Hi,
I am a newbie to the tube stuff and I have already loved it. With the "free" supply from a friend who sells tubes, I have lately conducted some tests on some of the popular brands of 12AX7. My system is reasonably fine (I mean high-end) except my valve preamp - it was my first tube DIY project - I built a AUD$138 preamp for fun, and that includes the PSU. The circuit was from a kit and uses 2 common cathode stages (for a guitar amp) and was modified to be used in HiFi by applying loads of negative feedback. Anyway, this was the amp used in the tests.
The following is part of the "email" I sent to my friend. Please note that what is good sound or bad sound is completely subjective.
* * * * * *
…… They are Ei Elite Gold, JJ, Sovtek and Svetlana. The result of my observation may be different from those that can be read on the Internet. These tubes sound quite different.
1. Ei Elite Gold - It has a reasonable resolution. On high and mid frequencies the sound is clear. The bass is not powerful but still reasonably clear. On first listen this tube sounded good but further listening revealed its weakness. This tube is very different from the others in that it gives quite a warm, coloured tone, possibly due to the rich even order harmonics some audiophiles love. I personally dislike this type of artificial warmth. On a very analytical system like mine it sounds lacking of naturalness, openness and life. On cold sounding systems the warmth of this tube may cover the coldness and I am not surprised some people may prefer this tube to others. Personally, I put the lowest score on this tube for my system. I think it is the least HiFi tube among the group I tested. However, for guitar amps, where accuracy is immaterial while rich harmonics are desirable, this tube may well be a good candidate, despite various reports on its microphonic problem.
2. JJ - This tube, comparing to Ei Elite Gold and the Sovtek, has a smooth sound. It is more neutral sounding and more open than the Ei Elite Gold. It does not provide the best resolution though. The sound is not harsh or offensive. However, I found a problem with it - the high frequency is obviously lacking though the bass is powerful. It sounded like a shelving low pass filter was applied to the sound. It appears that this would be a good tube for a system that sounds harsh or has a rising response. It does not sound bad, just not brilliant.
3. Sovtek - This tube, from everywhere I read over the net, is the most ordinarily sounding tube, i.e. it is not good and not bad. However, it actually sounds quite good on my system. It is not brilliant, but very good. I think the reason was because when I was tuning both my passive and active XOs I was using this tube! So every capacitor value, every resistor and inductor in the XO was tuned for this tube. If the sound of the tube was too lay-back I would have brought the sound forward, and if the sound was too forward I would have pushed it back. Therefore, the Sovtek sounded very well balanced on my system and comparing with the Ei Elite Gold and the JJ, a lot more "life" in the sound and was much better. It is an overall good performer in all areas and I have not found any serious problems with it. Indeed, without comparing with better tubes, I simply didn't know how to improve the sound. It sounded very good.
4. Svetlana - Until I tried this tube, the Sovtek was unbeatable because I tuned my system based on it. While the Sovtek, the JJ and the Ei Elite Gold are probably in the same league despite their individual characters, the Svetlana is ahead and is the next level up in sound quality. It has the highest resolution among the group I tested. Human voices are now with finer textures, so as everything else. The sound is clean and effortless, although slightly on the dark side. The bass department is substantially cleaner than any other tubes in the group. The bass is strong, the high is reasonably extended, and the mid is clear - despite sounding a bit lay back comparing with other tubes in the group - lay back but without losing details. I may be contradicting myself to say that the sound has the openness and neutralness while being reasonably warm and very smooth. However, I had to do some adjustments on my active XO to trim the bass down a bit to make the system sound more balanced. Now Svetlana is the tube running on my preamp. For HiFi sound, this is my pick. For a guitar amp, I am not sure if it is the best because it has a very smooth but slightly lay-back sound.
* * * * * *
I will be looking for the best sounding 12AX7 and 12AT7 for my second valve preamp project. If I am happy to pay up to US$100 for a tube, which tubes from which brarnds do you recommend?
Regards,
Bill
I am a newbie to the tube stuff and I have already loved it. With the "free" supply from a friend who sells tubes, I have lately conducted some tests on some of the popular brands of 12AX7. My system is reasonably fine (I mean high-end) except my valve preamp - it was my first tube DIY project - I built a AUD$138 preamp for fun, and that includes the PSU. The circuit was from a kit and uses 2 common cathode stages (for a guitar amp) and was modified to be used in HiFi by applying loads of negative feedback. Anyway, this was the amp used in the tests.
The following is part of the "email" I sent to my friend. Please note that what is good sound or bad sound is completely subjective.
* * * * * *
…… They are Ei Elite Gold, JJ, Sovtek and Svetlana. The result of my observation may be different from those that can be read on the Internet. These tubes sound quite different.
1. Ei Elite Gold - It has a reasonable resolution. On high and mid frequencies the sound is clear. The bass is not powerful but still reasonably clear. On first listen this tube sounded good but further listening revealed its weakness. This tube is very different from the others in that it gives quite a warm, coloured tone, possibly due to the rich even order harmonics some audiophiles love. I personally dislike this type of artificial warmth. On a very analytical system like mine it sounds lacking of naturalness, openness and life. On cold sounding systems the warmth of this tube may cover the coldness and I am not surprised some people may prefer this tube to others. Personally, I put the lowest score on this tube for my system. I think it is the least HiFi tube among the group I tested. However, for guitar amps, where accuracy is immaterial while rich harmonics are desirable, this tube may well be a good candidate, despite various reports on its microphonic problem.
2. JJ - This tube, comparing to Ei Elite Gold and the Sovtek, has a smooth sound. It is more neutral sounding and more open than the Ei Elite Gold. It does not provide the best resolution though. The sound is not harsh or offensive. However, I found a problem with it - the high frequency is obviously lacking though the bass is powerful. It sounded like a shelving low pass filter was applied to the sound. It appears that this would be a good tube for a system that sounds harsh or has a rising response. It does not sound bad, just not brilliant.
3. Sovtek - This tube, from everywhere I read over the net, is the most ordinarily sounding tube, i.e. it is not good and not bad. However, it actually sounds quite good on my system. It is not brilliant, but very good. I think the reason was because when I was tuning both my passive and active XOs I was using this tube! So every capacitor value, every resistor and inductor in the XO was tuned for this tube. If the sound of the tube was too lay-back I would have brought the sound forward, and if the sound was too forward I would have pushed it back. Therefore, the Sovtek sounded very well balanced on my system and comparing with the Ei Elite Gold and the JJ, a lot more "life" in the sound and was much better. It is an overall good performer in all areas and I have not found any serious problems with it. Indeed, without comparing with better tubes, I simply didn't know how to improve the sound. It sounded very good.
4. Svetlana - Until I tried this tube, the Sovtek was unbeatable because I tuned my system based on it. While the Sovtek, the JJ and the Ei Elite Gold are probably in the same league despite their individual characters, the Svetlana is ahead and is the next level up in sound quality. It has the highest resolution among the group I tested. Human voices are now with finer textures, so as everything else. The sound is clean and effortless, although slightly on the dark side. The bass department is substantially cleaner than any other tubes in the group. The bass is strong, the high is reasonably extended, and the mid is clear - despite sounding a bit lay back comparing with other tubes in the group - lay back but without losing details. I may be contradicting myself to say that the sound has the openness and neutralness while being reasonably warm and very smooth. However, I had to do some adjustments on my active XO to trim the bass down a bit to make the system sound more balanced. Now Svetlana is the tube running on my preamp. For HiFi sound, this is my pick. For a guitar amp, I am not sure if it is the best because it has a very smooth but slightly lay-back sound.
* * * * * *
I will be looking for the best sounding 12AX7 and 12AT7 for my second valve preamp project. If I am happy to pay up to US$100 for a tube, which tubes from which brarnds do you recommend?
Regards,
Bill
HiFiNutNut said:
If you're building your own circuits, I find it's more fun (and more different) to try different types rather than rolling different brands.
I'd suggest trying some lower gain triodes for a preamp circuit. You could then dispense with feedback (which I presume is present in your preamp due to the high gain tubes used.)
Re: Re: 12AX7 Compared!
Hell yes! Leave the 12AX7's to geetar amps where they belong.jeff mai said:
If you're willing to spend $100 per tube for a 12AX7, you're someone just waiting to be fleeced.
It's not hard to set up a test jig to get you distortion spectra, noise, and microphonics- all it takes is a decent soundcard, some free software, and an hour or two making a jig. One good example is the 6SN7 test circuit shown in Morgan Jones "Valve Amplifiers" or my adaption in the "SY gets jiggy" thread. You can adapt the jigs to the particular operating point for the 12AX7 in your circuit.
With this set up, you can buy a pile of cheaper 12AX7s of various makes and origins and cherry-pick them. You'll spend a lot less per tube and probably end up with something better than the unreliable stuff that the tube rollers peddle to the unwary.
It's not hard to set up a test jig to get you distortion spectra, noise, and microphonics- all it takes is a decent soundcard, some free software, and an hour or two making a jig. One good example is the 6SN7 test circuit shown in Morgan Jones "Valve Amplifiers" or my adaption in the "SY gets jiggy" thread. You can adapt the jigs to the particular operating point for the 12AX7 in your circuit.
With this set up, you can buy a pile of cheaper 12AX7s of various makes and origins and cherry-pick them. You'll spend a lot less per tube and probably end up with something better than the unreliable stuff that the tube rollers peddle to the unwary.
SY is right (again)... US$100 is an absolutely inordinate amount of money to spend on a single 12AX7 or 12AT7. I don't think I've spent that much on any single valve - not even the power ones!
Eeek!!
Tons of negative feedback does not necessarily mean hifi - it may reduce distortion and output impedance, but we would prefer to eliminate as much of the source of these problems rather than treating the symptoms!
By the way, would that happen to be the valve preamp kit sold by Jaycar?
SY's suggestion of making up a test jig would be preferable, but for fundamentally lazy people like me, it's a bit too much effort. 😉
If this is a line preamp - you will likely need basically no gain. I would suggest something along the lines of a high gm valve cathode follower sitting on a constant current source (preferably of the pentode kind instead of the semiconductor type since this allows more glowing glass 😉) If, say, you use 6C45pi (6S45P) sitting on an EF184/6EJ7 CCS - all the valves for a stereo linestage won't come close to the US$100 you're willing to spend on a single boring 12AX7!
HiFiNutNut said:
Eeek!!
Tons of negative feedback does not necessarily mean hifi - it may reduce distortion and output impedance, but we would prefer to eliminate as much of the source of these problems rather than treating the symptoms!By the way, would that happen to be the valve preamp kit sold by Jaycar?
HiFiNutNut said:
SY's suggestion of making up a test jig would be preferable, but for fundamentally lazy people like me, it's a bit too much effort. 😉
If this is a line preamp - you will likely need basically no gain. I would suggest something along the lines of a high gm valve cathode follower sitting on a constant current source (preferably of the pentode kind instead of the semiconductor type since this allows more glowing glass 😉) If, say, you use 6C45pi (6S45P) sitting on an EF184/6EJ7 CCS - all the valves for a stereo linestage won't come close to the US$100 you're willing to spend on a single boring 12AX7!
Hi,
Thank you all for your valuable input. I have been away for a few days and have just come back to this.
If the 12AX7 sounds boring in a preamp, can you suggest a schematic with an alternative?
I am a newbie and I am unable to design my own tube stuff at the moment. I started DIY about a year ago and the only thing that I have designed is a pair of speakers – they now sound much better than the BBC monitor Roger Studio 1A I own and I am very pleased with the fruitful result of DIY.
I know that there are thousands of schematics available on the internet. But for a newbie, there is no way I can know which sounds good or bad. I went through a very long process of selecting a SS power amp. I could easily find half a dozen DIY SS power amps that were very popular. However, after 6 months searching I auditioned 3 extremely popular DIY amps that had a large following and found they hardly sound good. Fortunately, I eventually built a less popular one and it happened to sound fantastic. I then built the second one and in the process of building a third one - a pair of 400W mono block. Choosing an amp without first auditioning it is a kind of gamble.
My system is very good now but its preamp. I read through this forum and found that PCB replicas of some famous preamps, like Marantz M7, Audionote M7, Macintosh C22, Matisse, etc are available. I thought this would be a “lazy man” quick and cheap way to get a very good sounding preamp. All of those amps seem to use 12AX7 or 12AU7, except that Matisse uses 12AT7 for its cathode follower. I thought this would be the best amp in the group and am thinking about building one, hence my questions of best sounding 12AX7 and 12AT7.
If you guys know a better preamp and have the schematic, please point me to the right direction.
Jason,
Yes, that is the Jaycar valve preamp. It does not sound bad, but not good either. I am actually thinking about trying its first version (documented in the note that comes with the kit) which uses a cathode follower in the 2nd stage without negative feedback. What do you think?
Thank you all for your valuable input. I have been away for a few days and have just come back to this.
If the 12AX7 sounds boring in a preamp, can you suggest a schematic with an alternative?
I am a newbie and I am unable to design my own tube stuff at the moment. I started DIY about a year ago and the only thing that I have designed is a pair of speakers – they now sound much better than the BBC monitor Roger Studio 1A I own and I am very pleased with the fruitful result of DIY.
I know that there are thousands of schematics available on the internet. But for a newbie, there is no way I can know which sounds good or bad. I went through a very long process of selecting a SS power amp. I could easily find half a dozen DIY SS power amps that were very popular. However, after 6 months searching I auditioned 3 extremely popular DIY amps that had a large following and found they hardly sound good. Fortunately, I eventually built a less popular one and it happened to sound fantastic. I then built the second one and in the process of building a third one - a pair of 400W mono block. Choosing an amp without first auditioning it is a kind of gamble.
My system is very good now but its preamp. I read through this forum and found that PCB replicas of some famous preamps, like Marantz M7, Audionote M7, Macintosh C22, Matisse, etc are available. I thought this would be a “lazy man” quick and cheap way to get a very good sounding preamp. All of those amps seem to use 12AX7 or 12AU7, except that Matisse uses 12AT7 for its cathode follower. I thought this would be the best amp in the group and am thinking about building one, hence my questions of best sounding 12AX7 and 12AT7.
If you guys know a better preamp and have the schematic, please point me to the right direction.
Jason,
Yes, that is the Jaycar valve preamp. It does not sound bad, but not good either. I am actually thinking about trying its first version (documented in the note that comes with the kit) which uses a cathode follower in the 2nd stage without negative feedback. What do you think?
HiFiNutNut said:
If that's the case, I will gladly sell you my prized pair of Computor tubes:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
West Germany make, diamond base (IIRC), flat gray plate. Clearly TF, though not printed anywhere.
Tim
Not so much boring as very round and coloured, and quite often dirty sounding. I use a lot of them in guitar amps for that reason; there's better for that too, but it's what the market demands.HiFiNutNut said:
From your first post, it isn't clear whather you want a line stage or a combination of a line and phono, but I suspect it's only a line. Is that correct? They have very different requirements.
I owned a Marantz 7C (an original) which I then proceeded to POOGE and finally restored it and sold it for an obscene price. It's not that great but some people really like the warm, smudgy sort of sound these make. Can be very pleasant to listen too, but in the long run I found it a bit 'samey' on recordings. There's also lots of similar vintage designs and they all sound similar to me.
If you just need a linestage, and I suspect that's so, then I have a simple 12B4A design, Frank has a design also published here with a long thread called Frank's Ultimate preamp or similar. Also, though I haven't built it, I suspect the Aikido by John Broskie could be excellent. I'm contemplating adding an Aikido (with OPTs) to the preamp I'm rebuilding as a dynamic headphone driver.
http://www.tubecad.com/2004/blog0011.htm
http://www.tubecad.com/2005/January/blog0030.htm
Re: Re: 12AX7 Compared!
I would have suggested a common cathode 12B4, but Brett already has, and Dave has posted the schematic 😀 It has only modest gain (about 5 or 6 I think), and has low output impedance, so it should do well in a linestage. As has also been stated, 12B4s can be a little microphonic - so be wary of chassis design, and buy more than you need so you can choose. They can be sourced for around A$14 each, maybe a little cheaper.
Phono preamps are a completely different game. The schematic posted just before Brett's 12B4 design includes a phono stage, which is then coupled to a cathode follower (rightmost valve) being used as a linestage.
I recall seeing the schematic somewhere and thinking it was rather boring. I'll dig around to see if I can find it again. I have a completely irrational aversion to 12AX7s... so I would prefer not to use them in a preamp. But if you already have them we might as well try to use them properly!
A cathode follower is just another case of negative feedback anyway - in fact 100% negative feedback. So we won't be getting rid of the feedback by using cathode followers! The problem I have with 12AX7 cathode follower outputs in preamps (especially line preamps) is that they run at meagre levels of current, which causes problems, including increasing distortion, when driving capacitive loads like interconnects or power amp inputs.
Computor 😀
While on this train of thought (unfortunately I ditched any 12AX7s I came across) I have some Gold Pin E180Fs which make very nice linear triodes. Yours for US$100ea. The fact that they cost less than A$10 of course will never get out...
HiFiNutNut said:
I would have suggested a common cathode 12B4, but Brett already has, and Dave has posted the schematic 😀 It has only modest gain (about 5 or 6 I think), and has low output impedance, so it should do well in a linestage. As has also been stated, 12B4s can be a little microphonic - so be wary of chassis design, and buy more than you need so you can choose. They can be sourced for around A$14 each, maybe a little cheaper.
Phono preamps are a completely different game. The schematic posted just before Brett's 12B4 design includes a phono stage, which is then coupled to a cathode follower (rightmost valve) being used as a linestage.
HiFiNutNut said:
I recall seeing the schematic somewhere and thinking it was rather boring. I'll dig around to see if I can find it again. I have a completely irrational aversion to 12AX7s... so I would prefer not to use them in a preamp. But if you already have them we might as well try to use them properly!
A cathode follower is just another case of negative feedback anyway - in fact 100% negative feedback. So we won't be getting rid of the feedback by using cathode followers! The problem I have with 12AX7 cathode follower outputs in preamps (especially line preamps) is that they run at meagre levels of current, which causes problems, including increasing distortion, when driving capacitive loads like interconnects or power amp inputs.
Sch3mat1c said:
Computor 😀
While on this train of thought (unfortunately I ditched any 12AX7s I came across) I have some Gold Pin E180Fs which make very nice linear triodes. Yours for US$100ea. The fact that they cost less than A$10 of course will never get out...
Adding to the sudden prolific posting on this thread:
HiFiNutNut's preamp schematic (or so I think...)
EDIT: A link to the Silicon Chip Magazine project article (or what you can read of it without paying for a subscription!)
HiFiNutNut's preamp schematic (or so I think...)
An externally hosted image should be here but it was not working when we last tested it.
EDIT: A link to the Silicon Chip Magazine project article (or what you can read of it without paying for a subscription!)
And if you want something complex but very good (and developed in Oz)
from http://www.vacuumstate.com/
I think Brett has said he has built one of these (or its BIG brother)
This also has a phono stage.
dave
An externally hosted image should be here but it was not working when we last tested it.
from http://www.vacuumstate.com/
I think Brett has said he has built one of these (or its BIG brother)
This also has a phono stage.
dave
Re: Re: Re: 12AX7 Compared!
I've still never found a microphonic 12B4A. Maybe I'm just lucky....
I also have an amended version from my notebook with slightly different anode and cathode R's that my notes say I preferred. Will put it up later tonight after I finish some stuff here. Don't remember the values OTTOMH
I don't like the SLCF in any of it's variants compared to a simple anode follwer like the 12B4.
Brillliant preamps, but not a beginner project. Need an excellent PS.
This really is a nice sounding tube, and for a beginner, it's so easy and sounds so good, and it really isn't critical on values or op points.planet10 said:
I've still never found a microphonic 12B4A. Maybe I'm just lucky....
I also have an amended version from my notebook with slightly different anode and cathode R's that my notes say I preferred. Will put it up later tonight after I finish some stuff here. Don't remember the values OTTOMH
I paid less than that for my last lot, but it's still not too bad.audiousername said:
I've built both, and ran them together in the one chassis for the two TT's I use. The pre is dismantled at the moment and I'm going to build a better chassis for them.planet10 said:
I don't like the SLCF in any of it's variants compared to a simple anode follwer like the 12B4.
Brillliant preamps, but not a beginner project. Need an excellent PS.
Hi, many thanks to you all. I am overwhelmed by your responses.
I am still spending time digesting the information. So far the choice seems to be the Brett's 12B4A Linestage schematic Dave posted because of its simplicity - good for a beginner like me.
Brett, that Aikido amp seems to be very interesting and I may give it a go one day.
Dave, some component values are not given in the schematic. What is the voltage supply for the heater? Would a volume control be a 50k pot at the input? Any links to more info about this amp on the net? Sorry for being such an idiot because I am really a beginner. I will spend some time learning the tube stuff but for now too many things to do with too little time.
Jason, that Jaycar schematic you posted is for the guitar amp. Component values were changed for a HiFi amp. There is a different schematic with the second stage being cathode follower, which was abandoned by the designer due to lower gain and higher distortion. For the time being, I am only looking for a line preamp. In the future, I will probably get a phono preamp as well. I bought about 200 mostly second hand LPs and a Thorens turntable but never got around to build the phono stage or afforded the time to clean the records. Good LPs are either too expensive or difficult to find. I don't think I can afford them in a long run but to get a few nice ones to appreciate the sound of LPs would be good. Sadly, CDs, including Xrcd, HDCD, SACD, etc, do not match the sound of LPs.
Where in OZ can I get the 12B4A? I searched the WES and Farnell catalogues and they don't sell them.
I am thinking of first building a variable power supply (220-300VDC, 6V-70VDC) so that I can experiment different tube preamp circuits.
Regards,
Bill
I am still spending time digesting the information. So far the choice seems to be the Brett's 12B4A Linestage schematic Dave posted because of its simplicity - good for a beginner like me.
Brett, that Aikido amp seems to be very interesting and I may give it a go one day.
Dave, some component values are not given in the schematic. What is the voltage supply for the heater? Would a volume control be a 50k pot at the input? Any links to more info about this amp on the net? Sorry for being such an idiot because I am really a beginner. I will spend some time learning the tube stuff but for now too many things to do with too little time.
Jason, that Jaycar schematic you posted is for the guitar amp. Component values were changed for a HiFi amp. There is a different schematic with the second stage being cathode follower, which was abandoned by the designer due to lower gain and higher distortion. For the time being, I am only looking for a line preamp. In the future, I will probably get a phono preamp as well. I bought about 200 mostly second hand LPs and a Thorens turntable but never got around to build the phono stage or afforded the time to clean the records. Good LPs are either too expensive or difficult to find. I don't think I can afford them in a long run but to get a few nice ones to appreciate the sound of LPs would be good. Sadly, CDs, including Xrcd, HDCD, SACD, etc, do not match the sound of LPs.
Where in OZ can I get the 12B4A? I searched the WES and Farnell catalogues and they don't sell them.
I am thinking of first building a variable power supply (220-300VDC, 6V-70VDC) so that I can experiment different tube preamp circuits.
Regards,
Bill
Something simple would be my recommendation for a first scratch project as it exponentially increases the chances of success.HiFiNutNut said:
This is also a quite simple design.
Don't attempt this as a first project. When you've got a linestage working, email me and I'll walk you through it. I've built a couple.
www.evatco.com.au
My test bench supply is a huge transformer I got surplus and allows me to vary the B+ voltage from 700V down via a variac. The heaters and bias supplies are on seperate transformers that aren't connected to the variac and so stay stable as I change the B+
Let me know if you decide to go ahead with the 12B4 pre and what you have for a mains transformer and I'll work out a power supply for it.
Brett,
When I asked Dave questions about the schematic I was referring to the first schematic he posted "Brett's Linestage", not the more complicated one he posted later. I guess the first one may be yours but not 100% sure, since many people share your name.
I was thinking of getting a +-70-300V PSU board kit (designed for tube preamp), and a +-7-72V 100-400mA PSU kit, and a +-4-40V 125-250mA kit, all completed with components (except transformer) for about AUD$100. I can replace some electro caps with better quality ones when needed. I can also get a transformer (100W 300V-0-300V/0.06A, 0-6.3V/2A, 0-12.6V/2A, 0-15V-18V/2A, 0-15V-18/2A) for AUD$55. I thought this could give me a PSU that can work with most tube preamps. Let me know if this is not the right approach. Do you have an existing design for the PSU for your pre? Of course I am interested in a simple 12B4 pre since all of you guys recommended it and it seems that it would cost very little to build it.
By the way, what initially inspired me to build a valve preamp was that my friend brought along his Audio Research LS8 to my home and hooked it up in my system, the sound was instantly out of the 3rd heaven and my system was at least 2 levels up, comparable to some of the best sounding systems I had ever listened to (and I have listened to many mega systems). The LS8 is not the best AR preamp yet it does wonder on my system. I bet your 12B4 would beat the AR LS8. I previously played with a reference grade SS preamp which was later stolen. I then built the Jaycar valve pre for an experiment.
Regards,
Bill
When I asked Dave questions about the schematic I was referring to the first schematic he posted "Brett's Linestage", not the more complicated one he posted later. I guess the first one may be yours but not 100% sure, since many people share your name.
I was thinking of getting a +-70-300V PSU board kit (designed for tube preamp), and a +-7-72V 100-400mA PSU kit, and a +-4-40V 125-250mA kit, all completed with components (except transformer) for about AUD$100. I can replace some electro caps with better quality ones when needed. I can also get a transformer (100W 300V-0-300V/0.06A, 0-6.3V/2A, 0-12.6V/2A, 0-15V-18V/2A, 0-15V-18/2A) for AUD$55. I thought this could give me a PSU that can work with most tube preamps. Let me know if this is not the right approach. Do you have an existing design for the PSU for your pre? Of course I am interested in a simple 12B4 pre since all of you guys recommended it and it seems that it would cost very little to build it.
By the way, what initially inspired me to build a valve preamp was that my friend brought along his Audio Research LS8 to my home and hooked it up in my system, the sound was instantly out of the 3rd heaven and my system was at least 2 levels up, comparable to some of the best sounding systems I had ever listened to (and I have listened to many mega systems). The LS8 is not the best AR preamp yet it does wonder on my system. I bet your 12B4 would beat the AR LS8. I previously played with a reference grade SS preamp which was later stolen. I then built the Jaycar valve pre for an experiment.
Regards,
Bill
HiFiNutNut said:
One & the same Brett... the heater, like in a 12ax7 can be wired for 6.3/0.6A or 12.6 V/0.3A heaters.
I was surprised to find that Duncan Amps had no real info on this tube so i have attache dthe data sheet that Bill @ PEARL recreated.
And the ARC pres are not the best... well implemented the 12B4 ....
dave
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