Hey all,
I'm an EE student and want to get my hands dirty on some diy audio equipment for my hifi system at home.
Currently this is my system:
Laptop -> Optical in Yuan Zero DAC -> Yamaha Integrated Reciever rx367 -> stereo paradigm mini monitors.
The yuan zero dac has a preamplifier stage but i have it turned off because I don't think its very good.
I was browsing around for a DIY kit for $100-200USD and found these chinese copy preamp of the Jadis JP-200 and Marantz 7
DIY Kit ref Jadis JP-200 JP200 Tube Pre Amplifier 2 Ch | eBay
I know that these where originally designed for phono line amplification. But im wondering if it would serve any benefit to my system?
I know the rx367 has a preamplifier internally, so is adding another pre-amp overkill?
Im aware that adding a LNA at the start of a cascade drastically reduces noise figure and improves S/N.
Any advice is greatly appreciated
I'm an EE student and want to get my hands dirty on some diy audio equipment for my hifi system at home.
Currently this is my system:
Laptop -> Optical in Yuan Zero DAC -> Yamaha Integrated Reciever rx367 -> stereo paradigm mini monitors.
The yuan zero dac has a preamplifier stage but i have it turned off because I don't think its very good.
I was browsing around for a DIY kit for $100-200USD and found these chinese copy preamp of the Jadis JP-200 and Marantz 7
DIY Kit ref Jadis JP-200 JP200 Tube Pre Amplifier 2 Ch | eBay
I know that these where originally designed for phono line amplification. But im wondering if it would serve any benefit to my system?
I know the rx367 has a preamplifier internally, so is adding another pre-amp overkill?
Im aware that adding a LNA at the start of a cascade drastically reduces noise figure and improves S/N.
Any advice is greatly appreciated
Be careful with this stuff: phono inputs are very sensible, and uses a non flat audio response curve, so, using it for other function will be very unsatisfatory: excess in bass response and saturated audio output. You must use a flat preamp.
olmeister: As already mentioned, you want a line level pre, not a phono pre. Phono stages have lots more gain (like around 70db) and RIAA eq (not needed for line stages) than line level stages. Line level preamps typically have less than about 20db or so gain, sometimes lots less.
The Aikido preamp is well regarded around here, and quite straightforward to build with lots of threads and support on the forums here. Stuffing a PCB is easier than point to point wiring IMO. The Aikido is very configurable for gain by choice of tube types.
There are many good choices for the Aikido power supply as well. You can roll your own, or buy one of broskie's kits, and there may be a PCB that you can pick up from the vendor forums here (username=Geek) to make a nice PS for the Aikido. There is a long thread here covering that also.
I'm sure there are a few other tube line amp projects around here that may be a little simpler, but stuffing a well-documented PCB based project is hard to beat.
I imagine that Bottlehead also offers a few tube based kits as well........
Do you have a soldering iron and a multimeter? Are you comfortable working around high voltage?
The Aikido preamp is well regarded around here, and quite straightforward to build with lots of threads and support on the forums here. Stuffing a PCB is easier than point to point wiring IMO. The Aikido is very configurable for gain by choice of tube types.
There are many good choices for the Aikido power supply as well. You can roll your own, or buy one of broskie's kits, and there may be a PCB that you can pick up from the vendor forums here (username=Geek) to make a nice PS for the Aikido. There is a long thread here covering that also.
I'm sure there are a few other tube line amp projects around here that may be a little simpler, but stuffing a well-documented PCB based project is hard to beat.
I imagine that Bottlehead also offers a few tube based kits as well........
Do you have a soldering iron and a multimeter? Are you comfortable working around high voltage?
@boywonder
Hi, thanks for the reply, yes I have experience with dealing with high-voltage & soldering/multimeter.
Does the octal all-in-one Akido kit (Aikido Octal All-in-One Kit)
require its own power supply? I was under the impression that a linear step down transformer was needed only, which is usually much more stable than switching regulators.
@DF96
I know I want to build something that comes in a kit and I like the idea of vacuum tubes, searching around for complete kits I found these 'preamps'..
But your absolutely right ~$180 dollars is alot to spend on a tube preamp if It does nothing for my sound system..
Hi, thanks for the reply, yes I have experience with dealing with high-voltage & soldering/multimeter.
Does the octal all-in-one Akido kit (Aikido Octal All-in-One Kit)
require its own power supply? I was under the impression that a linear step down transformer was needed only, which is usually much more stable than switching regulators.
@DF96
I know I want to build something that comes in a kit and I like the idea of vacuum tubes, searching around for complete kits I found these 'preamps'..
But your absolutely right ~$180 dollars is alot to spend on a tube preamp if It does nothing for my sound system..
Looks like the all-in-one setup just requires a power transformer, more like a "step-up" as you need to provide B+ for the tubes, as well as filament voltage and current. Broskie spells it out fairly well; you'll need something between 200-250V and 12VCT for filaments. Looks like the board can provide either 6.3V or 12.6V to the tubes. A 40 ma transformer is probably plenty, which is what you will typically find for preamp duty. The 48V that Broskie mentions will work with a few tube types (I don't know much about what tubes are happy at low voltages) but your common types (6SN7/6SL7 etc) will require the 200-250V.
Linear supplies are typically used because they are quieter ie they don't throw a bunch of switching related harmonics on the B+ rail. The smoothing RC stuff is on the PCB.
You actually need to work backwards, and determine how much gain you need, that will determine tube choice, which will determine the power transformer (to some extent). DF96 has a good point......you may not need any gain at all.
Look at Edcor's and Hammond's offerings for this. I'm sure that there are other places as well. You'll need to do a little studying to determine your desired B+ voltage
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olmeister,
I believe that your Yamaha unit is an A/V receiver. There is a distinct chance you are pouring money down the drain, in trying to improve things.
Please post a photo of the rear panel. Seeing what the RCA jack labels look like may provide some clues. Is there some sort of bypass that works with 2 channel sources? On a 2 channel receiver or "integrated" amp, the desirable feature is preamp out/amp in. That feature allows an external preamp to drive the power section, without any interference from the internal control circuitry.
I believe that your Yamaha unit is an A/V receiver. There is a distinct chance you are pouring money down the drain, in trying to improve things.
Please post a photo of the rear panel. Seeing what the RCA jack labels look like may provide some clues. Is there some sort of bypass that works with 2 channel sources? On a 2 channel receiver or "integrated" amp, the desirable feature is preamp out/amp in. That feature allows an external preamp to drive the power section, without any interference from the internal control circuitry.
Yes, you are right, there is no preamp line in, or anything resembling this feature. But this yamaha receiver was only ever a temporary solution, considering i borrowed it from a friend..
Perhaps i could bi-amplify the power amplifiers instead? Are there any good tube power amplifier kits around?
Perhaps i could bi-amplify the power amplifiers instead? Are there any good tube power amplifier kits around?
Hello,
I have an update: I purchased an Marantz SM-80U power amplifier to rid myself of the integrated yamaha rx-367.
So i will continue on this path to building an Aikido..
I've got abit of experience analysing circuits and I understand much of what their is to know practically regarding BJT/FET amplifiers, but are their any quality reads about tubes floating around anyone can recommend? Specifically the voltage requirements to get a tube operating in saturation (that is if they operate in saturation???), or other things that have alluded me regarding tubes...
Also regarding the tube itself, i see that their are 8pin and 9pin variants, are 3 of these pins the "base/collector/emitter" equivilants and the 5 or 6 pins left over for this "B+" rail?
I'm also still a little confused how I go about figuring out my tube requirements for my system.
Any pointers?
Thanks
I have an update: I purchased an Marantz SM-80U power amplifier to rid myself of the integrated yamaha rx-367.
So i will continue on this path to building an Aikido..
I've got abit of experience analysing circuits and I understand much of what their is to know practically regarding BJT/FET amplifiers, but are their any quality reads about tubes floating around anyone can recommend? Specifically the voltage requirements to get a tube operating in saturation (that is if they operate in saturation???), or other things that have alluded me regarding tubes...
Also regarding the tube itself, i see that their are 8pin and 9pin variants, are 3 of these pins the "base/collector/emitter" equivilants and the 5 or 6 pins left over for this "B+" rail?
I'm also still a little confused how I go about figuring out my tube requirements for my system.
Any pointers?
Thanks
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'Saturation' is not a concept usually used with valves, although I suppose it could be applied to the usual operating regime for a pentode. Triodes behave a bit like an FET, and pentodes a bit like an FET cascode.
For valves try to read all of the following:
Morgan-Jones' book (3rd edition probably still available in print?, 4th edition electronically)
Radiotron Designers Handbook
Valve Wizard website
For valves try to read all of the following:
Morgan-Jones' book (3rd edition probably still available in print?, 4th edition electronically)
Radiotron Designers Handbook
Valve Wizard website
Hey guys, so i'm looking at the nine-pin Aikido board.
I've chosen the C6G7s for the input tubes to get a voltage gain of approx 10.
I need to chose an output tube appropriate for my Marantz SM-80U.
The input Impedance of the SM-80U is 20kOhms, due to my lack of knowledge, im unsure if this is low or not.
EDIT: I assume this is pretty low actually
From these tubes, which would be most suitable for input Z = 20k?
ECC802
ECC88
ECC99
C6G7
Thoughts?
Thanks!
I've chosen the C6G7s for the input tubes to get a voltage gain of approx 10.
I need to chose an output tube appropriate for my Marantz SM-80U.
The input Impedance of the SM-80U is 20kOhms, due to my lack of knowledge, im unsure if this is low or not.
EDIT: I assume this is pretty low actually
From these tubes, which would be most suitable for input Z = 20k?
ECC802
ECC88
ECC99
C6G7
Thoughts?
Thanks!
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I opted for the EC99 output tube if anyone is curious.
Power supply is the Aikido Janus Solo.
Janus Solo HV Regulator Kit
I was going to employ an ATMega32 microcontroller for an LCD screen with a spectrum analyser and perhaps a temperature sensor for various regions of the preamplifier.
I could go as far as a digital/analogue volt metre.
As far as preheating the tubes, im going to use the atmega32 to use a timer function before the tubes are exposed to the B+ rail (If i got the tube theory right).
I'm a little bit wary with regard to actually switching the B+ rail, considering its 300V+, does anyone know if the janus solo has this sort of flexibility?
What could be used to switch this sort of voltage?
I was thinking an electrical contactor would work (Although this magnetic field will have reactive properties)..
Power supply is the Aikido Janus Solo.
Janus Solo HV Regulator Kit
I was going to employ an ATMega32 microcontroller for an LCD screen with a spectrum analyser and perhaps a temperature sensor for various regions of the preamplifier.
I could go as far as a digital/analogue volt metre.
As far as preheating the tubes, im going to use the atmega32 to use a timer function before the tubes are exposed to the B+ rail (If i got the tube theory right).
I'm a little bit wary with regard to actually switching the B+ rail, considering its 300V+, does anyone know if the janus solo has this sort of flexibility?
What could be used to switch this sort of voltage?
I was thinking an electrical contactor would work (Although this magnetic field will have reactive properties)..
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