This guy built an impressive JP200 which he is very happy with, and gives a nice detailed sound with soundstage... YouTube
He responded with the following alterations in an email to me - what do you think ??
" I have successfully built a complete JP-200 "deluxe" kit (with some alterations, see below). Analogmetric as a company are easy to deal with but delivery is not exactly the fastest. They respond quick to emails.
If you are a beginner as a kit builder I have to warn you about lack of building support. The information on the analogmetric web site and forum is very basic and all you get. There is no overall wiring diagram or step by step instructions to lead you. So you have to know what goes where.
I have no idea if that preamp is even close to the original Jadis JP-200. I guess not because the original is a 4-chassis design including phono preamp stages.
The sound of this line stage is very much depending on the tubes you use. If you put in Mullards you get that typical (brown) Mullard sound which is not my cup of tea.
With the right tubes you can build a very transparent and detailled preamp featuring a huge soundstage. Before I have used a Silk-based TVC from DIYHifiSupply which tends more to the lean side. Compared to the TVC the JP-200 clone has more timbre, body and weight. Amount of detail is on the same (high) level.
Over the years I have come to the conclusion that a preamp is really a necessary component in a decent sounding system. Not to add voltage gain but to add those properties mentioned above. For me it is a deliberate departure from a "neutral" amplifier system. But sins of omission are not tolerated!
The rest of my system is a slightly moddified SlimDevices Transporter as source and Hypex-based Class-D poweramp feeding my Tannoy IIILZ Monitor Mk II speakers.
I have made the following alterations to the kit:
Power supply:
- Use the optionally available 10H choke
- Use 6x4 as rectifier tube (7-pin socket is not included!)
- Replace C1 and C3 with a single Mundorf tube cap of 10uF, 1000V
- Replace C7 with a TAD Oil Cap of 0.25uF, 600V
Amplifier board:
- Replace all resistors with Takman REY 0.5W metall film types
- Change R7A and B to 1kOhm
- Change R10A and B to 1.5 kOhm
- Change R14A and B to 100 Ohm
- Add C9A an B (which are not supplied with the kit) two TAD Oil Caps 0.25 uF / 600 V
- Replace C1A and B with Ampohm Aluminium Foil, Paper in Oil Cap 0,047 uF / 630 V
- Replace C2A and B with Ampohm Aluminium Foil, Paper in Oil Cap 0.1 uF / 630 V
- Replace C5A and B with Ampohm Aluminium Foil, Paper in Oil Cap 1.0 uF / 630 V (depending on the imput inpedance of your poweramp you might need a bigger value)
- Replace C4A and B with silver mica 8 pF / 500 V and place a silver mica 22 pF / 500 V capacitor between grid and cathode of T1A and B to fight self oscillation
- Use ECC81 / 12 AT7 for the cathode follower position (T3A and B) to lower output impedance
Lowering gain from 20 to 12dB:
- Change R5A and B to 33 kOhm
- Change R3A and B to 1 kOhm
General:
Be warned about the input selector and output delay protection kit which are included in the "deluxe" version of the kit: Both have ground planes which are connected to the local power supply ground. There is no dedicated signal ground plane! If you use the Analogmetric tube tube power supply there is only one low voltage supply you can use to feed both modules which is the unregulated part of the heater supply. Bad thing is that the heaters are connected to pin 4 and 5 of the ECC83s and pin 9 is grounded. As a result the ground plane of both modules is at -6.3V to ground! This converts ground planes to perfect anntenas.
- Add two ceramic 10 nF / 500 V capacitors to HF-wise shunt the "ground planes" of the input and output modules to signal ground
- The delivered Shuguang 12AX7B are not too bad for chinese tubes but I would recommend to find out which NOS tubes you like
Best regards,
Norbert
He responded with the following alterations in an email to me - what do you think ??
" I have successfully built a complete JP-200 "deluxe" kit (with some alterations, see below). Analogmetric as a company are easy to deal with but delivery is not exactly the fastest. They respond quick to emails.
If you are a beginner as a kit builder I have to warn you about lack of building support. The information on the analogmetric web site and forum is very basic and all you get. There is no overall wiring diagram or step by step instructions to lead you. So you have to know what goes where.
I have no idea if that preamp is even close to the original Jadis JP-200. I guess not because the original is a 4-chassis design including phono preamp stages.
The sound of this line stage is very much depending on the tubes you use. If you put in Mullards you get that typical (brown) Mullard sound which is not my cup of tea.
With the right tubes you can build a very transparent and detailled preamp featuring a huge soundstage. Before I have used a Silk-based TVC from DIYHifiSupply which tends more to the lean side. Compared to the TVC the JP-200 clone has more timbre, body and weight. Amount of detail is on the same (high) level.
Over the years I have come to the conclusion that a preamp is really a necessary component in a decent sounding system. Not to add voltage gain but to add those properties mentioned above. For me it is a deliberate departure from a "neutral" amplifier system. But sins of omission are not tolerated!
The rest of my system is a slightly moddified SlimDevices Transporter as source and Hypex-based Class-D poweramp feeding my Tannoy IIILZ Monitor Mk II speakers.
I have made the following alterations to the kit:
Power supply:
- Use the optionally available 10H choke
- Use 6x4 as rectifier tube (7-pin socket is not included!)
- Replace C1 and C3 with a single Mundorf tube cap of 10uF, 1000V
- Replace C7 with a TAD Oil Cap of 0.25uF, 600V
Amplifier board:
- Replace all resistors with Takman REY 0.5W metall film types
- Change R7A and B to 1kOhm
- Change R10A and B to 1.5 kOhm
- Change R14A and B to 100 Ohm
- Add C9A an B (which are not supplied with the kit) two TAD Oil Caps 0.25 uF / 600 V
- Replace C1A and B with Ampohm Aluminium Foil, Paper in Oil Cap 0,047 uF / 630 V
- Replace C2A and B with Ampohm Aluminium Foil, Paper in Oil Cap 0.1 uF / 630 V
- Replace C5A and B with Ampohm Aluminium Foil, Paper in Oil Cap 1.0 uF / 630 V (depending on the imput inpedance of your poweramp you might need a bigger value)
- Replace C4A and B with silver mica 8 pF / 500 V and place a silver mica 22 pF / 500 V capacitor between grid and cathode of T1A and B to fight self oscillation
- Use ECC81 / 12 AT7 for the cathode follower position (T3A and B) to lower output impedance
Lowering gain from 20 to 12dB:
- Change R5A and B to 33 kOhm
- Change R3A and B to 1 kOhm
General:
Be warned about the input selector and output delay protection kit which are included in the "deluxe" version of the kit: Both have ground planes which are connected to the local power supply ground. There is no dedicated signal ground plane! If you use the Analogmetric tube tube power supply there is only one low voltage supply you can use to feed both modules which is the unregulated part of the heater supply. Bad thing is that the heaters are connected to pin 4 and 5 of the ECC83s and pin 9 is grounded. As a result the ground plane of both modules is at -6.3V to ground! This converts ground planes to perfect anntenas.
- Add two ceramic 10 nF / 500 V capacitors to HF-wise shunt the "ground planes" of the input and output modules to signal ground
- The delivered Shuguang 12AX7B are not too bad for chinese tubes but I would recommend to find out which NOS tubes you like
Best regards,
Norbert
...and also this correspondence...
"...the preamp is made according to analogmetric suggestions and they helped me with the? needed changes.. I've started with talkman 1watt carbon resistors but found them a bit too doll/warm in sound seems a bit slow.. and I couldn't changed that by tube rolling, so together with Brian from analogmetric we found that talkman 1watt metal film resistors changed a lot in the right direction and the two feedback capacitors has been changed to 2um instead of 1um, the rest is according to pcb.
I will upload some extra pictures. The pcb on the left side is the power supply, it is the PS200 tube variable voltage regulator from analogmetric,? I don't use the rectifier tube, but except from that nothing is changed… I have tested it against some very expensive preamps and this one is absolutely the best one
Hi Polaxed1. i have tried different components, but my referance and chosen are. Capacitors: Mundorf silver/oil Recistors: Takman carbon film 2w and the tubes has been changeds to:
v1: RCA 12ay7 gray plate
v2: Philips JAN 5751
v3inverter tube) TAD 7025 HIGHGRADE? i havent changed the power supply it is standart, but have added a choke 15mh from audio note.
"...the preamp is made according to analogmetric suggestions and they helped me with the? needed changes.. I've started with talkman 1watt carbon resistors but found them a bit too doll/warm in sound seems a bit slow.. and I couldn't changed that by tube rolling, so together with Brian from analogmetric we found that talkman 1watt metal film resistors changed a lot in the right direction and the two feedback capacitors has been changed to 2um instead of 1um, the rest is according to pcb.
I will upload some extra pictures. The pcb on the left side is the power supply, it is the PS200 tube variable voltage regulator from analogmetric,? I don't use the rectifier tube, but except from that nothing is changed… I have tested it against some very expensive preamps and this one is absolutely the best one
Hi Polaxed1. i have tried different components, but my referance and chosen are. Capacitors: Mundorf silver/oil Recistors: Takman carbon film 2w and the tubes has been changeds to:
v1: RCA 12ay7 gray plate
v2: Philips JAN 5751
v3
inverter tube) TAD 7025 HIGHGRADE? i havent changed the power supply it is standart, but have added a choke 15mh from audio note.Well, this is the way I am going to go - I believe it will work out well once I get it all figured out.
What I am wondering is: should I go with a SS power supply ie: HV400 Variable High Voltage Regulator Kit (100-300V 0.1A & 0-30V 5A)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...or a valve power supply ie: PS200 Tube Variable Voltage Regulator 190V-450V(100mA) 0-30V(1.5A)x2 Kit, Mod Based on JP200_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
Would using the cheaper SS power supply affect the sonic quality in a more compromising manner, than using a tube PS ??
What I am wondering is: should I go with a SS power supply ie: HV400 Variable High Voltage Regulator Kit (100-300V 0.1A & 0-30V 5A)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...or a valve power supply ie: PS200 Tube Variable Voltage Regulator 190V-450V(100mA) 0-30V(1.5A)x2 Kit, Mod Based on JP200_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
Would using the cheaper SS power supply affect the sonic quality in a more compromising manner, than using a tube PS ??
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SS in the form of Cree SiC, Schottky work quite well. I have used them many times, and was in each quite pleased with their function.
As for actively regulated supplies, what you are doing is putting another amplifier in series with the one you want top performance from. Not a good idea IMO. Just build a solid supply that does not move when the amp makes a demand from it.
So what are you going to buffer that 12AX7 mess with?
cheers,
Douglas
As for actively regulated supplies, what you are doing is putting another amplifier in series with the one you want top performance from. Not a good idea IMO. Just build a solid supply that does not move when the amp makes a demand from it.
So what are you going to buffer that 12AX7 mess with?
cheers,
Douglas
Hi Douglas,
BTW, as a matter of interest, an actively regulated power supply generally has a much lower output impedance than a static solution such as a zener diode or gas regulator tube. So your analogy of putting amplifiers in series doesn't make any sense at all. The result of using a reasonably well designed regulator circuit is a lower noise floor (less noise on the power supply). How on earth can that be a bad thing?
-Chris
Given that the 12AX7 was designed as an audio amplifier, and I have seen and heard several successful implementations of equipment that use 12AX7 tubes, I really have to disagree with you. I don't think that blanket statements like this are at all helpful. Not only that, but you are condemning many highly trained engineers that came before us who know precisely what they were doing. Additionally, while I am no fan of Jadis equipment either, you can't use one example of poor engineering to malign a decent audio tube.
I design and use actively regulated HV power supplies often and improve the performance of the original Zener or gas tube regulated supplies easily. I'm very surprised you would make this claim given how many different topologies are available for use. Now, if you aren't good at designing actively regulated supplies, just say so. There is no need to use a broad brush to paint folks who are good at active regulator designs as making a bad / poor choice. So I have to disagree with you again.
BTW, as a matter of interest, an actively regulated power supply generally has a much lower output impedance than a static solution such as a zener diode or gas regulator tube. So your analogy of putting amplifiers in series doesn't make any sense at all. The result of using a reasonably well designed regulator circuit is a lower noise floor (less noise on the power supply). How on earth can that be a bad thing?
-Chris
Hi TS,
I can't give an opinion on something I have no experience with, or way to examine how it works, like a schematic and a picture of how it is assembled. It's easy to ruin an otherwise good design with poor layout.
Most of my power supplies are designed with solid state parts. So if I were to design a power supply (I have a few on the go now), I would probably use solid state components. A mixture of Mosfets, bipolars and D-Mosfets. Each part type having it's strengths and weaknesses.
The main reason I use solid state approaches is that tubes are generally noisier, and they aren't as stable if you consider a gas-discharge voltage regulator. Other than that, they can also be used to create excellent supplies. Some even use a mixture of solid state and tubes (not as just the rectifier). The output impedance tends to be higher as they are lower gain devices, but they can naturally handle higher voltages and don't have any second breakdown mechanisms that I know of. Really high voltage supplies would probably demand at least a couple of tubes for the sections that can bite without contact.
I'm sorry I can't be more definitive than that, but your question involves cheaply produced power supplies that I would question the reliability of. Both power regulators have reasonable specifications, so I don't think the reported specs are questionable. I do like that the tube based regulator is spaced out better to (hopefully) distribute the heat. With linear regulators, there will be heat.
One factor will be your raw DC voltage compared to the required output voltage. That difference x the current = heat. If you have a low input to output voltage, the solid state one should perform better. The tube based regulator needs more voltage headroom to operate properly whereas the solid state one might only need 50 volts or less to operate well. I'm talking about both voltage stability vs input voltage shifts, and also noise rejection.
-Chris
I can't give an opinion on something I have no experience with, or way to examine how it works, like a schematic and a picture of how it is assembled. It's easy to ruin an otherwise good design with poor layout.
Most of my power supplies are designed with solid state parts. So if I were to design a power supply (I have a few on the go now), I would probably use solid state components. A mixture of Mosfets, bipolars and D-Mosfets. Each part type having it's strengths and weaknesses.
The main reason I use solid state approaches is that tubes are generally noisier, and they aren't as stable if you consider a gas-discharge voltage regulator. Other than that, they can also be used to create excellent supplies. Some even use a mixture of solid state and tubes (not as just the rectifier). The output impedance tends to be higher as they are lower gain devices, but they can naturally handle higher voltages and don't have any second breakdown mechanisms that I know of. Really high voltage supplies would probably demand at least a couple of tubes for the sections that can bite without contact.
I'm sorry I can't be more definitive than that, but your question involves cheaply produced power supplies that I would question the reliability of. Both power regulators have reasonable specifications, so I don't think the reported specs are questionable. I do like that the tube based regulator is spaced out better to (hopefully) distribute the heat. With linear regulators, there will be heat.
One factor will be your raw DC voltage compared to the required output voltage. That difference x the current = heat. If you have a low input to output voltage, the solid state one should perform better. The tube based regulator needs more voltage headroom to operate properly whereas the solid state one might only need 50 volts or less to operate well. I'm talking about both voltage stability vs input voltage shifts, and also noise rejection.
-Chris
OK - thanks...
So I am considering using the SS HV400 with this tube filter: RT400 AC DC Tube Power Rectifier Kit (880uF/400V)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
this R-core transformer: R-Core R80 100W Transformer Series_R-Core_Power Transformer_Analog Metric - DIY Audio Kit Developer
this 10mH choke: Choke 10H 150mA B-043 Upright_Choke_Analog Metric - DIY Audio Kit Developer
...seems to be a solid cost-effective choice
So I am considering using the SS HV400 with this tube filter: RT400 AC DC Tube Power Rectifier Kit (880uF/400V)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
this R-core transformer: R-Core R80 100W Transformer Series_R-Core_Power Transformer_Analog Metric - DIY Audio Kit Developer
this 10mH choke: Choke 10H 150mA B-043 Upright_Choke_Analog Metric - DIY Audio Kit Developer
...seems to be a solid cost-effective choice
...I have come to the conclusion, that using SS rectifier and power supply will lead to a more constant and tight voltage supply - eliminating 'sag' to the pre-amp tube from the rectifier/power supply. So the RT400 rectifier with ie: KBU1010 instead of tube with a 10H choke configured as CLC - and Siemens AC input noise filter appears to be a good solution to power supply.
...while I quite enjoy the natural valve sound, I also like clean - fast and tight delivery with transparency, soundstage and dynamism - hence combining valve pre with SS amp. The power supply being SS I feel would aid in this result...just clean strong effiecient power supply to the tubes...
...while I quite enjoy the natural valve sound, I also like clean - fast and tight delivery with transparency, soundstage and dynamism - hence combining valve pre with SS amp. The power supply being SS I feel would aid in this result...just clean strong effiecient power supply to the tubes...
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OK, so if I was to use the tube filter with tube (RT400) ie: RT400 AC DC Tube Power Rectifier Kit (880uF/400V)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...with the SS PS (HV400) ie: HV400 Variable High Voltage Regulator Kit (100-300V 0.1A & 0-30V 5A)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...if it was you, and you had the choice between the above combination -or- using the RT400 with the Valve PS (PS200) ie: PS200 Tube Variable Voltage Regulator 190V-450V(100mA) 0-30V(1.5A)x2 Kit Set, Mod Based on JP200_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...for driving the JP200 valve preamp ... which would you choose for best performance in your mind - if you were restricted with only that choice ??
...with the SS PS (HV400) ie: HV400 Variable High Voltage Regulator Kit (100-300V 0.1A & 0-30V 5A)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...if it was you, and you had the choice between the above combination -or- using the RT400 with the Valve PS (PS200) ie: PS200 Tube Variable Voltage Regulator 190V-450V(100mA) 0-30V(1.5A)x2 Kit Set, Mod Based on JP200_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
...for driving the JP200 valve preamp ... which would you choose for best performance in your mind - if you were restricted with only that choice ??
Hi TS,
I would very probably go with the solid state version, but use the resistor trick I just mentioned. The voltage drop will reduce dissipation as well. The most important thing is to lose the diode switching transients. All regulators are very good at eliminating 120 Hz ripple. It's the higher frequency stuff you want to attack right where it starts.
I would not use the tube rectifier under any circumstances. Just go with the solid state rectifier with a (maximum!) 47 uF input capacitor using a resistor to isolate the two. You have to determine the resistor value empirically. The last time I tried PSUDII, it didn't work out that well.
-Chris
Edit: Use PSUD-2 from Duncan's amp pages to simulate various resistor sizes. I got a reasonable response using a 220nF input capacitor, 47R series resistance and a 47uF filter capacitor. Play with that and see how the reasonable capacitor size and series resistor remove the HF hash you would normally have by connecting the rectifier directly to a 47 uF capacitor. Try it again with 220 uF. Simulate and look at the current waveforms through the rectifier and filter capacitor, and also the voltage across the capacitor. The 220nF capacitor can be any low value, high voltage type. It's purpose is to shunt HF "garbage" from the line to ground, as well as from the diodes switching.
I would very probably go with the solid state version, but use the resistor trick I just mentioned. The voltage drop will reduce dissipation as well. The most important thing is to lose the diode switching transients. All regulators are very good at eliminating 120 Hz ripple. It's the higher frequency stuff you want to attack right where it starts.
I would not use the tube rectifier under any circumstances. Just go with the solid state rectifier with a (maximum!) 47 uF input capacitor using a resistor to isolate the two. You have to determine the resistor value empirically. The last time I tried PSUDII, it didn't work out that well.
-Chris
Edit: Use PSUD-2 from Duncan's amp pages to simulate various resistor sizes. I got a reasonable response using a 220nF input capacitor, 47R series resistance and a 47uF filter capacitor. Play with that and see how the reasonable capacitor size and series resistor remove the HF hash you would normally have by connecting the rectifier directly to a 47 uF capacitor. Try it again with 220 uF. Simulate and look at the current waveforms through the rectifier and filter capacitor, and also the voltage across the capacitor. The 220nF capacitor can be any low value, high voltage type. It's purpose is to shunt HF "garbage" from the line to ground, as well as from the diodes switching.
Oh, thanks for that Chris,
...my feeling was to go with the SS power supply (HV400)...
...so you are saying if it was you, you would not go with the tube rectifier/filter (RT400)??RT400 AC DC Tube Power Rectifier Kit (880uF/400V)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
I was previously considering using the SS variation of it using KBU1010 ie: 3. Either use tube rectifier (5AR4, 5Z3P, 5U4G, etc) or solid-state rectifier (RS1005/ KBU1010)
...would that be something you would avoid even as SS option, and just use the resistor with HV400 SS PS??
...my feeling was to go with the SS power supply (HV400)...
...so you are saying if it was you, you would not go with the tube rectifier/filter (RT400)??RT400 AC DC Tube Power Rectifier Kit (880uF/400V)_Power Supply Kit_Analog Metric - DIY Audio Kit Developer
I was previously considering using the SS variation of it using KBU1010 ie: 3. Either use tube rectifier (5AR4, 5Z3P, 5U4G, etc) or solid-state rectifier (RS1005/ KBU1010)
...would that be something you would avoid even as SS option, and just use the resistor with HV400 SS PS??
Hi TS,
Yes, I would go with solid state rectification. Note that the capacitors on the rectifier PCB are way too large! Install 47uF or lower. When you get the transformer, it will run cooler without having to heat the rectifier tube also.
In this case I think you would be further ahead to either make your own rectifier / filter circuit up, or buy the combination, but modify the rectifier boart to use a small capacitor in the first position, a resistor that you will figure out, then sane values of capacitance. You only need the small capacitor and filter capacitor for the regulator circuit. Of course, the heater circuits could probably be used with minimal changes, so buying the rectifier / filter PCB would save you money and time. Just think about what you are doing as you build it up. Reduce the input capacitor sizes and let the resistance control the current spikes.
So after thinking it through, buy the SS regulator kit along with the transformer and rectifier/filter kit that goes with it. I can't see the schematics so I can't give you specific advise, also the voltage and current draws for your preamplifier would help.
When using PSUD, the current after the regulator can be modeled as a current source, or current tap I think they call it. Don't forget to add the currents taken by the regulator circuit itself.
-Chris
Yes, I would go with solid state rectification. Note that the capacitors on the rectifier PCB are way too large! Install 47uF or lower. When you get the transformer, it will run cooler without having to heat the rectifier tube also.
In this case I think you would be further ahead to either make your own rectifier / filter circuit up, or buy the combination, but modify the rectifier boart to use a small capacitor in the first position, a resistor that you will figure out, then sane values of capacitance. You only need the small capacitor and filter capacitor for the regulator circuit. Of course, the heater circuits could probably be used with minimal changes, so buying the rectifier / filter PCB would save you money and time. Just think about what you are doing as you build it up. Reduce the input capacitor sizes and let the resistance control the current spikes.
So after thinking it through, buy the SS regulator kit along with the transformer and rectifier/filter kit that goes with it. I can't see the schematics so I can't give you specific advise, also the voltage and current draws for your preamplifier would help.
When using PSUD, the current after the regulator can be modeled as a current source, or current tap I think they call it. Don't forget to add the currents taken by the regulator circuit itself.
-Chris
Thanks Chris...
Regarding the schematics the RT400 (rectifier filter) is here: RT400 AC DC Tube Power Rectifier Kit (880uF/400V) - Analog Metric - DIY Audio Kit Developer
...and the schematic for the SS Power supply ie: HV400 is here: http://analogmetric.com/download/HV400 variable high voltage regulator New Schematic.pdf
...it would avoid confusion if you would refer to them as 'RT400' and 'HV400...if you would...
Cheers
Regarding the schematics the RT400 (rectifier filter) is here: RT400 AC DC Tube Power Rectifier Kit (880uF/400V) - Analog Metric - DIY Audio Kit Developer
...and the schematic for the SS Power supply ie: HV400 is here: http://analogmetric.com/download/HV400 variable high voltage regulator New Schematic.pdf
...it would avoid confusion if you would refer to them as 'RT400' and 'HV400...if you would...
Cheers
What the tube was designed to do is quite irrelevant: it is just stupid to use it in a line stage where you generally expect gain between 0 and 6db.
The "highly trained engineers" had to deal with outputs from magnetic heads and pickups, not from dacs capable of 10v p-p. So unless you are looking forward to gobs of useless nfb and a puny drive capability it is better to leave the 12AX7 to the proud Jadis owners
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