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Old 23rd March 2014, 03:50 PM   #1741
toobhed is offline toobhed  United States
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I don't, but if you have the heat sinks, PCB board and parts, its easy enough to make any kind of chassis with wood if you wish
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Old 23rd March 2014, 04:40 PM   #1742
bcmbob is offline bcmbob  United States
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Great source for heat sinks if one wants to build rather than buy. Looks like toobhed may have used one of their products.
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Old 23rd March 2014, 08:23 PM   #1743
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Default Presence control

How can I implement presence control? - shunt high frequencies from feedback to ground so at the output high frequencies will be amplified.

I have tried implementation as in the schematics, but it works exactly opposite way - cutting high frequencies instead boosting them.
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Old 24th March 2014, 10:26 AM   #1744
zany is offline zany  Australia
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Quote:
Originally Posted by docrob View Post
Anyone know of a source for chassis suitable for the Amp Camp amp?
I used this chassis... worked well.

Enclosure RE2109H 211x90x257 - Boards | Kits | Components | Modules | Tools
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Old 25th March 2014, 12:41 AM   #1745
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Quote:
Originally Posted by kacernator View Post
How can I implement presence control? - shunt high frequencies from feedback to ground so at the output high frequencies will be amplified.
If you must have a presence control, try the schematic attached below. You will probably need to increase the presence cap to 220nF or 470nF. Be aware that the input has no protection and driving the power amp too hard can damage the JFET and/or the lower MOSFET. For more fun, just disconnect the 68K and run with no feedback. Change the electrolytics on the input, you can use much smaller film caps. They will recover faster when the amp is overdriven.
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Old 11th April 2014, 10:29 AM   #1746
rmgvs is offline rmgvs  Netherlands
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Default BS170

Has anybody tried putting in BS170 for Q4? Seems it might work.

Don't know if there is an advantage of putting this in instead of 2SK170, but BS170 is widely available for a few cents and it sounds more mellow (from memory from earlier experiments).

Sometimes more hiss with BS170 in my experience.
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Old 11th April 2014, 10:33 AM   #1747
Zen Mod is offline Zen Mod  Serbia
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just try it

somewhat different bias potential , but nothing what trimpot can't set
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Old 12th April 2014, 06:04 PM   #1748
rmgvs is offline rmgvs  Netherlands
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Default works allright bs170

For the sake of knowledge, I have put in BS170 for Q4. The pot has to be adjusted just the normal way. At the gate of Q4 now appears around +6,7 Volts (to get around 4 - 4.5 Volt at the gate of Q1).

The sound is okay to me, can't tell the difference with the 2SK170 yet (around the same quality I guess, not too bad for this cheapie component). Pinning and orientation is the same as 2SK170. so it's easy to swap.
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Old 12th April 2014, 06:14 PM   #1749
Zen Mod is offline Zen Mod  Serbia
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forgot to say - in case of BS170 as Q4 - you must put gate stopper resistor ; say that 150R will do

cut the trace near gate and solder small SMD resistor

or regular size metal film - what you have in drawer
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Old 12th April 2014, 06:54 PM   #1750
BigE is offline BigE  Canada
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With a 60 volt Vdss, could the BS170 be used in an F5T as opposed to cascode?
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