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12/01/22 at 09:48:32 




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Need help in understanding the variable feedback (Read 1908 times)
jdm
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Need help in understanding the variable feedback
04/15/21 at 17:42:44
 
A 'feature' of the Mini Torii is the ability to change the sound and control presence with the use of variable feedback.  Most of the other amps have the 'feature' of zero negative feedback.

So are we talking the same kind of feedback or are they different?
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Amps: Mini Torii (2), CSP2 (retired), Taboo (retired)
Speakers: DNA2, Trapezium, MG944
Source: Bluesound Node 2i
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4krow
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Re:  Need help in understanding the variable feedback
Reply #1 - 04/16/21 at 01:38:38
 
I wasn't aware of this feature on the Mini-Torii. Negative feedback is often used to decrease distortion in an amplifier. It works, but at the price of a clearer sound. IMO, less is better even on your amplifier. Steve is famous for adding possibilities to many of his products. Even though I occasionally fiddle with these sorts of things myself, it almost always ends up with the simplest signal path. In this case, I am betting that you will prefer less than more.

Just to add, yes the feedback that you are wondering about is the same with these products. Usually it isn't 'designed into' Decware amps, but this case you have a choice of a variable amount.
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Decware 34I.3 integrated amp/Forte' 3 bass amp/Velodyne SMS-1 bass mngmnt system/Decware ZOB speakers/Audio Nirvana 8" bass drivers/Xiang Seng DAC/ LR Audio Computer/Rega Apollo R CDP/Emotiva ERC3 CDP/BPT 3.0 power cond.
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jdm
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Re:  Need help in understanding the variable feedback
Reply #2 - 04/16/21 at 21:28:47
 
Thanks
"I found this from my Taboo manual:

The lucid mode switch can be used on-the -fly
while listening to music. When engaged it creates
an esoteric feedback scheme where feedback
from one channel is fed to other channel
and visa-versa. This effect creates more space
and a better sense of dimensionality with most
recordings."

It provides a little insight.
So is it correct to assume (guess) that the cross channel feedback is more like the crossfeed that some solid state headphone amps have and is different that negative feedback?
If so, then it's the negative feedback that I need a better (any) understanding.
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Amps: Mini Torii (2), CSP2 (retired), Taboo (retired)
Speakers: DNA2, Trapezium, MG944
Source: Bluesound Node 2i
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4krow
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Re:  Need help in understanding the variable feedback
Reply #3 - 04/17/21 at 01:59:24
 
Now THAT'S interesting. I never knew how lucid mode worked. Well, I would be very interested in trying that out. Feedback takes a small portion of the signal and feeds to a spot 'earlier' in the circuit, and out of phase. This cancels much of the total harmonic distortion when complete. It has been used for decades. Who but Steve would have thought of using cross cancellation style?
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Decware 34I.3 integrated amp/Forte' 3 bass amp/Velodyne SMS-1 bass mngmnt system/Decware ZOB speakers/Audio Nirvana 8" bass drivers/Xiang Seng DAC/ LR Audio Computer/Rega Apollo R CDP/Emotiva ERC3 CDP/BPT 3.0 power cond.
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Rivieraranch
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Re:  Need help in understanding the variable feedback
Reply #4 - 09/17/22 at 13:29:26
 
You use the feedback to lower the hum when using headphones.
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MINI TORII ANNIVERSARY MODIFIED; ZROCK2; MONOLITH SPEAKERS; TECHNICS SL1200MK2 KAB MODDED TT; ONKYO 6 DISC CD; MARANTZ 2226B; SCHIIT MULTIBIT DAC; SENNHEISER HD-580s
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jdm
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Re:  Need help in understanding the variable feedback
Reply #5 - 09/18/22 at 20:45:12
 
River, thanks for your comment.  Since my previous posts, I have received my Mini Toriis and I am very happy to have the feedback adjustment.  I also just previously replaced my MG944 speakers with DNA2.  My CSP2/Taboo combination was having a difficult time balancing and taming the midrange - my DNA2 has the midrange/phase guide option.  My options were room treatments and tube rolling.  The room treatments improved soundstage and transparency.  Tube rolling (rectifiers had the biggest impact) improved balance and musicality, but the mids were too bright and harsh.

Swapping out the CSP2/Taboo with the Mini Torii made all the difference.  With the feedback adjustment on full (full clockwise rotation) the sound is deep, a little muddy and treble deficient.  Each click counter clockwise brings more detail and treble.  The sweet spot seems to be 1 or 2 clicks.  The third click makes it too bright and the midrange of the DNA2s start to sound like they did with the CSP2/Taboo.  So, for me, 1 or 2 clicks off of full feedback tamed the DNA2s midrange that the CSP2/Taboo could not.  

My Mini Toriis have a headphone/speaker switch which makes switching back and forth really quick.  I find that my 250 ohm headphone (DT880) has a slight hum on the feedback setting my Trapezium speakers like, and increasing the feedback 1 click eliminates that hum.  The other Mini Torii feeds 600 ohm DT880s and they like the same setting as as the DNA2 speakers.

My experience in using the variable feedback is that it offers an additional method of tuning the amp to the rest of your system.
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Amps: Mini Torii (2), CSP2 (retired), Taboo (retired)
Speakers: DNA2, Trapezium, MG944
Source: Bluesound Node 2i
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