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L7 MOSFET AMP
L7 MOSFET AMP
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Old 25th September 2017, 01:05 PM   #171
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
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Join Date: Mar 2007
L7 MOSFET AMP
Quote:
Originally Posted by ekremy18 View Post
Your built is very beautiful, are the L7s parallelled or bridged?
Not bridged. Meant to triple amping with digital filters.
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Old 25th September 2017, 02:38 PM   #172
carlmart is offline carlmart  Brazil
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Location: Brazil
Quote:
Originally Posted by Erlend Sæterdal View Post
I have built one with 6 L7 2x 33 vac. As I remember

Attachment 637213
Is that for a 5.1 HT system?

What is the previous stage?
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Old 11th January 2018, 12:41 PM   #173
ekremy18 is offline ekremy18
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Quote:
Originally Posted by Uncle Fedor View Post
Hi

I have finished my amp based on this kit.

The parts I used:
- kit containing 2 pcbs and all parts soldered by myself
- 2 of large aluminium heatsinks
- 200W transformer 220/4*25V
- 4 of capacitors 10000u*50V
- 2 of rectifiers KBPC1010
- speaker protection board kit soldered by myself
- ALPS 27 potentiometer (not fake I hope)
- large 44mm knob
- input and speaker terminals
- some speaker wire
- some microphone wire
- power socket and switch
- 2 little leds with resistors
- plywood cabinet, handmade

Finally, it was worth it. The sound is so clear and so nice that I decided to send to retire my Sony reciever that served to me for 10 years. Goodbye, Sony )

PS: while writing it, I realized my error: I shoud use 2*50AC power. Although, then I should buy other filter capasitors for 80V or 100V (50V ones was on hand). Yet, I like the result. Maybe, one time I make another amp, using right transformer, right cabinet, and add some new features. Likely, it will be another L7.

Click the image to open in full size.
Hi, do you need a seperate preamp with L7 amp? or gain of L7 is already enough for home use, such as lm3886 gain clone?
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Old 11th January 2018, 01:38 PM   #174
Erlend Sæterdal is offline Erlend Sæterdal  Denmark
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Join Date: Mar 2007
L7 MOSFET AMP
2 x 50 vac is way to much. 2 x 50 dc I will recommend.
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Old 11th January 2018, 04:06 PM   #175
carlmart is offline carlmart  Brazil
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Join Date: Mar 2001
Location: Brazil
Certainly so. 2 x 50 VAC would mean +/-68 VDC, which is too much for that output.

What is the speaker's load you have now?
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Old 17th February 2018, 10:08 AM   #176
Nanoloop is offline Nanoloop  Hong Kong
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Join Date: Feb 2013
Location: Beyond Infinity
Hi guys - I've been enjoying an L7 for years. Good job! Unfortunately, I turned it on again today and it seems to have lost gain. It still drives 8 ohm cleanly but has lost maybe 20dB or so. Any idea what might have died? Input transistors? The speakers test fine and the source is fine but my investigation hasn't got any further than isolating the issue to the amp. Any ideas?
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Old 18th February 2018, 09:05 AM   #177
daveayerst is offline daveayerst
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Join Date: Nov 2012
Have you measured your power supply voltage/current ?

Quote:
Originally Posted by Nanoloop View Post
Hi guys - I've been enjoying an L7 for years. Good job! Unfortunately, I turned it on again today and it seems to have lost gain. It still drives 8 ohm cleanly but has lost maybe 20dB or so. Any idea what might have died? Input transistors? The speakers test fine and the source is fine but my investigation hasn't got any further than isolating the issue to the amp. Any ideas?
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Old 19th February 2018, 10:43 AM   #178
Nanoloop is offline Nanoloop  Hong Kong
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Join Date: Feb 2013
Location: Beyond Infinity
Thanks for the reply. I haven't opened it up yet...still. And actually after trying another amp in its place, I probably won't follow this up. Too little time, too many amps. ;-) It is a curious issue though - functioning clean sound but v little, if any, gain.
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Last edited by Nanoloop; 19th February 2018 at 10:47 AM.
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Old 19th February 2018, 11:28 AM   #179
Rupertos is offline Rupertos
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Join Date: Feb 2018
I will try to measere it too couse i have this problem too
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Old 25th February 2018, 03:15 AM   #180
Nanoloop is offline Nanoloop  Hong Kong
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Join Date: Feb 2013
Location: Beyond Infinity
Cool - let us know if you find out.

I checked my psu today and it is fine - it is a 150VA toroid, 43-0-43, with a Sigma22 regulator set to +/-45V, fitted with 2x 10,000uF pre-regulator caps. I never ran the amp hard - the psu is designed for 1A continuous, with higher bursts easily managed - and the speakers are very efficient Klipsch. Perhaps +/-45V was a little too much, but the amp has not burned out - it works but little or no gain.

I checked the psu because I decided to harvest it and will use if for an LME49810 amp. I won't be trying to fix the L7.

Given the psu fully checks out, I have no idea what the problem might be.
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