From my experience Brett's 12B4, properly implemented, would absolutely spank the transcendent gg.
regards
regards
mach1 said:
well, I have the feeling that you'd like it even more with a MOSFET mu-folower plate load. The output Z is an order of magnitude less, and I'd suggest running 20 mA with a few red LED's instead of the bypassed cathode R.
The 12B4 is just one of 'those' tubes. I have not heard a GG but, I have heard a few 12B4 circuits, and they were all fantastic.
cheers,
Douglas
It might if one is using the Brett to feed a high input impedance amp... Of course it will sound good its a single stage, its really only just a part of whats in most line stages out there. But it can't drive a "low Impedance" anything... so its a useless line stage for alot of us and anyone bothering to build a line stage better be famuluar with what it takes to drive his/her power amp properly.
I've built and owned ALOT of line stages over the years both tube and solid state and the Grounded Grid is the one that comes out on the top of all of them and by a wide margin. As a comparison......
It will easily beat the socks off preamps costing multi thousands of dollars..... As testified to by myself and other DIY members on this site that have built them and then discarded those expensive units.
Even the factory sold kit is relatively inexpensive these days.....
Can easily drive low impedance inputs without sacrificing any sound quality........ Some of us have several amps we enjoy lisenting to from time to time......
Can be easily built DIY for under $100.00 in its "Stock" form......
Does not sound like a "tube" line stage, or a "silicon" one for that matter or like anything else that you've ever heard...... Dynamic range beyond belief!
Can also be built DIY using 12SN7, 6SN7 or other convenient tubes you might have laying around..... yes... even 12B4's.
Use what ever type of power supply "you think" it will sound best with.
Most of all have fun!
Mark
Mark A. Gulbrandsen said:
Well Mark, how does this GG achieve its low output Z? For that matter, what is its output Z? now that you bring up a challenge to a circuit that offers ~1kOhm direct from its plate as being inadequate.
Not picking on you for anything personal, mind you. Also, since I suspect you're going to point to a few additional stages, I must ask you, what do all these stages contribute towards an exceptional linestage circuit?
cheers,
Douglas
Choke-loaded parafeed using 5687, ECC99, etc., into cheap power torroids...with some feedback wrapped from plate to grid. Getting the bass right can be a real pain.
...floats my boat...subject to change in a skinny minute... YMMV... don't quote me on this... I'm not too religious about these things.
...floats my boat...subject to change in a skinny minute... YMMV... don't quote me on this... I'm not too religious about these things.
Douglas,
Of course the GG uses more stages but they are also implemented a very unique manner unlike any other LS in use out there today. You ask how do these other stages contribute....? I couldn't answer that as I've not listened to each stage isolated by iteslf, I've listened to it as a whole circuit. The GG has a 300 ohm output impedance and this low output impedance is NOT accomplished by using a cathode follower type output stage, in fact the GG is in effect somewhat of a backwards LS in that it uses a cathode follower as it's input stage. Another nice feature is that the GG stage itself is non inverting... you are modulating the cathode of the GG stage and taking off at the plate, that plate of the GG stage is fed by an active constant current source(another tube) instead of just a simple plate resistor.... hence the very low output impedance ability and its uniqueness.
I am somewhat familiar with the characteristocs of the 12B4 and although it is certainly capable of its 1K output impedance it isn't necessarily gouing to be quite as linear as the GG would be at those low impedances we sometimes use but it would be very linear at higher impedances say 10K and up.
Mark
Of course the GG uses more stages but they are also implemented a very unique manner unlike any other LS in use out there today. You ask how do these other stages contribute....? I couldn't answer that as I've not listened to each stage isolated by iteslf, I've listened to it as a whole circuit. The GG has a 300 ohm output impedance and this low output impedance is NOT accomplished by using a cathode follower type output stage, in fact the GG is in effect somewhat of a backwards LS in that it uses a cathode follower as it's input stage. Another nice feature is that the GG stage itself is non inverting... you are modulating the cathode of the GG stage and taking off at the plate, that plate of the GG stage is fed by an active constant current source(another tube) instead of just a simple plate resistor.... hence the very low output impedance ability and its uniqueness.
I am somewhat familiar with the characteristocs of the 12B4 and although it is certainly capable of its 1K output impedance it isn't necessarily gouing to be quite as linear as the GG would be at those low impedances we sometimes use but it would be very linear at higher impedances say 10K and up.
Mark
Mark,
If you require an output impdedance lower than 12B4's 1k the solution is simple. Use an IXCP10M45S as CCS and take the output from the top of the current set resistor a la mustage. Sounds great, super cheap, and you have an output impedance lower than a lot of CFs.
Still way cheaper than a transcendent gg and sonically in a different league. The transcendent has a niche market: it is easy to build, performs adequately, and is a nicely finished item a few step up cosmetically from the foreplay - but the last word in sonics ??
sorry
If you require an output impdedance lower than 12B4's 1k the solution is simple. Use an IXCP10M45S as CCS and take the output from the top of the current set resistor a la mustage. Sounds great, super cheap, and you have an output impedance lower than a lot of CFs.
Still way cheaper than a transcendent gg and sonically in a different league. The transcendent has a niche market: it is easy to build, performs adequately, and is a nicely finished item a few step up cosmetically from the foreplay - but the last word in sonics ??
sorry
That in fact is pretty close to what is done in the GG. The only differnece is he uses a 12AU7 stage as the CSS on top of the GG stage itself.
The last word in sonics..... now where did I hint it was that. There is no active stage period that can be the last word in sonics but one thing you need to consider is that the designer came up with it specifically to use with his own OTL's because he couldn't find a good enough L.S. He thought it a good match to use with his own OTL's which in that league may very well be the last word in sonics!!
Mark
Just jumpin in, a bit late but good info from my newb eye. I have been lurking and like the DIY idea as is represented by Franks design. One question, has anyone done a write up on a step by step, possibly with pics, for the new bloods to go along with the schematic? What would be a good 8w SE AMP to match this design, DIY mindset and quality match? There are sooooooo many designs out there, what I need is one that is proven and has builders notes to help me thru the process like parts placement and parts list. There was an AMP build notes thread I REALLY liked, but got kinda lost in the parts substitution and later upgrades:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=13399&highlight=
But I got kinda lost in the parts substitutions and later tweeks, not sure if anyone updated the original schematics and if there is a final parts list. Awesome build process and DIY view for a newb as myself. I may try to go thru and work out the final myself unless it has been done already.
I built a set of Olson's ME2 speakers I want to drive, soon to be upgraded to Ariel boxs.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=13399&highlight=
But I got kinda lost in the parts substitutions and later tweeks, not sure if anyone updated the original schematics and if there is a final parts list. Awesome build process and DIY view for a newb as myself. I may try to go thru and work out the final myself unless it has been done already.
I built a set of Olson's ME2 speakers I want to drive, soon to be upgraded to Ariel boxs.
This thread became more of GG vs 12B4.
Now after more than 5 years from the last post, which DIY tube preamp would you vote for?
Now after more than 5 years from the last post, which DIY tube preamp would you vote for?
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