Thanks Jason.
Regarding the rail voltage,hooked up my 30Vac transformer and the bias didn't change at all.
Regarding the rail voltage,hooked up my 30Vac transformer and the bias didn't change at all.
Using a high input impedance will can result in higher noise. May not be a problem in a given application, but more care in proper grounding between components might be needed if noise becomes an issue - particularly important in multiamped situations. Star grounding among the components (not just within a component) will often solve those issues.
Sheldon
Hi Jason,
I apologize for not reading the 51 pages on this thread, I'm just wondering which type of supply is best suited for the VSSA, I am aware it must be very quiet (noise free). Would a CM or SMPS be well suited or should I stick to a more conventional CRC or even CLC type. If you or other member have any recommendation of supplier with cat. model no. this would be appreciated.
TIA,
Eric
I apologize for not reading the 51 pages on this thread, I'm just wondering which type of supply is best suited for the VSSA, I am aware it must be very quiet (noise free). Would a CM or SMPS be well suited or should I stick to a more conventional CRC or even CLC type. If you or other member have any recommendation of supplier with cat. model no. this would be appreciated.
TIA,
Eric
It isn't a problem to use a regular CRC supply, the VSSA doesn't have exceptional PSSR but it isn't bad either. Some have chosen SMPS for their projects; Hypex (SMPS400A100 or SMPS400A180), Audio Power (DPS400LV) and Connexelectronic (SMPS300RE or SMPS500R) would be a few to consider. I'm sure there are others. I can't recommend ColdAmp, their SPS30 blew a switching MOSFET almost immediately an I got zero response when I requested support and it was rather expensive at that. I did repair it and do use it for testing. A capacitance multiplier has been popular too.
For ease of construction and reliability I suggest a plain 'ol CRC unregulated linear supply.
For ease of construction and reliability I suggest a plain 'ol CRC unregulated linear supply.
Old Skool or SMPS .. Clean DC supply being the holy grail.
Unregulated is IMO sketchy.. at best.
Unregulated is IMO sketchy.. at best.
Best of both worlds would be regulated for VAS and unregulated for the power section. Much easier to do with unregulated power supply and by adding a zener for the VAS.
Most amplifier PSUs are unregulated; old school is the plain vanilla capacitive smoothing only approach. Regulation is for designs that have effectively zero PSRR.
It is possible to feed the front end with a regulated supply but I don't feel it is needed.
These through hole VSSAs are pretty tolerant I think. I have used Mr evil cap multipllier, Connex SMPS, plain vanilla bridge/filter cap. even a $30, +-25V SMPS. They just play nice.
Just have a look at where you installed the 20Ω zobel resistors. Make sure you didn't use the pads inside the rectangles representing the device body. They are just vias connecting traces between top and bottom. Use the pads located outside the rectangle on either end.
I didn't make it real clear on the silk or documentation and some have been confused by those 'extra' pads.
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OK, It wasn't clear in your picture showing your test arrangement so I just wanted to make sure they gut installed onto the proper pads.
Potential Revision 'D' Board?
I started re-arranging the VSSA board and am getting something in a PMI-like form factor. It is however not a copy of the PMI board. Some have mentioned with prior layouts that output device placement could have been more idealized and that accommodating lower profile heat sinks might be of benefit. This will be 3" high and 4" wide, so the same size board as before, just horizontal in orientation. This layout is not yet complete.
I don't know if the little VSSA has played out or not, but if there's still interest I'll continue to develop it. I'm looking to improve the CCSs with precision shunt references and if there's room maybe a cascode device to help keep the CCS output impedance high. There is also some influence from the discussions in the SlewMaster thread pertaining to the CFA-XH IPS and improvements in its design as well.
Thoughts, suggestions or constructive criticism welcomed.
I started re-arranging the VSSA board and am getting something in a PMI-like form factor. It is however not a copy of the PMI board. Some have mentioned with prior layouts that output device placement could have been more idealized and that accommodating lower profile heat sinks might be of benefit. This will be 3" high and 4" wide, so the same size board as before, just horizontal in orientation. This layout is not yet complete.
I don't know if the little VSSA has played out or not, but if there's still interest I'll continue to develop it. I'm looking to improve the CCSs with precision shunt references and if there's room maybe a cascode device to help keep the CCS output impedance high. There is also some influence from the discussions in the SlewMaster thread pertaining to the CFA-XH IPS and improvements in its design as well.
Thoughts, suggestions or constructive criticism welcomed.
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That looks really nice Jason. I would be surprised if the VSSA will not still be of interest. There is nothing else like it.
The blade connectors are really close together. Will insulated connectors slide in without interference? Nice looking symmetrical layout!
I don't know about the big clunky automotive insulated spades, but there are ones with close fitting sleeves that certainly will. I usually buy uninsulated female spades and use heat shrink over them.
I chose 0.200" spacing should someone want to use a screw terminal block or Molex type pin headers. More variety in connection options.
I chose 0.200" spacing should someone want to use a screw terminal block or Molex type pin headers. More variety in connection options.
Thomas & Betts insulated connectors are .230" thick, but I like the idea of the terminal blocks. I've seen way too may cheap Sta-Kons loose their grip with age.
So, I did some measurements, after that I connect amp to proper PSU. Sine at 200 kHz is fine, square at 20 kHz also.. I did some listening, so nice sounding amp, I think with comparison with SKA more bass, more fun 🙂
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