Hi Ari,
Where DJN is sailing, I have to finish the chores on my house before, I know it seems forever away, the fall kicks in. I have not even finished my Harley I planned on riding this summer. I 'd better hurry before this turns into summer 2011. Bought great speakers though, I am dying to hear how they sound on Duplex, which I plan on building during the winter.
It should provide for some nice additional heating
Take care,
Rob, AKA "Midlife"
What model/year Harley are you working on?
I've got a 1975 XLCH setting in the garage that has been down since Jan 2009 for a busted third gear tooth that turned into a full rebuild with valve job/head porting, new rod set, pistons / rings, bearings, etc.
On the amp schematic it says 200V 220mA is the operating point for the output stage.
The power supply schematic shows 210V with a 500mA fuse. It seems like the intention is that 10V is dropped across the OPT + R17, leaving 200V from the output tubes plate to cathode. Since it is fixed bias transformer coupled stage, B+ remains constant, but the idle current can be adjusting by varying the grids voltage.
That fuse doesn't have a cap after it, so it is passing AC current as well as DC. It is most likely a fast acting type that he is using, so he has chosen 500mA fuse so it can handle the peaks without blowing. As a rough approximation, an SE amp will swing to 2x the idle DC current on one half of the cycle and then towards 0ma for the second half of the cycle (when driven to full power).
Neither. In Michigan, when you build a custom, the state give you a sticker to place on the neck of the bike. That is then the VIN.
Thanks for the reply Jeb, that makes sense. I've found an Edcor trans. thats good for 450mA, so one of those per channel should do the trick. I'm trying to figure out a realistic way to tube rectify the B+ for both stages but it's tough finding rectifiers with a high enough peak current. It's possible I could parallel 2 or 3 5AR4's, I think they'll handle about 250mA ea, so 3 to be on the safe side.
In the article it mentions the driver producing 55V at the 6C33C's grid, looking at a + or - 55v swing on the load line it looks like the current shouldnt rise above about 400mA if I'm looking at this correctly.
BTW, your amp looks fantastic! Are you still enjoying it?
Thx
In the article it mentions the driver producing 55V at the 6C33C's grid, looking at a + or - 55v swing on the load line it looks like the current shouldnt rise above about 400mA if I'm looking at this correctly.
BTW, your amp looks fantastic! Are you still enjoying it?
Thx
I recommend the 5C8S/5U8C rectifier. It looks like the 6c33c and has similar characteristics (low impedance high current). My memory is foggy, but I seem to recall that they are rated 300mA DC and have a repetitive peak current rating of 1A. To keep the repetitive peak current down, you want to use a small valued cap for the first filter cap (10-33uF). The second cap (after the choke or resistor) should be the large one.
If doing full wave rectification, the transformer will only require an AC current equal to the DC current draw (220mA for the borbley output stage). If doing bridge rectification, AC current rating will need to be approximately 1.4 - 2 x the DC current draw. That's because Full-wave has essentially 2 windings alternating the load. Bridge rectifier has 1 winding doing double duty. The VA is the same in either case though. So there is no free lunch, but it should be sized appropriately.
Yes, I still enjoy my amps. When paired with the right speakers, the sound quality would be very hard to top. Paired with the wrong speakers, things can go south quick (as with any SET). My only complaints are that they consume a lot of power and put off a lot of heat.
Last edited:
Click below URL's.
It uses 8 tubes of 6C33C in a mon-block !!
http://www.bezdz.com/images2/F-6C33C-H.JPG
http://www.bezdz.com/images3/F-6c33c-8--600.bmp
It uses 8 tubes of 6C33C in a mon-block !!
http://www.bezdz.com/images2/F-6C33C-H.JPG
http://www.bezdz.com/images3/F-6c33c-8--600.bmp
G. Cesar,
The O/P transformers I have came from Eastern Audio in Hong Kong. I found them on ebay, still waiting for them to arrive. They are 600 ohm on the primary and 8 on the secondary, supposed to be good for up to 350mA.
I am planning on building the Borbely circuit but I'm tube rectifying the B+ using a 5C8S for the 210VDC and a 5AR4 for the 380VDC. I'm building two monoblocks on (2) 10"x17" chassis so there will be two power transformers for each. Edcor XPWR005 and XPWR137. I'm still in search of a small transformer for the Bias supply (which will be solid state rectified) and I need to find a small 5v transformer for the 5C8S filaments.
Other changes, I'm considering replacing the paralleled WIMA interstage caps with larger poly caps. I'm not sure what the intent was in paralleling the WIMAs unless it was just to save space? or perhaps lower ESR? not sure.
Thats where I'm at so far.
The O/P transformers I have came from Eastern Audio in Hong Kong. I found them on ebay, still waiting for them to arrive. They are 600 ohm on the primary and 8 on the secondary, supposed to be good for up to 350mA.
I am planning on building the Borbely circuit but I'm tube rectifying the B+ using a 5C8S for the 210VDC and a 5AR4 for the 380VDC. I'm building two monoblocks on (2) 10"x17" chassis so there will be two power transformers for each. Edcor XPWR005 and XPWR137. I'm still in search of a small transformer for the Bias supply (which will be solid state rectified) and I need to find a small 5v transformer for the 5C8S filaments.
Other changes, I'm considering replacing the paralleled WIMA interstage caps with larger poly caps. I'm not sure what the intent was in paralleling the WIMAs unless it was just to save space? or perhaps lower ESR? not sure.
Thats where I'm at so far.
After much internal debate I think I've decided to take this project in the direction of the Simplex circuit by Ari Polisois. Still planning on tube rectifying everything but I can't escape the intrigue of the D.C.M.B. design. If I don't build it, I will never know right? Also on the plus side, this allows me to ditch the -70V bias supply , so that's one less transformer in an already overcomplicated power supply. Anyone else care to take this plunge with me?
Hi Gabriel,
There is an opportunity to listen to a Simplex end November, during the European Triode Festival, that will be held north of France, at Le Touquet, this year.
However, should you be interested ( maybe it's a remote possibility) and if ( like I think) you are not living too faar, you could attend, but it is compulsory to register, as a visitor and the fee is between 235 and 275 Euros.
The interest of this meeting is that there will be many lectures by wellknown audiophiles and a lot of ampolifiers of every kind, playing. The attendants come from every part of the world, including US, Japan, etc. See what you can do.
The link is found through Google ( ETF 2010 - European Triode Festival and/or Melaudia - from the name of the organizers' company).
Some diyaudio members that I know will be there and you could meet them personally.
The number of available places is now very limited, I believe.
The list of attendants is also available on the Melaudia's site.
Cheers,
Ari
There is an opportunity to listen to a Simplex end November, during the European Triode Festival, that will be held north of France, at Le Touquet, this year.
However, should you be interested ( maybe it's a remote possibility) and if ( like I think) you are not living too faar, you could attend, but it is compulsory to register, as a visitor and the fee is between 235 and 275 Euros.
The interest of this meeting is that there will be many lectures by wellknown audiophiles and a lot of ampolifiers of every kind, playing. The attendants come from every part of the world, including US, Japan, etc. See what you can do.
The link is found through Google ( ETF 2010 - European Triode Festival and/or Melaudia - from the name of the organizers' company).
Some diyaudio members that I know will be there and you could meet them personally.
The number of available places is now very limited, I believe.
The list of attendants is also available on the Melaudia's site.
Cheers,
Ari
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.