I have emailed Plitron and the next day I got an email back from Menno van der Veen. He included the 6c33c datasheet and asked if this was what I needed to get started. Of course this datasheet did not help me very much, so I refrased the question to him.
But now, looking at the white paper of the BAT VK-60.
link
I don't know for sure, but I think BAT uses these toroids (probably slightly modified). The white paper says the VK-60 is a Single-Ended Bridge Design. Is this some sort of transformer coupled circlotron?
Could this be the way the toroids are intended?
But now, looking at the white paper of the BAT VK-60.
link
I don't know for sure, but I think BAT uses these toroids (probably slightly modified). The white paper says the VK-60 is a Single-Ended Bridge Design. Is this some sort of transformer coupled circlotron?
Could this be the way the toroids are intended?
I have got a response from Victor Khomenko, one of the big guys from Balanced Audio Technology. First of all he said 150R is too low and 600R is too high. They use a somewhat similar OPT in the vk-55 amplifier, but specified 300R. The 150R suggested indeed a setup of four tubes. And also he suggested mismatching the OPT's. There is even a 2 Ohm section, so connecting wouldn't be a problem even with 4 Ohm speakers.
The setup I'm going to start with will probably be 180V and 150mA with fixed bias.
The setup I'm going to start with will probably be 180V and 150mA with fixed bias.
Hi Dr Strangelove
I read and saw lots of menno's work and, well, I am quite sure he did not ever made a circlotron amp. Also, sending you the datasheet of the 6C33C when you asked how the trafo was intended to be used...all very strange...
About the load on the 6C33C...at sowter's site I saw OPT's for 6C33C with a specified primary of 600R and 1200R. So, I already thought 600R was on the low side. But now 300R, and even 150R... Don't know, maybe because it is a tube that has just started to get popular in PP amps - in about 20 years there will be a standard
Ya, actually I did not add anything. I am curious how this project turns out! Someday I will try it to...6C33C's are cheap, power supply is easy and relatively cheap, standard toroidals would make goor OPT's. Just, how to drive it? (I still think morgan jones has a good solution for this)
Erik
I read and saw lots of menno's work and, well, I am quite sure he did not ever made a circlotron amp. Also, sending you the datasheet of the 6C33C when you asked how the trafo was intended to be used...all very strange...
About the load on the 6C33C...at sowter's site I saw OPT's for 6C33C with a specified primary of 600R and 1200R. So, I already thought 600R was on the low side. But now 300R, and even 150R... Don't know, maybe because it is a tube that has just started to get popular in PP amps - in about 20 years there will be a standard
Ya, actually I did not add anything. I am curious how this project turns out! Someday I will try it to...6C33C's are cheap, power supply is easy and relatively cheap, standard toroidals would make goor OPT's. Just, how to drive it? (I still think morgan jones has a good solution for this)
Erik
Hi Erik,
I agree. These are strange OPT's As I understand the 150R would imply 4 tubes while the power rating is 80W while with only two tubes this 80W is already possible... I'm stil a little curious why the 150R was chosen.
Also what I think is a bit strange is that my OPT's are slightly different from the datasheet. The datasheet shows one primary winding whith a center tap on the primary while mine have two primary windings.
When I've got something up and running I'll surely post some pics and comments. I'll probably start with something ultra simple like the input/driver stage from the monobill from Triodedick. I don't know if that would do it for this amp, so I have to do some further investigations in that.
I agree. These are strange OPT's As I understand the 150R would imply 4 tubes while the power rating is 80W while with only two tubes this 80W is already possible... I'm stil a little curious why the 150R was chosen.
Also what I think is a bit strange is that my OPT's are slightly different from the datasheet. The datasheet shows one primary winding whith a center tap on the primary while mine have two primary windings.
When I've got something up and running I'll surely post some pics and comments. I'll probably start with something ultra simple like the input/driver stage from the monobill from Triodedick. I don't know if that would do it for this amp, so I have to do some further investigations in that.
This is another thing I have to find out... a pair of 6C33C have a max.dissipation of 120W...how do you take 80W rms of music power out of this? it's a rendement of 67% (excluding heaters) I see 6AS7 PP based amplifiers, which delivered at moste 7W with a total of 25W plate dissipation. Maybe because tubes are being drived into AB2 class... have some homework
And about the trafo...you said it has a 2 ohms tap, but this is also not mentioned on the datasheet. Maybe you have an earlier version?
I think the input/driver stage from the monobill has too low a gain. The stereo bill would probably be better, at least it has more gain.
Erik
ErikdeBest said:
The pictures in balanced.com show the more powerfull VK-75 having some more tubes compared to the VK-55. Probably these tubes are needed to drive them into AB2.
Abouth the 2 Ohm tap, mistake from my side. I meand the tap between 4 and 6 or 6 and 8.
I'll probably try the stereo bill if gain is too low.
thoughts
if you have dual primaries, you probably have more options. Could wire in series or parallel probably - would change the impedance the tranny and tube wants to see.
what's the inductance? that's what really matters, not some (useless) arbitrary number like 150R. The things that matter are turns ratio, inductance, and power handling, when talking about trannies. Don't obsess about the 150R number. Just try it and see what happens. you already own them so you have nothing to lose.
the BAT VK-55 is basically a cheaper, dumbed-down, smaller version of the Vk-60. The vk75 is almost identical to a vk60, with the exception of the CCS-loaded driver stage using 6H30. So from the 6C33's point of view all 3 amps are very similiar, esp. vk60 and vk75.
Single-ended bridge mode is a fairly unique method of operation. BAT is kinda coy on how it works, I think. it's not PP, more akin to parallel SE I'd think.
BAT uses Plitron OPTs and power trannies, but likely not these exact same ones, (or if they do Plitron and BAT won't confirm it, I am sure), probably something similar but spec'ed slightly differently I'd guess.
Paralleling 4 tubes per channel is more than you want to consider biting off for a first-amp project, IMNSHO.
Good luck
-Ed
if you have dual primaries, you probably have more options. Could wire in series or parallel probably - would change the impedance the tranny and tube wants to see.
what's the inductance? that's what really matters, not some (useless) arbitrary number like 150R. The things that matter are turns ratio, inductance, and power handling, when talking about trannies. Don't obsess about the 150R number. Just try it and see what happens. you already own them so you have nothing to lose.
the BAT VK-55 is basically a cheaper, dumbed-down, smaller version of the Vk-60. The vk75 is almost identical to a vk60, with the exception of the CCS-loaded driver stage using 6H30. So from the 6C33's point of view all 3 amps are very similiar, esp. vk60 and vk75.
Single-ended bridge mode is a fairly unique method of operation. BAT is kinda coy on how it works, I think. it's not PP, more akin to parallel SE I'd think.
BAT uses Plitron OPTs and power trannies, but likely not these exact same ones, (or if they do Plitron and BAT won't confirm it, I am sure), probably something similar but spec'ed slightly differently I'd guess.
Paralleling 4 tubes per channel is more than you want to consider biting off for a first-amp project, IMNSHO.
Good luck
-Ed
Hi Ed Sawyer,
I'll indeed go for a two tube amp, and even that makes my head spin.
I hope to get the amp running as simple as possible and hope to have learned as much by then to start experimenting and see what happens.
If the OPT's would be used parallel, would't that saturate the core?
btw, I really loved your tube reviews!!!
I'll indeed go for a two tube amp, and even that makes my head spin.
I hope to get the amp running as simple as possible and hope to have learned as much by then to start experimenting and see what happens.
If the OPT's would be used parallel, would't that saturate the core?
btw, I really loved your tube reviews!!!
I think if you try to use them in a PSE mode, you will need to do it as a parafeed circuit. Not as difficult as it sounds with the low voltage you will be using. There can be no DC in the transformer and parafeed achieves that.
I think you can get by with 2 tubes per channel if you have them running at about 100V across them and 200mA per tube. That arrangement should be quite managable for a starter amp.
Shoog
I think you can get by with 2 tubes per channel if you have them running at about 100V across them and 200mA per tube. That arrangement should be quite managable for a starter amp.
Shoog
So I picked up the Morgan Jones book (great book btw!), and read through the 'crystal palace' amp scheme. My only question with using this front end with the 6C33C's is the supply voltage. Far too high for the 6c33c, but then if you don't use this high of a B+ then will you need to do seperate supplies?
I am also looking to do the phase splitting with an input tx, so then I don't know if this front end is best for my purposes. Dave's schematic looks like it'll work, but maybe I'll try 5842's instead of 6c45pi's. I haven't heard too many good things about the sound of 6c45pi's.
I am also looking to do the phase splitting with an input tx, so then I don't know if this front end is best for my purposes. Dave's schematic looks like it'll work, but maybe I'll try 5842's instead of 6c45pi's. I haven't heard too many good things about the sound of 6c45pi's.
Hi JoshK
Sure the supply voltage is too high for the 6C33C, but if you look good, you see Morgan Jones uses a separate trafo/winding to power the end stage (the 13E1). The front stage has got its own supply. I would say the 6C33C could be fed very well with a cheap insulation transformer with 220VAC out into a fullwave rectifier with a C input (maybe RC) and than burn some volts - and lot of watts - with resistors.
Phase splitting with TX's is possible, sure, but I don't know if it is worth doing in this case. To drive the 6C33C you will need lots of swing, which are provided through the cascaded front end of the Crystal Palace. Just one amplifying stage will probably not be sufficient...but then, you have to look at it. I think the scheme as shown is excellent as a starting point, and tweaking is always possible (afterwards).
Erik
Sure the supply voltage is too high for the 6C33C, but if you look good, you see Morgan Jones uses a separate trafo/winding to power the end stage (the 13E1). The front stage has got its own supply. I would say the 6C33C could be fed very well with a cheap insulation transformer with 220VAC out into a fullwave rectifier with a C input (maybe RC) and than burn some volts - and lot of watts - with resistors.
Phase splitting with TX's is possible, sure, but I don't know if it is worth doing in this case. To drive the 6C33C you will need lots of swing, which are provided through the cascaded front end of the Crystal Palace. Just one amplifying stage will probably not be sufficient...but then, you have to look at it. I think the scheme as shown is excellent as a starting point, and tweaking is always possible (afterwards).
Erik
I used a main toroidal as a interstage phase splitter. It worked, but interwinding capacitance knocked the response over 8K. I had to pump a lot of current into it to make it working well. I also rapped some feeback around it and used plate to plate feeback to get the output Z of the driver down. After all that it has worked out well, though the -3db point is still only 35khz.
My suggestion is either get an expensive interstage - or step down the split signal and then put it through another meaty driver tube to drive the 6c33 grids.
Shoog
My suggestion is either get an expensive interstage - or step down the split signal and then put it through another meaty driver tube to drive the 6c33 grids.
Shoog
I used to own a VK-60 and it was by far the best sounding tube amp I've ever owned, and I've owned quite a few! The dynamics for a 60 wpc amp that it can muster is really amazing! A 60 wpc tube amp with slam is a more apt description and my speakers are only 89db! Its more like running a 75 to 100 wpc solid state amp with some headroom beyond that.
If you guys can reverse engineer it I would also like to build it. Used Vk-60's go for $1500 to $2500 U.S. depending on version and condition. I never had to replace the 6C33's in my amp and I had it about two years and ran it almost every day. This would be a very worthy tube project to do, the only one worthy enough in thaat power range for me to become interested!
BTW: I think there are P-P and SE versions of the VK-60... a number of board revisions too but I never followed it all after I let go of mine. The OPT's just about have to be custom made... Perhaps at least a small group buy might be able to happen here???
Mark
If you guys can reverse engineer it I would also like to build it. Used Vk-60's go for $1500 to $2500 U.S. depending on version and condition. I never had to replace the 6C33's in my amp and I had it about two years and ran it almost every day. This would be a very worthy tube project to do, the only one worthy enough in thaat power range for me to become interested!
BTW: I think there are P-P and SE versions of the VK-60... a number of board revisions too but I never followed it all after I let go of mine. The OPT's just about have to be custom made... Perhaps at least a small group buy might be able to happen here???
Mark
Hi,
I want to build this amplifier.
6C33C - PP-Amp von Ernst Roessler
Does anyone have experience with this?
Thank you!
I want to build this amplifier.
6C33C - PP-Amp von Ernst Roessler
Does anyone have experience with this?
Thank you!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.