is there any benefits opting for an amp with a Toroidal transformer

[spirovious]

I am not sufficiently qualified. In the world of audio design and electronics, I am 0.0001 on a scale of 1 to 10...

I cant count myself then :sad:

 

[SAMUEL]

Thank you cranky. You really are an asset to our forum.
I'm just spellbound after reading your post.keep up the good work:clapping:.
Cheers,
Sam

 

[corElement]

There is no difference between an amp designed with a toroid vs EI from a SQ perspective. EIs are a little less efficient and need to be slightly oversized, but conversely deal with overload much better than a toroid, which can saturate fast due to gapless design.

Also toroids are very wide bandwidth by design, whereas EIs have very high inter-winding capacitance, which act as a natural HF filter for some mains hash.

Large cap banks cause huge amount of inrush current, requiring soft start circuitry for toroid-powered amps with more than 20,000uF capacitance after the rectifiers. EIs saturate slowly, so this is not a problem they face. Toroids cannot handle any DC at all, and are quite prone to loud hum when there is a bit of broadband noise in the input line.

This is just to offset the criticism of EIs - though toroids are modern designs and have considerable advantages, none of those translate into sound quality benefits.

Toroids are lighter and smaller, taking less space and generating less heat. This means smaller footprints and lighter chassis, which contribute to freight savings as well as some efficiency savings. They have better load regulation upto the saturation point, which results in smaller heatsinks for the output stages, and less supply sag and boost with changing power outputs. Of course, under overload conditions this all goes out of the window. And most supplies for multichannel amps are undersized.

If I was a manufacturer using lots of transformers, toroids make more sense to buy for sure, but not because of sound quality. If I were making an amp for myself, it wouldn't matter diddly squat whether I used a toroid or EI. The SQ is no different if the transformers are decently constructed.

The thing is that most modern amps do use toroids, but they are not the only reason for the improved performance/lesser heat. The performance is a sum of a number of other factors - so it's not as if you can lay the performance of an amp only at the door of the transformer's performance. It's like attributing the entire performance of a car to the fuel system. there's more to the story - an amplifier consists of a few hundred parts, of which the transformer is only one.

As long as the mains transformer is rated to load and power output (current/voltage) plus enough for momentary overload, it will work no matter what the core geometry is. Output transformers for tubes and HF designs such as Class D amplifier chokes, as well as transformers used in SMPS supplies are a totally different ballgame, those require a different set of considerations.

@JamoGuy: 40,000uF is actually not much, not for a 5-speaker receiver. I'm looking at a tiny little Pioneer receiver that cost me 10K, and it has 30,000uF total, so not that far behind. And you don't even want to know how much capacitance we use in stereo amps we build - a Pass Labs clone of the F5 I built uses 160,000 uF of capacitance - and for just 25 watts a channel.

Lol! I wasnt criticising XD. Got nothing against EI's. Yes, toroids produce considerably lesser heat - I was surprised how cool it was running after 5 hours. While it is true the difference in sound quality isn't noticeable, my hands on experience was that I found the one toroid at the store at a much lesser price (maybe other things in the amp also decide those factors) which was driving the speakers much better than higher priced models which kind of lost...I dunno, the lows and highs just didnt seem as playful..

Depending on the price point the end of the day it really depends on the individual components how well one can control noise and power stability etc. If one is adamant about it - they'll find a way to correct any issue within their budget. Theres nothing "BAD" about either of the two, many other aspects of the amp can matter more than the xformer itself.

This is a great thread though, Im glad someone asked this question. So much to learn. I love this forum!

 

[spirovious]

Can regular transformer be replaced by Toroidal?any prob?
Just a Q.

 

[Hiten]

@Cranky :

There is no difference between an amp designed with a toroid vs EI from a SQ perspective. EIs are a little less efficient and need to be slightly oversized, but conversely deal with overload much better than a toroid, which can saturate fast due to gapless design.

Thats good to know, Never liked Torroids for their round shape. EI being square Just fit in perfectly.

Large cap banks cause huge amount of inrush current, requiring soft start circuitry for toroid-powered amps with more than 20,000uF capacitance after the rectifiers.

Sorry everyone to side step the thread . Cranky, why are large caps required (Sp. for gainclone) ? Is more caps better ?
-----------------------------------------------------------------------------------------------------------------------------------
@ psychotropic

you should write a book cranky.....

We could gather all the posts made by cranky and make a book

 

[thevortex]

thank you for this....this is exactly the kind of gyan i keep looking for and rarely find.....you should write a book cranky.....a practical guide to the ins and outs of high-end audio....something like that......which will be useful for people generally interested in components and as a reference guide for someone looking to get into, or already into DIY.

Not that I understood much of those numbers, but in principle I agree.

Cranky - when is your book coming out?

 

[grubyhalo]

Extremely enlightening thread. Thanks for your insights, Cranky!

I have a couple of questions though:

"Large cap banks cause huge amount of inrush current, requiring soft start circuitry for toroid-powered amps with more than 20,000uF capacitance after the rectifiers."

Could you please tell me which part of this PS circuit performs the 'soft-start' function?

"...one needs to work out methods to also reduce HF ripple due to the capacitor banks' large inductance. 'Snubbers' are a possible workaround, but even small, ultra-low ESR capacitors near the chips can help."

If I intend to 'snubberize' the caps, should I be adding a (low-value?) low ESR cap in parallel to each cap (C1-C8, I'm guessing)?

P.S: Sorry if the questions are a tad OT...

 

[sachi]

The thermistor in the circuit is being used to limit inrush current.

very commonly used in such applications.

 

[grubyhalo]

The thermistor in the circuit is being used to limit inrush current.

very commonly used in such applications.

Ah, I see. Thank you. I've also read that the F5's sound better without the thermistors. Hmmm...

 

[grubyhalo]

Thanks again! Makes (a wee bit of) sense now!

 

[GeorgeO]

Another benefit is that it is far easier to replace the mains tranny if it's a toroidal-I had such an experience on my DHT PP 2A3 valve amp when the mains tranny packed up and I just went across to Miracle Electronics and ordered one which was practically drop fit!

 

[gobble]

The thermistor in the circuit is being used to limit inrush current.

very commonly used in such applications.

Is this the "DC offset surge" talked about commonly?

Curious

Regards

 

[sachi]

Is this the "DC offset surge" talked about commonly?

Curious

Regards

No, you must be referring to the output protection circuit which monitors for DC offset in the outputs. Beyond a certain level of DC in the signal the prootection circuit kicks in and cuts off the output of the amp boards from the speaker/headphone jacks to prevent damage to the speaker/headphone drivers.

 

[GeorgeO]

The Importance of Transformers

 

[IndianEars]

There IS a school of thought that DOES believe that Thermistors in the Power ckt, to limit current in-rush at switch on DO (adversely) affect sound quality.

That is over come by a delay circuit that simply shorts out the thermister, a couple of seconds after switch on, ie after the Switch On in-rush current has been limited.