i want to use a trodoial tranformer in my amp. it presently gives a out put of 40 + 40 Watts and then i'm using a 3amp transformer for the power supply. but i have some doubts: do i need a core with the tordoil or do i use a air core. i need one in the higher amp range ... around 8 to 10 amps. please advice where i might get them in indai and how expensive are they
Binil |
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| ashok |
Brokenbinil,
If you are trying to fit a budget , you might go broke buying toroidal transformers. For the same VA , toroids are more expensive. Toroid power transformers are not air core , they all have a iron strip core that's wound like a ring.
Why would you want a 10A transformer for a 40 watt amp? What voltage?
It might be a great idea for you to read up about toroidal transformers on the Net. You will get to know its plus and minus points. I think for normal applications there is nothing to beat the lowly EI core transformer.
You can go to www.toroidal.com for a supplier from Bangalore . There are also suppliers in Delhi who keep advertising in EFY and Elektor (India) magazines. Check it out. But first get on to the Net and read more about toroidal transformers.
Cheers. |
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| corbato |
| quote: | Originally posted by ashwin
roadkill,
thanks for that info! I see that they also offer audio output transformers for tube amps. I didn't know that kind of thing was still being manufactured! So now I can play around with tubes for a while :)
Any particular reason (apart from size) you're using torroidals instead of EI?
- Ashwin |
Those are line matching transformer and not OPT's. They are used mostly in running long lengths of connector to Horns (you know...chonga’s..) spread across several zones. Well that’s the idea. I don't know how many of the local PA rental folks actually use such things.
Besides, as Ashok has rightly posted, there are several factors involved in making a good OPT. You can wind an OPT to exact load lines as per the Tube datasheet and it still may sound horrible. Winding techniques, core material, interleaving and such make a lot of difference. Most OPT's that were made in India in the past were PA quality accept some Philips SE OPT’s and some Delta "Hi-Fi" range.
I’ve tested/used most Indian OPT’s. Recently, I came across a small company in Calcutta who really impressed me with their work. They are still winding OPT’s for a small niche market of Guitar amps. You will surprised to know just how many Cal musicians still use valve combo’s. The guys had his funda very clear. I’m getting a pair of SE OPT’s for a EL34 project from them. I also bought from them, off the shelf, a spring reverb driver transformer for suitable for the 12AT7. Pending a critical tetsing of these guy's product, I thing importing a Hammond is still the best option. They are cheap, reasonable good and available in a wide spec. I can see George disapproving :whazzat: He has been thoroghly spoilt by his Magnequests.
Nevertheless, an interesting find that b’lore company is |
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| ashwin |
| quote: | Originally posted by corbato
Those are line matching transformer and not OPT's. They are used mostly in running long lengths of connector to Horns (you know...chonga’s..) spread across several zones. Well that’s the idea. I don't know how many of the local PA rental folks actually use such things.
Besides, as Ashok has rightly posted, there are several factors involved in making a good OPT. You can wind an OPT to exact load lines as per the Tube datasheet and it still may sound horrible. Winding techniques, core material, interleaving and such make a lot of difference. Most OPT's that were made in India in the past were PA quality accept some Philips SE OPT’s and some Delta "Hi-Fi" range.
I’ve tested/used most Indian OPT’s. Recently, I came across a small company in Calcutta who really impressed me with their work. They are still winding OPT’s for a small niche market of Guitar amps. You will surprised to know just how many Cal musicians still use valve combo’s. The guys had his funda very clear. I’m getting a pair of SE OPT’s for a EL34 project from them. I also bought from them, off the shelf, a spring reverb driver transformer for suitable for the 12AT7. Pending a critical tetsing of these guy's product, I thing importing a Hammond is still the best option. They are cheap, reasonable good and available in a wide spec. I can see George disapproving :whazzat: He has been thoroghly spoilt by his Magnequests.
Nevertheless, an interesting find that b’lore company is |
Ashok, thanks for that info. I didn't realise that such an application existed (Googling gave me more info here : http://www.edcorusa.com/gadgeteer/tech_notes/tn13.htm)
Would measuring the freq response of a transformer be as simple as connecting a signal generator at one winding and sweeping it while measuring the ourput at the other winding? If that's the case, then I would be interested in measuring some transformers. The latest Elektor has an article on tube headphone amps where the author uses power supply transformers as the OPTs. It would be interesting to see their response. Perhaps you already know the frequency limits of some power transformers?
- Ashwin |
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| brokenbinil |
| quote: | Originally posted by ashok
Brokenbinil,
If you are trying to fit a budget , you might go broke buying toroidal transformers. For the same VA , toroids are more expensive. Toroid power transformers are not air core , they all have a iron strip core that's wound like a ring.
Why would you want a 10A transformer for a 40 watt amp? What voltage?
It might be a great idea for you to read up about toroidal transformers on the Net. You will get to know its plus and minus points. I think for normal applications there is nothing to beat the lowly EI core transformer.
You can go to www.toroidal.com for a supplier from Bangalore . There are also suppliers in Delhi who keep advertising in EFY and Elektor (India) magazines. Check it out. But first get on to the Net and read more about toroidal transformers.
Cheers. |
hey ashok... thanks ... well the website was very infomative and it kinda of kleared my doubts.... tell me does tordoils help reduse the humming .... well any way keep in touch |
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| corbato |
| quote: | Originally posted by ashwin
Would measuring the freq response of a transformer .... |
A basic test setup would be an AF generator in the primary applying a sinewave with a constant voltage to be measured by an AF meter at the other end. You will need to apply several hundred voltages to properly measure the low freq response. I had some details on how to conduct such test on a wider level somewhere. Will try to find and post here.
Philips OPT's I have tested down to 40Hz and the Delta rolls off at 55Hz. But thet are not consistent across samples.
brokenbini:
You will really be 'broken' purchasing a several hunderd VA tranny (as your application seem to suggest). I have used toriods only with low power cricuits. And they are very still expensive.
What is you actually application? What class and rating amp you are building? |
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| ashok |
There are two kinds of 50Hz hum. One is magnetically induced and the other is electrical . You also have 100 Hz ripple from the rectified power supply . The 100Hz ripple does not sound like 50Hz "hum".
Toroidal transformers radiate less magnetic field around them and so tend to induce less 50 Hz hum in circuits sensitive to magnetic fields. Electrical hum pick is generally not due to the transformer.
The EI transformer if placed properly can also work very well. If the transformers are placed at a distance , it doesn't make a difference which type you use.
Toroids generally have less power loss and better regulation ( ac voltage drop ) . They are good especially for very compact amps. If you have more space , you can make do with an EI type. Especially for power amps - like the one you have - an EI should be good enough. Then again , you have good and bad power transformers. Make sure you use one with good regulation. Less than10% drop at full load is a minimum. Average transformers in the market are MUCH worse than that and also very cheap. So check the regulation specs carefully.
Cheers. |
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| tcpip |
| quote: | Originally posted by ashok
The EI transformer if placed properly can also work very well. If the transformers are placed at a distance , it doesn't make a difference which type you use.
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I have been thinking of enclosing an E+I transformer in a metal box, ensuring full electrical conductivity through all its surfaces. Will this take care of the magnetic radiation? Randy Slone's book seems to indicate so.
Incidentally, this has in fact become a constraint on the size of the power amp chassis for me. I need to place the (largish) E+I transformer in a small metal box, and place this box inside the chassis. For instance, with the 5A 25-0-25 E+I that I have, the smallest enclosing box I found on L.Road is 4" in height, thus making 2U height chassis impossible.
Tarun |
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| corbato |
| quote: | Originally posted by tcpip
....enclosing an E+I transformer in a metal box... |
For a majority of Power Amp I don't think that is a necessity. Just take care to orient it in such a way that the flux doesn’t interfere with the signal. At most you can think of a metal sheet partition, e.i, dividing your amp into a tranny and the signal section. But if you application is a Phono amp then enclosing and grounding the tranny would definitely help matters. It will be even better if the tranny is external. Phono amp will require a small tranny so finding a small enclosure wouldn’t be a problem.
Tube amp will off-course be an exception. You will need to consider the relative flux field of your OPT, Power T and Choke (if any) to ensure that thing don't cross into each another. |
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| gjo |
Hi Folks
Just saw this thread. I bought two toroidals(IIRC 150-200VA or therabouts) for my AKSA ss amp from Miracle Electronics. Nilesh Vad is the guy there, he is a customer service oriented guy, and I have no hesitation in recommending him. I used two trannies and used a mu-metal partition to shield the two, since mine was a dual mono design.
Ashok, Magnequest OPTs are a different kettle of fish, you know that! My latest toy-arrived this morning- is a Grounded Grid tube preamp kit from Transcendent Sound, which is to be mated to my tube power amp. Check www.transcendentsound.com for details. The customs guys gave my brother a hard time when he arrived at Bangalore on the Lufthansa flight-they first told him that the duty free allowance for him(He is a US citizen) is only Rs 4000, then when he said he would pay duty, they told him that the bank counter was closed, so it would be better to remit it into their pockets!! He was tired out after the long trip, he decided that when in India play by Indian rules..
Is ko sunne ke liye aap jaroor idhar ek trip plan karna..
Rgds
George |
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| corbato |
George bhai,
Saar..you keep us salivating onleee :smash:
I can visualise the scenario. Your Welbourne and the 12 saal ka maal giving good company.
But if your latest acquisition features anything less than a decent pair of NOS 12AU7, them chuck them out (the tubes) immediately. I will send to you, free, a prefect pair of Telefunken NOS Ribbed Plates. This is one is on me. Kya karen. Compulsion hai naa. Gotta keep my source of 12 saal ka maal in good humour ;) |
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| tcpip |
| quote: | Originally posted by corbato
For a majority of Power Amp I don't think that is a necessity. Just take care to orient it in such a way that the flux doesn’t interfere with the signal... |
Okay, will try orientation without enclosure. What should I listen for to know there are any problems? Will it be just a clear hum, or do I look for more subtle problems? And if it doesn't work, I guess I'll turn it by 90 deg and try again.
BTW, I wrote to the www.toroidal.com chaps more than a week ago, asking them whether they could supply me four of their 15-0-15V, 500mA model. No answer.
Tarun |
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| tcpip |
| quote: | Originally posted by roadkill
ashwin, I used a toroid mostly for the size reduction. I am planning to try a cabinet design featured in Elektor, where they bolt on aluminium sheets to a pair of heatsinks. The heatsinks form the side walls, and the sheets form the top, bottom, rear and front panels. The largest heatsink extrusions I could find did not have enough height to fit an E-I of 225VA. Then there are other issues, like less EMI, simple means of mounting, etc. |
I got heatsinks from Precious and Visha on L.Road (both source from the same place, I think, because they both carry the same catalog), and I've seen at least two sections with straight tall fins of 100mm width, and one of at least 180mm width. These can be purchased to any length you want, and they bill by the centimetre length. The widest one is priced at Rs.25/cm. Once you place an order, they cut a piece of the right length, clean the rough-cut edge somewhat using files, and then anodise it black. All this takes two weeks, but at least you can get good heatsinks of arbitrary lengths at a price a small fraction of the Weikfield ones in the US. :)
So, with these sizes, you can easily get a heatsink wide enough to stand on its side taller than even a fairly large E+I transformer. I once got a 600VA E+I made and its height is certainly less than 180mm. The 250VA one I got from Delhi is about 82mm tall.
Tarun |
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| ashwin |
| quote: | Originally posted by tcpip
I got heatsinks from Precious and Visha on L.Road (both source from the same place, I think, because they both carry the same catalog), and I've seen at least two sections with straight tall fins of 100mm width, and one of at least 180mm width. These can be purchased to any length you want, and they bill by the centimetre length. The widest one is priced at Rs.25/cm. Once you place an order, they cut a piece of the right length, clean the rough-cut edge somewhat using files, and then anodise it black. All this takes two weeks, but at least you can get good heatsinks of arbitrary lengths at a price a small fraction of the Weikfield ones in the US. :)
So, with these sizes, you can easily get a heatsink wide enough to stand on its side taller than even a fairly large E+I transformer. I once got a 600VA E+I made and its height is certainly less than 180mm. The 250VA one I got from Delhi is about 82mm tall.
Tarun |
Argh! why isn't there such a place in Bangalore? Does someone know of such a place in B'lore?
- Ashwin |
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| gjo |
| quote: | | BTW, I wrote to the www.toroidal.com chaps more than a week ago, asking them whether they could supply me four of their 15-0-15V, 500mA model. No answer. |
Tarun
FYI the email id for these guys is miracle@vsnl.com. Ph 23485149. If you need me to talk to them let me know. I found them to be very prompt. You can email me offlist at gjo@dtsam.com
Ashok ( alias Gen Al Sahaf)
Tubes are 12AU7 JJs, and not NOS. So I may take you up on your very generous offer. I have done the parts list inventory today, found two resistors short (10K, 2w, will buy them locally) hope to start on assembly shortly. Luckily I had bought some good silver solder from Welborne Labs last year for future projects.
George
P.S. I just got the Diana Krall Live in Paris CD and am enjoying listening to her. |
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| peterpan73 |
OK I .... I am a Ham radio operator (besides a novice Audio DIY) and am homebrewing a 35 Ampere 13.8V DC power supply for my transceivers. Now can someone tell me how much it would cost me to buy one of those nice toroid transformers with an appropriate VA rating for my application and from where in india??
peterpan73
:confused: |
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| tcpip |
| quote: | Originally posted by corbato
Those are line matching transformer and not OPT's. They are used mostly in running long lengths of connector to Horns (you know...chonga’s..) spread across several zones. |
Have you checked out the audio frequency transformers on www.rsindia.com? I found quite a range. Unfortunately, I have absolutely no knowledge of such stuff, so I don't know whether it'll meet the needs of you bottlehead types. :)
| quote: | Originally posted by ashwin
Argh! why isn't there such a place in Bangalore? Does someone know of such a place in B'lore? |
Hey, don't insult India's only cosmopolitan city by comparing it with small towns like B'lore and Sunnyvale and other Silicon Valley shanty towns. :D
BTW, you can get quite a large sample of high-power heatsinks from RS Components. Check out www.rsindia.com. I was just looking through their Website, and was quite impressed. Unlike the hand-made stuff on L.Road, these have fixed lengths, but I daresay one of them may meet your needs. They have extrusions of widths greater than 200mm... what more does one need? :)
Tarun |
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| tcpip |
| quote: | Originally posted by gjo
FYI the email id for these guys is miracle@vsnl.com. |
That's the email address I wrote to, and it didn't even bounce back.
| quote: | | If you need me to talk to them let me know.... |
If it's not too much trouble, will you please ask them whether they'll be willing to deliver four toroidal transformers, 15-0-15V, 500mA, to Bombay? I can't even tell you the model number; their Website is timing out each time I try. And I'm not in a hurry; I can even wait a month for your reply. :)| quote: | | P.S. I just got the Diana Krall Live in Paris CD and am enjoying listening to her. |
Great CD! The term that best describes her piano playing style on some of those tracks is probably "rock piano." :) My favourite from that album is probably track 9... "Oh I could drink a crate of you and still be on my feet..." She's really poured her heart out into that one. :)
Tarun |
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| gjo |
Hi Tarun
I just called Nilesh's office, he's expected back after an hour and half, will try later today if I can, otherwise tomorrow. I have a few jobs to do today, so I may overlook calling him if I dont remember.
I have four of the other Diana Krall CDs-all are good. Thank God for CD burners!! There are also a lot of American artistes who's labels are not available here easily, but who are also very good. In fact I got a couple of Diana Krall albums from the US about two years ago, after someone recommended her music. The late Eva Cassidy is another really good singer..Another good group is Phish. Even CDs of some golden oldies like BS&T arent easily available here.
George |
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| gjo |
Tarun
I just spoke to Nilesh, and he said that he sees the email himself, doesnt recall your email. Anyway he wants you to resend your enquiry to him at the same email id, he will respond directly, as soon as he sees it.
In case you dont hear from him after a reasonable time frame let me know.
George |
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| tcpip |
| quote: | Originally posted by gjo
I just spoke to Nilesh, and he said that he sees the email himself, doesnt recall your email. Anyway he wants you to resend your enquiry to him at the same email id, he will respond directly, as soon as he sees it.
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You're a real brick. Thanks a ton. :)
Tarun |
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| tcpip |
| quote: | Originally posted by gjo
I just called Nilesh's office, he's expected back after an hour and half, will try later today if I can, otherwise tomorrow. I have a few jobs to do today, so I may overlook calling him if I dont remember. |
Just asked my friend to re-send his email to Miracle. Has been re-sent. Let me see whether I get replies this time.
| quote: | | I have four of the other Diana Krall CDs-all are good. |
I have just two DK CDs in all. One is "The Look of Love" and the other is Paris live. I have been curious about Eva Cassidy; will pick up something whenever I get a chance next. I recently was gifted a Kiri Te Kanawa CD by my wife for my birthday. :) Her voice is really something, but this album (a collection of "standards" sung with different big bands at different times) is a bit more of orchestra than I'd have liked. I would like to see her sing with just her plain voice sometime. Maybe I'll find some such album someday.
Two other female singers I've recently discovered (they've both been around for years) are Bonnie Raitt and Patricia Barber. After "Cafe Blue", I'm now a total PB fan. I believe a new album has been released; I'll see if any of my overseas friends will buy it for me. I believe some of them are even coming out on SACD, which should be most interesting... as of now I have precisely four SACDs. And Bonnie Raitt too is really worth re-visiting. Do you like these singers?
Tarun |
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| tcpip |
| quote: | Originally posted by peterpan73
...am homebrewing a 35 Ampere 13.8V DC power supply for my transceivers. Now can someone tell me how much it would cost me to buy one of those nice toroid transformers with an appropriate VA rating for my application and from where in india??
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You seem to be talking of something like 500VA, roughly. I once got a hefty 600VA transformer made (E+I) for Rs.2750 in Bombay, from a winding works in L.Road. I don't know whether too many people make off-the-shelf 500VA transfies to the specs you want (your current requirement is "abnormally" high :) , while voltage rating is low), so you may have no option but to get a custom job done. If you are on a budget, and space is not much of a problem, why don't you go the E+I way?
Tarun |
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| peterpan73 |
Well I already have a custom wound E-I transformer with the same specs but I have a lot of problems using it for RF work, EMI, excessive back RF leakage owing to antenna system imp.mismatches and other ground loop probs besides hum, inspite of really good LC filtering. I am hoping to try toroids to lessen if not entirely eliminate my noise probs as most MNCs manufacturing PSUs for ham radio purpose use the same.
I don't see or know anyone making the same in North east India.
Please help!
Peterpan73 |
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| peterpan73 |
Hello all,
is there any Inc in India manufacturing these nice Audio isolation trannys that I am hoping to employ in my new homebrew audio amp project. It is a 100W X 10 board amp rack mounted for live/stage use. I intend to use isolated tranny input isolation stages with flat responses in the preamp input of each of these 100W amps to make balanced inputs for connecting to XLR sockets for the amps. I do not want opamp balanced inputs because I have no time making additional circuitry for that. besides modifyuing my present unbalanced input preamp stage circuitry into a balanced input one is not contemplated owing to the fact that the PCBs were bought in kit form to minimise PCB making/etching hassles and I want to finish off this project ASAP. Further more I do not intend using external DI boxes for my inputs. I find the sight of DI boxes dangling everywhere an eyesore.
ALSO Considering THIS TO BE a powerful 1KW RMS power amp consisting of 10 boards, I would appreciate it very much if any of our friends here could help me in recommending an appropriate VA rating for the power toroid tranny to accomodate 1kw of power at 18V max.
Please direct me to useful Indian resources or if they are not known to you, at least to the more promising ones. I would also like to know where I could procure Jensen isolation trannies in India.
I am also looking for 4th order two or three way active crossover schematics employing NE5532s.
Regards and peace to all in the forum.
peterpan73
(DIY audio novice) |
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| peterpan73 |
I checked into the www.rsindia site and tried to get a quick quote for my selected items. It tells me that my items cost P.O.A. What does that mean?
Peterpan73 |
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| gjo |
Tarun
I have Patricia Barber Companion, got it a couple of years ago. I have a fairly large collection of American female vocal-Barbra Streisand, Linda Ronstadt, Carole King, Carly Simon. Joan Baez, Linda Eder(quite good), Faith Hill, Emmylou Harris,Sarah McLachlan, etc, etc. By and large I find that I enjoy listening to them. I plan to get some Alison Krauss when I go to the US hopefully sometime soon. I havent heard Bonnie Riatt, though I have heard of her.
I picked up Norah Jones CD recently it's quite good(hadnt heard the album before I bought it)..Like Navin I( and my sons) have maybe 550-600 CDs and the collection is growing rapidly. My sons are now into MP3, especially after I added a Kenwood CD/MP3 in my car , with Focal drivers, and bought a 120GIG HDD for my son so he could store MP3s to his hearts content..
For them .wav is passe!
I thnk we need to do a swap sometime, would have loved to come via Bombay on my next trip to the US, but with Lufthansa operating direct flights, it's worth paying the premium and avoid the hassles of Santacruz and Sahar-for us folks its really nightmarish walking the plank there-the touts, the weather and the stress of one extra layover are just too much for me to handle-esp on the way back..
Patrick
Let me know the exact specs-or even better email Nilesh Vad, if he doesnt reply in a reasonable time, send a reminder and let me know, I will follow up. Your specs are not complete-the toroidals will only output AC, which you will need to rectify to convert to DC. Check the website and see which model you want from them.
George |
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| peterpan73 |
OK thanks there Tarun.
Don't worry about the rectification.. I'll do that... I'm more worried if I can ever get my hands on such a toroid. 30 to 35 amps at say 15 Volts AC secondary is all that I'm looking for in the V-0-V version.
Peterpan73 |
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| peterpan73 |
| George not Tarun I mean |
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| peterpan73 |
Hello all
Thanks again Tarun and George. Yes these are two seperate toroids I need. One is for my Ham radio POwer supply Unit and the other one for my 1KW/10 Amp. Each amp board of the latter project outputs 100WRMS and consumes 5 Amps at 18VDC, and so i presume I will need a 50 Amp Toroid at 20 V or so AC. Probably 25 Amps each in two toroids to break the heat will also do so long that price differences are not too significant.
I am also in great need for small ferrite and iron core toroid cores of types FT-240-61, T-12 to 200 and FT 23 to 114 in different Mixes (u of 1 to 75 for Iron and 40 to 5000 for ferrites).
Rs india gives me a P.O.A. for a quote what does this mean??
Regards
peterpan73 |
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| gjo |
Patrick
Send your enquiry to Nilesh Vad at Miracle Electronics as I suggested to Tarun, with complete details, I have posted his email id on this thread. In case he doesnt respond, let me know I will follow up.
George |
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| peterpan73 |
Thankyou George, I will do that an hour from now.
I have this very wild idea though.. but please don't make a hilarious one out of this. Welding transformers... at such a high ampere rating and low voltage could they not be used to power up a rack of amps in the 5KW to 10KW region. It could work as a standalone PSU. Even if there were any hum from the windings the cooling oil (in oil cooled ones) could dissipate the mechanically induced hum I think (as a result of loose windings). The only question is .. where do we find the rectifier and filter caps for this monster PSU.
I know this sounds like a crazy idea. but its just a thought OK :confused:
peterpan73 |
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| tcpip |
I had asked for a quote for four pieces of their M1530 (15-0-15v, 500mA). I was told the following breakup: Rs.170 per transformer, totalling Rs.680. Add 16% excise: Rs.109. Add 13% CST: Rs.103. Add 2% P&F (whatever that is): Rs.18. Add courier charges to Bombay: Rs.200. Total: Rs.1109.
So, my landed cost for four transformers in Bombay will be about Rs.280 each. Compare that with Rs.50 each for an E+I picked up without any bill from L.Road. Out of the Rs.280, only Rs.170 is going to the manufacturer's pocket, an amount he fully deserves.
I think Rs.280 is probably affordable if I want to make a high-quality preamp with the transformer close to the rest of the circuitry.
Thanks for the help, George.
Tarun
PS: I hope Hunter Audio reads these posts and picks up some tips about how to do business. :D |
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| peterpan73 |
This wild idea of using a welding trasnformer to power the amps had come about as I would like to 'desperately' minimise POwer supply making costs for my amps. The thought that seperate PSUs need to be constructed for my 3 to 5KW Homebrewed amps of 100 to 500W each deters me. Besides a Welding Tranny cost less than Rs.2500 each. I am eagerly soliciting a reply from any of our readers on this.
Looks like u;'re online Tarun... please PM me at my yahoo ID patrick_pugh2000
Patrick |
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