Idiot discovers transformers!

Hi,

I have no original audio transformers but i have lots of power transformers.I'm trying to use it with audio and understand designs with transformers.

Today i built passive di box with power transformer.I've used this diagram.



I got really good result.If i disconnet 1&3,i'm getting hum.

Now can i use power transformers like this as 1:10 mic preamp input transformer?

Thanks.

Sure you could... but it will probably sound like poop...

JR

JohnRoberts said:

Sure you could... but it will probably sound like poop...

JR

Click to expand...

What a wonderful response.

Perhaps better to say it may sound like hummmmmmmmm.

And may be short of bass and treble.

Transformers invite hum. Low-level signals will show this the most. High-price mike transformers include lots of shielding, both special iron and copper.

In a few rooms, a naked un-shielded transformer may not sound like "poop". I had a power transformer for a mike transformer up in a lighting grid, but in a plain steel (electrician's) box. Nobody complained, but it was only to send the stage-sound into the dressing rooms.

As a mike-input transformer... a 24V:240V will probably reach 50Hz at 200 Ohms input 20,000 Ohms output. Many mikes are OK with 200 Ohm loading, though designed for 2,000 Ohms.

A big problem with PTs for audio is that the "best kind" (for clean power) have widely separated primary and secondary, and severe "treble loss". If all in one lump you are sure to go 5KHz and I have seen 20KHz. If pri and sec are separate lumps on different legs of the iron core, treble may be falling above 400 Hz, "very muffled".

Use in guitar chains is complicated. Passive pickups with volume control are not intended for 20K loads. Most of the guitar comes through but some high "sparkle" is damped-down by the low impedance. OTOH buffers and such can drive 20K easily.

Thanks for reply,PRR.

Actually i know that i can't get good performance with power transformer but i can't find audio transformers.For now i'm trying to understand.I'm building 312 preamp.I will add good transformer but for now i'm trying it with power transformers.With this transformer i got nice result as di box.I didn't hear freq loss but i believe high freqs are gone.And i didn't get hum when 1&3 connected.

BTW it's my transformer.



How can i measure freq response of transformers?

ForthMonkey said:

..but i can't find audio transformers

Click to expand...

ForthMonkey,

If you post your location in your profile, it's much easier to help with location-specific stuff like sourcing etc..

Jakob E.

gyraf said:

ForthMonkey said:

..but i can't find audio transformers

Click to expand...

ForthMonkey,

If you post your location in your profile, it's much easier to help with location-specific stuff like sourcing etc..

Jakob E.

Click to expand...

Sorry for this.I added my infos.Thanks!

I'm from Turkey.I can't find audio transformers.I don't know why...If i buy online,it will be really expensive.I tried to buy Edcor transformer about $5 but shipping is 47$!Only i can buy if i find on ebay with free shipping or cheap.

ForthMonkey said:

gyraf said:

ForthMonkey said:

..but i can't find audio transformers

Click to expand...

ForthMonkey,

If you post your location in your profile, it's much easier to help with location-specific stuff like sourcing etc..

Jakob E.

Click to expand...

Sorry for this.I added my infos.Thanks!

I'm from Turkey.I can't find audio transformers.I don't know why...If i buy online,it will be really expensive.I tried to buy Edcor transformer about $5 but shipping is 47$!Only i can buy if i find on ebay with free shipping or cheap.

Click to expand...

Audio transformers don't generally wear out, so if on a budget you might be able to salvage used transformers from old audio gear.

JR

For medium-Z transformers, there is the car-hifi-audio isolation transformers, available nearly everywhere. Also on places like dx.com, at "price includes shipping"

"Monacor" has a couple of useable transformers - e.g. LTR-110 - and is distributed in Turkey: www.kalepro.com

Jakob E.

ForthMonkey said:

gyraf said:

ForthMonkey said:

..but i can't find audio transformers

Click to expand...

ForthMonkey,

If you post your location in your profile, it's much easier to help with location-specific stuff like sourcing etc..

Jakob E.

Click to expand...

Sorry for this.I added my infos.Thanks!

I'm from Turkey.I can't find audio transformers.I don't know why...If i buy online,it will be really expensive.I tried to buy Edcor transformer about $5 but shipping is 47$!Only i can buy if i find on ebay with free shipping or cheap.

Click to expand...

You might check Don Audio who is Edcor distributor for Europe:
http://www.don-audio.com/Start

You might check Don Audio who is Edcor distributor for Europe:
http://www.don-audio.com/Start

Click to expand...

Thank you My3gger! I'm checking.

EDIT.

I checked and shipping cost is really good to me! Thanks again!

BTW any site like this?

You could also check Farnell for their OEP transformers, i use them for inputs only. It might be cheaper to order some Lundahl inputs and Edcor outputs from Don-Audio, check this guys too:
http://www.audiomaintenance.com/acatalog/Transformers_and_Inductors.html
I guess local EI transformer winders in your area can wind you some output transformers for cheap, it shouldn't cost much more than small power transformers. CJ's dissections are impressive resource if you want to go this way.

www.tube-town.net also got stuff for us europeans. A lot of powertrafos and signal.

Otherwise: blast your powertransformes with heatgun, pick out the lams and rewind. Tattoo-colilwinders are available cheap from ebay. There are a lot of transformer designs here within GDIY you can use. Ive done it with great results.

Thank you Landins! I'm checking.

EDIT

OMG! Transformers are really cheap to me.But shipping cost 35€+VAT.Transformer is 16€... :-X

I have a question.

I found a handmade input transformer.It's 1:10.But it has only 2 input & 2 output cable.How can i fit it to this circuit?

http://www.davegroupjapan.com/am10-2.gif

Now i'm building this preamp.

Thread;

http://groupdiy.com/index.php?topic=55984.0

ForthMonkey said:

I have a question.

I found a handmade input transformer.It's 1:10.But it has only 2 input & 2 output cable.How can i fit it to this circuit?

http://www.davegroupjapan.com/am10-2.gif

Now i'm building this preamp.

Thread;

http://groupdiy.com/index.php?topic=55984.0

Click to expand...

Case goes to ground?

ramshackles said:

ForthMonkey said:

I have a question.

I found a handmade input transformer.It's 1:10.But it has only 2 input & 2 output cable.How can i fit it to this circuit?

http://www.davegroupjapan.com/am10-2.gif

Now i'm building this preamp.

Thread;

http://groupdiy.com/index.php?topic=55984.0

Click to expand...

Case goes to ground?

Click to expand...

Thanks for reply.

I thought like you.But i wanted to be sure.I'm still trying to understand.

By the way i used BC550C instead of 2N5088.It has reverse pinout.And waiting for 2N3906...

And i still need help about capacitors.I can't find tantal.Can i use elect. type?

ForthMonkey said:

And i still need help about capacitors.I can't find tantal.Can i use elect. type?

Click to expand...

Yes.

tommypiper said:

ForthMonkey said:

And i still need help about capacitors.I can't find tantal.Can i use elect. type?

Click to expand...

Yes.

Click to expand...

Thanks for reply!

Lots of old mixers, even the fixed installation mixers from halls, have usable mic transformers in them.  This stuff is often salvage, or cheap, Altec, Shure, Yamaha and lots of other names... in the old days lots of them were transformer coupled (when transformers were manufactured everywhere).  Many also have output transformers in them (but only one per mixer).  Some of the mic trafo's can be run backwards as output transformers (Shure did this in some mixers).  There are good quality transformers in many of them with excellent frequency response,  though sometimes the maximum level they handle without distortion can be a little low.