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Old 28th December 2012, 01:20 PM   #1591
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Default Juan had a goog idea to fix heatsinks that does not have the fixing feature

And i made a complementary blade to increase shielding using metalic can blade.

Juan's idea complementary video - YouTube

regards,

Carlos
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Old 28th December 2012, 02:13 PM   #1592
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The heat sink I using does not have the solder taps at the bottom last night I was thinking how to provide GND to the heat sink to protect the VAS transistor from magnetic field now mister Carlos even get a new idea of placing a piece of metal material that can be solder to the copper wire that has GND already of course this will apply more to Dx Super A but also can be done in MKIII it does not have the holes like I did to Dx Super A but it can be shielded as Carlos mention on his video, here is the video of the idea.

http://www.youtube.com/watch?v=M9Uof...6nemTQ&index=2 first one


Dx Super A Heat Sink ideas 2 - YouTube second one




I apologize for my horrible Spanish accent been leaving in Puerto Rico for too long lol.

Regards
Juan

Last edited by vargasmongo3435; 28th December 2012 at 02:19 PM.
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Old 28th December 2012, 02:16 PM   #1593
BMW850 is offline BMW850  Netherlands
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I have the new resistors now 4 x 56R and 4 x 100R.
I have also done a modification R09 390R changed to 2.2 K.
What is the value of resistance will I take for R23A and R23B, the 56R (Bonfis has installed) or the 100R (Martin has installed) ?

Regards,
Rudy
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Last edited by BMW850; 28th December 2012 at 02:39 PM.
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Old 28th December 2012, 04:46 PM   #1594
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Quote:
Originally Posted by bonfis View Post
Mart
I agree with your philosophy? of sonic and technical assessment. I'm curious about how you simulate the dent. I have been trying to replicate it using Multisim 12 but it just won't appear. Are you using the original MK III design in your simulations with no changes other than the stopper resistors at 100r and the bias at 54 mv? Also the 16 ma VAS emitter current is lower than what I measure with a probe during simulation. Have you made any mods that would change the VAS current? I didn't see a change in VAS current when I deleted the bootstrap cap.
I've updated some components simulations parameters with the ones provided by OnSemi. I noticed that it made a difference in behavior in simulation. Anyhow, I can send you my simulation file if you wish. Just PM me your e-mail address...

Martin.
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Old 28th December 2012, 07:06 PM   #1595
bonfis is offline bonfis  United States
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Quote:
Originally Posted by BMW850 View Post
I have the new resistors now 4 x 56R and 4 x 100R.
I have also done a modification R09 390R changed to 2.2 K.
What is the value of resistance will I take for R23A and R23B, the 56R (Bonfis has installed) or the 100R (Martin has installed) ?

Regards,
Rudy
Hi Rudy-
They both work. I used the 56R because it was a small increase over the original value but still eliminated the parasitic.
Steve
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Old 28th December 2012, 08:04 PM   #1596
BMW850 is offline BMW850  Netherlands
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Originally Posted by bonfis View Post
Hi Rudy-
They both work. I used the 56R because it was a small increase over the original value but still eliminated the parasitic.
Steve
Hi Steve,

Have you also C10 changed from 180pf to 100pf ?

Regards,
Rudy
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File Type: jpg 2012-12-21 schema Martin 180pf naar 100pf.jpg (207.7 KB, 209 views)
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Old 29th December 2012, 02:25 PM   #1597
bonfis is offline bonfis  United States
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Originally Posted by BMW850 View Post
Hi Steve,

Have you also C10 changed from 180pf to 100pf ?

Regards,
Rudy
Yes but I wouldn't recommend that unless you make the other change I made to the input stage. I think it would also be wise to have access to a scope to make sure the amp is stable after changing C10. I think Cannonica has C10 at 100pf also. Maybe he can comment on how his input stage is configured.

Steve
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Old 29th December 2012, 02:36 PM   #1598
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My input stage is exactly as the pic posted by BMW850. From my simulations, the increased base stop resistor let me confident to decrease the miller cap. I got no issue at all with the real thing either concerning oscillations. I only had oscillations getting out of clip without the baker clamp, but it was not relevant to Cdom value.
Mart.
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Old 29th December 2012, 03:10 PM   #1599
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Default Reduce the gain is a very good idea...the amp is too much sensitive

and this helps to unstabilize the system.

Carlos
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Old 29th December 2012, 06:09 PM   #1600
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Mr. Carlo,s My Friend Why would you design a very beautiful amp to be driven off an IPOD? Or is my question out of content. Evette
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