Kind of Bride of Zen

15th September 2002, 11:40 PM

If you don't need balanced inputs, balanced outputs or are having trouble finding a 4-gang pot, and want a non-inverting output then you may consider trying something like the circuit below.

It is a variant of BoZ with some of the features of BoSoZ.
I gave it the name of KoBoZ - Kind of Bride of Zen.
Tell me what you think.

PS. The supply voltages and bias current reflect what I've got in my arsenal of spare (leftover) parts.

Stan

16th September 2002, 04:44 AM

C'mon guys

I can't believe no-one has posted a reply yet. I've seen sillier posts attracting more answers than this.

Stan

Peter Daniel · 16th September 2002, 04:51 AM

My guess is that with a popularity of Aleph X project, everybody needs a balanced preamp these days.

jh6you · 16th September 2002, 08:07 AM

Stani772577

I think your amp looks very nice.

You like to invite more attention...?
Okay, here is my silly question. What made you consider
the differential amp for the unbalanced operation?
How is the taste of the sound, red wine or white wine?

JH

16th September 2002, 10:02 AM

Hi JH,

Well, we all know about the advantages of diff amps - high CMRR, balanced to unbalanced conversion ability, etc. What follows is an extract from one of my old electronics books in regard to differential amps:

" When operating as a single ended amplifier, the Q2(or the fet which gate is grounded in my case) common gate stage provides the voltage gain and Q1 stage provides the current gain. Since the whole circuit is biased by a current suorce, the voltage gain remains fairly constant over a wide range of frequencies. This, coupled with the fact that the common drain - common gate circuit has inherently good frequency response, results in a circuit characterizes by excellent voltage gain with high input and moderate output impedance and with excellent frequency response."

Initially I wanted to build the BoSoZ, but have great difficulties finding a 4-gang pot here Down Under. Then I examined the BoZ project and thought it would be a good starting point, but did not like one aspect of it - its output is inverted, which means that somewhere else along the system the signal must be inverted again to be in phase with the input. I know, many people will say that the absolute phase is notso important, but I'm from a different school.

Also the fact that I have no balanced sources or loads (read amps) with balanced inputs made me think about a simpler solution which will still achieve good results.

I haven't built the circuit yet, building it at the moment, but considering its simplicity I'll probably have a prototype by the end of the week.

The aim of my first post was to initiate a discussion about this circuit, about its pros and cons so to have a better idea whether I should go this path.

That's about all for the time being, thanks for your response.

Stan

Nelson Pass · 16th September 2002, 07:41 PM

I don't think the 1n4148 is performing any function here,
so you should be able to remove it.

jh6you · 17th September 2002, 08:29 AM

Thanks Stan for the kind explanation.

My short knowledge made me think
only about the CMRR and its loss.

Would appreciate if you post your
successful result of the nice looking KoBoZ.

16th September 2002, 04:51 AM	#3
Peter Daniel diyAudio Member Join Date: Jul 2002 Location: Toronto, Canada	My guess is that with a popularity of Aleph X project, everybody needs a balanced preamp these days. __________________ www.audiosector.com “Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC

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16th September 2002, 04:44 AM	#2
stani772577 Guest	C'mon guys I can't believe no-one has posted a reply yet. I've seen sillier posts attracting more answers than this. Stan

16th September 2002, 08:07 AM	#4
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Stani772577 I think your amp looks very nice. You like to invite more attention...? Okay, here is my silly question. What made you consider the differential amp for the unbalanced operation? How is the taste of the sound, red wine or white wine? JH

16th September 2002, 10:02 AM	#5
stani772577 Guest	Hi JH, Well, we all know about the advantages of diff amps - high CMRR, balanced to unbalanced conversion ability, etc. What follows is an extract from one of my old electronics books in regard to differential amps: " When operating as a single ended amplifier, the Q2(or the fet which gate is grounded in my case) common gate stage provides the voltage gain and Q1 stage provides the current gain. Since the whole circuit is biased by a current suorce, the voltage gain remains fairly constant over a wide range of frequencies. This, coupled with the fact that the common drain - common gate circuit has inherently good frequency response, results in a circuit characterizes by excellent voltage gain with high input and moderate output impedance and with excellent frequency response." Initially I wanted to build the BoSoZ, but have great difficulties finding a 4-gang pot here Down Under. Then I examined the BoZ project and thought it would be a good starting point, but did not like one aspect of it - its output is inverted, which means that somewhere else along the system the signal must be inverted again to be in phase with the input. I know, many people will say that the absolute phase is notso important, but I'm from a different school. Also the fact that I have no balanced sources or loads (read amps) with balanced inputs made me think about a simpler solution which will still achieve good results. I haven't built the circuit yet, building it at the moment, but considering its simplicity I'll probably have a prototype by the end of the week. The aim of my first post was to initiate a discussion about this circuit, about its pros and cons so to have a better idea whether I should go this path. That's about all for the time being, thanks for your response. Stan

16th September 2002, 07:41 PM	#6
Nelson Pass The one and only Join Date: Mar 2001	I don't think the 1n4148 is performing any function here, so you should be able to remove it.

17th September 2002, 08:29 AM	#7
jh6you Account Disabled Join Date: Aug 2002 Location: Near to the Pacific Ocean	Thanks Stan for the kind explanation. My short knowledge made me think only about the CMRR and its loss. Would appreciate if you post your successful result of the nice looking KoBoZ.