What causes reduced spatial ambience?

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I built me an amplifier based on the J2 concept and used matched JFETs and so on. The amplifier is overall awesome! :cool: I love it! :D

In my system this amplifier provide lower sense of room ambience compared to an Atma-Sphere S30 OTL (2 dB feedback).
The two amplifiers is comparable for everything else on my speakers (the JFET amp do have better bass grip though).

As I own the JFET amp and not the OTL I want to improve my amp (you know... the first fix was free and I really need that fix - now! :eek: )

So... What can cause the reduced spatial ambience? Feedback? Capacitance in PSU? :confused:
 
Atmas-phere will have bigger halo sound due to hollowstate devices, may i suggest the use of some headphones, fed from direct source and see which is closer or which is effects box ...
;)
Thanks, I've no headphones.
I find the OTL to be very neutral (whatever that is) and as detailed as the J2 variant I built but with better sense of the room by having more air around acoustic instruments on good recordings (like Jazz at the Pawnshop).
I like to hear the same from my SS amp... :D

My primary PP tube without feedback does not provide the great sense of spatial ambience either.
 
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So... What can cause the reduced spatial ambience? Feedback? Capacitance in PSU? :confused:

IMO
Phase response and armonics and speed
not gettin in to which one is best as it is all a mater of taste.

Whit what records
? Tried Masterpiece the Temptations ?
can you tell where the band is positioned how tall they are when hand clapping.

Figure up 2 guitars say Fender or Gibson tuned exactley to same note do they sound the same?

No they don't is all down to wood how they are built how the pick ups are wound and so on the note is exactley yhe same frequency so what change?

Which one is better? no one just do things a different way for different taste
IMO
 
The one and only
Joined 2001
Paid Member
Lord of the SIT sez:

In the case of the J2, try removing the Source resistance on the bottom
Jfet and then lowering the amount of feedback. Easiest place for that is
increased value of the feedback resistor from output to (-) input. Make the
input resistor to ground for the same value if you are running balanced.

Don't forget to re-adjust the DC offset.

6 dB more super-happy-fun gain!

:darkside:
 
Member
Joined 2009
Paid Member
Lord of the SIT sez:

In the case of the J2, try removing the Source resistance on the bottom
Jfet and then lowering the amount of feedback. Easiest place for that is
increased value of the feedback resistor from output to (-) input. Make the
input resistor to ground for the same value if you are running balanced.

Don't forget to re-adjust the DC offset.

6 dB more super-happy-fun gain!

:darkside:

Yes i did it.....and i like it! I choose 150k for the feedback resistor.

I even replaced the the chain of the drain resistor of the lower SS and the source resistor of the upper SS (around 0R8) by a chain of 8 0R1 resistors and changed the node where output and feedback connection meet step by step...
Sound change was interesting, but Helas! I liked the masters point most!:cool:

And the omitting of the source resistor and loosening the feedback was more important for the sound improvement finally.:D
 
The one and only
Joined 2001
Paid Member
There is an important DIY point imbedded here, which is that given the
particular sound of an amplifier (or other component) there are often
inexpensive ways of adjusting it in a particular direction. I happen to
have known the answer through experimentation, and the J2 sound
was a particular choice, but not the only one available.

Contrast this inexpensive approach with "Recap everything with the all
new Vera$$ity mk 4 teflon$, replace all the wire with 99.999999
gold filament$ wound helically around organic $paghetti noodles boiled
in $quid ink and align the magnetic pole$ of the transformer to the center
of Orion'$ belt during the $olar eclip$e"

:cool:
 
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