I have built most of the published 12b4 linetage on this forum. The only one that works is Brett's: that preamp has bass, highs, mids, the lot... I don't even have the luxury of using a CCS.
I don't think putting a 2mf coupling cap will do the trick (just my 2...
)
BTW, I am using the ordinary 12B4 without the A suffix. They are not noisy as some people may suggest...microphonic, yes, only if you tap them.
All the best Bryan
I don't think putting a 2mf coupling cap will do the trick (just my 2...
)BTW, I am using the ordinary 12B4 without the A suffix. They are not noisy as some people may suggest...microphonic, yes, only if you tap them.
All the best Bryan
The one I can highly reccomend is Brian Beck's design that uses an LM 317 as a cathode based css. This one really works well!! I have completed building it and the performance is quite a bit better than Brett's straight straight 12B4 stage, although that is no slouch either!
Also you really need to use a small film bypass cap across the 440 mf cathode bypass caps, I used a .22uf Wonder Cap SETI in mine in each channel, my output coupling caops are 5mf paralleled by a .01 Wonder cap. The cicruit as shown runs the 12B4 at a high 30 mils.......... so yes, it sounds great!
Also see this thread in case you haven't.
Mark
Also you really need to use a small film bypass cap across the 440 mf cathode bypass caps, I used a .22uf Wonder Cap SETI in mine in each channel, my output coupling caops are 5mf paralleled by a .01 Wonder cap. The cicruit as shown runs the 12B4 at a high 30 mils.......... so yes, it sounds great!
Also see this thread in case you haven't.
Mark
OK, so I figured out the problem... I was using my mp3 as a source during the test. I know, I know....
Once I put the pre back into the chain, I was AMAZED. This thing sounds better than anything I have ever heard... Seriously. From top to bottom, the sound is GREAT. This is with only about 1 hour of play time on the finished version, so I imagine it will sound even better with a few days use...
I will post the final schematics including any changes made between from the breadboard to the final form with pics of the finished project.
Ahh, what a huge smile I have on my face!!!!!
Once I put the pre back into the chain, I was AMAZED. This thing sounds better than anything I have ever heard... Seriously. From top to bottom, the sound is GREAT. This is with only about 1 hour of play time on the finished version, so I imagine it will sound even better with a few days use...
I will post the final schematics including any changes made between from the breadboard to the final form with pics of the finished project.
Ahh, what a huge smile I have on my face!!!!!
Sorry about the delay, but things have been busy wioth Grad School, the holidays, and the family. Too much **** to do, and not enough time!
Anyway, here is the PS Schematic as promised. I will try to get the Audio Schematic up this weekend. The only other components are the timer relay mute, which keeps the output shorted for about 30 seconds and then instantly mutes the output when I power off the pre-amp. The B+ supply has enough reserve to maintain voltage during the .5 seconds it takes for the mute to activate, so no bumbs and thumos on the output! As mentioned earlier in the thread, the 12B4As use regulated DC, with one regulator sharing the load of both tubes. This is the only spot where things are not completely dual mono...
Thanks,
Bryan
Anyway, here is the PS Schematic as promised. I will try to get the Audio Schematic up this weekend. The only other components are the timer relay mute, which keeps the output shorted for about 30 seconds and then instantly mutes the output when I power off the pre-amp. The B+ supply has enough reserve to maintain voltage during the .5 seconds it takes for the mute to activate, so no bumbs and thumos on the output! As mentioned earlier in the thread, the 12B4As use regulated DC, with one regulator sharing the load of both tubes. This is the only spot where things are not completely dual mono...
Thanks,
Bryan
Attachments
Sunrise, Thanks for the comment! I am enjoying it more each time I power her up. The sound has come together quite nicely in the past couple days, and she is sounding very very good!
Mark,
That's per channel, probably not including the 12VAC fillament transformer for the 12AX4s.... I think you could get away with 6AX4s and use the secondary on the 369EX if you wanted...
When I biult the preamp, I wanted to do an "all out, cost no issue" design. The total product was VERY expensive, with boutique parts like rikens, DACT attenuator, surgical solid silver teflon insulated wire, and Mundorf caps. I built it over a long period, so the daily cost was little when I consider that the build lasted such a long time, and the knowledge I gained was worth every penny... Hopefully now I won't need another pre for a LONG LONG time.
I'm sure the SS route can be effectively and affordably done. Please let me know how things go and what you think.
I may build a couple of these for some friends and depending on their budgets alternatives are always nice to have.
Thanks,
Bryan
Mark,
That's per channel, probably not including the 12VAC fillament transformer for the 12AX4s.... I think you could get away with 6AX4s and use the secondary on the 369EX if you wanted...
When I biult the preamp, I wanted to do an "all out, cost no issue" design. The total product was VERY expensive, with boutique parts like rikens, DACT attenuator, surgical solid silver teflon insulated wire, and Mundorf caps. I built it over a long period, so the daily cost was little when I consider that the build lasted such a long time, and the knowledge I gained was worth every penny... Hopefully now I won't need another pre for a LONG LONG time.
I'm sure the SS route can be effectively and affordably done. Please let me know how things go and what you think.
I may build a couple of these for some friends and depending on their budgets alternatives are always nice to have.
Thanks,
Bryan
Hi Bryan,
Congratulations for your determination. I enjoyed reading your thread. It is over a year.
Would it be possbile that you might summarize major decision in designing this pre-amp. I can't follow everything you've gone through. Pros and cons would be very useful for new commers.
Mine sounds fantastic but I'm seeking for a way to improve it. Would you put up the final schematics.
Thanks a million. Great posts folks.
Congratulations for your determination. I enjoyed reading your thread. It is over a year.
Would it be possbile that you might summarize major decision in designing this pre-amp. I can't follow everything you've gone through. Pros and cons would be very useful for new commers.
Mine sounds fantastic but I'm seeking for a way to improve it. Would you put up the final schematics.
Thanks a million. Great posts folks.
Kind of a personal question, but how much do you guys spend when making these.
I am speaking of the component parts, not the chassis. I understand the chassis has a ton of variations as well.
I also understand the possibility of high cost power supplies, I am wondering how much the PS would cost before you run into diminishing returns!
I am curious because I am going to build one, but do not want to run out of money half way through!!!
Thanks guys - Evan
BTW.. thanks for all the very helpful information, I am learning a TON from this thread alone!!!
I am speaking of the component parts, not the chassis. I understand the chassis has a ton of variations as well.
I also understand the possibility of high cost power supplies, I am wondering how much the PS would cost before you run into diminishing returns!
I am curious because I am going to build one, but do not want to run out of money half way through!!!
Thanks guys - Evan
BTW.. thanks for all the very helpful information, I am learning a TON from this thread alone!!!
Hey Guys,
I was just discussing final costs with a friend over the weekend. To be honest, I have not calculated the amount I have spent on this project to the closest dime, but if I had to guess.... $700.
Keep in mind that I have some pretty expensive caps, attenuator, and a LOT of iron. There are many ways to build a good preamp for less money. You can skip complete dual mono, and split a common PS for both channels. You can exchange chokes for resistors in the PS, you can use less expensive passives, and a less expensive attenuator....
At the end of the day, you need to build something that is within your budget, and it has been my experience that building an amp will GENERALLY cost a little more due to iunexpected costs and errors... I have blown a few pieces and melted a couple trannies
At the end of the day, I considder not only the finished project, but also the knowledge gained as ample payback for the monitary expense, time, and effort.
I was just discussing final costs with a friend over the weekend. To be honest, I have not calculated the amount I have spent on this project to the closest dime, but if I had to guess.... $700.
Keep in mind that I have some pretty expensive caps, attenuator, and a LOT of iron. There are many ways to build a good preamp for less money. You can skip complete dual mono, and split a common PS for both channels. You can exchange chokes for resistors in the PS, you can use less expensive passives, and a less expensive attenuator....
At the end of the day, you need to build something that is within your budget, and it has been my experience that building an amp will GENERALLY cost a little more due to iunexpected costs and errors... I have blown a few pieces and melted a couple trannies
At the end of the day, I considder not only the finished project, but also the knowledge gained as ample payback for the monitary expense, time, and effort.
Thanks Bryan. I am a sucker for a project. I have been through the same situations with cars. Whoops, cooked ECU etc... I understand the growing pains that come with these things.
I was curious about price, not as a deciding factor, but preperation.
I probabally will not go as wild as you did with power supply at first. Seems cheaper to cook a couple transistors than Iron lol. I plan on going outboard power supply for future upgrades.
I have quite a few parts already, IE a tweaked AES AE-1 preamp. Nice volume pot etc.. kimber caps and all that stuff. Ill use what I can.
Knowing that this thing can be built really well for $700 is kind of a relief honestly LOL. I was considering the likes of audio research (and entry level A/R equipment costs that). When I do this, I will likely go all out on the chassis the first time because looks are important. I want something I can take pride in.
Thanks, any other thoughs fellas?
Evan
BTW.. an audio research preamp does not lend ANY sense of accomplishment or pride either!!
I was curious about price, not as a deciding factor, but preperation.
I probabally will not go as wild as you did with power supply at first. Seems cheaper to cook a couple transistors than Iron lol. I plan on going outboard power supply for future upgrades.
I have quite a few parts already, IE a tweaked AES AE-1 preamp. Nice volume pot etc.. kimber caps and all that stuff. Ill use what I can.
Knowing that this thing can be built really well for $700 is kind of a relief honestly LOL. I was considering the likes of audio research (and entry level A/R equipment costs that). When I do this, I will likely go all out on the chassis the first time because looks are important. I want something I can take pride in.
Thanks, any other thoughs fellas?
Evan
BTW.. an audio research preamp does not lend ANY sense of accomplishment or pride either!!
interesting how one tiny line stage can be more than tiny
and interesting,also, how several ppl around globe suddenly became aware of same things.....Brian's (or "Brian's") preamp ,few others and mine share same approach in PS...
I spend almost a year tweaking my preamp with generic PSU and then I make one propper for tube stage ;tnx to God that I learned my s*it yrs ago,when my ears decided finally that plain repetitive LC or RC filtration always sound better to me than SS stab
in any case,shunt reg is bingo in not just low level tube stage,and only
bean counter fabrication approach in last few decades make them rare
if you know what I mean-my brain is pretty in red field in this moment..........
and interesting,also, how several ppl around globe suddenly became aware of same things.....Brian's (or "Brian's") preamp ,few others and mine share same approach in PS...
I spend almost a year tweaking my preamp with generic PSU and then I make one propper for tube stage ;tnx to God that I learned my s*it yrs ago,when my ears decided finally that plain repetitive LC or RC filtration always sound better to me than SS stab
in any case,shunt reg is bingo in not just low level tube stage,and only
bean counter fabrication approach in last few decades make them rare
if you know what I mean-my brain is pretty in red field in this moment..........
Bryan,
I will never forget your massive breadboard with miles of cables It has been a very long journey since.
We can agree on one thing: we have learned a lot from your experience.
Very easy to bang together a couple of resistors and capacitors, but the art is to perfect the blend until we get that musical bliss.
Well done! I hope you'll take the time to enjoy your music,
I will never forget your massive breadboard with miles of cables
It has been a very long journey since.We can agree on one thing: we have learned a lot from your experience.
Very easy to bang together a couple of resistors and capacitors, but the art is to perfect the blend until we get that musical bliss.
Well done! I hope you'll take the time to enjoy your music,
Hi Bryan,
Kool's right. You've been working on this for almost a year, and you deserve to kick back and enjoy.
I'm curious, though, which AR preamp are you selling, and how does your 12B4A pre sound in comparison? My dream is to start as a NewB and make a 12B4A balanced line stage (over the next year or so) that sounds as good as a BAT VK-51SE. I was just wondering if this was an impossible dream.
Thanks for keeping this great thread going for so long. There is a lot to learn here.
Kool's right. You've been working on this for almost a year, and you deserve to kick back and enjoy.
I'm curious, though, which AR preamp are you selling, and how does your 12B4A pre sound in comparison? My dream is to start as a NewB and make a 12B4A balanced line stage (over the next year or so) that sounds as good as a BAT VK-51SE. I was just wondering if this was an impossible dream.
Thanks for keeping this great thread going for so long. There is a lot to learn here.
Looney,
Yup, many hours to be spent in the sweet spot, with a good glass of red! My girlfriend keeps telling me the smile on my face is from cheek to cheek when I settle infront of my rig. I guess she is right
My old pre was an ARC SP9 MKIII. Hmm, comparison wise.....
Well, the ARC's soundstage was not as clearly defined, the bass was a little muddier, and a little less extended in the highs... I think the 12b4a does just about everything better than the ARC, but it does not have a phono stage (future project?). The bass presence in the 12b4a is tighter and easier to follow. It is very tuneful, and subtle nuances of each note are present. At first it was a little sloppy, but with hours everything has come together in the lower end. The mids are clear, not overly warm, and the highs are crystal clear. When I listen to music I often find myself following just one of the musicians closely and listening to the remainder of the band in the background. Following the drummer is GREAT, as the high hat is so clear, but not overly bright. Cymbals actually sound like Cymbals.
The soundstage is what I like the most. Everything is placed with great accuracy. I can really differentiate everyone/everything in front of me spatially. Overall, the depth is good, but my room is not suited for great 3-dimensionality... Unlike what some others have stated about the 12b4a, my pre is not forward in presentation.
Dont get me wrong, the ARC was a lot of fun, and I still think about keeping it as a backup, but to me there is no comparison. This could be partially due to pride, biased non-objective view, the emotional need to justify work/expense/inhaled solder fumes and burned fingers... or just simply that the 12b4a IS that much better!
Yup, many hours to be spent in the sweet spot, with a good glass of red! My girlfriend keeps telling me the smile on my face is from cheek to cheek when I settle infront of my rig. I guess she is right
My old pre was an ARC SP9 MKIII. Hmm, comparison wise.....
Well, the ARC's soundstage was not as clearly defined, the bass was a little muddier, and a little less extended in the highs... I think the 12b4a does just about everything better than the ARC, but it does not have a phono stage (future project?). The bass presence in the 12b4a is tighter and easier to follow. It is very tuneful, and subtle nuances of each note are present. At first it was a little sloppy, but with hours everything has come together in the lower end. The mids are clear, not overly warm, and the highs are crystal clear. When I listen to music I often find myself following just one of the musicians closely and listening to the remainder of the band in the background. Following the drummer is GREAT, as the high hat is so clear, but not overly bright. Cymbals actually sound like Cymbals.
The soundstage is what I like the most. Everything is placed with great accuracy. I can really differentiate everyone/everything in front of me spatially. Overall, the depth is good, but my room is not suited for great 3-dimensionality... Unlike what some others have stated about the 12b4a, my pre is not forward in presentation.
Dont get me wrong, the ARC was a lot of fun, and I still think about keeping it as a backup, but to me there is no comparison. This could be partially due to pride, biased non-objective view, the emotional need to justify work/expense/inhaled solder fumes and burned fingers... or just simply that the 12b4a IS that much better!
I need to build a simple line stage with low gain, and I´m impressed by the clean and simple design presented here.
Though, the gain is a bit higher than I need so I´m thinking about building something similar with this tube:
http://frank.pocnet.net/sheets/113/6/6S19P.pdf
Lower mu, lower Rp and better linearity as far as I can tell.
What do you guys think?
Though, the gain is a bit higher than I need so I´m thinking about building something similar with this tube:
http://frank.pocnet.net/sheets/113/6/6S19P.pdf
Lower mu, lower Rp and better linearity as far as I can tell.
What do you guys think?
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