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VSSA Lateral MosFet Amplifier

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Lazy Cat

Lazy Cat

Member
Joined 2007
Output bias tested, at room temp starts at 220 mA, 5 W dissipation (without heatsinks) heats the outputs to 90 deg at stable 240 mA bias. Looks promissing without the need of any tempco regulation. :yes:
 

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C

chunek

Member
Joined 2010
The amps was singing yesterday night with 4 ohms KEF speakers. :D
An externally hosted image should be here but it was not working when we last tested it.

The background noise is very clean even stick to speakers hard to hear and seperation is very good with 2 smps. Overall sound is warm, details and musical. Soundstage is still tight especially on the high. I think this will be improved after more burn in. Thanks LC for this amp.

James :)
 
Lazy Cat

Lazy Cat

Member
Joined 2007
chunek said:
The amps was singing yesterday night with 4 ohms KEF speakers. :D
An externally hosted image should be here but it was not working when we last tested it.

The background noise is very clean even stick to speakers hard to hear and seperation is very good with 2 smps. Overall sound is warm, details and musical. Soundstage is still tight especially on the high. I think this will be improved after more burn in. Thanks LC for this amp.

James :)
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Congratulations James :up:

You're one of the first complete VSSA builders, very nice case and as recommended with SMPS PSU. Yes, burn in period is funny since different elcos act very differently soundwise. All I can say enjoy in music. :cheers:
 
Nikitas

Nikitas

Member
Joined 2011
Lazy Cat said:
This VSSA official case is made out of the best Aluminum material possibly find around here because of the final brushing finish. All plates are fine brushed so the material needs to be very homogeneous. Plates thickness is 5 mm, they're pre-drilled with threads where needed and the case is adjusted to zero gap, plates tightly touches each other. :cool:

Regarding SQ (sound quality) I can tell that it is much better than my demo wooden "case" since the grounding is perfect so the lowest level signals are not lost in any kind of noise. No interferences from outside, all Aluminium material meaning no amplified magnetic fields formed in plate material. :cool:
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Darn! Where can I get one of these cases?!
 
C

chunek

Member
Joined 2010
metallicus69 said:
Nice one James! :D Congratulations for your success!
Is that a custom case?
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Thanks metallicus69! :D
The case I order from China Taobao website through local agent.

Lazy Cat said:
Congratulations James :up:

You're one of the first complete VSSA builders, very nice case and as recommended with SMPS PSU. Yes, burn in period is funny since different elcos act very differently soundwise. All I can say enjoy in music. :cheers:
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Thanks LC for your kind words! This is the amp let me start to enjoy in music ... :cheers:

baswamin said:
James,

Is it only me or do I see a electrolytic capacitor (green in colour) in place of film cap?

Edit: ok, my bad. It is 2200uF, 6.3V cap. I see the film cap now.

Thanks
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Yes, it is Matsushita 2200uF electrolytic cap.

Cheers,
James:)
 
R

Renioo

Member
Joined 2012
One channel is not stable :( There was a noise in the speaker and I measured 0,5V DC on it. When I checked the channel it sometimes got 0,5V DC on the output (and correct input bias) and sometimes switched to 0mV on output and no input bias between TP1 and TP2 :( On second TPs there were about twice the input bias then. When it's 0,5V DC then both biases are ok. Gonna replace one VAS and see what's happening...
 
Lazy Cat

Lazy Cat

Member
Joined 2007
brianco said:
I intend using 200mm with 40mm fins (includes 9mm back- plate. Fins are well tapered and corrugated. What do you suggest is a safe minimum height. (I have 200mm each available, but can cut down. The box will be from 7mm alloy panels)
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Hi Brian :wave:

Look for your's heatsink efficiency data of °K/W at height of 100 mm. Than calculate the height according to desired 0,5°K/W end result. ;)

brianco said:
Is a soft start advisable with Hypex dual mono PS?
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NTC on each SMPS400A180 PCB has to be shorted. Than connect them according Soft Start schematic.

Sequence starts by powering the switch, inrush current controled by CL90 NTC, after 2,5 s relay shorts the NTC enabling live phase direct connection to both SMPS-s. :up:
 

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