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Old 19th June 2017, 10:21 AM   #2151
Harry3 is offline Harry3  Australia
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Default Curve tracer

I purchased this inexpensive curve tracer kit. Transistor Curve Tracer adapter Oscilloscopes Plus Power supply UnAssembled Kit | eBay

Surprisingly the cheap meters that allow hfe measurements are close.
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Old 21st June 2017, 01:56 AM   #2152
Harry3 is offline Harry3  Australia
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Quote:
Originally Posted by jwilhelm View Post
It would be interesting to see if the big change came from moving the servo ground or the feedback ground. Is it possible to repeat testing with the servo ground connected to supply ground?
Hi Thimios,
I would be interested in this as well as I cannot do the test myself.

Regards
Harry
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Old 21st June 2017, 04:51 AM   #2153
thimios is offline thimios  Greece
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Quote:
Originally Posted by jwilhelm View Post
It would be interesting to see if the big change came from moving the servo ground or the feedback ground. Is it possible to repeat testing with the servo ground connected to supply ground?
Quote:
Originally Posted by Harry3 View Post
Hi Thimios,
I would be interested in this as well as I cannot do the test myself.

Regards
Harry
Ok give me some time and i will do this.
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Old 21st June 2017, 08:01 AM   #2154
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I wonder how many people use the Spooky to drive subs and if they are used for general amplification on normal speakers. I now OS said they have more bass and are better for subs, but they should be good for driving normal speakers ?
ps Thimios, thanks for the experiment !
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Regards
Jan
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Old 21st June 2017, 08:55 PM   #2155
Liliya is offline Liliya  Norway
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In my first Slewmaster this things happens when I turn the power down: A very weak tone on a high frequency( I guess around 5kHz) start, but get weaker and weaker. On the power unit there are bleeder mounted, and I feel that the tone die out together with the emting of the power bank. Any idea?

Eivind S
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Old 21st June 2017, 11:09 PM   #2156
Harry3 is offline Harry3  Australia
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Default Spooky grounding

Quote:
Originally Posted by thimios View Post
Ok give me some time and i will do this.
Thanks from me as well!
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Old 21st June 2017, 11:56 PM   #2157
Harry3 is offline Harry3  Australia
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Quote:
Originally Posted by Vrystaat View Post
I wonder how many people use the Spooky to drive subs and if they are used for general amplification on normal speakers. I now OS said they have more bass and are better for subs, but they should be good for driving normal speakers ?

ps Thimios, thanks for the experiment !
Hi Jan,
there are many that use the Spooky for their main amp as they like the sound.
OS does as well. I think for his sub he uses the Wolverine but I cannot find the post.

To do a fair comparison we need to sort out the "grounds" for the Spooky.
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Old 22nd June 2017, 01:11 AM   #2158
nattawa is offline nattawa  Canada
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Quote:
Originally Posted by Liliya View Post
In my first Slewmaster this things happens when I turn the power down: A very weak tone on a high frequency( I guess around 5kHz) start, but get weaker and weaker. On the power unit there are bleeder mounted, and I feel that the tone die out together with the emting of the power bank. Any idea?

Eivind S
When the rail voltage goes way down while reservoir caps drain the storage, there could be a moment the front end stages drop out of their designed working conditions far enough, and from that moment on the feed back loop no longer have sufficient phase margin to stay stable. An oscillation would start. That is probably what you heard. This behavior is part of the reasons many speaker protection designs would cut out speakers early at power off, and delay speaker connection at power on.....So that you would not hear it.
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Old 22nd June 2017, 03:22 AM   #2159
bimo is offline bimo  Indonesia
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Quote:
Originally Posted by Vrystaat View Post
I wonder how many people use the Spooky to drive subs and if they are used for general amplification on normal speakers. I now OS said they have more bass and are better for subs, but they should be good for driving normal speakers ?
ps Thimios, thanks for the experiment !
I modify Spooky amplifier for 90VDC PSU, the high frequency quality is good. I use slightly different compensation to achieve more slew rate.
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Old 22nd June 2017, 05:09 AM   #2160
thimios is offline thimios  Greece
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Quote:
Originally Posted by bimo View Post
I modify Spooky amplifier for 90VDC PSU, the high frequency quality is good. I use slightly different compensation to achieve more slew rate.
If you want you can share your modified version here.
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