Toroid transformer or not

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
As I said in another post, I will probably try my hand a building a GC pretty soon. This is gonna be my first try at this and I don't want to break the bank. I'm thinking about building 5-7 monoblock amps for our home theater in the future but first I need to show my wife that I can do it within a relatively low budget.

Will there be a big difference in the sound of my amp if I choose to use a "regular" cube style transformer instead of a toroid one ? It seems to me that toroid transformers cost quite a bit more than the regular ones. For this first project, I guess it would probably make sense to buy a regular transformer. It would porbably be cheaper and easier to source in Canada.

BTW, any good tips on where to find affordable transformers in Canada ?
 
Salut Jean-Pierre,

I can't really answer if there's any significant advantages of one type over the other when talking about sound quality... but it may get more difficult to find high current E-Core trannies... Why ? I don't know ;) Probably another member on the forum could answer that.

Here's some places where you can find toroids transformers :

http://www.hammondmanufacturing.com
(sold trough http://www.digikey.ca)

http://www.plitron.com

http://www.victoriamagnetics.com/

I don't really have sources for E-Core transformer suitable for a GainClone project. Maybe you could try http://www.partsexpress.com

I hope this helps
 
I have tried both EI core and toroid transformers with my LM1875 NIGC. Toroids do sound better-smoother,clearer sound.I was surprised that there was a difference at all,but there is. Keep in mind that most EI cores have only a single secondary winding+center tap,which means using a single bridge rectifier with the center tap hooked up to ground for a balanced supply.This was my initial setup,and I can tell you that this is a BAD idea.If you want to keep your costs low,use a single power supply for two channels,there is not much of a difference between this and a dual mono supply.
 
skyraider said:
In malaysia most of the EI transformers are cheap and bad.... I have to use toroids through mail order. For me, toroids dont create humming as much as EI transformers.


cheap ei trafos can be made to behave, if you mean humming by the trafo itself, you can tighten the screws on the mounting brackets, or you can put wooden shims wedged on the center legs, then polyurethane bath should fix your problem....

on the other hand, if humming is comming from the speakers, then you have ground loop problems....

torroid cores are prone to saturation easy.....
 
mrskinny said:
Keep in mind that most EI cores have only a single secondary winding+center tap,which means using a single bridge rectifier with the center tap hooked up to ground for a balanced supply.This was my initial setup,and I can tell you that this is a BAD idea.

You can use a ct transformer with dual bridges without problem. I've built three different power supplies with ct transformers and all of them use dual bridges.

Just hook it up like this if using Brian's board- use the first AC secondary to connect to AC1H on the board, connect the ct to both AC1N and AC2H and connect the other AC secondary to AC2N. Try it, it works.
 
fireman said:
I found these for sale on the Net. Would they work ?

As you can see, they are 115V for the primary and 20 V 2.5 amps for the secondary. Is it enough or would I need a beefier transformer ?

Don't even bother answering it. I just realised that there is only one secondary. So that won't work... Too bad. At 3.50 $ US that would have been interesting. Oh well !!!
 
fireman said:
I found these for sale on the Net. Would they work ?

An externally hosted image should be here but it was not working when we last tested it.


As you can see, they are 115V for the primary and 20 V 2.5 amps for the secondary. Is it enough or would I need a beefier transformer ?




if you have them on hand, might as well use that, you can use a full wave voltage doubler, and your rails will be at +/- 28 volts which is quite good...

go ahead and do it!!!

tony
 
depending on the slack found in the center leg of your traffo, wedge wooden shims, about a 16th of an inch thick and width about the size of the tounge, between the core and bobbins..

this is to compress the laminations at the center legs of your traffo, you have to use rubber mallet to push that shim in...

once done, preheat the traffo in an oven about 50degrees above ambient, them dip it in a container filled with electrical grade insulating varnish, (polyurethane)....once the bubbling subsided, lift it out and drip dry..

an oven can speed things up, i use air drying type of varnish so i never had to oven bake my traffos...

good luck
tony
 
I don't know if this is germaine or not regarding the original question but here goes. I just faced the same question sort of. I recently designed (sort of) and built a headphone amp. The first version used rather crude single sided pcbs that weree easy to work on and modify. Once I thought they were in a state to actually start listening to them, I suffed them into a cheapo project box along with a $9.00 unshielded E-I transformer. Something you would more likely use to run toy motors. The power supply was an equally simple unregulated supply. I just wanted "proof of concept" before spending much more money. I made little attempt to optimize the wiring in the box.

I fully expected some kind of noise from the transformer and supply. What I gor was total silence - except for music. The point is that I would expect a headphone amp to be especially vulnerable shortcommings in a power supply/trandformer due to the low signalk levels and the fact I'm using isolating headphones.
The upshot of this is that I'm more respectful, now, of "square" transformers than previously and I'm not as certain about the benefits of toroids beyond those of size and weight.
 
Ive had a similar experience on more than one occasion. Back when I was a teenager I never had much money, so all of my projects back then were built from salvaged parts and components and a minimum of el cheapo parts. Transformers being relatively expensive, were usually salvaged from anything from matrix printers to photocopy machines. All of them being EI type. They do just fine. The only limitation is high power applications where their shortcommings are obvious.

Magura:)
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.