Hi Tom, I'm playing around with that configuration on a couple of amps - a 6C45-KT100 (soon to be GU-50) and a 6C45-EL84. It's the all-purpose front end. 
You might find the attached graph interesting. It's zipped to get past the forum size limits without reducing resolution. It shows a spectral analysis of a 6C45 biased with two series green LEDs and an IXYS solid state current source for a plate load. The output is driving a 100 kohm resistor at about 95 volts peak-to-peak. The operating conditons are as specified in the PNG's name, 3.9 Vdc grid to cathode, 5.4 ma plate current. This places the plate at ~200 Vdc, nominally 50 over limit. I've had no issues, this tube is tough as nails and others have abused it much harder. Static plate dissipation is barely a watt, less than 20% rated. THD is about 0.2% as shown and nearly pure second harmonic. The junk above 10 kHz is a measurement artifact. The LEDs are unbypassed. Bypassing with a 1000 uF cap actually brough the 3rd harmonic up a few dB. The LEDs' internal resistance apparently generates a little negative feedback. It had almost no effect on the 2nd.
This will be as good a starting point as any at driving a 300 with a single stage of 6C45. Don't most 300's bias around 100 Vdc? Four volts bias on the cathode doesn't leave much headroom and the gain of ~40 will require significant drive voltage from the source.
You might find the attached graph interesting. It's zipped to get past the forum size limits without reducing resolution. It shows a spectral analysis of a 6C45 biased with two series green LEDs and an IXYS solid state current source for a plate load. The output is driving a 100 kohm resistor at about 95 volts peak-to-peak. The operating conditons are as specified in the PNG's name, 3.9 Vdc grid to cathode, 5.4 ma plate current. This places the plate at ~200 Vdc, nominally 50 over limit. I've had no issues, this tube is tough as nails and others have abused it much harder. Static plate dissipation is barely a watt, less than 20% rated. THD is about 0.2% as shown and nearly pure second harmonic. The junk above 10 kHz is a measurement artifact. The LEDs are unbypassed. Bypassing with a 1000 uF cap actually brough the 3rd harmonic up a few dB. The LEDs' internal resistance apparently generates a little negative feedback. It had almost no effect on the 2nd.
This will be as good a starting point as any at driving a 300 with a single stage of 6C45. Don't most 300's bias around 100 Vdc? Four volts bias on the cathode doesn't leave much headroom and the gain of ~40 will require significant drive voltage from the source.
Thanks for your good inputs!
I don't have a CCS on my 6C45pi, but I am using a beefy PSU with LCLCRC with BG and grid choke; running 12mA. I am not a tube specialist, but can I substitute my NiMH 2x1.2V battery with one LED with Vf about 2V for improved sonics? I don't think I will go for CCS now, perhaps later.
Cheers,
Tom
I don't have a CCS on my 6C45pi, but I am using a beefy PSU with LCLCRC with BG and grid choke; running 12mA. I am not a tube specialist, but can I substitute my NiMH 2x1.2V battery with one LED with Vf about 2V for improved sonics? I don't think I will go for CCS now, perhaps later.
Cheers,
Tom
Here, here!
My Tri-amp (300B/10Y/50) uses 417/5842 as the driver and I must say I'm a recent convert to the LED bias
I changed the cathode resistor to LED (Orange) that gives me 1.9V on the cathode. I should say the improvement is unbelievable for just two LED. Mine is unbypassed, by the way.
My 45 amp with the same driver was the first conversion.
My Tri-amp (300B/10Y/50) uses 417/5842 as the driver and I must say I'm a recent convert to the LED bias
I changed the cathode resistor to LED (Orange) that gives me 1.9V on the cathode. I should say the improvement is unbelievable for just two LED. Mine is unbypassed, by the way.
My 45 amp with the same driver was the first conversion.
gimme your overall xperience with 10Y..........arnoldc said:Here, here!
My Tri-amp (300B/10Y/50) uses 417/5842 as the driver and I must say I'm a recent convert to the LED bias
I changed the cathode resistor to LED (Orange) that gives me 1.9V on the cathode. I should say the improvement is unbelievable for just two LED. Mine is unbypassed, by the way.
My 45 amp with the same driver was the first conversion.
on your site that line is gray .......
choky!
re: 10Y-
I've heard a pair at a friend's house driving a vintage Altec and has glorious mids.
After that I searched for them tubes You might remember that I posted here sometime back (http://www.diyaudio.com/forums/showthread.php?s=&threadid=54696) about a pair that was broken, which the seller said is caused by the filament voltage I used.
Anyway, since I liked the 5842 as a driver and the grid voltage to drive is it similar to the 45 (in fact a bit lower) I thought it would work out just right.
I got it to sound to my liking in this prototype -
And I used it for months, until friends saw them and thought they're ugly. So I looked for a "nicer" chassis which I posted at the pictures section of diyAudio (bad pic actually)
In the end I was gifted a pair of 50, made sume adjustments and I posted the project here - http://www.diyaudio.com/forums/showthread.php?s=&threadid=54336
I guess that's the story and thank you for reminding me that I don't have anything about that project on my site
re: 10Y-
I've heard a pair at a friend's house driving a vintage Altec and has glorious mids.
After that I searched for them tubes
You might remember that I posted here sometime back (http://www.diyaudio.com/forums/showthread.php?s=&threadid=54696) about a pair that was broken, which the seller said is caused by the filament voltage I used.Anyway, since I liked the 5842 as a driver and the grid voltage to drive is it similar to the 45 (in fact a bit lower) I thought it would work out just right.
I got it to sound to my liking in this prototype -
And I used it for months, until friends saw them and thought they're ugly. So I looked for a "nicer" chassis which I posted at the pictures section of diyAudio (bad pic actually)
In the end I was gifted a pair of 50, made sume adjustments and I posted the project here - http://www.diyaudio.com/forums/showthread.php?s=&threadid=54336
I guess that's the story and thank you for reminding me that I don't have anything about that project on my site
Attachments
Here they are now in a "nicer" chassis-
It uses a 417A variant- the Amperex gold pin 5842 and now uses LEDs on the cathode.
My 45 uses plate choke on the drivers but in this chassis I don't have a place for another transformer so I will be putting in a pair of diyAudio's CCS boards in a coming experiment.
Why the 417A (and variants)?
1) Simple to implement (1 tube)
2) Have balls as a driver
It uses a 417A variant- the Amperex gold pin 5842 and now uses LEDs on the cathode.
My 45 uses plate choke on the drivers but in this chassis I don't have a place for another transformer so I will be putting in a pair of diyAudio's CCS boards in a coming experiment.
Why the 417A (and variants)?
1) Simple to implement (1 tube)
2) Have balls as a driver
Attachments
What brand and type do you recommend for the (orange) LED?
I guess there are types that are better suited than others. I looked at a few datasheets, but what else than Vf is interesting for the LED BIAS application?
BTW, I had WE417A for driver before, now I am using 6C45pi with better result IMO, tighter mid bass...
Best,
Tom
I guess there are types that are better suited than others. I looked at a few datasheets, but what else than Vf is interesting for the LED BIAS application?
BTW, I had WE417A for driver before, now I am using 6C45pi with better result IMO, tighter mid bass...
Best,
Tom
Hi Tom! Unfortunately, I have no idea. Junkbox unlabeled spares. Fortunately, it's not that critical. The important part seemed to be hitting around 3.9 Vdc cathode to grid. Three IR LEDs in series measured about the same. From what I could tell the main effect was moving the third harmonic around a few dB well down in the mud.
The important part seemed to be hitting around 3.9 Vdc cathode to grid. Three IR LEDs in series measured about the same. From what I could tell the main effect was moving the third harmonic around a few dB well down in the mud.hi,
this is my first thread in this 'WE417/437 with battery or RC on cathode'
I was a SE tube lover. I use 300B,2a3,45,50, PX4 & 25 already.
Previous year I still use 104db horn speaker so I only need few watts to push my speaker.
I try 417/5842, 6c45,6463, EC8010,437a,CV5112, 5687 & EC52 already.
I my opinion that if U lke to choose the best tube for RC, EC52 will be the best.
For Transformer couple 417a/437a/6c45 will e the best since this tubes had very low plate resistance. large magnification& large current( means the driving power will be better).
Also choose 6463,5965,5687 parallel two plate will be a good choice but the sound will less detail tha single plate.
I choose EC52 was the cathode voltage was 2.4~2.6V. choose two AAA battery incathode running will approx 2.4~2.6V. if not charge ( put into the cathode region) will 2.4V only.
pls try, choose NICd will better than the NIMH.
I don't know why, but test in this result.
thx
thomas
this is my first thread in this 'WE417/437 with battery or RC on cathode'
I was a SE tube lover. I use 300B,2a3,45,50, PX4 & 25 already.
Previous year I still use 104db horn speaker so I only need few watts to push my speaker.
I try 417/5842, 6c45,6463, EC8010,437a,CV5112, 5687 & EC52 already.
I my opinion that if U lke to choose the best tube for RC, EC52 will be the best.
For Transformer couple 417a/437a/6c45 will e the best since this tubes had very low plate resistance. large magnification& large current( means the driving power will be better).
Also choose 6463,5965,5687 parallel two plate will be a good choice but the sound will less detail tha single plate.
I choose EC52 was the cathode voltage was 2.4~2.6V. choose two AAA battery incathode running will approx 2.4~2.6V. if not charge ( put into the cathode region) will 2.4V only.
pls try, choose NICd will better than the NIMH.
I don't know why, but test in this result.
thx
thomas
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