Hi navin,
The position of the amps is dictated by how much space you have (you said not enough) and the closest power outlet(s). The shortest distance between the pre and power is the best solution IMHO. Given that that doesn't work for your layout I think you are stuck with high quality balancing transformers. At least they aren't noisy. Pay attention to loading so you don't have frequency response problems.
-Chris
The position of the amps is dictated by how much space you have (you said not enough) and the closest power outlet(s). The shortest distance between the pre and power is the best solution IMHO. Given that that doesn't work for your layout I think you are stuck with high quality balancing transformers. At least they aren't noisy. Pay attention to loading so you don't have frequency response problems.
-Chris
Hi,
You could consider a White cathode follower using a stack of 12BH7As or ECC99s.
Zout is around the 40 Ohm mark and it can deliver enough juice to drive a 10 m cable with aplomb.
It does like a stiff, well filtered, preferably regulated PS as PSRR of this topology is pretty much non-existant.
Cheers,
You could consider a White cathode follower using a stack of 12BH7As or ECC99s.
Zout is around the 40 Ohm mark and it can deliver enough juice to drive a 10 m cable with aplomb.
It does like a stiff, well filtered, preferably regulated PS as PSRR of this topology is pretty much non-existant.
Cheers,
fdegrove said:
Frank,
I have been looking for a schematic to your 12B4 line stage but could not find it.
anyway thanks for your suggestion. which tube would you prefer the 12BH7 or ECC99? How long a cable can they safely drive? 5m? 10m?. Where would I find a schematic for this line stage?
My intention is to use a input selector and volume pot before Steve bench's ECC88 based crossover. then use this line drive to drive the signal to 2 power amps. I woul dneed 4 tubes. 2 per channel (one for Low pass and one for High Pass).
Hi,
The part I'm talking about is the last stage of this preamp:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=12042&highlight=
The ECC99 is pretty similar but I only did a paperbuild with that tube so no real life experience.
The WCF is capable of driving long cable lengths beyond your requirement without losses other than pure resistive ones but I'd still keep resistance and capacitance as low as possible to be on the safe side of caution.
Especially if you suffer from high EMI in your listening environment it may be wise to use shielded cable which of course will up capacitance/m considerably.
It worked fine for me and anyone else that tried it so far with bandwidth still well beyond audio requirements, + 300KHz was no problem over 15m with 100K Zin and 23pF/m.
Cheers,
The part I'm talking about is the last stage of this preamp:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=12042&highlight=
The ECC99 is pretty similar but I only did a paperbuild with that tube so no real life experience.
The WCF is capable of driving long cable lengths beyond your requirement without losses other than pure resistive ones but I'd still keep resistance and capacitance as low as possible to be on the safe side of caution.
Especially if you suffer from high EMI in your listening environment it may be wise to use shielded cable which of course will up capacitance/m considerably.
It worked fine for me and anyone else that tried it so far with bandwidth still well beyond audio requirements, + 300KHz was no problem over 15m with 100K Zin and 23pF/m.
Cheers,
just remembered that the thread of the EL34 power amp is located here
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69042&highlight=EL34+schematic
http://www.diyaudio.com/forums/showthread.php?s=&threadid=69042&highlight=EL34+schematic
fdegrove said:Hi,
The part I'm talking about is the last stage of this preamp:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=12042&highlight=
The ECC99 is pretty similar but I only did a paperbuild with that tube so no real life experience.
The WCF is capable of driving long cable lengths beyond your requirement without losses other than pure resistive ones but I'd still keep resistance and capacitance as low as possible to be on the safe side of caution.
Especially if you suffer from high EMI in your listening environment it may be wise to use shielded cable which of course will up capacitance/m considerably.
It worked fine for me and anyone else that tried it so far with bandwidth still well beyond audio requirements, + 300KHz was no problem over 15m with 100K Zin and 23pF/m.
Cheers,
Frank, is this the schematic for the preamp?
http://www.diyaudio.com/forums/attachment.php?s=&postid=165345&stamp=1051125046
I have to slip this ckt after Steve's crossover
http://members.aol.com/sbench101/Crossover/xover.gif
is there anything to be concerned about?
fdegrove said:
That's the one.
There have some minor modifications for using it as a standalone line preamp in a separate thread but nothing major.
The B+ used a dedicated valve regulated supply per channel which should be in the same thread....Somewhere.
Cheers,
That thread is 30 pages long! and i am on dial up in India. being in India means I am in left field. there are few DIYers here and evne fewer that work on tube amps. None in Bombay (Mumbai).
This forum is my sole source of knowledge.
BTW is pin 2 connected to pin 7 in that schematic.
I am thinking of using a SS power supply. BTW I hope these posts are not too much of a bother to you.
found this...it says MM phono so i doubt it is the line drive
http://www.diyaudio.com/forums/attachment.php?s=&postid=169960&stamp=1051880359
btw I found the 12B4 ckt!
http://www.diyaudio.com/forums/attachment.php?s=&postid=365768&stamp=1081255813
and one that uses 2 12BH7
http://www.diyaudio.com/forums/attachment.php?s=&postid=397265&stamp=1085011046
and one that uses 6SN7
http://www.diyaudio.com/forums/attachment.php?s=&postid=454821&stamp=1092149935
http://www.diyaudio.com/forums/attachment.php?s=&postid=169960&stamp=1051880359
btw I found the 12B4 ckt!
http://www.diyaudio.com/forums/attachment.php?s=&postid=365768&stamp=1081255813
and one that uses 2 12BH7
http://www.diyaudio.com/forums/attachment.php?s=&postid=397265&stamp=1085011046
and one that uses 6SN7
http://www.diyaudio.com/forums/attachment.php?s=&postid=454821&stamp=1092149935
Hi,
Don't worry about the PS then, about 300VDC well filtered should do the trick.
NO.....
Input is on the top grid, pin #2, feedback is taken to the lower grid from the plate of the top triode (pin#1 to pin# 7) via a 100nF cap.
Cathode Rs are both 680R/1W, output is taken from the node between plate of the lower triode and cathode of the top one.
Plate stopper of the top triode is 1K/2W but can be made lower, not really important unless you suffer from EMI radiation or a flaky tube.
Rg and Rg' are both 1M 1/8W or higher.
The 1M pot is only there because previous stage (RIAA) needs to see a 1M input so that can be changed if you're not using that part.
The input cap is there to protect the wiper of the pot. If you're not using one, you can discard it but make sure thre's no DC coming from the output of whatever you want to hook up to it.
Finally, this stage is a buffer so take a mild loss of gain (0.97-98) into the equation.
Calculated Zout is roughly 47R into a 100K load, bandwidth is about 400kHz IIRC.
The circuit is the one you first posted.
As said it was orphaned from a phono preamp.
That should about cover it.
Don't worry about the PS then, about 300VDC well filtered should do the trick.
NO.....
Input is on the top grid, pin #2, feedback is taken to the lower grid from the plate of the top triode (pin#1 to pin# 7) via a 100nF cap.
Cathode Rs are both 680R/1W, output is taken from the node between plate of the lower triode and cathode of the top one.
Plate stopper of the top triode is 1K/2W but can be made lower, not really important unless you suffer from EMI radiation or a flaky tube.
Rg and Rg' are both 1M 1/8W or higher.
The 1M pot is only there because previous stage (RIAA) needs to see a 1M input so that can be changed if you're not using that part.
The input cap is there to protect the wiper of the pot. If you're not using one, you can discard it but make sure thre's no DC coming from the output of whatever you want to hook up to it.
Finally, this stage is a buffer so take a mild loss of gain (0.97-98) into the equation.
Calculated Zout is roughly 47R into a 100K load, bandwidth is about 400kHz IIRC.
The circuit is the one you first posted.
As said it was orphaned from a phono preamp.
That should about cover it.
fdegrove said:The circuit is the one you first posted.
As said it was orphaned from a phono preamp.
That should about cover it.
that ckt says the tube is a 7025. same as 12BH7? I thought it was similar to the ECC83. can i replace it with the ECC99? The 12BH7 is rather impossible to come by in India.
Hi,
Hell no!
Like I said : The first one you posted.
http://www.diyaudio.com/forums/attachment.php?s=&postid=165345&stamp=1051125046
The other one you dug up with the 2 12BH7As can be used as well as the last section is nearly identical but uses a SRPP of a 12BH7A in front of it to provide some gain. But you don't need that first section I suppose.
Cheers,
Hell no!
Like I said : The first one you posted.
http://www.diyaudio.com/forums/attachment.php?s=&postid=165345&stamp=1051125046
The other one you dug up with the 2 12BH7As can be used as well as the last section is nearly identical but uses a SRPP of a 12BH7A in front of it to provide some gain. But you don't need that first section I suppose.
Cheers,
fdegrove said:
http://www.diyaudio.com/forums/attachment.php?s=&postid=165345&stamp=1051125046
The other one you dug up with the 2 12BH7As can be used as well as the last section is nearly identical but uses a SRPP of a 12BH7A in front of it to provide some gain. But you don't need that first section I suppose.
Cheers,
thanks Frank,
I cannot find a 7025 in India either. So I'd have to stick to the ECC99. so what i should really use is a ckt that resembles the latter half of the 12BH7 ckt mentioned but using a ECC99 instead.
fdegrove said:
I think I must have done the calculus for the ECC99 at some point in time and arrived at the same values.
So that's good news.....
Now this is good news! where do I chop the ckt. Do connect the output of Steve'c ECC88 based crossover to pin 2 of the second 12BH7 (in my case a ECC99)? What do I connect to Pin 1 (2 x 10uf caps, the 10K resistor, 100K resistor and the 1N4007 diode?
I have included links of both ckts for your ready reference below.
http://members.aol.com/sbench101/Crossover/xover.gif
http://www.diyaudio.com/forums/attachment.php?s=&postid=397265&stamp=1085011046
Hi,
Pin #2 is your input so, yes.
Pin #1 is your anode so that takes the PS.
Only conect the 1K resistor to pin #1.
The rest is just local PS decoupling (the two MKP caps) and a bleeder resistor (the 100K) and a voltage dropping resistor (10K) which you probably won't need provided your PS voltage is about 300VDC.
Keep in mind that you'll need a buffer per x-over output/amp input so it may all add up to a substantial investment.
Cheers,
Pin #2 is your input so, yes.
Pin #1 is your anode so that takes the PS.
Only conect the 1K resistor to pin #1.
The rest is just local PS decoupling (the two MKP caps) and a bleeder resistor (the 100K) and a voltage dropping resistor (10K) which you probably won't need provided your PS voltage is about 300VDC.
Keep in mind that you'll need a buffer per x-over output/amp input so it may all add up to a substantial investment.
Cheers,
fdegrove said:
Pin #2 is your input so, yes.
Pin #1 is your anode so that takes the PS.
Only conect the 1K resistor to pin #1.
Keep in mind that you'll need a buffer per x-over output/amp input so it may all add up to a substantial investment.
Cheers,
I know I would need 4 tubes. The bad nes is that the ECC99 are not available either (in India). I have 2 choices.
1. look for an alternate tube. any opinions/suggestions on this?
2. import 12BH7 or ECC99 from Singapore.
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