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Old 26th February 2006, 05:49 PM   #1
latala is offline latala  United Kingdom
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Default transformer coupled amplifiers

it is with regret that after perusing the site i have found no tranformer coupled amplifiers
amongst my collection of amplifiers some of the sweetest sounding units have used this method of coupling
beside this i feel that they offer some distinct advantages
re if you have a problem the whole design is unlikley to go up in smoke
i foundly remember a design that that used only 4 transistors for
20 watts rms into 8 ohms that sounded wonderfull would any one be interested in this ?
i am thinking of the newcomers to the audio art
it would be very easy i feel to make very high power amps using this technique
after spending 35 byears of building on a reguilar basis i often wonder re the supposed advantages of dc coupling
after all we have to use louspeakers to couple the sound to our ears and they are hardley direct coupled to our ears ! i only ask as i would like to hear other peoples views
regards trev
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Old 26th February 2006, 06:11 PM   #2
KlausB is offline KlausB  Germany
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Hi there,

it will be quite difficult to find solid state designs with output transformers over here, though I fully agree with you that a first class audio transformer offers a couple of advantages, even in a solid state design.

I assume that most designers who take the first step and decide in favor of an costly output transformer also take the second step and go from transistor to tube.

Regards
KlausB
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Old 26th February 2006, 06:34 PM   #3
DIYdo is offline DIYdo  United Kingdom
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To me the extra cost and space while using a transformer. Also the high frequency roll off due to inductance of the transformer.
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Old 26th February 2006, 06:45 PM   #4
Bazukaz is offline Bazukaz  Lithuania
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The transformer produces extra distortion.Qulity audio trannies are really expensive.What is the reason to use it ?
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Old 26th February 2006, 09:22 PM   #5
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Default Xfmr Coupled SS Amp

Zeus Amp

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Old 26th February 2006, 09:41 PM   #6
latala is offline latala  United Kingdom
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from the reply i have allready had i can see that i was not clear in my description i meant a transistor amplifier that use a driver transformer for both the phase splitting and drive funtions as per early rogers radford designs have you people out there any thoughts in this regard ?
the only transistor amplifier of quality that used output transformers was the late lamented quad 50 e and i agree that in that case cost would be high although in that case impedance matching and isolated outputs could be a great advantage
a small diver transformer can be made by almost any one at home using scrap cores etc i have done this many times
any thoughts or comments out there?
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Old 27th February 2006, 07:36 AM   #7
rozak is offline rozak  Israel
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Default Re: transformer coupled amplifiers

Quote:
Originally posted by latala
it is with regret that after perusing the site i have found no tranformer coupled amplifiers
My new (old) way
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Old 27th February 2006, 07:52 AM   #8
Bazukaz is offline Bazukaz  Lithuania
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Quote:
Originally posted by latala
from the reply i have allready had i can see that i was not clear in my description i meant a transistor amplifier that use a driver transformer for both the phase splitting and drive funtions as per early rogers radford designs have you people out there any thoughts in this regard ?
the only transistor amplifier of quality that used output transformers was the late lamented quad 50 e and i agree that in that case cost would be high although in that case impedance matching and isolated outputs could be a great advantage
a small diver transformer can be made by almost any one at home using scrap cores etc i have done this many times
any thoughts or comments out there?

For as i know , driver transformers were used in old times to save transistors. I can see no advantage of using it.
Have you made any measurements of your self wound transformers ? THD,IMD , noise , capacitance , leakage inductane ? The greatest thing when transistors were inverted was no need of transformers.
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Old 27th February 2006, 08:15 AM   #9
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Quote:
Originally posted by Bazukaz
For as i know , driver transformers were used in old times to save transistors. I can see no advantage of using it.
Have you made any measurements of your self wound transformers ? THD,IMD , noise , capacitance , leakage inductane ? The greatest thing when transistors were inverted was no need of transformers.
I dunnow 'bout that. Xfmr-based equipment probably got a bad reputation due to the use of cheap iron. However, we have Susan Parker and rozak building just such equipment and it always seems to get good reviews. Of course, they're using the good stuff. Lundahls, Sowters and custom wound jobs don't come cheap. Conventional wisdom here may be due for a rethink.
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Old 27th February 2006, 11:49 AM   #10
mtlin12 is offline mtlin12  Taiwan
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Default Re: transformer coupled amplifiers

Quote:
Originally posted by latala
it is with regret that after perusing the site i have found no tranformer coupled amplifiers
amongst my collection of amplifiers some of the sweetest sounding units have used this method of coupling
beside this i feel that they offer some distinct advantages
re if you have a problem the whole design is unlikley to go up in smoke
i foundly remember a design that that used only 4 transistors for
20 watts rms into 8 ohms that sounded wonderfull would any one be interested in this ?
i am thinking of the newcomers to the audio art
it would be very easy i feel to make very high power amps using this technique
after spending 35 byears of building on a reguilar basis i often wonder re the supposed advantages of dc coupling
after all we have to use louspeakers to couple the sound to our ears and they are hardley direct coupled to our ears ! i only ask as i would like to hear other peoples views
regards trev
I and my friend's company will make a final prototype amp test
using a step-up transformer with a power follower this weekend.

After 6 time failures, the seventh according to his rough measurement
can achieve 20~20KHz +/-0.5dB and sounds very
good.

Our plan is to make a 0/10dB switchable Power Follower, if the
pre-amp gain or output swing is not enough, then we can use
this step-up transformer as a higher voltage driver.

How about a Power Follower with an IPT?


This is the 0DB Power Buffer PCB using SANKEN BJTs.


Click the image to open in full size.
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