meeskees Posted July 21, 2014 Report Posted July 21, 2014 http://www.ampdesign.eu/pi4/pd73.htm This one? Quote
insanity Posted July 21, 2014 Report Posted July 21, 2014 For that money, you can probably almost get a custom one from toroidy.pl with all secondaries you need. We were talking about this one: http://www.antekinc.com/as-1t275-100va-275v-transformer/ http://www.ampdesign.eu/pi4/pd73.htm This one? Quote
Mangler Posted July 21, 2014 Report Posted July 21, 2014 Would this one also work?http://www.antekinc.com/as-3t275-300va-275v-transformer/ Sent from my iPhone using Tapatalk Quote
kevin gilmore Posted July 21, 2014 Author Report Posted July 21, 2014 nope, you need 2 high voltage windings Quote
Mangler Posted July 21, 2014 Report Posted July 21, 2014 Thanks, glad I asked Sent from my iPhone using Tapatalk Quote
spritzer Posted July 21, 2014 Report Posted July 21, 2014 This one would work with 500V capacitors (450V might be ok but we don't work well with "might") and larger heatsinks in the PSU. http://www.antekinc.com/as-1t300-100va-300v-transformer/ Quote
Laowei Posted July 21, 2014 Report Posted July 21, 2014 It looks ok but I'd go for a single 30VCT@500ma winding instead of two separate windings.Getting ready to send out for some quotes on a custom transformer. I tried to capture all the needs for a KGST in a single unit, using the out of stock Antek transformer and posted info here as a basis. For those that have more experience ordering custom transformers, do any of the following specs look too constraining or impractical? KGST POWER TRANSFORMER SPECIFICATIONS: 120VA toroidal audio power transformer with: -Static shield between primary and secondary coils. -Heavier gauge wires than normal requirement to avoid the copper lost at full power. -Magnetic shield around the outside to reduce the magnetic leakage. -HiPot 3500V between primary and secondary coils. -Approximate overall dimensions: 100mm diameter x 50mm height. -Mechanically silent operation. -45C maximum temperature in ambient 20C environment. -Mounting hardware included. -All wires out minimum 300mm long. ELECTRICAL CHARACTERISTICS: Power: 120VA Inputs: 2X Voltage-Hertz 117V-50/60hz 117V-50/60hz Outputs: 5X Voltage@Current [email protected] [email protected] [email protected] [email protected] 6.3V @1.5A Thanks for any suggestions. I will send for quotes in a few days. Quote
spritzer Posted July 21, 2014 Report Posted July 21, 2014 It looks ok but I'd go for a single 30VCT@500ma winding instead of two separate windings. Quote
nopants Posted July 22, 2014 Report Posted July 22, 2014 This one would work with 500V capacitors (450V might be ok but we don't work well with "might") and larger heatsinks in the PSU. http://www.antekinc.com/as-1t300-100va-300v-transformer/ does aavid make anything taller than 2.5 inch? I've got a bunch of those leftover from kgsshv parts binging- they seem like the only things that will fit... Quote
Laowei Posted July 22, 2014 Report Posted July 22, 2014 It looks ok but I'd go for a single 30VCT@500ma winding instead of two separate windings. Fixed. Quote
chiguy Posted July 22, 2014 Report Posted July 22, 2014 The silk screening on the boards say 36VCT so anywhere in between 30VCT and 36VCT is okay? Is there any point going higher than 30? Quote
Laowei Posted July 22, 2014 Report Posted July 22, 2014 Not really, only more heat to dissipate. Quote
Mangler Posted July 22, 2014 Report Posted July 22, 2014 Antek has a very nice transformer at 275V (i.e. close enough) and then you just need a 30VCT transformer for the +/-15V supply In case anybody was wondering or didn't already know, the secondaries all of Antek's transformers have 2 individual coils which can be wired in series or parallel, so they can be used as center tapped transformers. In this case, this spritzer-selected transformer would serve the role of a 30VCT transformer perfectly :http://www.antekinc.com/as-0515-50va-15v-transformer/ Sent from my iPhone using Tapatalk Quote
Laowei Posted July 23, 2014 Report Posted July 23, 2014 In Birgir's and Kevin's photos of populated KGST boards there is a socket, for but no OP27 installed. Is the OP27 needed? Quote
insanity Posted July 23, 2014 Report Posted July 23, 2014 If you want the servo to work, then you need it ;-) Quote
kevin gilmore Posted July 25, 2014 Author Report Posted July 25, 2014 this is the cap you should use for the servo, fits the smaller holes 667-ECQ-E2105KF Quote
Remolon Posted July 28, 2014 Report Posted July 28, 2014 I am waiting for the PCBs to build the KGST but I am considering the option to duplicate, with the appropriate values, the set R20/VR2 for having separate adjustment for each valve and the possibility to correct some valve mismatch. Quote
kevin gilmore Posted July 28, 2014 Author Report Posted July 28, 2014 no, absolutely not. Output stage is a differential amplifier. Quote
Remolon Posted July 28, 2014 Report Posted July 28, 2014 I believe that not all the valves evolve similarly, and although they are matched at the beginning it will not last for ever. For this reason, I prefer to substitute the need of matching with a procedure of measuring and adjusting a fundamental parameter in the response of the valve. For example, in a power amplifier with a push-pull of EL34 the procedure is to measure the cathode current and to correct it adjusting the grid bias, but what is the procedure for a circuit such as the KGST, if any? Quote
kevin gilmore Posted July 29, 2014 Author Report Posted July 29, 2014 half of the differential gain comes at the output stage. there is a offset and balance control. This takes care of everything. Really! Quote
Remolon Posted July 29, 2014 Report Posted July 29, 2014 Thanks Kevin. It is a excellent information. Quote
Remolon Posted August 7, 2014 Report Posted August 7, 2014 @headinclouds: Would be nice to read about the progress of the PCB order. Regards Quote
headinclouds Posted August 8, 2014 Report Posted August 8, 2014 @headinclouds: Would be nice to read about the progress of the PCB order. Regards Yes - good timing on that. The pcbs will be with me Monday 11 Aug and I'll be posting out over Monday /Tuesday. Quote
Laowei Posted August 8, 2014 Report Posted August 8, 2014 Yes - good timing on that. The pcbs will be with me Monday 11 Aug and I'll be posting out over Monday /Tuesday. That sounds great Geoff. Many thanks for doing this group buy. Kevin or Birger, what is the max P-P output voltage of the KGST with 350V rails? ~850-990V? Also what is the KGST's gain? I am trying to map out the gain structure of my system. Thanks. Quote
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