I'm trying to see if there is a way to buy the stuff from one place. Given that I need PCB from jlc. I searched their parts and found these:
I have 1K metal resistors at home. All the others I found some in DigiKey and Mouser. I guess is there a "simpler" way that I don't need to manage multiple orders?
I have 1K metal resistors at home. All the others I found some in DigiKey and Mouser. I guess is there a "simpler" way that I don't need to manage multiple orders?
I am trying the PCB assembly service from JLC. They ask for BOM and CPL files. I think I picked all parts from their library so that is done. For the CPL file, does the software generate these? I'm doing the no buffer stereo input board.
I just read it is a list with the center coordinates of each component. I do not have that.
What is the input and output impedance of your tube buffer board? As far as I know, we'd need its input impedance to be at least 10:1 ratio of the preamp's output impedance, and the tube buffer output impedance to be 1:10 to 1ET400A's inlet 2.2kΩ (SE) / 4.4kΩ (BAL).
About the tube buffer's gain, does it have any? So I could plan for the preamp's gain and output impedance accordingly.
Thank you very much for offering your board design for free.
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A lot of answers are in the schematic of post 55.
R1/R11 define input impedance, now set on 100k/200k. But you may change this as you need.
Gain is defined by jumper J3 , 3 or 9 times gain. You can also change that by changing value of R9/10.
About the output impedance I do not know because of the applied feedback.
R1/R11 define input impedance, now set on 100k/200k. But you may change this as you need.
Gain is defined by jumper J3 , 3 or 9 times gain. You can also change that by changing value of R9/10.
About the output impedance I do not know because of the applied feedback.
When you say 3 or 9 times gain, how does it translate to dB or Volts? In comparison, 1ET400A gain is 12.8dB. Eval1 Stereo gain is 0/14 db.
For example, if I feed with a 2 Vrms signal and a RCA to XLR cable, how many volts would I get? Or in other words, which input voltage would get to clipping with either gain?
About the 6.3V/3.3A external supply, wouldn't it be possible to use SMPS1200A400 own 12V aux, as VTV tube buffer does? (I believe).
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No it is not possible to use the 12V aux supply(max 500mA) of the smps1200A400. See hypex documentation page 5.
VTV use other tubes(Other topology, other specs)
Gain is 3 or 9 times the input signal, you can do your own calc.(You need 9.6Vrms to get max power at 1% distorsion).
VTV use other tubes(Other topology, other specs)
Gain is 3 or 9 times the input signal, you can do your own calc.(You need 9.6Vrms to get max power at 1% distorsion).
Thanks, sorry I had looked at the Hypex doc for aux but didn't locate the current output (max. 500mA). I guess you can't take the mains 65V either and a voltage regulator to 6.3V.
I understand the tubes' current requirement, it's a pity that it requires two external supplies, as it complicates to find a case to fit the buffers and supply connections. I only have the Ghent case for reference, but it's only designed to fit Eval1 board.
I've checked 3 and 9 times gain equals to 9.5 and 19 db respectively. So a 2 Vrms input would get 6V and 18V resp., if I'm not wrong. 9.6 Vrms is the clip limit. Using a 4.2V capable balanced signal with average compressed music would need quite attenuation with minimum 3 times gain since it reaches max power at 3.2V, so a preamp with gain wouldn't be needed, only passive attenuation, with any pot impedance (10k, 50k), since the buffer input impedance is high enough (100k/200k).
I understand the tubes' current requirement, it's a pity that it requires two external supplies, as it complicates to find a case to fit the buffers and supply connections. I only have the Ghent case for reference, but it's only designed to fit Eval1 board.
I've checked 3 and 9 times gain equals to 9.5 and 19 db respectively. So a 2 Vrms input would get 6V and 18V resp., if I'm not wrong. 9.6 Vrms is the clip limit. Using a 4.2V capable balanced signal with average compressed music would need quite attenuation with minimum 3 times gain since it reaches max power at 3.2V, so a preamp with gain wouldn't be needed, only passive attenuation, with any pot impedance (10k, 50k), since the buffer input impedance is high enough (100k/200k).
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I use for asymetrical/rca input the 9 x gain and for symmetrical input the 3 x gain. But you can adjust the gain between 1 and 20 times by changing the feedback resistor.
And yes you do not need a preamplifier just source select and volume control.
And yes you do not need a preamplifier just source select and volume control.
I have thought of bypassing the Eval1 buffer and use a tube preamp such as this to control volume. It has 6 times voltage gain, an ALPS27 potentiometer, and is a Marantz 7 clone. It is not very expensive.
The problem is tube preamps have high output impedance, this preamp has 50kΩ, too high for 1ET400A 2.2kΩ SE unbuffered.
The key is I don't want to enable Eval1 buffer, because I don't want its gain or its opamp amplification, I only want the preamp for that.
A buffer with at most 200Ω is unavoidable. Even a well regarded and popular preamp, Shiit Freya+ or Kara have 600Ω output impedance balanced, shouldn't even drive the Purifi load well at 4.4Ω (only 7:1 ratio).
The problem is tube preamps have high output impedance, this preamp has 50kΩ, too high for 1ET400A 2.2kΩ SE unbuffered.
The key is I don't want to enable Eval1 buffer, because I don't want its gain or its opamp amplification, I only want the preamp for that.
A buffer with at most 200Ω is unavoidable. Even a well regarded and popular preamp, Shiit Freya+ or Kara have 600Ω output impedance balanced, shouldn't even drive the Purifi load well at 4.4Ω (only 7:1 ratio).
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You can build your own preamp with this,
https://www.diyaudio.com/community/...c85-6922-6dj8-etc-mu-follower-or-srpp.388295/
https://www.diyaudio.com/community/...c85-6922-6dj8-etc-mu-follower-or-srpp.388295/
It looks great, but I don't see the advantage to this one since it doesn't have volume control.
I would like your 1ET400A design to be compatible physically with Eval1 available casing, such as soundimports or ghent.
So far the only way is an open installation. It is difficult to make a custom case.
I would like your 1ET400A design to be compatible physically with Eval1 available casing, such as soundimports or ghent.
So far the only way is an open installation. It is difficult to make a custom case.
First get/build your optimal sounding amp. Then (let)build the housing.
Or as I and a view more people do. Build the power amp as just amp and powersupply in one housing.
And inputselect/volume control/preamp in an other housing.
I can also share PCB design file for designspark software as starting point.
Or as I and a view more people do. Build the power amp as just amp and powersupply in one housing.
And inputselect/volume control/preamp in an other housing.
I can also share PCB design file for designspark software as starting point.
I know this post is about the purify amps, but I think you do know my question related to NC500/NCX500 input boards.
I want to build an amp with two NCX500 modules and one PSU. I am looking for information how to correctly connect the two NC500 evaluation boards (input buffers) to one SMPS1200A700? To my understanding I need to split the PSU cable, SMPS (J1) to two times evaluation board (J17), and also split the signal cable (UcD/NCore Interface) from SMPS (J4) to two Evaluation boards (J12). I can find a splitted PSU cable at Ghentaudio. But I can't find a splitted signal cable. Anyone can help me out here? Any tips are very welcome.
I want to build an amp with two NCX500 modules and one PSU. I am looking for information how to correctly connect the two NC500 evaluation boards (input buffers) to one SMPS1200A700? To my understanding I need to split the PSU cable, SMPS (J1) to two times evaluation board (J17), and also split the signal cable (UcD/NCore Interface) from SMPS (J4) to two Evaluation boards (J12). I can find a splitted PSU cable at Ghentaudio. But I can't find a splitted signal cable. Anyone can help me out here? Any tips are very welcome.
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