Thanks, Arnold. So you have only a single 100uF BG (35V, I presume) in the CCS? I only ask because the original states 445uF + bypass, which is quite a bit more capacitance.
I thank you for the schematic, whether you call it crappy or not.
So, the - point on the left comes from the bridge and the one on the right connects to ground, n'est-ce pas?
I thank you for the schematic, whether you call it crappy or not.
So, the - point on the left comes from the bridge and the one on the right connects to ground, n'est-ce pas?
HI
I would like to ask for some help please .
I'm planing to build these 12B4 preamp after the ArnoldC schematic . Unfortunately I don't find ZTX758 & LM317 CCS parts for the power supply .
Please if someone know from were I can order these parts let me know , or if you have at home I will gladly buy them .
Thanks ArnoldC for the schematic !!
Regards
I would like to ask for some help please .
I'm planing to build these 12B4 preamp after the ArnoldC schematic . Unfortunately I don't find ZTX758 & LM317 CCS parts for the power supply .
Please if someone know from were I can order these parts let me know , or if you have at home I will gladly buy them .
Thanks ArnoldC for the schematic !!
Regards
Hi Adam, Brian Beck mentioned in a previous post that 100uF, 200uF or 220uF x 2 paralleled with quality film will do. So you can use whatever your fancy.
Yes the output from the bridge goes to the left side (+) (-) and the right side (+) (-) goes to the circuit. Make sure you have a heatsink on the MOSFET.
gaborbela, the ZTX and LM317 can be ordered from Farnell. Our local RS Components does not have the ZTX...
Yes the output from the bridge goes to the left side (+) (-) and the right side (+) (-) goes to the circuit. Make sure you have a heatsink on the MOSFET.
gaborbela, the ZTX and LM317 can be ordered from Farnell. Our local RS Components does not have the ZTX...
Just thought I'd mention that you people would have an impossible time convincing anyone that attends the Amp Shootouts that I have ay my house from time to time that the 12B4 line stage sounds thick or congested when run at 30 ma. In fact just the opposite... it sounds better. I have been through all the avenues you guys are now exploring! Its pretty clear that you are adjusting the coloration of the 12B4 to compensate for defficiencies elsewhere......
Mark
Nice one Mark. A while back I remember trying to convince you that a simple 12B4 with ccs would outclass your grounded grid linestage. After protestations to the contrary you actually built one - and now you are apparently the self appointed Grand Wazoo of twelvebeeforedom who has been down all the avenues others are now exploring.
Sorry mate, but coming from a guy who provides 'advice' stating that the 12B4 is not linear at 15ma (if you can read plate curves, just draw a horizontal line at 15mA to represent a ccs load and have a look at an operating point around 160 - 180V . If you can find a more linear transfer characteristic over a plus or minus 40-50V swing anywhere in tubedom please let me know) and that late manufacture JAN GE12B4 is the pinnacle of the species I might just pass on your latest gem.
FWIW I have collected and tried various vintage 12B4 tubes by RCA, GE, Mullard and Sylvania over a wide range of voltages and currents and therefore feel reasonably comfortable with my personal choice of tubes and operating point. I have also tried a variety of circuit / psu configurations and personally prefer a cascoded 10M45s or Gary Pimm plate CCS to the bypassed LM317 in the cathode arrangement you run.
You will recollect my reply to Arnold stated:
This comment was related to the tubes I run in MY linestage, and was intended to indicate to Arnold that (i) he wasn't the only one who had consciously made a decision to run his/her tubes at a fairly low current, and (ii) that perhaps we had similar sonic preferences. It was not intended to indicate that anyone who thought otherwise was a cloth eared miscreant.
Well, I hope your high testosterone, high current LM317 based linestage with the JAN tubes and depth charge output capacitors continues to provide state of the art performance for you and your shootout buddies. Meanwhile, I guess Arnold and I will have to adjust the coloration of our 12B4s to compensate for defficiencies (sic) elsewhere in our systems.
I genuinely hope you get round to trying a DHT linestage one day. Perhaps we might get a new thread - 'Yet another DHT line stage, or is the DHT better than the 12B4' ?
regards
pm
HI
Yes LM317 is common but what is the CCS letters there .
Another think I never used them so I tough better to ask than be sorry ...
Regards
Yes LM317 is common but what is the CCS letters there .
Another think I never used them so I tough better to ask than be sorry ...
Regards
Hi All
I have built a Headphone amp with the 12B4a Tube with Bat bios and it sounds good I now would like to have a go at this pre amp and would like to ask if some one can let me have the pre amp and PSU schematics pleas
Cheers
Colin
I have built a Headphone amp with the 12B4a Tube with Bat bios and it sounds good I now would like to have a go at this pre amp and would like to ask if some one can let me have the pre amp and PSU schematics pleas
Cheers
Colin
not being familiar with the circuit it may be a CCS (constant current source) built around an LM317 which is just a cheapass voltage comparator.
Mark A. Gulbrandsen said:
Oh Mark, I do not make projects to convince anyone. You're happy with your 30mA, and I don't need convincing for that.
All the avenues? Then good for you as well, but I don't have to take your word for it. I made a disclaimer in my post.
Mark, deficiencies? Wow! You must have a real perfect system huh. If you like your 30mA coloration, good for you, but please it doesn't mean we'll all like it. Let us have our own "coloration."
Mach-1... its all about sound, not specs. As I mentioned you would have to convince the multitude of others, including a pretty well known speaker designer that have been here and listened. Yes, My GG has been shelved for over a year now and yes I took the 12B4 though many variations of both operating current and quite a number of both plate and cathode options and found that Brians still sounds the best of the bunch.
As for the 12B4's I have tried a half dozen different manufacturers tubes of all of them except the JAN tubes(irregardless of manufacturer) were VERY microphonic. Careful selection might yield some usable pairs but the usable lifespan will more than likely be alot shorter too. I have both GE and Sylvania made JAN 12B4's and they sound more or less the same.
BTW: I should make mention that my 12B4 is operating off regulated bench supplies...both H-V and L-V and they further feed both a filament regulator and the 0D3 gas regulators right at the line stage.
Do I have a perfect system...Definately not. But I have owned my Dynaudios for a long time and know how they can and should sound. They are very good speakers at revealing very small changes made in equipment. Even for visitors its easy hear slight changes.
Mark
OK got the 12BA4 schematic But still looking for good PSU schematic
can anyone post one up
thanks
can anyone post one up
thanks
colin.hepburn2 said:
Modesty Blaze aka Zen Mod
http://www.diyaudio.com/forums/showthread.php?postid=910671#post910671
I agree with you entirely Mark. But don't you think it might just be possible that different people prefer different sounds, or find different sounds accurate because they get their musical 'cues' from different aspects of music reproduction ?
Just look at all the different types of speakers out there:
box dynamic (single driver / multiple driver), open baffle dynamic, Magneplanar panel, electrostatics, ESS, horns, plasma, and there must be some I left out.
They all sound quite different and excel at reproducing different aspects of the musical experience - but all have their adherents who wouldn't swap them for anything else.
Does that make all the alternatives 'defective' ?
regards
pm
For those building the 12B4 based linestage and other tube gear, you might want to consider joining the group buy for CCS boards.
http://www.diyaudio.com/wiki/index.php?page=CCS+PCBs
http://www.diyaudio.com/wiki/index.php?page=CCS+PCBs
For us non-brainy types, if I put a 300V tranny with bridge rectifer in front of Zen Mod's schematic in post 616, am I there? Or do I have to do further smoothing first?
jswen said:
it's ok ,but anyway you can increase that 100UF before 1K67........
check voltage-if it's above 400V,increase 1K67 ..........150E for each 10V above 400.......all that assuming that you'll use SS rectifier