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Lateral CFA 120W - BSA
Lateral CFA 120W - BSA
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Old 13th June 2019, 06:30 AM   #41
dadod is offline dadod  Croatia
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Quote:
Originally Posted by schillg11 View Post
According to the BOM from post#1, shouldn't R45 =550R(560)/8W be made of 4 resistors with 560R/2W . The layout shows two parallel resistors in series and the BOM says this should be done by 4x1,1k /2W resistors.


GŁnni
Yes, you are correct. For ClassB there should be four 560R 2W resistors and for ClassA two of 1k1 2W resistors are enough, but if you want to combine ClassA and ClassB in the same amp (like active speakers) then use four 560R resistor even for ClassA.
I will edit BOM accordingly and will put correction note in first post.

Damir
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Old 13th June 2019, 09:44 AM   #42
maty tinman is offline maty tinman  Spain
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Hi to ALL and two questions.

1. How much phase shift at 20 kHz, at 1 watt.

2. Can you make a THD+N graph like this? Rotel A11.

Click the image to open in full size.
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Old 13th June 2019, 10:49 AM   #43
dadod is offline dadod  Croatia
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Quote:
Originally Posted by maty tinman View Post
Hi to ALL and two questions.

1. How much phase shift at 20 kHz, at 1 watt.

2. Can you make a THD+N graph like this? Rotel A11.

Click the image to open in full size.
1. Less then 1 degree and it depends of input LP filter.
2. No
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Old 13th June 2019, 11:01 AM   #44
maty tinman is offline maty tinman  Spain
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Only one degree is a very good value!

I already assumed it, but I had to ask. For the graph you have to build the amplifier and, depending on its construction, PSU, components and ability, it will change.

Thank you.
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Old 13th June 2019, 11:21 AM   #45
AKSA is offline AKSA  Australia
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That is very good, Damir, outstanding...... there is some belief that low phase shift maintains image integrity at very high frequencies, but there are other influences I believe.

I have a feeling that the very curvy transfer function at very low drain currents on latfets leave to the inactive device in AB remains on for longer than hexfets, which turn off around 2-4V off crossover even at higher bias quiescent. This might explain a smoother sound, less harshness, with latfets. With high Iq is might be as high at 15V above and below crossover, and this means a lot of headroom in Class A.

Thoughts?

Hugh
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Old 13th June 2019, 04:28 PM   #46
dadod is offline dadod  Croatia
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Originally Posted by AKSA View Post
That is very good, Damir, outstanding...... there is some belief that low phase shift maintains image integrity at very high frequencies, but there are other influences I believe.

I have a feeling that the very curvy transfer function at very low drain currents on latfets leave to the inactive device in AB remains on for longer than hexfets, which turn off around 2-4V off crossover even at higher bias quiescent. This might explain a smoother sound, less harshness, with latfets. With high Iq is might be as high at 15V above and below crossover, and this means a lot of headroom in Class A.

Thoughts?

Hugh
Hugh, you have much more experience in the way to recognize what makes smother less harsh sound, and you are probably right.
I am more on engineering side, with much less listening experience.
Damir
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Old 13th June 2019, 04:58 PM   #47
maty tinman is offline maty tinman  Spain
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Default Feedback

Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

by AKSA

Quote:
In conclusion, the spatial qualities of the Alpha are outstanding and the result of careful use of feedback and input stage speed. It is this spatial information which hugely engages the listener, because with large sound fields like orchestra and rock concerts knowing the positions of all the sounds makes realism. This is particularly important with large orchestras because the instrument positions are traditionally fixed and a music lover can follow the sounds from the instrument groups as though he sees the conductor. This makes it very engaging; typically only tube amps can do this but a very few SS amps can. This makes the Alpha worthwhile to build, and thank you, JW, for building it. I hope it's a keeper!
Lateral CFA 120W - BSA, how much feedback? Less or more 29 dB?
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Old 13th June 2019, 05:42 PM   #48
dadod is offline dadod  Croatia
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Originally Posted by maty tinman View Post
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

by AKSA



Lateral CFA 120W - BSA, how much feedback? Less or more 29 dB?
You can see that in first post.
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Old 14th June 2019, 02:55 AM   #49
bimo is offline bimo  Indonesia
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Quote:
Originally Posted by maty tinman View Post
Aksa Lender P-mos Hybrid Aleph (ALPHA) Amplifier

by AKSA



Lateral CFA 120W - BSA, how much feedback? Less or more 29 dB?
Several technics can have same result. Same technics can have different result. It is depend of the implementation. If you have deep knowledge of engineering, you know it. Unless you just doing trial-error design.
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Old 14th June 2019, 03:29 AM   #50
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Bimo,
I thought all of us were operating on trial and error!
What is your secret?
HD
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