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Old 20th March 2011, 05:12 PM   #1
generg is offline generg  Germany
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Default Balanced versus unbalanced input with not perfect matched devices

Maybe there some people around that can write a few words....

I repaired my little brothers Marantz 2265 receiver (about 40 years old) and it sounded in some aspects better than my Aleph P 1.7 and Babelfish J2! ........

I made some experiments....

First I took the unbalanced output of my cd-player..... sounded better and then I made an unbalanced output of the Aleph pre to an unbalanced input of Babelfish J2....

now I liked the sound more than the sound of the old Marantz....the world was round again......(and my little brother device in the right order given by birth).

My reflections....

Is for Aleph P the same true as for First Watt F1 and F2, unbalanced Aleph P ( F2) more k2 and balanced Aleph P (F1) more K3 distortion?

than I seem to prefer K2 in this case....

Is it also possible that not perfect matched IRF610 in Aleph P and not perfect matched J74, driven balanced, make the sound worse, more harsh?
So when I use them unbalanced, there could be less distortion in this case because the mismatch is smaller?

thank you!
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Old 20th March 2011, 07:25 PM   #2
Zen Mod is offline Zen Mod  Serbia
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what else I can say to you , except that you're obviously dumb enough , to have perpetual membership in Pass Pub .........

if you prefer - read "dumb " as "wakoo"

everything else is unclear to me ......
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Old 20th March 2011, 07:40 PM   #3
generg is offline generg  Germany
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hm, hm .... when a man like Zen Mod says
"...everything else is unclear to me"

I am a bit confused about the relevance and comprehensibility of my question......
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Old 20th March 2011, 07:57 PM   #4
Zen Mod is offline Zen Mod  Serbia
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no ..... just trust your ears ......

I meant - I wasn't there near you to hear/see the same ..... so I can't know what exactly you found as "better" in Marantz sound

besides that - now I know very little - waiting for start of Quatar MotoGP ........

Forza Vale !!!!
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Old 21st March 2011, 11:04 AM   #5
Itsmee is offline Itsmee  England
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Hi generg,

I too have been pondering over the symmetry question for a while.

I thought of a couple of quick experiments that should tell which is preferable, push pull V single ended; and balanced V unbalanced.

1. DCB1 V B4 input buffer.

2. Balanced in & out Pumpkin V Pumpkin single ended - Q5, Q6, R9, R10 removed, free end of R5 to ground, R3 input to ground via 10uF cap.

If you try this, I would be interested in your preferences.
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Old 21st March 2011, 12:54 PM   #6
generg is offline generg  Germany
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hi itsmee,

happy you you pondered over balanced v unbalanced too.....

normally I prefer balanced.... more details, more panoramic sound, maybe sound is a bit slimmer or less body.

my impression was this time, using for a try the combination of Aleph P and an output stage with a quadruple of J74 (all input devices not very good matched), the balanced sound more worse than normally...

and I only wanted to know, when I short the negative side of the balanced inputs to ground, if I get than more k2 distortion
and if a possible mismatching of J-fets or 610 leads in this case (unbalanced) theoretically to less distortion...

maybe my questions are stupid and simple but I just heard the differences so clearly that I had to ask......

maybe I take a simulation program and try to get an abstract answer too....

I will take a try on your suggestions!

how is the B4 input buffer looking? I try to find the circuit of DCB1...
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Old 21st March 2011, 03:34 PM   #7
Itsmee is offline Itsmee  England
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Quote:
Originally Posted by generg View Post
how is the B4 input buffer looking?:
Oops, I have dyslexic fingers again , that should have been F4, my apologies.
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Old 21st March 2011, 03:41 PM   #8
AndrewT is offline AndrewT  Scotland
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Maybe shorting cold to audio ground does not suit the source amplifier/s !
The cold channel will be trying to drive the output impedance and thus delivering enormous current. This could have a profound effect on the hot amplifier's performance.
Depends on how the source has been built.
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Old 21st March 2011, 05:44 PM   #9
Itsmee is offline Itsmee  England
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Hi Andrew,

This was the idea of 'single ended' pumpkin, I forgot to add a signal ground connection at the input, but it's only a drawing.

The other two are the F4 buffer and the DCB1, I suspect that the DCB1 would 'sound' best.
Attached Images
File Type: gif Pumpkin-se.gif (33.0 KB, 167 views)
File Type: jpg F4 Buffer.jpg (13.5 KB, 167 views)
File Type: jpg DCB1 Buffer.jpg (13.2 KB, 167 views)
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Old 21st March 2011, 06:35 PM   #10
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Quote:
Originally Posted by generg View Post
maybe my questions are stupid and simple
but I just heard the differences so clearly that I had to ask......
The question is simple but not stupid. There is a simple
answer - 2nd vs 3rd harmonic, and there is a complicated
answer.

I spend a lot of time speculating over the complicated
answer on the assumption that if I figure it out, I'll make
lots of money

There is a world of variables, all the things which occur
before the circuit and after the circuit, but even within
the circuit you have to consider the devices, the specific
topology, the load lines, feedback loops, degeneration
and so on. So far measurements have been helpful, but
have not delivered definitive answers.

The same applies to listening tests, but in this industry
they are the final arbiter, so that's where most of my
time goes.

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