well, after a few PP amps built with a big negative rail, I tried the CCS and small negative supply. Big improvement in the performance across the board.
Also, by what frequency to you plan to achieve your 300R output Z?
You guys can also adjust gain by adding a plate load to the input section.
I'd also suggest a voltage ref to allow a larger bias resistor on the plate load section. The bigger the effective plate load, the better things like that have worked. A cascode is even better, and a triode/pentode the best of them I've tried so far. A triode MOSFET has been the best, but since it's not a tube...
cheers,
Douglas
Also, by what frequency to you plan to achieve your 300R output Z?
You guys can also adjust gain by adding a plate load to the input section.
I'd also suggest a voltage ref to allow a larger bias resistor on the plate load section. The bigger the effective plate load, the better things like that have worked. A cascode is even better, and a triode/pentode the best of them I've tried so far. A triode MOSFET has been the best, but since it's not a tube...
cheers,
Douglas
Member
Joined 2002
Hi guys, I am following the thread since it started and I am very intrested in building a GG and also in the PCB, but I have some problem in finding the correct components and values ratings. I don't know but if, because of copyrigts, the schematics and part list cannot be posted in the forum, someone could send a file to my private e-mail?
Thank you very much
Nat
Thank you very much
Nat
Preamp Shootout
Stay tuned guys.
Mark has been burning the midnight oil, and he will be posting some interesting results either tonight or more likely tomorrow. I am "taking the trip to Bountiful" this afternoon to join him, and to lend my ears.
I am stoked for this!
Lyndon
Salt Lake City😀
Stay tuned guys.
Mark has been burning the midnight oil, and he will be posting some interesting results either tonight or more likely tomorrow. I am "taking the trip to Bountiful" this afternoon to join him, and to lend my ears.
I am stoked for this!
Lyndon
Salt Lake City😀
Member
Joined 2002
Re: Preamp Shootout
Please give detailed details about the switching noise if there is any 😀 id like to buy one of these volume kit's now. Me totaly intrested.
J'
LuckyLyndy said:
Please give detailed details about the switching noise if there is any 😀 id like to buy one of these volume kit's now. Me totaly intrested.
J'
Well, I wanted Mark to post first, but he may be working on other projects this morning.
Mark is convinced that the 12B4 linestage smokes the Grid. We couldn't do a good A/B test, as Mark only had one attenuator, which he had removed from his Grid, and so that was that.
The 12B4 sounded clean and precise, very little microphonics (I guess someone on another thread had complained about that...).
I listened for about two hours, and varied my music from small jazz combos, large orchestra, vocals, and again, found it uncolored and precise. Considering how simple it is to build, one really doesn't need any kind of PCB for this linestage. Because it is so simple, I am going to build one next week. But I am not throwing my Grid to the gutter. I really liked that remote control Grid that "Ultrachrome" built from LiteAudio on another thread!
I want to give an extended listening time to the 12B4 linestage in my system. I think in another thread, people complained of its presentation as being to analytical, too "etched" in the high end. I would concur that the high hat, the snare, the cymbals were amazing! As I am using an Aleph 3 and soon, a Krell Klone amp, I may want to have some warmth somewhere in my system. Mark will give you the hard facts, as he had the scopes hooked up, etc. He is pretty happy, and says it is the most neutral presentation he has ever heard. Also, Mark will tell you which configuration he built his from...it looked like he made an amalgamation of three different schematics. Still, it was simplicity personified, with 5 parts between the tube and the power supply.
Lyndon
Mark is convinced that the 12B4 linestage smokes the Grid. We couldn't do a good A/B test, as Mark only had one attenuator, which he had removed from his Grid, and so that was that.
The 12B4 sounded clean and precise, very little microphonics (I guess someone on another thread had complained about that...).
I listened for about two hours, and varied my music from small jazz combos, large orchestra, vocals, and again, found it uncolored and precise. Considering how simple it is to build, one really doesn't need any kind of PCB for this linestage. Because it is so simple, I am going to build one next week. But I am not throwing my Grid to the gutter. I really liked that remote control Grid that "Ultrachrome" built from LiteAudio on another thread!
I want to give an extended listening time to the 12B4 linestage in my system. I think in another thread, people complained of its presentation as being to analytical, too "etched" in the high end. I would concur that the high hat, the snare, the cymbals were amazing! As I am using an Aleph 3 and soon, a Krell Klone amp, I may want to have some warmth somewhere in my system. Mark will give you the hard facts, as he had the scopes hooked up, etc. He is pretty happy, and says it is the most neutral presentation he has ever heard. Also, Mark will tell you which configuration he built his from...it looked like he made an amalgamation of three different schematics. Still, it was simplicity personified, with 5 parts between the tube and the power supply.
Lyndon
Thanks for the info Lyndon.
Not realy good news because I don't have any 12B4's
I just wait until Mark releases his comments.
Regards
Not realy good news because I don't have any 12B4's
I just wait until Mark releases his comments.
Regards
I certainly don't see any point at all in persuing it any longer myself. It has its merits but no where near the merits the 12B4 has. On a 1 to 10 I would rate the GG as a 4.8 and the 12B4 as a 7.8, so the 12B4 makes alot more sense.
You have to decide for yourself if you ALSO want whats in the music or or if you JUST want the music? The 12B4 is the only line stage I've used that lets you hear whats in the music...... Its quite amazing.
Mark
You have to decide for yourself if you ALSO want whats in the music or or if you JUST want the music? The 12B4 is the only line stage I've used that lets you hear whats in the music...... Its quite amazing.
Mark
Hey-Hey!!!,
While the 12B4 has worked well for me, there are lots that have failed with it. Claims of extreme noise issues, microphony abound. I wonder what the deal is?
I have even had good luck with pulls from hard working 'scope power supplies serve well.
Any thoughts on this?
cheers,
Douglas
While the 12B4 has worked well for me, there are lots that have failed with it. Claims of extreme noise issues, microphony abound. I wonder what the deal is?
I have even had good luck with pulls from hard working 'scope power supplies serve well.
Any thoughts on this?
cheers,
Douglas
Good points, Doug. My feeling after owning the Grid, and listening for some extended time on the 12B4, is the Grid is more forgiving on poor recordings, and earlier compact disc issues. The same comment is made on tube ampflifers and preamps. Also you are right that people have had problems ironing out the 12B4 design. For sheer clarity I would give it to the 12B4, but I am keeping my Grid for the bedroom system.
Lyndon
Salt Lake City
P.S. Paulie in Rhode Island, if you are reading this thread, you have the lushest sounding tube system I have ever heard! I would not change out your super modified Grid!
😀
Well there are alot of different sounding line stages out there..... there's lush sound, there's just sound, there's dry sound, there's that liquid midrange sound, and then theres being able to hear whats IN the music sound..... and I must admit that I much prefer the latter.... with the 12B4 its much more like being at a live performance and after all isn't that what we're all after.....? I would certainly urge Paulie to build one and judge for himself......
Mark
LuckyLyndy said:
Lyndy,
It was not the character of the 12B4's sonics...that is more of a perceptual issue. I know I like the sound, but when I have had some that were not useful.
More if a general success issue. If the tube can behave itself in-circuit. No noise, no microphony...that sort of thing. Some folks have had lots of this. This is the effect I was speaking of.
cheers,
Douglas
A note of caution with the 12B4
According to Morgan Jones, in his book “Valve Amplifiers”, the 12B4 is especially prone to poor heater-cathode insulation, resulting in leakage currents from heater to cathode. He says that if the insulation is also contaminated, the resultant leakage current will be noisy in a 1/f (flicker) manner. I have not seen this problem in my experiments with 12B4s, but I don’t doubt it. This effect may explain some of the comments above about varying experiences with this tube.
There are at least three things that you can do to mitigate this potential problem: select for good 12B4s (they’re pretty cheap), run DC on the heater, and make sure that the heater-cathode DC voltage is small by elevating the DC heater supply if need be.
According to Morgan Jones, in his book “Valve Amplifiers”, the 12B4 is especially prone to poor heater-cathode insulation, resulting in leakage currents from heater to cathode. He says that if the insulation is also contaminated, the resultant leakage current will be noisy in a 1/f (flicker) manner. I have not seen this problem in my experiments with 12B4s, but I don’t doubt it. This effect may explain some of the comments above about varying experiences with this tube.
There are at least three things that you can do to mitigate this potential problem: select for good 12B4s (they’re pretty cheap), run DC on the heater, and make sure that the heater-cathode DC voltage is small by elevating the DC heater supply if need be.
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