Interesting. Well, if you have something with a 6N1P in it, try using a 6CG7 as a direct replacement, and see what happens.
What is it about the 6H30 that you like the most?
Ray
I don't have any 6CG7's to try...but might pick some up off of ebay.
Mainly it is the level of detail. The 6H30's are the best at bringout out the finer details in the music. One thing though...the gain on the 6H30 is much lower than the others...so you need to keep that in mind.
hi, Well, i've heard good tings about the 6H30 tube.
As far as the 12AU7 goes, as far as I can read, there are better tubes out there that are much more open. The 12AU7 is supposed to be fast. It wouldn't take much to convert your present 12AU7 preamp to a 6CG7. I don't know what the optimum B+ voltage is for the 6CG7.
Anyway, do you happen to know what the output impedance of the circuit is?
Ray
As far as the 12AU7 goes, as far as I can read, there are better tubes out there that are much more open. The 12AU7 is supposed to be fast. It wouldn't take much to convert your present 12AU7 preamp to a 6CG7. I don't know what the optimum B+ voltage is for the 6CG7.
Anyway, do you happen to know what the output impedance of the circuit is?
Ray
Here are the specs from Frank:
Specifications Line preamp:
Powerconsumption: 40W.
Weight 2 Kgs. preamp and 3.5 kgs for the PSU.
Sensitivity (IHF 0.5V)
Line: 525mV into 100K.
THD Typically better than 0.05%.
Frequency Response: 10Hz - 200KHz. +/- 0.2dB.
Noise: better than -90dB.
Input overload: Infinite.
Maximum Output level: 45V
Output Impedance: 47 Ohm.
Stereo Separation: better than 100dB at 1KHz.
Hi,
Wow, sounds good. So do you have a link to the discussion on Frank's preamp? I think he calls it the ultimate preamp or something like that. There was a thread that I started to read about Frank's preamp, but I am not sure if that was the one.
So which did you build the one from Frank or Carlos?
Ray Bronk
Wow, sounds good. So do you have a link to the discussion on Frank's preamp? I think he calls it the ultimate preamp or something like that. There was a thread that I started to read about Frank's preamp, but I am not sure if that was the one.
So which did you build the one from Frank or Carlos?
Ray Bronk
http://www.diyaudio.com/forums/tubes-valves/12042-franks-ultimate-tube-preamp.html
If you go to the end of the thread...I have pictures of my build...
Look at posts 324 and 327
As far as the output impedance goes...I have no idea. Throughout the original thread he talks about the low output z... so I suspect it's correct.
Here is my build:
Attachments
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Hi, Ok, will look at that again. I asked because you had used a 12bh7/12AU7 tube in your version. Since 6CG7's tubes might be a bit cheaper to buy, I'll try that. Meanwhile, do you have a good schem for the 6H30 tube?
Ray Bronk
Ray Bronk
Not for a preamp. Only for the headphone amp. If you are into headphones I highly recommend it (the Bijou). I have a couple of extra boards for it (in case you are interested... at one point I was considering a balanced version).
The Bijou Headphone Amplifier
My version has regal's mod and is set up to roll tubes.
The Bijou Headphone Amplifier
My version has regal's mod and is set up to roll tubes.
Because the source impedance of a cathode follower is roughly 1/gm. What's the gm of the 6SN7 at that current?
Listening with headphones is currently awesome. But I've been working on improving my speaker setup. My current project is a high end version of the Tubelab SE using 300B's and all film caps. Followed by a mod to my JBL L150A's.
Hi,
Well, at this point, I am just looking for a good preamp to either buy or build. Frank's preamp is ok, certainly, but I don't need the phono part of things. So just the linestage will do nicely. I wonder if I could just use a single supply, or just one transformer. anyway, thanks for the info.
Ray Bronk
Well, at this point, I am just looking for a good preamp to either buy or build. Frank's preamp is ok, certainly, but I don't need the phono part of things. So just the linestage will do nicely. I wonder if I could just use a single supply, or just one transformer. anyway, thanks for the info.
Ray Bronk
I really don't know how much benefit there is from the dual xfmrs...but I think you would probably be fine with one. I swapped to the 6N1P's in my Bijou...it's been a while and I'm kind of curious as to the difference. I don't think it's fair to rate it until it breaks in for a while... but it was initially a noticable step down in quality. I kind of look at it as the "WOW" factor. Right now it's not quite there. I'll break it in with a little Rush...and see how it does...
I think if you stick with the linestage version (no phono) and go with the one transformer...you would be pleased. It appears to me that 12AU7 and 12BH7A are interchangable directly...but possibly could be tweeked by a resistor change?
I think if you stick with the linestage version (no phono) and go with the one transformer...you would be pleased. It appears to me that 12AU7 and 12BH7A are interchangable directly...but possibly could be tweeked by a resistor change?
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Hi, Well, I'll probably look in to building that line stage. The 12BH7 uses more current than the 12AU7 for the heater. Did you look at the other schematic by Carlos?
Ray
Ray
I'm not sure which one you speak of...post a copy of the schematic.
I just switched back to the 6H30's (maybe a bit prematurely). I love these tubes. Geddy Lee is sounding pretty awesome right now...(the "WOW" is definitely there...)
I just switched back to the 6H30's (maybe a bit prematurely). I love these tubes. Geddy Lee is sounding pretty awesome right now...(the "WOW" is definitely there...)
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Hi, if you read the whole thread, Carlos has this favorite schematic that uses a 12AU7 that he likes versus the 6SN7 or the 6CG7 tube.
Now, gotta ask you because I can't see your pics because I am blind. So in some respects building this preamp won't be as hard to do as it would if it were a PCB. Anyhow, what did you end up doing as far as the supply and transformer. There's just the 12BH7/12AU7 tube and that's it. I saw the parts list, and some of it didn't understand what the stuff was. I'll go back and look at the parts list again. What did you do concerning the volume control? If memmory serves me right, he is using an Attenuator of 1 Meg. Don't think I can get a volume pot that big.
So if I don't hear from you tomorrow, I hope your Easter day is a nice one.
Ray Bronk
Now, gotta ask you because I can't see your pics because I am blind. So in some respects building this preamp won't be as hard to do as it would if it were a PCB. Anyhow, what did you end up doing as far as the supply and transformer. There's just the 12BH7/12AU7 tube and that's it. I saw the parts list, and some of it didn't understand what the stuff was. I'll go back and look at the parts list again. What did you do concerning the volume control? If memmory serves me right, he is using an Attenuator of 1 Meg. Don't think I can get a volume pot that big.
So if I don't hear from you tomorrow, I hope your Easter day is a nice one.
Ray Bronk
I used left over 3/4 inch cherry hardwood flooring for the case. The top is two pieces of aluminum separated by a piece of cherry wood. I used several pieces of terminal strips with posts to do the p2p wiring. Transformers and big caps are mounted on top, except for the 14v filament transformers are mounted underneath. I tried to place the components such that the other parts would reach. The star ground is a sheet of copper that I mounted to a board located under the transformers. The pictures in the thread show the guts well. Maybe you could get someone to describe them to you. I am using a Goldpoint 500k attenuator. I thought it was a "make before break" type...but it must not be, because I have to mute the circuit to avoid the annoying pops when adjusting it.
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Hi Carlos,
Ok, reading your info you gave me, I am real new at this stuff, so bear with me. Your description of the power supply, that first cap 150 Uf probably at 400V? now are this configuration is that all in series off one leg of the diode bridge, having trouble visualizing the circuit.
We can take this offline and email me directly:
raybronk@gmail.com
Then you can give me more details about the circuit. Don't wish to hijax this thread. Thanks.
Ray Bronk
Ok, reading your info you gave me, I am real new at this stuff, so bear with me. Your description of the power supply, that first cap 150 Uf probably at 400V? now are this configuration is that all in series off one leg of the diode bridge, having trouble visualizing the circuit.
We can take this offline and email me directly:
raybronk@gmail.com
Then you can give me more details about the circuit. Don't wish to hijax this thread. Thanks.
Ray Bronk
