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VSSA Lateral MosFet Amplifier

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Lazy Cat

Lazy Cat

Member
Joined 2007
JOHN BALI said:
I know it not simple, but if we use regulated rails for VAS + front end maybe that the way.
But how to do that, how much we need voltage for that?
I just want to know :)
Click to expand...

Regulated PSU for front-end (input & VAS) would stabilize DC currents, but downside is it's complicated and you loose few volts of an output Vpp (power). It's much better to use fet CCSs instead, among stable DC conditions, no Vpp loss, the best part of it: AC performance is way better. :yes:
 
Lazy Cat

Lazy Cat

Member
Joined 2007
trunek said:
hi LC
1) datasheet for ALF 8A shows max current. There will be better Zener diode 8V2? What happens if there is a short circuit at the output? Kaput? Alf or will live on? As it is short-circuit protected output? It could limit with the help 8V2 - there is a max current of about 8 A, ALF survive and destroy the fuse.
Click to expand...
Gate-Source zeners are there to protect mos gate junction against over voltage peaks breakdowns. Lowering the zener would act like voltage limiter, but would not limit the drain current. Short circuit is usually less than 50 mOhms, that means 0,4 V is enough to exceed 8 A limit. Short circuit protection or current limit can be a part of PSU's over current protection. Also fuses on rails helps sometimes. ;)

trunek said:
2) Can you give measurements 4R +1 uF / MKT parallel? Sine is up to MHz, rectangle is nice to 100kHz (hats off) but how it behaves on the capacitive load? At the output coil is not - it will be OK or not? I hope so, it's super amp
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For that kind of measurements output RL filter is recommended, since 1 uF acts like a short circuit at 500 kHz and higher. Amps with high power bandwidth would try to regulate output signal according to closed loop voltage gain and would try to deliver currents over its ability. So for such loads at HF response, serial output RL filter (1 uH parallel to 2,2 Ohm) is essential. In reality there are very rare speakers with clean 1 uF across speakers terminals in their passive crossover network. :rolleyes:
 
Lazy Cat

Lazy Cat

Member
Joined 2007
GB info

Intermediate call for all Proforma Invoice recepients to confirm their orders, since this week I will start to send parcels to your addresses. VSSA PCBs will be ready on Wednesday as I'll confirm with pics as soon as I'll get them. :up:

Installation manual is ready, semiconductors are ready, addresses prepared, so let the fun begin. :yes:

BTW last week we have one more comparison test, this time duel was between VSSA and Accustic Arts AMP l - MK2. System is high-end according to prices, all together around 30 k€, and VSSA shined through and through, I should not even start to explain what happened in low level volumes where resolution and transparency are at stake. :cool:
 
jkuetemann

jkuetemann

Member
Joined 2010
Lazy Cat said:
Intermediate call for all Proforma Invoice recepients to confirm their orders, since this week I will start to send parcels to your addresses. VSSA PCBs will be ready on Wednesday as I'll confirm with pics as soon as I'll get them. :up:

Installation manual is ready, semiconductors are ready, addresses prepared, so let the fun begin. :yes:

BTW last week we have one more comparison test, this time duel was between VSSA and Accustic Arts AMP l - MK2. System is high-end according to prices, all together around 30 k€, and VSSA shined through and through, I should not even start to explain what happened in low level volumes where resolution and transparency are at stake. :cool:
Click to expand...

Getting excited now LC! Been listening to my PeeCeeBee version of the VSSA for some time now and it makes all my other amps sound like they were designed and built by chimpanzees; I'm just itching to get my hands on the 'Official' Lazy Cat version of the VSSA. Hope shipments begin soon.
 
S

sng001

Member
Joined 2009
Pre-treatment for the feedback EL-cap

Confirmed & paid for one stereo pair.

I have build one channel of VSSA 1.4 using thru-hole parts.

I could not buy Nichicon FG 2200uF EL-cap for reasonable price so I bought the following:
Rubycon ZL - Buy Aluminium Capacitors Capacitor,electrolytic,aluminium,radial,105C,6.3V,2200μF,20%,6.3ZL2200MLST10X23 Rubycon 6.3ZL2200MLST10X23 online from RS for next day delivery.
and
Panasonic FR - Buy Aluminium Capacitors Capacitor,Electrolytic,Aluminium,radial,low impedance,10V,2200F Panasonic EEUFM1A222 online from RS for next day delivery.

I did some prep work on the Rubycon ZL before I used it and it does sound better than the brand-new Panasonic FR.

I suggest that we should order parts & do some prep works whilst waiting the kits from LC.

- sng001
 

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