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Old 21st March 2013, 12:26 AM   #1871
davada is offline davada  Canada
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Quote:
Originally Posted by RNMarsh View Post
davada -- I am really looking forward to a new design as I have tried several existing sources and tried to upgrade/modify them. A new and flexible oscillator source of the same general level as Viktors or the ShibaSoku (Ag16 -- which i cannot find), would be a great addition. So, I'm done with the mods... until I find schematic of AD725D. I now have a base line from what is commercially available to compare against.

When I see my A-P again (its still in Thailand), I'll do similar to its oscillator to see how much more can be done to it. Such as drop in an AD797 (if my early Model One doesnt already use it?).

Thx-RNMarsh
Hi Rick,

Your model one uses 5534 with a two pole compensation.

Cheers,
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Old 21st March 2013, 11:18 AM   #1872
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Quote:
Originally Posted by RNMarsh View Post
the A-P page says it does around -115dB THD+N with a 22Khz BW.
You are close to the limit of the A-P.

BTW--- I do my THD+N tests/comparisons with a 100KHz BW.

Thanks- RNMarsh
I don't think I will ever replicate it again -- most of the time the 4402B is 0.00035 to 0.00067. This measurement was done under pretty quiet conditions -- the computer monitor was moved away a few feet, the fluorescent lights were off, no solder station etc., etc. The 400Hz and 22kHz filters were on.

WRT 100kHz bandwidth -- if you want to measure noise, measure noise. If you want to measure THD, measure the value of each harmonic.

I did spend one summer working in a room enclosed in brass screening -- when I asked my alma mater if I could purchase it, they said the room had been turned into an undergrad lab!
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Old 21st March 2013, 05:48 PM   #1873
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Quote:
Originally Posted by davada View Post
Hi Rick,

Your model one uses 5534 with a two pole compensation.

Cheers,
If it is truly a 5534 then you can usually drop in a LT 1468 and gain 6-10dB of improvement.
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Old 21st March 2013, 06:11 PM   #1874
davada is offline davada  Canada
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Quote:
Originally Posted by myhrrhleine View Post
If it is truly a 5534 then you can usually drop in a LT 1468 and gain 6-10dB of improvement.
If we are talking about the SYS1 then the OSC has four 5534 including the multiplier.
Can't accommodate the two pole comp if going to 1468.

The output amplifier is discrete. It looks more like a power amp.

Is that 6-10dB of disto, noise or both?

Cheers,
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Old 21st March 2013, 06:14 PM   #1875
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by jackinnj View Post
I don't think I will ever replicate it again -- most of the time the 4402B is 0.00035 to 0.00067. This measurement was done under pretty quiet conditions -- the computer monitor was moved away a few feet, the fluorescent lights were off, no solder station etc., etc. The 400Hz and 22kHz filters were on.

WRT 100kHz bandwidth -- if you want to measure noise, measure noise. If you want to measure THD, measure the value of each harmonic.

I did spend one summer working in a room enclosed in brass screening -- when I asked my alma mater if I could purchase it, they said the room had been turned into an undergrad lab!
Pay attention:
You touch on all the points I have been trying to make.
1. you can drop the the distortion by changing the opamp and retune.
2. I am improving BOTh thd and noise.
3. The results i am forwarding doesnt require a screen room or anything unusual.

-RNM

Last edited by RNMarsh; 21st March 2013 at 06:26 PM.
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Old 21st March 2013, 06:16 PM   #1876
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by davada View Post
If we are talking about the SYS1 then the OSC has four 5534 including the multiplier.
Can't accommodate the two pole comp if going to 1468.

The output amplifier is discrete. It looks more like a power amp.

Is that 6-10dB of disto, noise or both?

Cheers,

But I have not tried it on the A-P... as I said it is in Thailand (Bangkok) a.t.t.

The changes have been to 318 osc opamp used in KH440/4402 models and the opamp in the HP339a so far.

I mention the A-P as something to try next BUTnoted for others as a bench-mark --> the spec for A-P One for thd+n is .001% or less. The KH and even the 339a can do as well or better when changing opamp and retuning.

Thx-RNMarsh


-Thx RNMarsh

Last edited by RNMarsh; 21st March 2013 at 06:28 PM.
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Old 21st March 2013, 06:20 PM   #1877
davada is offline davada  Canada
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One other oscillator type I'm interested in is a Twin T.
I don't know of any commercially available ones.

Larry sent me an interesting paper from Bell labs on Twin T networks.
bstj-twintee-1.pdf

It's too big to post here but if anyone is interested I can email it.
It shows how to use equal caps for tuning and other ways to manipulate the transfer function.
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Last edited by davada; 21st March 2013 at 06:26 PM.
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Old 21st March 2013, 06:30 PM   #1878
RNMarsh is offline RNMarsh  United States
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Quote:
Originally Posted by davada View Post
One other oscillator type I'm interested in is a Twin T.
I don't know of any commercially available ones.

Larry sent me an interesting paper from Bell labs on Twin T networks.
bstj-twintee-1.pdf

It's too big to post here but if anyone is interested I can email it.
It shows how to use equal caps for tuning and other ways to manipulate the transfer function.
I believe the newer ShibaSoku is a twin-T (?)
I would be interested... pls email me at rmarsh@calweb.com (it isnt a secret unless you got spam to send me)
I am finishing loading a pcb of a twin-t notch and need to add the filter C and R's... this would be good timing.
I have a high precision LCR instrument to match parts when/if needed.


-RNM

Last edited by RNMarsh; 21st March 2013 at 06:34 PM.
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Old 21st March 2013, 06:54 PM   #1879
davada is offline davada  Canada
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Quote:
Originally Posted by RNMarsh View Post
I believe the newer ShibaSoku is a twin-T (?)
I would be interested... pls email me at rmarsh@calweb.com (it isnt a secret unless you got spam to send me)
I am finishing loading a pcb of a twin-t notch and need to add the filter C and R's... this would be good timing.
I have a high precision LCR instrument to match parts when/if needed.


-RNM
The file is sent. My ISP might reject it for size.
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Old 21st March 2013, 09:12 PM   #1880
mlloyd1 is offline mlloyd1  United States
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David:

What is the title of the paper and who is(are) the author(s)?
I am wondering if this might be in my stash of bstjs i kept when i left.

thanks,
mlloyd1


Quote:
Originally Posted by davada View Post
One other oscillator type I'm interested in is a Twin T.
I don't know of any commercially available ones.

Larry sent me an interesting paper from Bell labs on Twin T networks.
bstj-twintee-1.pdf

It's too big to post here but if anyone is interested I can email it.
It shows how to use equal caps for tuning and other ways to manipulate the transfer function.
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