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TSSA V1.7 mosfet Current feedback amp module

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pdb

pdb

Member
Joined 2007
PSU capbanks - and the bypass tweak

Hi Sonny, Some days ago I posted this

pdb said:
Thanks. I will ask Sonnya if he thinks 2 capbanks is worth the extra money. I remember a picture from him (in TSSA 1.7 or 1.6 thread) with a 1 trafo 2 capbanks setup. Regarding bypass caps, I am in the hands of Sonnya as he is building the amp for me.... ;-) All the best, Per
Click to expand...

It would be great if you would comment on this in the forum when you can find the time. Thanks :)
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Some updates on the amps.

A major concern when going up in power is protection circuit.

On the TSSA V4 and V8 we have added a CMOS switch working on the GND pin to the speaker.

This CMOS switch has fast turn off behaviour and an series resistance of 5.2mOhm. Yes that is correct. It can handle up to 195Apeak.

So the switch will not be a limiting factor and it will also have less impact on the sound than an relay.

The TSSA V4 will be limited to 20Apeak equally to 2Ohm load at an supply voltage of +/-45VDC.

DC protection is planed to hit in at 500mVDC for 2 seconds.

Both will trigger the protection.

The circuit itself (TSSA V4) will not be changes radically compared to TSSA V1.7/V1.8.. Only all part of the circuit is updated to run at up to +/-55VDC.
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Status update on TSSA V4 and V8

What have been added to the TSSA V4 (Which is also the case for TSSA V8)

1) +/-15V shunt regulator borrowed from the Mirand A2
2) small microcontroller to ensure correct startup and protection through the solidstate relay. Startup delay is 1 second and 1 second recovery from current limit or DC.
3) Higher working voltage on some stages.
4) temp. sensing transistors to give better bias stability.
5) DC sense ... .6V DC timeconstant of 1sec.
6) Current limit 20A. (40A in TSSA V8)

..

Basically the circuit is identical to TSSA V1.7 and V1.8.. But improvement is made on front-end supply voltage stability.
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
sonnya said:
Status update on TSSA V4 and V8

What have been added to the TSSA V4 (Which is also the case for TSSA V8)

1) +/-15V shunt regulator borrowed from the Mirand A2
2) small microcontroller to ensure correct startup and protection through the solidstate relay. Startup delay is 1 second and 1 second recovery from current limit or DC.
3) Higher working voltage on some stages.
4) temp. sensing transistors to give better bias stability.
5) DC sense ... .6V DC timeconstant of 1sec.
6) Current limit 20A. (40A in TSSA V8)

..

Basically the circuit is identical to TSSA V1.7 and V1.8.. But improvement is made on front-end supply voltage stability.
Click to expand...

I forgot the balanced input in the list above.

What have been added to the TSSA V4 (Which is also the case for TSSA V8)

1) +/-15V shunt regulator borrowed from the Mirand A2
2) small microcontroller to ensure correct startup and protection through the solidstate relay. Startup delay is 1 second and 1 second recovery from current limit or DC.
3) Higher working voltage on some stages.
4) temp. sensing transistors to give better bias stability.
5) DC sense ... .6V DC timeconstant of 1sec.
6) Current limit 20A. (40A in TSSA V8)
7) Balanced input 10K input impedance.
 
sonnya

sonnya

Member
Joined 2001
mirand-audio.dk/?post_type=product
Update for softstart.

We have an new firmware for the softstart which supports the use of thermal switch. When the termal switch breaks, the softstart switches off..

Every one who would like this new firmware can write to me.

An suitable programmer would be:

AVRdragon, AVR-ISP MKII, olimex AVR-ISP-MK2, Atmel-ICE BASIC, Zeptoprog II.

I have only tested using AVRdragon, AVR-ISP MKII and ATMEL-ICE Basic.

But Olimex and Zeptoprog should work as well.
 
pdb

pdb

Member
Joined 2007
Last edited:
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
sonnya said:
Here are the shots

An externally hosted image should be here but it was not working when we last tested it.

An externally hosted image should be here but it was not working when we last tested it.


As you Can see it is really high frequent... 43MHz so you will not detect it unless you use >60MHz scope
Click to expand...

Sonny hi,

Got around to check mine too and when the output passed 38V P-P there it burst out. Could listen to the MOSFETS buzzing along too.:D
The 470pF U2 D to S cap cured it. Thanks.
BTW I still get a bit peaky corners square wave like this one. Its there if lower frequency test signal also. What best compromise method do you possibly recommend to iron it out?
 

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