| audio-gd |
| It's complete no feed back . It have some new ameliorate . The old type I had build more , tomorrow I'll build this. |
|
|
| audio-gd |
| It have protect circuit .But the power supply is another board. |
|
|
| anli |
| quote: | Originally posted by audio-gd
It's complete no feed back . It have some new ameliorate . The old type I had build more , tomorrow I'll build this. |
I have not see many schematics with such clean design!
- will you share your sonic impressions with us?
- also, FFT diagram may be interesting (in particular, harmonics lowering speed),
- what is done for thermal stability?
- what PS voltage and bjt models do you use?
Thanks! |
|
|
| darkfenriz |
| don't you think that a cap parallel to diodes in DCservo is redundant? and may couse troubles? i would use a resistor in there. |
|
|
| peranders |
| This cap is a major part in the servo, can't be removed. This input filter make sure the gain is constantly dropping instead of landing at 1, because this is an non-inverting integrator. |
|
|
| Jennice |
I would be concerned about thermal runaway (thermal bias compensation), but other than that, it's interesting.
Jennice |
|
|
| Drasius |
| I have made the amplifier, with output stage wich you can see, 4 years ago. It sounds very good. |
|
|
| audio-gd |
About POST #4 said the cap, I'm very agree POST #5 said, this cap with the resistance organize a filter, the filter touch the sound,
Today, i've complete the board and tset it . |
|
|
| Jennice |
audio-gd,
Nice amplifier units! Looks proff., nice and tidy.
A lot of power devices for this kind of heat sinks, though,.. I think.
My thought is that it's over-kill (but then again, isn't that what DIY is all about?) with the power transistor's power handling capabilities, compared to the heat sink's size.
Jennice |
|
|
| audio-gd |
This cooler weight about 2KG, and I'll put it on the amplifier both sides ,then it can cool faster. I think it can deal the family use.
But this is a cheapness edition to my Hi-END amplifer XA-100. In XA-100, the cooler is weight about 10KG, and the circuitry is quite complex .
But the cheapness edition can use simple circuitry and keep the sound good. It's circutry I'd ameliorate time after time .
Send the XA-100 picture under. |
|
|
| Jennice |
audio-gd,
Looks cool! *sitting here, trying not to look jealous* ;)
Jennice |
|
|
| darkfenriz |
yes, sorry then
it is non-inverting 2nd order filter
I prefer inverting one couse it is pure integrator (you could use 2 of them or integrator+inverter)
regards |
|
|
| Elso Kwak |
| quote: | | Originally posted by audio-gd It's complete no feed back . |
Hi audio-gd
I do see a feedback with the opamp as attached.
;) |
|
|
| anli |
| quote: | Originally posted by Elso Kwak
Hi audio-gd
I do see a feedback with the opamp as attached.
;) |
This FB is beyond of the sound range (I think, < 1Hz). The aim is to
eliminate DC shifting of output stage. The term "servo" is often used
for such subcircuits. |
|
|
| Elso Kwak |
| quote: | Originally posted by anli
This FB is beyond of the sound range (I think, < 1Hz). The aim is to
eliminate DC shifting of output stage. The term "servo" is often used
for such subcircuits. |
Hi anli,
I won't call this a servo.
:rolleyes: |
|
|
| darkfenriz |
| neither will I |
|
|
| audio-gd |
This amplifier is no feed back ,so if no DC sero , the output will have 0.1VDC, so it must use a sero to automatic adjust the output DC voltage ,
the DC sero feed back frequency is <2HZ , and this sero is at every turn use in a Hi-fi circuit , so the circuit can realization no capacitance ,that the sound will better. |
|
|
| audio-gd |
My English is so bad and poor , so the mean maybe punch-drunk
About the no feedback amplifier
In here say of no feedback, it¡¯s mean from input to output have no skip a grade feedback. All along technical application of feedback, for sound of hi-fi is have important action. However , the people detection, the skip a grade feedback is beneficial to sound and also have some blight to sound ,the beneficial is it can enlarge the frequency respond , keep down the THD, and keep down the noise and output impedance , and more¡_¡_ . The blight is it can bring on the TIM and phase distortion , and more¡_¡_
About the TIM, evrybody can know . it¡¯s owing to skip a grade feedback ,and touch the sound is bad.
In the other side, the amplifier drive the loudhailer ,then the loudhailer bring turn over Electromotive force, it will get across feed-back to the amplifier¡¯s input, each other brewage with the input signal, in the level, this feed-back singal can more about with the input signal ,so sometime, the distortion will be quite great, it same touch the sound more.
The dimensional sound is so lovely,, because it¡¯s Hi-Fi, and it have third dimension. But the TIM and other distortion will touch the sound , let the sound be bad.
Now , about the feedback¡¯s apply ,it¡¯s can differentiate three type:
1. perist in use deepness feedback , and use other means to reduce the TIM and other distortion , that¡¯s the better idea , but it will quite difficulty .
2. Use no feedback , it¡¯s can drastically eliminate TIM and some distortion , but it can not have the excellence about feedback, so the guideline is not better,but the sound can better. Build the no feedback amplifer better, will have some difficulty , but the people is hearing limit , so let the guideline upon people hearing limit, this is a sample and good means .
3. Certainly have a means between upon ,it is small feedback. |
|
|
| anli |
My english is ugly too, but I understand almos all your messages.
Probably, the main problem at the case, when global feedback is absent, is output
stage. I think, taking output stage from your schematics demands a using of very
linear (end expensive) transistors, if we want to eliminate hard FFT spectrum.
Have you tried some kinds of amplfier topologies with "very short"
feedback - only for follower (for an amplifier part after input and gain
stages)? |
|
|
| audio-gd |
In my design , it¡¯s sure complete no feedback . So , it need use the symmetrical configuration , that to get over semaphore other distortion .
And that ,the output stage have use three stage , it can advance linearity , aside ,the first output stage , I design a super linearity circuit , (see the circuit) .
I had balance to the conventionality output stage (Inc: FET output stage and other transistor output stage) ,this output stage is so better , it can let the sound better , and reduce the on-off distortion , I only give the end output stage 1MA current , the sound is so good , and I can not hear any on-off distortion ., and in test is same as I hear
Because it¡¯s no any feedback , so it can no need any phase capacitance..
I test it frequency , ( Input is without high frequency filter)
Frequency breadth
20HZ-20KHZ(+0DB,-0DB)
10HZ-75KHZ(+DB,-0DB,2.83V OUTPUT)
3HZ-510KHZ(+0DB,-3DB,2.83V OUTPUT
Tomorrow , I will send the picture of the livelong amplifier. |
|
|
| lumanauw |
Post #7
The input is not differential, its not ordinary current feedback. What is it called? |
|
|
| anli |
| quote: | Originally posted by lumanauw
Post #7
The input is not differential, its not ordinary current feedback. What is it called? |
It is one of versions of symmetrical cascode stage. Here cascode BJTs bases
follow stage output. Another version of symmetrical cascode may be
the case when cascode BJTs bases are fixed. Nothing mystic :-) |
|
|
| Drasius |
Sorry for my poor english....
My real Amplifier run with 0.25A idle Curent.
This have differ Driver Stage. Increasing Curent till 0.7A had no Differance In Sound?...
I have meashured perfomance with Yamaha V1 Mixer-is below 0.02% in 2001. same as Yamaha .
I will try new Driver Stage.
You can see Results of Simulation in .zip File.
Changing Nominal of R1 can adding more even Harmonics.
Its sound more like Tubes:) |
|
|
| Drasius |
| This is balanced version of this amplifier. |
|
|
| anli |
| quote: | Originally posted by Drasius
This is balanced version of this amplifier. |
Drasius,
I see, you use Hawksford error correction. Does this kind of "local"
feedback work well for you (I mean sonic impression)? |
|
|
| lumanauw |
Hi, Drasius,
Nice amp you have. Could you attach those cct one more time (the normal and balanced) but complete one? I cannot see the feedback and servo section. Or you can put the feedback and servo in the right of the picture so it dont cut off? |
|
|
| Drasius |
This amplifiers had no global negatyve feedback.
They have only Hawksford error correction.
Sonical perfomance is super, very detailed, with super microdynamic. Very good damping, explosive attacks....
Is my best designed amp:) |
|
|
| lumanauw |
Hi, Drasius,
I got the same idea as your front stage here http://www.diyaudio.com/forums/show...7866&highlight=
The idea is having a front stage that dont cancel harmonics. From JustCallMeDad's simulation, it does not cancel harmonic. (while LTP does cancel harmonics)
So, it sounds good as power amp? Im curious what it is like to have audio amp that do not cancel harmonics:D
The 510ohm is a must. In my prototype, (cannot call it a power amp, it is a 4 dimensional wiring), I use no R (just emitors heading emitors), it becomes an oscilator. In my prototype putting 100ohm already fix it. |
|
|
| Drasius |
I have read this. Your amp have global negative feedback...
They who havent sounds very differ. It needs to hear:)
Is esoteric, but for me is match important sonical perfomance,
but not technical data of amp.
Several my variations.... |
|
|
| audio-gd |
| The sound is quite well, it can compare to Maranzt PM14SA, but the cost is very cheap. |
|
|
| audio-gd |
| In the amplifier , it can work in well without compensate capacitance , the capacitance's capability can change the tone color ,so it can choice 0-33P . |
|
|
| anli |
| quote: | Originally posted by audio-gd
In the amplifier , it can work in well without compensate capacitance , the capacitance's capability can change the tone color ,so it can choice 0-33P . |
Is it possible to show power suppliers voltage values? |
|
|
| audio-gd |
| The power supply |
|
|
| anli |
| quote: | Originally posted by audio-gd
The power supply |
Thanks! But I mean something different. I mean voltage VALUES :-) |
|
|
| audio-gd |
| The voltage is +-30V to +-60V , it can work well, if change some parts , it can use higher voltage |
|
|
| anli |
| quote: | Originally posted by audio-gd
The voltage is +-30V to +-60V , it can work well, if change some parts , it can use higher voltage |
Thanks!
What is each output stage transistor quiescent current value? |
|
|
| audio-gd |
About the quiescent current value ,It's different value will have different sound.
In my model amplifier ,the each output stage transistor quiescent current value is 75MA, total is 300MA.
I've this PCB, only need $8.75 (2pcs, stereo board , without postage.) |
|
|
| DarkHorse |
audio-gd,you are Hi-Fi DIY Master!
Best Wish to you!
:) |
|
|
|
