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Audio amplifier question (Butler amplifier)

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Optikon

New Member
Does anyone have a schematic of a "butler" amplifier?

Google turns up alot of audio buffs talking about it but I have yet to see one. Apparently, it is (was) popular is some audio amplifiers as a low noise, high linearity front end input stage. It utilizes JFETS & bipolar's

It's called "butler" due to it's inventor?? Also used in some low noise opamps like OP275.

Does anyone have a schematic for one? I'd like to see it.

Thanks
 

Optikon

New Member
TekNoir said:
Home of Butler Amps -- https://www.butleraudio.com/

Out of the seven schematic sites that I could find claiming to have schematics for BK amplifiers, not a single one was accessible.


yeah I saw this, it's a commercial site. thanks though..

no schematics.. everyone raves about butler amplifier front end, where is a schematic design using it?

Some Audio-Guru..surely has one. No? :wink:
 

audioguru

Well-Known Member
Most Helpful Member
I'm an audioguru, but not one of those audiophile freaks who claim that expensive majic makes better sound.

I can't hear distortion less than about 0.1%, so newly invented circuits with 0.0006% distortion aren't any better for me, nor for anyone I know.

The OP275 has a Butler front end and performs the same as ICs without it.

I use cheap TL071 single, TL072 dual and TL074 quad opamps for all my audio circuits. They are cheap because they are made and sold by the millions. They have a FET input I need sometimes, fairly low noise, wide bandwidth and a typical distortion of only 0.003%. :lol:
 

Joel Rainville

New Member
audioguru said:
I can't hear distortion less than about 0.1%

And I bet most so-called audiophiles can't either. Maybe they just have too much money to burn? And lack ideas on how to spend it? It's so simple... Porsche guys, buy Porsches :lol:

Audioguru, do you have one prefered book/document/website on op/audio amps that you can recommend to the aspiring audio guru? Maybe a good book you always refer to?
 

k7elp60

Active Member
Audioguru,
I value your opinion, and would like your opinion on subsituting a TL074 for a LF347. I have a project I am building that uses the LF347 as a low noise audio amplifier. Since I have TL074's in my stock I think it will probably work. What do you think?

Ned
 

audioguru

Well-Known Member
Most Helpful Member
Hi Ned,
They are nearly identical.
The TL074 has lower distortion, noise and power supply current than the LF347. Their wideband response is about the same. Same output current and pinout. :lol:
 

Optikon

New Member
so no one has a schematic? I understand the arguments for hearing/needing the low noise type amplifiers but my interests in this circuit are not for audio reasons. I'm having thoughts about other non audio low noise applications which need to do much much better than these low noise, low distortion audio amps. It sounds like butler came up with something quite good (as the OP275 people will attest)
 

Optikon

New Member
audioguru said:
I'm an audioguru, but not one of those audiophile freaks who claim that expensive majic makes better sound.

I can't hear distortion less than about 0.1%, so newly invented circuits with 0.0006% distortion aren't any better for me, nor for anyone I know.

The OP275 has a Butler front end and performs the same as ICs without it.

I use cheap TL071 single, TL072 dual and TL074 quad opamps for all my audio circuits. They are cheap because they are made and sold by the millions. They have a FET input I need sometimes, fairly low noise, wide bandwidth and a typical distortion of only 0.003%. :lol:

I gotta agree, those TL0's are nice low cost parts with decent performance. The OP275 is not that costly either with very good low noise performance if you need it (not necessarily an audio application!)

I've got a discrete low noise front end JFet amplifier (with chopper amp) that I want to compare to Mr. Butlers ideas.
 

TekNoir

New Member
The site that I referenced above gives lots of information on Butler's amplifiers including his patented form of thermionic power output devices, supposedly reducing Total Harmonic Distortion (THD) to typically LESS than 0.10%.

You could also have a look at Butler's actual patents on his designs to get some ideas and lots more information. They are US patents numbers (4,987,381) , (5,705,950) , and (6,507,240). You can find the patents at https://www.uspto.gov/patft/index.html

No schematics, but schematics would have to come from someone who reverse engineered one of his designs and they seem hard to come by. I've never owned one of his amps, but his tube overdrive pedal has been a favorite for quite some time now. To hear what one of his amps sound like, apparently you can listen to the sounds of professional celebrity users including "Billy Gibbons (ZZ Top), David Gilmour (Pink Floyd), Eric Clapton, Elton John, Eric Johnson and hundreds more", to quote his site.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
To be honest, I wonder if the 'butler amplifier' is more a scam than anything else?. A google search finds very little about it, apart from a couple of chips (one of which has been discontinued) that apparently use it.

If it was any good I would expect to find plenty about it!.
 

k7elp60

Active Member
Audioguru,
Thanks for your input on my substituting a TL074 for the LF347.
Ned
 

Sam Ravindhran

New Member
To be honest, I wonder if the 'butler amplifier' is more a scam than anything else?. A google search finds very little about it, apart from a couple of chips (one of which has been discontinued) that apparently use it.

If it was any good I would expect to find plenty about it!.
I live near San Jose, California. Some years back, while reading the Obituary column of the San Jose Mercury News, I found this posting of a man with last name Butler. Reading this post, I found out that the post was written by a person whose father had invented a new design of the Operational Amplifier. The son was proud to state that his father was subsequently honored by having the design named after him as the Butler Op Amp.
I myself then recalled that at my undergrad college doing a major in Electronics and Telecommunications Engineering, I recall reading about the Butler Op Amp in my text book. See "Electronic Fundamentals" by Millman & Halkias.
Trust me, the Butler Op Amp is as real as you or me. Let's honor the man.
 
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