Hi all,
I am looking to borrow a Grounded Grid Preamp. If you have the kit built, and it's just sitting in your closet, i would like to borrow it for a week or so. I am looking at tube preamps with a low output impedance under 800 Ohms. The GGP fits the bill nicely.
You can either reply here, or email me directly:
raybronk@comcast.net
Thanks ahead of time for anyone who can help.
Ray Bronk
I am looking to borrow a Grounded Grid Preamp. If you have the kit built, and it's just sitting in your closet, i would like to borrow it for a week or so. I am looking at tube preamps with a low output impedance under 800 Ohms. The GGP fits the bill nicely.
You can either reply here, or email me directly:
raybronk@comcast.net
Thanks ahead of time for anyone who can help.
Ray Bronk
Hi ray,
I am interested in how you do with this endeavor. I am interested in a Tube Pre/linestage too but unsure of what would suit me best. Maybe the people that sell the kit at Transcendent Sound have a demo policy and will send you one to demo with a credit card number. Then return it and buy the kit if it suits you. Approach them about this!
I would like to build whatever I pick to keep it under $1K. I would like to add a remote volume attenuator and maybe an on/off switch to my choice. Not sure about an integrated Phono Stage and Headphone Amp but that would be a nice package.
I have also gotten suggestions for the Aikido that is here and a lot of support comes with that and a Bottlehead Foreplay III (with the upgrade option). Both would be reasonable but the Aikido would require sourcing the parts and chassis, etc. But the best sounding and most transparent (hopefully with a holographic soundstage), would be my choice. (Lots of inputs would be nice too.) Take a look at these and see if maybe they meet your specs too.
Good luck and I will be watching! Please let us know what happens! Thanks!
Regards//Keith
I am interested in how you do with this endeavor. I am interested in a Tube Pre/linestage too but unsure of what would suit me best. Maybe the people that sell the kit at Transcendent Sound have a demo policy and will send you one to demo with a credit card number. Then return it and buy the kit if it suits you. Approach them about this!
I would like to build whatever I pick to keep it under $1K. I would like to add a remote volume attenuator and maybe an on/off switch to my choice. Not sure about an integrated Phono Stage and Headphone Amp but that would be a nice package.
I have also gotten suggestions for the Aikido that is here and a lot of support comes with that and a Bottlehead Foreplay III (with the upgrade option). Both would be reasonable but the Aikido would require sourcing the parts and chassis, etc. But the best sounding and most transparent (hopefully with a holographic soundstage), would be my choice. (Lots of inputs would be nice too.) Take a look at these and see if maybe they meet your specs too.
Good luck and I will be watching! Please let us know what happens! Thanks!
Regards//Keith
Hi, Well, I don't think that Transcendentsound has that kind of policy. If I can't borrow one from someone, I'll just have to save up the pennies, nickels, and dimes, quarters too, and buy and have the kit put together for me. I am told it is one of these preamps that are extremely neutral. You either love it or hate it. There's a Minimax on the Gon for $600 and something. There are others to consider too. Anyway, that's what is up here. Thanks to all that can help.
Ray Bronk
Ray Bronk
Hi larry,
Well, that's real cool. Except the schem is for the 5842, not the 6678 or the later tube.
Another reason to look at the GGP with 12AU7, because it is already built. Being blind, can't read the schems. Can solder point to point so that would be ok. I would need that connect point A to Point B stuff.
Plus, don't know the cost of these two tubes either.
Ray Bronk
Well, that's real cool. Except the schem is for the 5842, not the 6678 or the later tube.
Another reason to look at the GGP with 12AU7, because it is already built. Being blind, can't read the schems. Can solder point to point so that would be ok. I would need that connect point A to Point B stuff.
Plus, don't know the cost of these two tubes either.
Ray Bronk
Ray, the GGP is not actually a grounded-grid stage. What it is, is a singly-driven diff-amp with the output taken off the noninverting (grounded-grid) side. I don't think, unless you build with a device that has insanely low rp, that you're going to get an 800Ω Zout; it is still just another plate-loaded amp.
A reason (not the only one) I like the SRPP is that it has gain like a plate-loaded stage, and Zout like a cathode follower. That said, I have searched for the optimum device and worked on operating points to get Zout as low as I can, and the circuit shown here (the 6T4 has rp about 1800Ω at this OP) has Zout just a little above 800Ω.
I think that this is maybe the lowest of any circuit not using, like, a 2A3 as the active, but I'm willing to hear arguments.
Aloha, Ray n' Ray,
Poinz
An externally hosted image should be here but it was not working when we last tested it.
A reason (not the only one) I like the SRPP is that it has gain like a plate-loaded stage, and Zout like a cathode follower. That said, I have searched for the optimum device and worked on operating points to get Zout as low as I can, and the circuit shown here (the 6T4 has rp about 1800Ω at this OP) has Zout just a little above 800Ω.
I think that this is maybe the lowest of any circuit not using, like, a 2A3 as the active, but I'm willing to hear arguments.
Aloha, Ray n' Ray,
Poinz
No. It's a good looking device, quite linear, and with a really outstanding plate resistance, about 1100Ω. It has a pretty low µ, though; about 6 at reasonable OPs, and so your in-circuit gain is going to be between 3 and 4, a little low for some predicaments. They're also a little rare, and thus expensive and also difficult to buy in quantities that allow good matching. I don't care what tube you like, they got to be tested and matched.
When I went and asked my good vendors about the three or four best candidates (the 12B4 was in there), two of them said, 'Yah, we be holding 6T4, talk to us.' It's just a little more linear over linestage-type swings, and I gots 170 of the cute little buggers (minus the dozen or so I've used) for $2.50 each.
You DIY guys don't have to worry about this sort of availability stuff, but I got guys to take care of. Unless I die and am no longer concerned with earthly music, the backup has to be there for them, so I admit that we diverge a bit on some of this stuff. Salas, I know you like the 12B4 a lot, and I think that you are correct in that; it's an awesome toob.
Ray B., If you need a text description of this circuit, or other guidance, don't hesitate. I am in awe of your dedication.
Aloha,
Poinz
When I went and asked my good vendors about the three or four best candidates (the 12B4 was in there), two of them said, 'Yah, we be holding 6T4, talk to us.' It's just a little more linear over linestage-type swings, and I gots 170 of the cute little buggers (minus the dozen or so I've used) for $2.50 each.
You DIY guys don't have to worry about this sort of availability stuff, but I got guys to take care of. Unless I die and am no longer concerned with earthly music, the backup has to be there for them, so I admit that we diverge a bit on some of this stuff. Salas, I know you like the 12B4 a lot, and I think that you are correct in that; it's an awesome toob.
Ray B., If you need a text description of this circuit, or other guidance, don't hesitate. I am in awe of your dedication.
Aloha,
Poinz
KP, I'm not sure what you're referring to; if you would provide a link to the thread, perhaps I can pontificate more magnificently.
:^)
This linestage began as grumpy ol' Bruce Rosenblit's article in a 1989 Glass Audio. It was actually my first scratch build, and I did almost every mod to it I could think of. The main one that stuck was the removal of the bypass capacitor on the 'lower' cathode resistor, and some small operating point and bandwidthe tweaks. It's a long and boring (unless you're me) story to here, the Mœbius 4.
Fortunately, my audio gooroo Tadaki is laid up with a fresh bionic knee, and subject to my blandishment of various probable (and maybe not so much) circuits to audition. The next (using 6SN7, per the original Terry Cain Mœbius) goes in his rig tomorrow.
Stay tuned.
Poinz
:^)
This linestage began as grumpy ol' Bruce Rosenblit's article in a 1989 Glass Audio. It was actually my first scratch build, and I did almost every mod to it I could think of. The main one that stuck was the removal of the bypass capacitor on the 'lower' cathode resistor, and some small operating point and bandwidthe tweaks. It's a long and boring (unless you're me) story to here, the Mœbius 4.
Fortunately, my audio gooroo Tadaki is laid up with a fresh bionic knee, and subject to my blandishment of various probable (and maybe not so much) circuits to audition. The next (using 6SN7, per the original Terry Cain Mœbius) goes in his rig tomorrow.
Stay tuned.
Poinz
http://www.diyaudio.com/forums/showthread.php?threadid=115115
The first post you made there looks like the one posted here. It seemed like you and others were evolving the design and some were building it! Thanks!
Just looking for the best to marry to my Michi amp!
Regards//Keith
The first post you made there looks like the one posted here. It seemed like you and others were evolving the design and some were building it! Thanks!
Just looking for the best to marry to my Michi amp!
Regards//Keith
jduffy said:I built Rozenblit's 12AU7 line stage from Glass Audio. I guess it the precursor to the GG. I love the thing. Cost about $90 to build and is so clean sounding it's nuts. I love the simple things in life!
Good luck with your GG search.
I'd like to give that line stage a try. What issue of Glass Audio was it from? I can seem to find a couple of references googling, but nothing specific.
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