Hi Ian
You can solder it directly. If seen some sockets but didn’t find them around (didn’t look hard either)
Ale
I prefer grid leak bias, anyway input current is too high for direct coupling (it is a planar frame grid tube with very close grid to cathode), a cap is needed. But a coupling cap on phono input is a totally different thing from a cup coupling of output tubes where it matters. Also, keep in mind that CCS would add own noises.
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if you use tubes the noise floor will be higher, however the D3a could be a winner there... I know they use it in some exotic Italian pre/phono.
I am more interested into getting a perfect phase out of the phono without feedback
Not this one though: Hi-end phono preamplifier
One ultimate amp could be quad // pp D3a's
lol
I am more interested into getting a perfect phase out of the phono without feedback
Not this one though: Hi-end phono preamplifier
One ultimate amp could be quad // pp D3a's
lol
input capacitance when you consider miller is still kind of high for D3a. This might be ok if you use an SUT with MC pickup, but for MM it is not good.
perfect phase at what frequency? or said a different way, I don't worry about that at lower frequencies so much... Also, there is nearly always some feedback in phono.
perfect phase at what frequency?
or said a different way, I don't worry about that at lower frequencies so much... Also, there is nearly always some feedback in phono.
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socket for 6S17k-V
I made some soldersocket to my phonoamp fore 6S17k-V feel free to copy.
https://i.imgur.com/6qVuPpF.jpg
I made some soldersocket to my phonoamp fore 6S17k-V feel free to copy.
https://i.imgur.com/6qVuPpF.jpg
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Hi, are you looking to sell them?. If so please PM.
E180F is way under priced as an alternative.
Hanze
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Does people really enjoy the dark sound it produces as a triode?
Dark in comparison with C3g.
Yes, mostly.
But LM Ericson D3a is different. This tube does not sound dark.
I think it is because of a somewhat different interior design with a visible small plate that looks like a G2 "cooler".
Dark in comparison with C3g.
Yes, mostly.
But LM Ericson D3a is different. This tube does not sound dark.
I think it is because of a somewhat different interior design with a visible small plate that looks like a G2 "cooler".
Attachments
Given Ian's comment about input capacitance and Miller in D3a ....
I am very attracted to D3a as a pentoda in one tube riaa preamp.
I did not try it, just simulated and looks very good.
I used Bartola idea for pentode driver in general. I switched it to RIAA preamp.
I am very attracted to D3a as a pentoda in one tube riaa preamp.
I did not try it, just simulated and looks very good.
I used Bartola idea for pentode driver in general. I switched it to RIAA preamp.
Attachments
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Yes, pentode works a lot like cascoded triodes.
for D3a, Cag1 in pentode is something like 0.035pF while in triode it is quoted at 2.7pF - this results in a huge difference for miller capacitance. Will the RIAA network in your design increase miller capacitance? I don't think so..
Ian
for D3a, Cag1 in pentode is something like 0.035pF while in triode it is quoted at 2.7pF - this results in a huge difference for miller capacitance. Will the RIAA network in your design increase miller capacitance? I don't think so..
Ian
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I found this list of equivalent input resistance for some tubes on the Web. Look 1/2 way down the page to the post by Alan Douglas.
Antique Radio Forums • View topic - Vacuum Tube noise figure
6JC6A is quite similar to these tubes below, and costs $1 on the ESRC Dollar Days list:
6688/E180F (R = 330 Ohm)
6EJ7/EF184 (R = 352 Ohm)
6JK6 ( R = 282 Ohm).
12HG7, 12GN7, 12HL7 are cheap 10 Watt frame grid pentode tubes, $3 to $6.
12HG7 (R = 148 Ohm ) is just beating D3a at R = 150 Ohm.
And then there are 5 Watt pentodes on the $1 list, with 20K+ gm frame grids and a spare triode:
6LQ8
6LY8
6KR8
6KV8
Antique Radio Forums • View topic - Vacuum Tube noise figure
6JC6A is quite similar to these tubes below, and costs $1 on the ESRC Dollar Days list:
6688/E180F (R = 330 Ohm)
6EJ7/EF184 (R = 352 Ohm)
6JK6 ( R = 282 Ohm).
12HG7, 12GN7, 12HL7 are cheap 10 Watt frame grid pentode tubes, $3 to $6.
12HG7 (R = 148 Ohm ) is just beating D3a at R = 150 Ohm.
And then there are 5 Watt pentodes on the $1 list, with 20K+ gm frame grids and a spare triode:
6LQ8
6LY8
6KR8
6KV8
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I've been thinking about how one could measure the equivalent noise input resistance of tubes without having to buy an expensive HP noise meter.
One could set up a test fixture for two tubes, one tube a known R_eq reference tube (from data sheet spec) and the other the tube under test. AC shorted inputs to the tubes, with very well filtered B+ and bias voltages (and +/- Op Amp supplies). Then AC couple the outputs of those (maybe Gyrator loaded) tubes, each to one input of a low noise Dual Op Amp configured for high gain. Probably need a grounded metal shield box over the test assembly.
Then the output of the Op Amps are AC coupled to two channels of an O Scope. Using alternate trace mode on the O scope, the two channels would be visually compared for equal (no alternating flicker) noise amplitude by adjusting an attenuator in one of the channels. (noise not having an obvious visual amplitude on the screen). (the scope channels and Op Amp channels would need to be previously equalized using the same noise signal source on both channels to adjust the scope gains)
The setting of the pot. attenuator for no alternating flicker would then give the ratio of the noise equivalent resistances between tubes. (relative to the reference tube; use a DMM to measure the potentiometer setting resistances)
All the bargain, high gm, frame grid tubes could be quantified as to noise performance. And one could even test tube circuit configurations to evaluate noise performance.
Using just a $5 Dual low noise Op Amp chip. And well filtered power supplies, with an O Scope.
.
One could set up a test fixture for two tubes, one tube a known R_eq reference tube (from data sheet spec) and the other the tube under test. AC shorted inputs to the tubes, with very well filtered B+ and bias voltages (and +/- Op Amp supplies). Then AC couple the outputs of those (maybe Gyrator loaded) tubes, each to one input of a low noise Dual Op Amp configured for high gain. Probably need a grounded metal shield box over the test assembly.
Then the output of the Op Amps are AC coupled to two channels of an O Scope. Using alternate trace mode on the O scope, the two channels would be visually compared for equal (no alternating flicker) noise amplitude by adjusting an attenuator in one of the channels. (noise not having an obvious visual amplitude on the screen). (the scope channels and Op Amp channels would need to be previously equalized using the same noise signal source on both channels to adjust the scope gains)
The setting of the pot. attenuator for no alternating flicker would then give the ratio of the noise equivalent resistances between tubes. (relative to the reference tube; use a DMM to measure the potentiometer setting resistances)
All the bargain, high gm, frame grid tubes could be quantified as to noise performance. And one could even test tube circuit configurations to evaluate noise performance.
Using just a $5 Dual low noise Op Amp chip. And well filtered power supplies, with an O Scope.
.
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If you look at the very first iteration of the my Muscovite Mini design in analog source you will see that I used a Russian 6J9P in pentode connection, and also evaluated the D3A which performed similarly in that circuit.
I had some problems that ultimately resulted in my abandoning the pentode front end and going back to my traditional cascode.
I found the design had incredible (no hyperbole here ) sensitivity to the quality of the screen supply. No screen bypass cap I found did no harm, every one imparted some sort of signature on the sound. I would recommend using an active low impedance regulator to feed the screen grid. I didn't have space for the proposed solution so I went to my traditional cascode.
The second thing is operating point, I wanted high transconductance I thought so I designed the input stage to operate at 15mA, there was a lot of 1/F noise to put it charitably. Reducing the current from 15mA to 10mA resulted in a 10dB reduction in this noise. Same behavior was observed with the D3A. Likely something on the order of 5 - 10mA is the sweet spot.
Something else to note is that pentode PSRR is just OK in this application and a good quiet supply is required.
I intend to revisit this approach in the future when I have more time.
I had some problems that ultimately resulted in my abandoning the pentode front end and going back to my traditional cascode.
I found the design had incredible (no hyperbole here
) sensitivity to the quality of the screen supply. No screen bypass cap I found did no harm, every one imparted some sort of signature on the sound. I would recommend using an active low impedance regulator to feed the screen grid. I didn't have space for the proposed solution so I went to my traditional cascode.The second thing is operating point, I wanted high transconductance I thought so I designed the input stage to operate at 15mA, there was a lot of 1/F noise to put it charitably. Reducing the current from 15mA to 10mA resulted in a 10dB reduction in this noise. Same behavior was observed with the D3A. Likely something on the order of 5 - 10mA is the sweet spot.
Something else to note is that pentode PSRR is just OK in this application and a good quiet supply is required.
I intend to revisit this approach in the future when I have more time.
Useful tips, thank you very much Kevin
I've just taken them into my scheme.
I very much liked the idea of Ale Moglia for pentode driver and I immediately got the idea for implementation in the RIAA preamp.
PS. Ian,
I switched to 10 Mohm. 69dB gain (or 1,5Vpeak).
Say if you need a .asc
I've just taken them into my scheme.
I very much liked the idea of Ale Moglia for pentode driver and I immediately got the idea for implementation in the RIAA preamp.
PS. Ian,
I switched to 10 Mohm. 69dB gain (or 1,5Vpeak).
Say if you need a .asc
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Thanks Rajko
Maybe a statistical regulator would do a good job with this kind of circuit.
I'm not sure, but it will still probably need some very small screen bypass cap if you tap off the zener stack for the screen though.
Thanks Kevin for pointing out your Muscovite Mini thread again. Is it still in service?
Maybe a statistical regulator would do a good job with this kind of circuit.
I'm not sure, but it will still probably need some very small screen bypass cap if you tap off the zener stack for the screen though.
Thanks Kevin for pointing out your Muscovite Mini thread again. Is it still in service?
This is impressive: D3a phono, serious stuff by connoisseurs, very knowledgeable of tubes. Just OMG:
VinylSavor: The D3a Phono Stage in Orange
VinylSavor: The D3a Phono Stage in Orange
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