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Building Marshall Lead 100 MOSFET
Building Marshall Lead 100 MOSFET
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Old 11th January 2019, 09:46 PM   #51
voltwide is offline voltwide  Ireland
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With full overdriven square and 8Ohm Speaker at +-50V supply rails 39Vrms might be obervable for a short time (until the speaker is burned).
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Old 12th January 2019, 07:44 AM   #52
Mooly is offline Mooly  United Kingdom
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Building Marshall Lead 100 MOSFET
Try this...

With NO load attached adjust the output to give 10 volts rms as measured on the meter. The scope will show around 14 volts peak (28 volts peak to peak).

Now connect your 8 ohm dummy load to the output.

The amplitude should remain unchanged. Does it ?
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Old 12th January 2019, 08:01 AM   #53
nigelwright7557 is offline nigelwright7557  United Kingdom
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If you truly want the "Marshall" sound then you are going to have to splash out on a 100 watt Marshall valve amp.

The valve pre amp Marshalls sound ok but don't match the full valve versions.
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Old 13th January 2019, 02:57 AM   #54
thoglette is offline thoglette  Australia
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Quote:
Originally Posted by nigelwright7557 View Post
If you truly want the "Marshall" sound then you are going to have to splash out on a 100 watt Marshall valve amp.
Agreed, but you don't need to run at 50 or 100W
One watt can be done (thanks to RobRobinette, again).
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Old 14th January 2019, 03:48 PM   #55
jrow is offline jrow
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Quote:
Originally Posted by nigelwright7557 View Post
If you truly want the "Marshall" sound then you are going to have to splash out on a 100 watt Marshall valve amp.

The valve pre amp Marshalls sound ok but don't match the full valve versions.
The point is that I wanted to make a solid state amp with good reputation. I made it, as you can see in earlier posts, but I have to change some stuff to fit another pair of FET's that aren't the original ones.

My intention is to learn a bit of electronics (this is my second amp project), and this amp is perfect because it can be made with few components and mosfet gain is interesting.
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Old 14th January 2019, 04:45 PM   #56
JMFahey is offline JMFahey  Argentina
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Please do the 6 tests suggested in post#49 and post results.

We need one set of consistent measurements to be able to diagnose your amp by "remote control".

You are posting non matching values measured under different conditions, that is useless.
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Old 14th January 2019, 05:14 PM   #57
thimios is offline thimios  Greece
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Wrong resistor!
This is a 33 Ohm.
You need 0.33R.
You must see R33,NOT 33R.
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Old 22nd January 2019, 06:58 PM   #58
shanx is offline shanx  Canada
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Good catch, that would account for a lot
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