low THD and no global feedback amp
Recently designed a circuit, the circuit reference circuit of a lot of friends, and very grateful to them, and also get a lot of help and inspiration from them.The circuit design principle is to make use of the already resource.
I already have three pairs Marantz HDAM-SA2 modules current, so I try to design the circuit this resource. Requirements of the circuit is the lowest possible distortion, high speed, and the best possible sense of hearing; so I decided this circuit uses a current-mode circuit, the input of the current signal input, output IV transform output amplified voltage signal to take no global feedback circuit configuration.
Circuit basic structure:
Actual production my input signal of the voltage type, and so the input by adding a buffer input terminal, the input of this buffer is a HDAM-SA2 module.
In order to better match the output IV transform a buffered output of the module HDAM-SA2 structure, so the whole diagram is as follows.
the picture at #7
Recently designed a circuit, the circuit reference circuit of a lot of friends, and very grateful to them, and also get a lot of help and inspiration from them.The circuit design principle is to make use of the already resource.
I already have three pairs Marantz HDAM-SA2 modules current, so I try to design the circuit this resource. Requirements of the circuit is the lowest possible distortion, high speed, and the best possible sense of hearing; so I decided this circuit uses a current-mode circuit, the input of the current signal input, output IV transform output amplified voltage signal to take no global feedback circuit configuration.
Circuit basic structure:
Actual production my input signal of the voltage type, and so the input by adding a buffer input terminal, the input of this buffer is a HDAM-SA2 module.
In order to better match the output IV transform a buffered output of the module HDAM-SA2 structure, so the whole diagram is as follows.
the picture at #7
Last edited:
Add your pictures directly 
"To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that. "
"To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that. "
When i read "no feedback" sticked with "low distorsion" i ve got some alarm
that start to ring...
This requirement is not compatible with a feedbackless topology.
Either you have low distorsions with feedback or inherently way
higher distorsions ratios if no feedback is used.
that start to ring...
This requirement is not compatible with a feedbackless topology.
Either you have low distorsions with feedback or inherently way
higher distorsions ratios if no feedback is used.
Add your pictures directly
"To add a photo, files or non standard files.
First click "go advanced" in the box below the "quick reply" message box. Doesn't matter if you decide half way through a message to do that, it carries it foward.
Then click "Manage attachements". Maximise the new Window so that you can see all the text.
Click browse in the first box at the top and find your picture. Repeat for any more pictures.
Click upload... a message appears "uploading"
When complete the files will show as being attached. Now click the small text that says "close this window"
The pictures should now be attached and when you submit your post they will appear.
Make sure your pics aren't too big, a couple of 100k is plenty, and many members object when they are massive and it alters the margins
It tells you in the attachments window what max sizes are allowed.
If you want to attach a file that has a non standard format for example excel, circuit simulation etc then try putting the files in a zipped folder and attaching that. "
thank you!
hi Boscoe!
No feedback to achieve low distortion, the closed-loop distortion I believe will be lower.
Are you sure about that way of thinking? It may be a common way of expressing what you really want to say but it's totally the reverse in correctly
designed amplifiers. The basic reason for feedback is to reduce the distortion. The 'closed loop' actually refers to completing, or closing the feedback path.
Negative feedback - Wikipedia, the free encyclopedia
Perhaps though, you are not talking about harmonic distortion but some other quality of amplified sound?
"No feedback" does not achieve low distortion, it requires low (open-loop) distortion.
In practice, most amps have (and need) lots of feedback, but feedback fearers just have to have lots of local feedback to compensate for the lack of global feedback. Alternatively they have to get used to hearing lots of distortion.
In practice, most amps have (and need) lots of feedback, but feedback fearers just have to have lots of local feedback to compensate for the lack of global feedback. Alternatively they have to get used to hearing lots of distortion.
instead of throwing your writings in Chinese at google translate and post whatever came out of it to the forum making such a nonsense mess, a better way of using google translate is probably to get it to translate its output back to Chinese and see how much error there is, then try to make adjustment and improvement in wordings, terms, grammar, phrasing, and so on, until satisfaction, prior to posting to the forum.
This is in fact a classic example of how a system without global negative feedback fails.
This is in fact a classic example of how a system without global negative feedback fails.
Let's add why we actually need feedback afterall.
Global or local feedback is needed to achieve a reasonable bandwith.
ZeroFeedback amplifiers will clearly have low dynamig intermodulation, but a very poos bandwith.
The world of HiFi is full of compromises all the way.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.