July 13, 20187 yr On 7/10/2018 at 10:45 PM, mwl168 said: This is a great sounding amp. For the parts cost (when you can get them), this ES CFA probably takes the crown of the ROI of all the ES amps I have built. So Glad you like it. never sure what someone else will think / hear its a good thing I did not build this first might have found an even more expensive hobby
August 18, 20187 yr Bought these PCBs from the GB awhile back. Looking to order the in-stock resistors to start. Are the values shown currently good to use? The schematic done earlier is a little different. Thanks.
August 18, 20187 yr I compared the resistors to my board and, without seeing the trace, they look right. This amp runs much hotter than I expected so make sure you have ample heatsink. The 500K bias resistors set the output current. Edited August 19, 20187 yr by mwl168
August 21, 20187 yr FYI, PBHV9560, PBHV8560, KSA1156 are all in-stock at Mouser and shipping. KSA2752 are still BO until November.
August 21, 20187 yr 58 minutes ago, Laowei said: FYI, PBHV9560, PBHV8560, KSA1156 are all in-stock at Mouser and shipping. KSA2752 are still BO until November. Kevin has noted that KSC5026 is a substitute for KSC2752. Last I checked it was BO at Mouser but in stock at Digikey! Edited August 21, 20187 yr by mwl168
August 21, 20187 yr On 8/18/2018 at 4:24 PM, Laowei said: the values shown Yes, have made boards from those gerber's and they work just fine. 51 minutes ago, Laowei said: KSA2752 are still BO until November. when I last ordered some (19-Oct-2017) it said Jan 2018
August 21, 20187 yr 54 minutes ago, mwl168 said: Kevin has noted that KSC5026 is a substitute for KSC2752. Last I checked it was BO at Mouser but in stock at Digikey! Thanks. I’ll give Digikey my order. Looks like I’ll have all the parts to try the little amp out. I’ll repurpose the PS from my KGST to power it. 56 minutes ago, congo5 said: Yes, have made boards from those gerber's and they work just fine. when I last ordered some (19-Oct-2017) it said Jan 2018 Thanks for the resistor confirmation. The BO slide on that BJT is not too encouraging...
January 16, 20197 yr The transistors on the inside, Don´t need a heatsink? For the temperatures that Mwl says, I think I'll need a big chasis.
January 16, 20197 yr 9 hours ago, jose said: The transistors on the inside, Don´t need a heatsink? No 9 hours ago, jose said: For the temperatures that Mwl says, I think I'll need a big chasis. 0,5 C°/W per channel will do if you go with stock values
January 22, 20197 yr Are these the right transistors? https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSC2752OSTU?qs=sGAEpiMZZMshyDBzk1%2fWi8oN7VHZ91OkpQ9k8BYJNao%3d https://www.mouser.com/ProductDetail/ON-Semiconductor-Fairchild/KSA1156OSTU?qs=%2fha2pyFadugv%2fWJliOE2i01ObXewH%2b9W60g4Ozyqyh8LU2w5on%2bF8w%3d%3d And for resistors I'm guessing RN60D's are ok? Edited January 22, 20197 yr by sbelyo
January 22, 20197 yr For resistors I used Koa like in other electrostatic amps. Transistors is OK. Front transistors I used PBHV8560/PBHV9560
January 22, 20197 yr 1 hour ago, jose said: For resistors I used Koa like in other electrostatic amps. Transistors is OK. Front transistors I used PBHV8560/PBHV9560 Thanks... Is metal film 1/4 watt 1% 100 ppm ok? Is one series better than another
January 22, 20197 yr 12 minutes ago, sbelyo said: Thanks... Is metal film 1/4 watt 1% 100 ppm ok? Is one series better than another Nop, for electrostatic amps I use this KOA. Metal film 1/2W 1% 50 ppm (or 100 ppm)
January 22, 20197 yr 2 minutes ago, jose said: Nop, for electrostatic amps I use this KOA. Metal film 1/2W 1% 50 ppm (or 100 ppm) cool thanks
January 22, 20197 yr I thought it was either the Xicon 271 or 273 series resistors that we’re used for the electrostatic amps? I could be wrong/behind the times...Sent from my iPhone using Tapatalk
January 22, 20197 yr 32 minutes ago, Pars said: I thought it was either the Xicon 271 or 273 series resistors that we’re used for the electrostatic amps? I could be wrong/behind the times... Sent from my iPhone using Tapatalk The problem with Xicon is max volt: 350v max (271 series), 500v max (294 series) vs 700v max (Koa MF1 series 1/2w). Edit: I'm reviewing the technical sheets and I see that the data is similar for both the Xicon (293 series) and the KOA (CF1). All my BOMs are with KOA resistors Edited January 22, 20197 yr by jose add dates
January 22, 20197 yr I just realized that the terminal blocks should be high voltage as well. Jose, what terminal block are you using?
January 23, 20197 yr Koa 1/2W (MF series IIRC) and RD60 should be fine in most positions with Electrostatic amps. I’ve used both without issues. From what I read, the Xicon is better for the battery positions in Kevin’s T2 - others seem to result in noise issues likely due to leakage. Edited January 23, 20197 yr by mwl168
January 23, 20197 yr I haven´t predilection for any particular resistors brand. I use what works but if there are better ones for these amplifiers, I'll buy them of course. For terminal I think we all use the same Phoenix (MKDSN series).
January 24, 20197 yr 18 hours ago, jose said: For terminal I think we all use the same Phoenix (MKDSN series). I measured the pin spacing on the boards as well as the BH Ultramini PSU. They're all 5.08mm The MKDSN series are all 7.62mm It doesn't look like they'll fit and I don't see anything in that size higher than 300V
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