@Samuel Jayaraj @Tubelab_com @jam Last night and tonight I tested the KSC1845 in the gain position. It settled in immediately at about 10 mA and 60 Vd. It is quite good at low volumes but on crescendos, it doesn't do well. At 10 mA and about 40V across the device, it is near the dissipation limit. Maybe it would be better at different operating points, but 10 mA minimum is the price of entry in the current circuit. If we add an output buffer then it would open up more choices, such as LND150, etc.
I have to say that the STP30N10F7 has seen a lot of competition and still remains at the top of the heap. Another thing I would say is that there is a definite 'house' sound. I thought that after recently testing the IRF510 in the gain position. The IRF devices have a sound, the Toshiba devices have a sound, and the ST devices have a sound. All devices of a given manufacturer have different specs that results in different sound but there are similarities between devices from a given manufacturer. Perhaps manufacturers have honed their techniques over the years and it does result in a sonic signature.
I have to say that the STP30N10F7 has seen a lot of competition and still remains at the top of the heap. Another thing I would say is that there is a definite 'house' sound. I thought that after recently testing the IRF510 in the gain position. The IRF devices have a sound, the Toshiba devices have a sound, and the ST devices have a sound. All devices of a given manufacturer have different specs that results in different sound but there are similarities between devices from a given manufacturer. Perhaps manufacturers have honed their techniques over the years and it does result in a sonic signature.
ra7, thanks for your report on the performance of KSC1845 in the gain position.
I repeat this aspect I had raised earlier, but what alternative Current Source can be used in place of DN2540, as the TO220 version is no longer available. An alternative would extend the usable run of the SCG Preamp. Thanks.
Is there a demand for STP30N10F7 among folks building the SCG? I can source quite a number of those here.
I repeat this aspect I had raised earlier, but what alternative Current Source can be used in place of DN2540, as the TO220 version is no longer available. An alternative would extend the usable run of the SCG Preamp. Thanks.
Is there a demand for STP30N10F7 among folks building the SCG? I can source quite a number of those here.
The DN2540N5, IXTP1R6N100D2, IXTP08N100D2, IXTP3N100D2, IXTP01N100D, IXCP10M45S, and IXCP10M90S have been tested to work in similar circuits recently, though I have not tried all of them in my SCG board. The last three are rated for only 100 mA, so don't go beyond 100 mA with them. A CCS can be made with any N-channel depletion mode mosfet having suitable voltage and current ratings. One can also be built with a pair of BJT's, but that would not be directly compatible with this board. One could also sub the CCS with a choke, but that would change the start up procedure and likely warrant a lower B+ voltage since no voltage is dropped across a CCS.
Progress on my experiments stalled when the USPS lost my Mouser order. I had gone back and forth with the USPS and Mouser for a week with no solution. The USPS has lost, misdirected, or severely delayed 6 incoming or outgoing mail pieces in the last two months. They claim, and their tracking shows that Mouser pulled a tracking number but never shipped the order. The USPS will not even accept a lost mail search request, since they can't lose what they never got. Mouser said that scenario is virtually impossible in their workflow, but they would investigate it.
Daily calls to Mouser went to the same person who said that they were still investigating, resulting in a "call back Tuesday" request last Friday. Tuesday's call was answered by a different guy who said that they had multiple issues with the USPS in the last few months as well and that they would reship the entire order for no charge, but it would go UPS, not USPS.
Tracking shows delivery Friday evening. Our weather has been delivering a mess of rain, snow and ice for three days, and the UPS guy's route brings him past our dirt road after dark. I wouldn't drive a UPS truck down this road in the dark myself, so I'm guessing I'll get the parts on Monday.
So far, the gain stage part in the high power version of this design is the IXTH6N100D2, which could also be used for a CCS at dissipations in the 100 watt range or less. I'm running them at 250 volts and 250 mA, but will go higher when better thermal management arrives.
The part was in very short supply and costs $10 each, but Mouser had 70 of them on Tuesday. 6 are in my order.
Progress on my experiments stalled when the USPS lost my Mouser order. I had gone back and forth with the USPS and Mouser for a week with no solution. The USPS has lost, misdirected, or severely delayed 6 incoming or outgoing mail pieces in the last two months. They claim, and their tracking shows that Mouser pulled a tracking number but never shipped the order. The USPS will not even accept a lost mail search request, since they can't lose what they never got. Mouser said that scenario is virtually impossible in their workflow, but they would investigate it.
Daily calls to Mouser went to the same person who said that they were still investigating, resulting in a "call back Tuesday" request last Friday. Tuesday's call was answered by a different guy who said that they had multiple issues with the USPS in the last few months as well and that they would reship the entire order for no charge, but it would go UPS, not USPS.
Tracking shows delivery Friday evening. Our weather has been delivering a mess of rain, snow and ice for three days, and the UPS guy's route brings him past our dirt road after dark. I wouldn't drive a UPS truck down this road in the dark myself, so I'm guessing I'll get the parts on Monday.
So far, the gain stage part in the high power version of this design is the IXTH6N100D2, which could also be used for a CCS at dissipations in the 100 watt range or less. I'm running them at 250 volts and 250 mA, but will go higher when better thermal management arrives.
The part was in very short supply and costs $10 each, but Mouser had 70 of them on Tuesday. 6 are in my order.
I had a couple spare but they have been spoken for. I am ordering some more. Stay tuned.
George has posted a number of alternatives. I will add DN2535 to the list, currently in stock at Mouser.
Yes, there is a demand. I have not checked availability but good to know you can get them.
Looking great! Such a clean build.
In my build with a pot, I found that connecting the preamp ground to chassis cured the residual noise. Is the chassis grounded to earth? Don’t see it in the pics but it might be. Be sure to do that.
Vunce, I don’t get any noise coz I do have a Papa amp with 12db gain, though I haven’t tried it in a while. I have also run two SCGs in series and again, no noise.
In my build with a pot, I found that connecting the preamp ground to chassis cured the residual noise. Is the chassis grounded to earth? Don’t see it in the pics but it might be. Be sure to do that.
Vunce, I don’t get any noise coz I do have a Papa amp with 12db gain, though I haven’t tried it in a while. I have also run two SCGs in series and again, no noise.
Thanks Vunce, I am testing this right now with my MacBook as input via headphone out and listening using on my headphones. So no power amp yetCongrats Manniraj!
If your power amp has >20dB gain in addition to SCG's gain you will get a bit of hiss heard from the speakers.
But now eager to connect to my SissySIT R3 which is my main power amp and listen to my Forte's.
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Good eye Ra!
Manniraj, connect the chassis GND on pcb (next to NTC) to the common point earth GND attaches to chassis.
I do get some audible hiss with my ear close to the speaker when "regular" amplifiers are in the chain. When 'Follower' amps are in the chain no hiss heard.
Also, speakers are 92dB efficient.
Manniraj, connect the chassis GND on pcb (next to NTC) to the common point earth GND attaches to chassis.
I do get some audible hiss with my ear close to the speaker when "regular" amplifiers are in the chain. When 'Follower' amps are in the chain no hiss heard.
Also, speakers are 92dB efficient.
Thanks @ra7, this is my spare chassis a bit small to hold both the Antek trafo and the pcb. I passed all the signal wiring underneath the board from the pot to the input of the preamp. Yes I have not yet connected the preamp ground via the thermistor on board to the chassis yet. Will do that over the weekend and as you said hopefully it should eliminate the hiss which I am hearing and increasing with the volume pot.