Hi Salas / all,
I have the sshv2 back into the itch, 300v & 35mA exactly, stable and without the output links in place.
I did swap the valves around For the best channel balance, until I measured a channel output of 1.08 & 1.03 vac.
Next step it to find two suitable chassis, 1 for transformer, three rectifier boards, the other for main circuit, sshv2 and heater reg.
Any suggestions for the chassis would be very welcome, I have limited skills ��
Thanks for the tips
Ian
I have the sshv2 back into the itch, 300v & 35mA exactly, stable and without the output links in place.
I did swap the valves around For the best channel balance, until I measured a channel output of 1.08 & 1.03 vac.
Next step it to find two suitable chassis, 1 for transformer, three rectifier boards, the other for main circuit, sshv2 and heater reg.
Any suggestions for the chassis would be very welcome, I have limited skills ��
Thanks for the tips
Ian
This is an oscilloscope's job really. So you can fully see what it registers. DMM can be put in AC mode on the Itch's output when its input is shorted with a tiny link and register some number of average noise be it harmonic, white, interference, not clear. If there is a strong enough 50Hz or 100Hz band (hum, buzz) it should at least be able to trigger the frequency counter if you will press or select "Hz" on the DMM while on AC mode.
Hi Salas,
My dmm was so old it didn't have frequency measurements, so I bought a new DMM with frequency, temperature and capacitance. I tweaked the voltages and current on the sshv2, shorted the input and measured frequency, but no read out on hz. I measured 0.006vac on both channels.
The temperature gave the following, sshv2 large heatsink runs very cool at 44°c, the regs at lot hotter at 74°c, anything to worry about?
Still haven't hooked it up to my main system, without a chassis, need the time when its safe from little hand and pets. Maybe tonight ☺
Many thanks
Ian
My dmm was so old it didn't have frequency measurements, so I bought a new DMM with frequency, temperature and capacitance. I tweaked the voltages and current on the sshv2, shorted the input and measured frequency, but no read out on hz. I measured 0.006vac on both channels.
The temperature gave the following, sshv2 large heatsink runs very cool at 44°c, the regs at lot hotter at 74°c, anything to worry about?
Still haven't hooked it up to my main system, without a chassis, need the time when its safe from little hand and pets. Maybe tonight ☺
Many thanks
Ian
The AC reading is miniscule, maybe just the DMM's lowest settling or about. Points to no important self generated output as the Itch now stands on your bench.
When saying "regs" at 74C you mean the smaller on board sink for the current source cascode MOSFET on the SSHV2? If yes, it would be better for the sink to stay at 55C max. That MOSFET runs power by the DCinRaw-DCoutStabi voltage difference times the CCS current. You could burn some extra DCinput voltage elsewhere, on a larger value and wattage resistor in the CRC for instance. 20V Dcin-DCout is enough for that reg, and 30-35mA CCS is good for it when powering two Itch channels. If on the other hand by "regs" you mean the MOSFETs themselves then its normal to be hotter than the sink but could be better if the transfer to the sink was better. Like with a better Silpad and/or by making sure the back of the tab presses evenly parallel and well against the sink. Anyway since the IRF840 has 1C/W junction to case spec it will not be hotter than 82C inside with 7.5W dissipation (300V*25mA extra to the load) when it melts at 150C inside. How high is your DCin and your CCS setting at the moment?
When saying "regs" at 74C you mean the smaller on board sink for the current source cascode MOSFET on the SSHV2? If yes, it would be better for the sink to stay at 55C max. That MOSFET runs power by the DCinRaw-DCoutStabi voltage difference times the CCS current. You could burn some extra DCinput voltage elsewhere, on a larger value and wattage resistor in the CRC for instance. 20V Dcin-DCout is enough for that reg, and 30-35mA CCS is good for it when powering two Itch channels. If on the other hand by "regs" you mean the MOSFETs themselves then its normal to be hotter than the sink but could be better if the transfer to the sink was better. Like with a better Silpad and/or by making sure the back of the tab presses evenly parallel and well against the sink. Anyway since the IRF840 has 1C/W junction to case spec it will not be hotter than 82C inside with 7.5W dissipation (300V*25mA extra to the load) when it melts at 150C inside. How high is your DCin and your CCS setting at the moment?
New tubes aren't made as well as old ones. That's my conclusion anyway. The new tube manufacturers probably can't get the same quality materials they used to be able to get. As I understand it, even the special nickel metal alloy for cathodes is not made any more. I don't know what type of nickel alloy they use now. Also, some of the materials now are apparently illegal/outlawed because of environmental impact or other hazards. Finally, new manufacturers don't spend as much time during evacuation and/or burn in as they used to do 50 years ago.
Hi Salad,
I should have been more specific, the regs at 74°c are the filament lm317's. The sshv2 q1 is running at 44°c and large sink at 45°c, and has a DC inputs voltage of 342vdc. I connected the itch to my main system last night, initial impressions are good, very detailed and airy compared to my old phono. I did hear some him, but its still on a board not in a chassis. I also noticed some distortion in the higher frequencies, not sure what was causing it, was only a quick test. I will try the 300hz measurement at 33rpm, was there a 45rpm measurement?
Many thanks
Ian
I should have been more specific, the regs at 74°c are the filament lm317's. The sshv2 q1 is running at 44°c and large sink at 45°c, and has a DC inputs voltage of 342vdc. I connected the itch to my main system last night, initial impressions are good, very detailed and airy compared to my old phono. I did hear some him, but its still on a board not in a chassis. I also noticed some distortion in the higher frequencies, not sure what was causing it, was only a quick test. I will try the 300hz measurement at 33rpm, was there a 45rpm measurement?
Many thanks
Ian
Hello Ian
300Hz at 33.3 rpm should read 405.4Hz at 45 rpm so 303Hz that the HFNRR really has should read 409.46Hz. 409 or 410 or jumping in between on the meter should do.
Its a matter of meter and TT stability also to read steadily especially without a notch filter, but you will be able to check it out sufficiently I guess.
What kind of HF distortion? Is it more on tracks near the record's label? Can it be mistracking? The overload margin is huge in valve circuits but something could have gone wrong, so let me know.
Hi Salas,
How embarrassing, sorry.
Bloody auto correct on my Kindle fire...
Its the Android auto corrector I know.
Since you mentioned salad, see if the TT's bearing needs some oil.
Attachments
Hi Salas / all,
TT bearing lubed up, extra virgin of course
Meter gave the following results 33.3rpm= 302.9Hz and 45 rpm = 409.1Hz. Happy with that, there are some trim pots i can adjust on my Thorens td321, but wont bother for now.
Was 74°c for the filament lm317 sinks ok?
The HF distortion I noticed on one track in particular, it was a quick listen. I switched the phono stage back to current and it went. Same TT cart.
I will test some more later.
I have the Partridge 977 to implement, 20K for R1 I think?
Any recommendations on switches etc for dual input MM & MC, keeping signal path short etc.
Many thanks
Ian
Many thanks
Ian
TT bearing lubed up, extra virgin of course
Meter gave the following results 33.3rpm= 302.9Hz and 45 rpm = 409.1Hz. Happy with that, there are some trim pots i can adjust on my Thorens td321, but wont bother for now.
Was 74°c for the filament lm317 sinks ok?
The HF distortion I noticed on one track in particular, it was a quick listen. I switched the phono stage back to current and it went. Same TT cart.
I will test some more later.
I have the Partridge 977 to implement, 20K for R1 I think?
Any recommendations on switches etc for dual input MM & MC, keeping signal path short etc.
Many thanks
Ian
Many thanks
Ian
-Better use double the now size sink for the 317 or cut its Vin-Vout down to 3V if its more. Use CRC.
-Yes 18K-20K for the 977 termination, matter of taste.
-DIP switch locally breaking both signal hot and ground maybe. Four way connecting the other feed when breaking the other.
-Hmm see if its about mistracking after all. Like check the platter with tubular spirit level facing 90 deg both ways first and try different protractors. Clean the stylus well before that.
-If it persists, try 1N4148 instead of the IR but its not that likely its in the electronics unless your valve samples and your particular IR Leds don't bias high enough in tandem.
-Yes 18K-20K for the 977 termination, matter of taste.
-DIP switch locally breaking both signal hot and ground maybe. Four way connecting the other feed when breaking the other.
-Hmm see if its about mistracking after all. Like check the platter with tubular spirit level facing 90 deg both ways first and try different protractors. Clean the stylus well before that.
-If it persists, try 1N4148 instead of the IR but its not that likely its in the electronics unless your valve samples and your particular IR Leds don't bias high enough in tandem.
Hi Salas,
The New meter is this cheapie,
Extech EX330 Autoranging Mini Multimeter with Built In Thermometer with Type K Remote Probe - Amazon.com
Has good reviews for a budget meter.
I'll look into lowering the voltage on the lm317's and distortion In a few days time.
Many thanks
Ian
The New meter is this cheapie,
Extech EX330 Autoranging Mini Multimeter with Built In Thermometer with Type K Remote Probe - Amazon.com
Has good reviews for a budget meter.
I'll look into lowering the voltage on the lm317's and distortion In a few days time.
Many thanks
Ian
Med oil?Its the Android auto corrector I know.
Since you mentioned salad, see if the TT's bearing needs some oil.