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Valve output transformers - toroidal or Laminated??

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nzoomed

Member
I am building a valve guitar amp, i have been advised that i should get a toroidal output transformer made rather than a laminated steel core like most amps use.
I am told that you get better sound quality and frequency response than a laminated core transformer.
I would like to know if this is correct or not, and if so, are there any other benefits other than reduced size and weight of the transformer itself?
TIA
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I would say not, audio transformers have always been normal laminated ones - I would stick with that, the added expense of having a toroidal one made is probably not worth it - it's also unlikely a quality audio transformer manufacturer would have the capability of doing so.

Considering you use a valve guitar amp for it's low quality, it would seem pretty pointless trying to improve it anyway?.
 

nzoomed

Member
Ok thanks for that info, i was going to go laminated, ive got a contact who has switched to toroidal and said he would never go back. Our local transformer manufacturer is doing them in toroidal as well as laminated, i think i will stick with laminated, i may consider toroidal for Hifi use perhaps.
 

audioguru

Well-Known Member
Most Helpful Member
Vacuum tube (valves) amplifiers are low quality due to their high distortion and poor damping of the resonances of speakers but some guitar people like their sound.

You should not say "hi-fi' in the same sentence of a vacuum tube (valves) amplifier.
Their output transformers have poor low and high frequency response plus the high distortion and poor damping.
 

nzoomed

Member
Vacuum tube (valves) amplifiers are low quality due to their high distortion and poor damping of the resonances of speakers but some guitar people like their sound.

You should not say "hi-fi' in the same sentence of a vacuum tube (valves) amplifier.
Their output transformers have poor low and high frequency response plus the high distortion and poor damping.

first time ive heard that valve amps are low quality, i have only heard that they can be low quality if you have a poor quality output transformer. A good output transformer should only loose power, not quality.

As far as hi-fi goes, yes you would build it totally different than a guitar amp, using pentodes such as the EF86 for example. Out of all the guitar amps ive worked on, the valve ones have a much wamer and nicer tone than solid state, ill never touch a solid state guitar amp again. And with valve Hi-fi gear, its value going up through the roof.

If valves development were continued, things would be much different today, Im glad to see the blackburn works in england producing tubes once more.
 

audioguru

Well-Known Member
Most Helpful Member
"Warmer and nicer tone" means rolled-off high frequencies, lots on even harmonic distortion and no damping of resonances of speakers.

I like reproduced sound to be crisp and clear with flat high frequency response to the highest audio frequencies, no distortion and tight damping of speakers.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
first time ive heard that valve amps are low quality, i have only heard that they can be low quality if you have a poor quality output transformer. A good output transformer should only loose power, not quality.

For a guitar you're looking for a specific low quality sound, anything you do that improves it (or alters it in any way) moves away from the sound you were looking for.

As far as hi-fi goes, yes you would build it totally different than a guitar amp, using pentodes such as the EF86 for example. Out of all the guitar amps ive worked on, the valve ones have a much wamer and nicer tone than solid state, ill never touch a solid state guitar amp again. And with valve Hi-fi gear, its value going up through the roof.

As Audioguru said, "warmer nicer tone" is poor frequency response and high distortion, MUCH lower quality than a trtansistor amp.

If valves development were continued, things would be much different today, Im glad to see the blackburn works in england producing tubes once more.

Why would it be different?, could valves have been developed any further?.

Are they making valves in England again?, I thought all the plant was sold to the Soviet Union decades ago?.

Like AG I come from the valve era, we both find it laughable that they have become fashionable and people pay stupid money for them :D
 

nzoomed

Member
Like AG I come from the valve era, we both find it laughable that they have become fashionable and people pay stupid money for them :D

lol then im on the bandwagon if i can sell lots of these!:D

Anyway i was born in the solid state generation of the early 80's when personal computers were taking hold and valve amps were almost a thing of the past. I have a few friends who were technicians in the early 70's when solid state was becoming more common in Hi-Fi, they all told me they hated the sound of the new transistor gear at the time.

I have mixed feelings about valves myself, and i hear alot from both sides, at the end of the day i guess its a matter of preference. All i know is when hear music through an old stereo using a valve amp, i was convinced it sounded better, i too used to think those old valve sets sound like rubbish , but when you actually put some decent music through a good reconditioned system with new speakers, capacitors and and transformers etc, it sounds totally different, i dont think i would go back to a transistor amp ever again.

Another thing as far as frequency response goes, can depend alot on the type of valves being used, and the configuration they are running in, as well as plate/screen voltages from what i understand in Hi-Fi configurations, they have a bigger gap between the plate and screen voltages than in guitar, that is supposed to affect the distortion level significantly, but then thats only what i hear from others, some may have different views! lol

here is the link for the blackburn Techtube valves that are being produced in the UK.
TechTube Valves - Blackburn MicroTech Solutions
 

grim

New Member
with regards to laminated v toroidal output transformers for valve amps, there are two advantages of laminated parts, firstly because of the air gaps between E and I lams, they can cope with a small amount of DC current without saturating, where the single lamination of a toroidal will saturate. You can have to cores cut and polished and then fit a gap, but that then increases core losses, which is why you want to use a toroidal in the first place.
Secondly toroidals don't lend themselves very well to the layering of windings you want when making an output transformer. You will have a primary of 300 odd volts, and a secondary as low as 20 or 30V depending upon the power. you want to sectionalise the winding as much as possible for high frequency response, which means on the secondary of a toroidal the winding doesnt fill a full layer. with a laminated, it's easier to have nice full sections for both primary and secondary.

having spent may happy afternoons in the listening room at PapworthAudio, I can confirm you certainly can have valve hifi amplifiers. yummy.

even guitar amps, when they have all the distorting effects turned off can sound very pleasant. beauty is in the ear of the beholder though ;)
 

audioguru

Well-Known Member
Most Helpful Member
The first amplifier I made (and oscilloscope and FM tuner) used vacuum tubes.
I replaced the output tubes in the amplifier every couple of months to keep them balanced enough that the distortion wasn't too high. Tubes were cheap in those days and were sold and tested in the corner convenience store.
 

grim

New Member
aye, and this were all fields ;)

i was told hifi valve amps required a lot less components than sold state, but that was in the days when we used components. i expect you can get an amp on a chip now with near hif performance, but it doesn'tglow in the dark does it?
 

Nigel Goodwin

Super Moderator
Most Helpful Member
aye, and this were all fields ;)

i was told hifi valve amps required a lot less components than sold state, but that was in the days when we used components.

Very true way back then - the crude designs of valve amps meant less components. Although decent quality HiFi amps probably used more than transistor ones.

i expect you can get an amp on a chip now with near hif performance, but it doesn'tglow in the dark does it?

Not 'near' HiFi performance, chips amps have been available with superb HiFi performance for decades. Currently there's a big resurgence of simple 'gain clone' designs that supposedly better top HiFi amplifiers at low cost.
 

nzoomed

Member
with regards to laminated v toroidal output transformers for valve amps, there are two advantages of laminated parts, firstly because of the air gaps between E and I lams, they can cope with a small amount of DC current without saturating, where the single lamination of a toroidal will saturate. You can have to cores cut and polished and then fit a gap, but that then increases core losses, which is why you want to use a toroidal in the first place.
Secondly toroidals don't lend themselves very well to the layering of windings you want when making an output transformer. You will have a primary of 300 odd volts, and a secondary as low as 20 or 30V depending upon the power. you want to sectionalise the winding as much as possible for high frequency response, which means on the secondary of a toroidal the winding doesnt fill a full layer. with a laminated, it's easier to have nice full sections for both primary and secondary.

having spent may happy afternoons in the listening room at PapworthAudio, I can confirm you certainly can have valve hifi amplifiers. yummy.

even guitar amps, when they have all the distorting effects turned off can sound very pleasant. beauty is in the ear of the beholder though ;)

Thanks for all that info.
I will take that onboard and stick with a laminated transformer.
I too agree that valve amps are usually more simple requiring less components, but with solid state, you have no bulky or heavy transformers and chassis etc, and everything is on a PCB.
 
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