Hello, everyone. I have designed a stereo power amp (2xLM3886), and no i need ideas about a siplest tube preamp join it. Any ideas? If you help me to finish this out, i'll publish my whole projecdt to net.
Cheers !!!
E.g. A qute ECC83 or a AU7 i prefer
100VDC or 250VDC plate voltage i prefer
No tube power rectifier, only pasive things
Cheers !!!
E.g. A qute ECC83 or a AU7 i prefer
100VDC or 250VDC plate voltage i prefer
No tube power rectifier, only pasive things
Why ECC83/12AX7 and ECC82/12AU7? There are better valves out there suited to line amplifier duty.
How much gain do you need (if any)?
How much gain do you need (if any)?
Very simple:
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Regarding the triode-strapped EF86 schematic above:
You generally won't need a gain of 25. This just means you will have to have the volume turned waayyy down, and compromise noise performance.
The usually low-ish input impedance of a SS amp will likely load down the stage, causing gain to droop and distortion to rise. The high output Z might also cause some HF loss when driving a capacitive load.
Something along the lines of a simple grounded cathode 12B4 (as shown in some other threads) would be more appropriate for linestage duty.
You generally won't need a gain of 25. This just means you will have to have the volume turned waayyy down, and compromise noise performance.
The usually low-ish input impedance of a SS amp will likely load down the stage, causing gain to droop and distortion to rise. The high output Z might also cause some HF loss when driving a capacitive load.
Something along the lines of a simple grounded cathode 12B4 (as shown in some other threads) would be more appropriate for linestage duty.
If you just want a tube buffer for the sole purpose of saying you have a tube buffer, use a CF. It kind of defeats the purpose of having a tube in the signal path, but people like to do irrational things like add stages they don't need.
If you actually need gain, anything from 12B4 to 6AU6 will provide gain. Higher gain tubes will need a buffer to match impedance to the amp.
Tim
If you actually need gain, anything from 12B4 to 6AU6 will provide gain. Higher gain tubes will need a buffer to match impedance to the amp.
Tim
audionote m1 uses 5687.. very simple circuit, and yet very good.
http://www.diyparadise.com/simplepreamp.html
Its designed to be used in SS gears to add so called 'warmth' effect.
http://www.diyparadise.com/simplepreamp.html
Its designed to be used in SS gears to add so called 'warmth' effect.
Hi Timos,
First of all:you don't need too much gain-what are you dealing with?
Second:try the schematic provided by Skyraider.5687 has a very good reputation and if you decide later to go for a tube amplifier,there is also an output transformer especially for this tube within you can drive anything.
You can also take a look at this schematic which i have allready constructed and it's very good.
But from the other hand,in the first schematic only one triode is used(half tube) which makes it simplier.
First of all:you don't need too much gain-what are you dealing with?
Second:try the schematic provided by Skyraider.5687 has a very good reputation and if you decide later to go for a tube amplifier,there is also an output transformer especially for this tube within you can drive anything.
You can also take a look at this schematic which i have allready constructed and it's very good.
But from the other hand,in the first schematic only one triode is used(half tube) which makes it simplier.
EF86 line amp
Hi Simpleton!
Could you tell me where can I read more about the EF86 in triode connected line amp?? It is looking very interesting to me!!
Greets:
Tyimo
Hi Simpleton!
Could you tell me where can I read more about the EF86 in triode connected line amp?? It is looking very interesting to me!!
Greets:
Tyimo
Tyimo,
That circuit used to be on the Svetlana website, now down 🙁
I'm using it as a pre-amp stage directly feeding a SE 2A3. Sounds very nice, though it doesn't have enough drive to full power. But who cares? 😀
That circuit used to be on the Svetlana website, now down 🙁
I'm using it as a pre-amp stage directly feeding a SE 2A3. Sounds very nice, though it doesn't have enough drive to full power. But who cares? 😀
Another interesting tube to look into is the C3g.
I can't help you with schematics. But it's a great tube. Ideal for a phono headamp. Then add the cool-looking AZ50 rectifier. It's as much overkill as the GZ34 for an E80F pre. Like if DIY has anything to do with restraint.
Simpleton,
Would you like to elaborate on not enough drive? This, as mentioned, is my first tube project, and only because I haven't found any other alternative. I would much rather buy a vintage preamp and tweak it. (I'm a bricoleur rather than a DIYer.) But vintage preamps tend to be anything but great. Or they are ridiculously overprised like the Marantz Model 7.
And I do have some issues with the gain. 1:10 would have been more to my liking. I have a vintage amp and it only needs about 500mV.
I can't help you with schematics. But it's a great tube. Ideal for a phono headamp. Then add the cool-looking AZ50 rectifier. It's as much overkill as the GZ34 for an E80F pre. Like if DIY has anything to do with restraint.
Simpleton,
Would you like to elaborate on not enough drive? This, as mentioned, is my first tube project, and only because I haven't found any other alternative. I would much rather buy a vintage preamp and tweak it. (I'm a bricoleur rather than a DIYer.) But vintage preamps tend to be anything but great. Or they are ridiculously overprised like the Marantz Model 7.
And I do have some issues with the gain. 1:10 would have been more to my liking. I have a vintage amp and it only needs about 500mV.
EF86 line amp
Hi and thanks for the help!
I would like to use the preamp with ca. +100V. Could you tell me how big will be the voltage gain and the max RMS output voltage?
I need "only" 15 V RMS, so I tought the 100V would be enough.
One more: Could you suggest a good, but simple PSU for the amp?
Greets:
Tyimo
Hi and thanks for the help!
I would like to use the preamp with ca. +100V. Could you tell me how big will be the voltage gain and the max RMS output voltage?
I need "only" 15 V RMS, so I tought the 100V would be enough.
One more: Could you suggest a good, but simple PSU for the amp?
Greets:
Tyimo
Phn,
By enough drive i mean that it puts around 30Vrms when i need some 40Vrms to full 3W output from the 2A3 (this from memory, it's been some months)
Tyimo,
I can't make the calculation right now, but you'll get more than 15V out at 100V, don't worry 😉
For a PSU, get a diode bridge rectifier, 2 transfomers, one 220/12V and teh other 220/6V, connected back to back (220V/6v-12V/220V), plus 440uF of capacitance and you're done with a little over 100V (maybe 120~130V or so). Shouldn't be too noisy.
By enough drive i mean that it puts around 30Vrms when i need some 40Vrms to full 3W output from the 2A3 (this from memory, it's been some months)
Tyimo,
I can't make the calculation right now, but you'll get more than 15V out at 100V, don't worry 😉
For a PSU, get a diode bridge rectifier, 2 transfomers, one 220/12V and teh other 220/6V, connected back to back (220V/6v-12V/220V), plus 440uF of capacitance and you're done with a little over 100V (maybe 120~130V or so). Shouldn't be too noisy.
the Shure M65 is a pretty simple preamp, it can be run in either line or RIAA mode
http://www.audioorigami.co.uk/FloppyProject/FloppyDIYMotor.htm
http://www.audioorigami.co.uk/FloppyProject/FloppyDIYMotor.htm
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