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03-14-2012 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,216
Joined on 10-12-2006

Post #: 61
Post ID: 17966
Reply to: 17964
Driving Miss Daisy
fiogf49gjkf0d
KOT, with the ML2s I found very little difference in the sound of various 6C33Cs, but the old Svetlanas certainly "held to spec" better (and longer..).  I find the 6C33C to be more "direct" sounding than 845 or 211, but this in the context of a 3-stage amp, and I was limited in my choice of 2nd stage tube.  The input tube was certainly a factor, so I ass-u-me the driver matters as well (as with most tube amps).

I have to say I think any low-power amp will be (and should be) critically limited as far as loading, rather than over-driven.  IMO, A2 is nice only to give more A1 headroom; but with the IHT I think feedback "helps the ML2 drive more difficult speakers", and I think parallel output would be the only option for more power from 6C33Cs, if to attempt 15" drivers.

Sure, some won't "like" the 6C33C because it is not "magical"; but I like that it allows fine tuning in other areas.

By the way, one should NOT get "elephant sound" from 6C33Cs (and I think this may be one reason why some don't "like" them...).

Maybe keep playing with operating points...

Best regards,
Paul
03-14-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 62
Post ID: 17967
Reply to: 17964
6C33C amp/preamp follow up
fiogf49gjkf0d
The reason that I built the 6C33C preamp was to explore the 6C33C true musical potential like I did with the 845. Not only did I compare the sound of these tubes in power amp, but also in preamp. The reason is that with power amp you might hit some limitation with commercially available output transformer. For 845 there are many excellent choice of output transformer, but it is very limited with the 6C33C. For preamp since the bias current is much lower you can basically use the same preamp output transformer for both tubes, which is what I did. The 845 gives much more bloom in the bass, goes much deeper and give you sense of plenty power, the 6C33C while quite good, has very tight bass but there some sense of dryness (where is the beef?) . But from 100Hz up it is where the 6C33C really shine, the 6C33C can focus on voice and instrument fantastically which I think the low microphonic level of this tube has something to do with it, the 845 imaging is blurred when compared to 6C33C. And then, the 6C33C high is so airy opened and extended, which would make it an excellent tweeter amp. I also think the power is the 6C33C Archille's heel, the linearity of the tubes rank probably at the bottom of your power tube list once you pushed them over 4-5 watts, yes you can corrected with feedback, but then you will loose some of its magic quality, which I dont implement in this amplifier.Now, I have forgot to mention the speaker type used when I raved about the midrange of the 6C33C. I tried them in 3 different system, a Supravox based 8in Field Coil and ribbon tweeter, an Open baffle Supravox field coil bass, midrange and RTR electrostat, and the Stacked Quad. All these systems, even with the 100db sensitivity of the Supravox would need more than 10W to drive, so that eliminates all the flea power amp such as 10Y, 2A3, VT62.... which does not leave much for choice as DHT amplifier. In the future, I would like to try the 6C33C in a horn system, which probably happen in the next 6 months or so, with the compression driver 1-2 watts power required, there will be more player.  So, the term "best midrange" so far would apply only to the speakers that I have tried. It is also very interesting that out of 4 different 6C33C tubes that I have tried, they are all sounded very familiar but my preference is the Svetlana labeled tubes so far, they performed as what a good tube should be, no crackling sound, no bias drift, no surprise.... so far.Regarding the "elephant sound", what I meant is that the 6C33C do throw a very large soundstage, depth, a big sound. What the 6C33C did that the 845 does not is the ability to focus on instrument and voices, the image size is just correct, not bloated like the 845, if you happen to compare the 845 side by side with the 6C33C you will feel like you just put on corrective lens with the 6C33C, the image become so sharp, you can hear every little detail but the size of the landscape still is the same as the 845.It is unfortunate that there is not many output transformer choice available out there to explore the 6C33C full potential, it would be nice that there is a transformer available for PSE 6C33C with 40 watts capability, I completely agreed with Paul that any 15 and even 12 inches woofer would appreciate 30-40 watts of power, even the ones with 100db sensitivity. Just for fun, you can see the Stereo 6C33C in action here in action in a tri-amp Supravox field coil + RTR electrostat system along with 845PP and 300BPSE but please dont judge the sound quality of the system through a $100 video camera.
http://www.youtube.com/watch?v=3qvoyh1jznQ
03-14-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 63
Post ID: 17968
Reply to: 17967
It will wary with implementation…..
fiogf49gjkf0d
I see now. Quad can’t be driven by single 6C33C. This is well know fact and I did a lot of experiments with Quads and Lamm ML-2.0. For whatever reason as ML-2.0 drives Quads it produces Stingy Sound. I can’t explain it but it is not the sound that ML-2.0 and Quads are capable under the best conditions. When I sold my Lamm then one of my ML-2.0 was interned to by a guy from West who was a big Quads devotee. I did tell him many times that it will not sound as ML-2.0 is able to sound but he bought them anyhow. He reported that he loved it but I never believed him, or cared. Warn you that ML-2.0 runs global feedback and it has to be able to drive Quads better then something like Melquiades. I never tried Melquiades with Quads but I think ti will be even worth then Lamms.

Also about the sub 100H bass.  For whatever reasons the amps with 6C33C are very sensitive to plate loading when they do lower bass.  I have seen the situation that 1/2R of secondary impacted bass hugely.

Now about the “some sense of dryness”. Yes, I would confirm that it might be the case and in some designs 6C33C do have a tendency to sound like SS amp. I think it is a properly of des but the property of the tube. In fact I feel that it is in many cases the properly of the driver. If you make 6E5P-6C33C two stages then you will see that the amp has some dry SS feeling. Add to the amp the Melquiades-style biasing of the driver stage and you will get superb most feeling with bass 10 times better then it was with battery or fix-bias of 6E5P.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-14-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 64
Post ID: 17969
Reply to: 17968
Quad and 6C33C
fiogf49gjkf0d
Forgot to elaborate the Quad system.It is actually a tri-amp Quad system, below 100Hz is the Supravox 15in Field coil in open baffle, then it's a Stacked Quad ,and about 5Khz there were 5 RTR ESL cell. I did try the 6C33C amp in a single pair Quad by itself, and I understand what you mean by Stingy sound, there is nothing to write about it. But in a tri-amp stacked Quad system with 6C33C (I did try couple different amp including the 845), I would say wow! Even the guy who sold me the pair of bronze Quad heard it and could not believe such difference in Quad sound when you stacked them. Anyway, the 6C33C was used here as at its best driving the Quad from 100Hz- 5Khz.Using the 6C33C in the preamp, alone without any driver tube, I do detect the bass as described, but it is not a bid deal as you think,the difference is there, but  in fact it never bother me at all, since the sonic qualities of the 6C33C is already way beyond my expectations. 

03-14-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 65
Post ID: 17970
Reply to: 17969
The 6C33C dehumidifier.
fiogf49gjkf0d
I see, this tri-way Quad system for sure shall be much different from regular Quas. I kind of even understand why you stay with open baffle bas to support the system’s bass. For sure it will not Bruckner-style pressurize a room as non-dipole bass would do but it for sure shall go alone with Quads well. I would like like to hear the think, which city are in? So, essentially when you talk about bass from 6C33C you were talking about the 6C33C amp drive sub 100Hz woofer or effectively in might be a bass DSET?  Try to play with 6C33C loading. I do not know the Supravox drivers and particularly in open baffle and electromagnets drive but among the drivers that I experienced I have seen that 6C33C is very sensitive for loading. If you feel that it was “but too dryness” and if you need to get more “beef” than just make the tube to idle a bit less. You will pick up more harmonies (and get more “beef”) and you get slightly more power from the tube. I mean if you load your 6C33C to let say 600R then make it 500R or 550R. It will be much softer sound with more “round” corners. You might not feel that it is too dry anymore. As the very temporary test, juts to preview the result you might short your woofer with 30-100R power resistor. You will lose some transients in bass and some other attributes of quality but you will get a preview how the heavier loaded 6C33C might sound and a send if it is a good direction for you to go.

Let me know about the results.


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-14-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 66
Post ID: 17971
Reply to: 17970
6C33C bass.
fiogf49gjkf0d
I am not too worried about the 6C33C bass, since I have other alternative. Even if lower loading will improve it, the problem is to get more power out of the 6C33C to a 40W (PSE perhaps) level to be able to drive the 12in or 15in woofer, even then the level of distortion of these tubes at that power would have been in double digit or some kind of feedback will have to be used. It's just curiosity that led me to experiment the 6C33C driving the 15" at 100Hz as DSET and in another case, the 15" (with 150Hz passive low pass) together with the 8in (2Khz passive lopass) in the OB system. Also, the OB 15in might not give thunderous bass as the a vented box, but then with its electromagnet would give the sense of speed that would be perfect for a horn system to come in the next few months (when I got the mechanical mounting problem sorted out), trying to match a 15in woofer to a horn at 500-600Hz is no easy feat. You will be surprise how a simple OB with 6db roll off can easily rattle the windows of your room playing Reference Recordings Firebird Suite.
PS. I lived in The Silicon Valley.
03-14-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 67
Post ID: 17972
Reply to: 17971
The experiments very worth to undertake.
fiogf49gjkf0d

KOTriode. One of the reasons why I advance the idea of using 6C33C for sub 100Hz bass is because it is very easy to say objectively if it is enough power. You see, when you use 845 for instance the tube might jumps in and out if A2. Since it is DHT it will work more or less fine in A2 but each tube at each operation point, with each driver and in each way of being connected/powering will sound differently. There is nothing wrong with it but we greatly would attribute of use if each tube in A2 to the sound of the lower bass for this particular tube.  With 6C33C it will be no ambiguity in sound: if it stays in A1 then it will sound as it sounds and if it reaches A2 then it must not be used for a given amp gain (efficiency of speaker + room size). So, I think to compare metrologicaly properly the lower bass between 6C33C and 845 we need to compare BOTH of the tubes in A1. It is not difficult to detect if ether of your tubes run in A1.

http://www.goodsoundclub.com/Forums/ShowPost.aspx?PageIndex=1&postID=6057#6057

Anyhow, I do understand how “simple OB with 6db roll off can easily rattle the windows” but in my view it is very different bass. I heard as large OB as largest Knlangfilm Bionors with both perm and electromagnets and even I do recognize some quality of THAT sound but I do not feel that anything below 50Hz is valuable for what I am interested.   It might not mean a lot but let agree to disagree as my position about OB for lower bass is well formed. BTW, Reference Recordings in my view has a bit idiosyncratic bass. For sure it is impressive but not the bass that I would recognize as too musical.  It is a bit overly-studio type of bass, I do like it but I do not find it to be my reference bass.

One more thing. Fell free to discard below – they are just the thoughts that pop up in my mind when I though about your loudspeakers.  I am sure that Quads in MF do fine and the RTR ESL panels do fine as tweeter but I have a filling (and I might be very wrong) that in this configuration the upper range will have some dynamic challenge. If it is what you feel then I would try to use “dynamic injection”. It might be very hard to at HF but still might be possible. You might try to use different type of tweeters that have the “dynamic injection” built-in juts for experiment to see if more virtual dynamics in tweeter would be appealing to you.  I do not want to suggest the models of tweeters at public forum as I know the ugly results of it but if you would like to experiment with “virtual dynamics” then contact me privately and I will pitch the tweeter for you. I personally do feel that if you add more dynamic tweeter above the Quads then you might make the Quad’s MF more fun. I do admit that more dynamic tweeter most likely will enrich the Quads but will not be VERY hard to make Quad’s FM and more dynamic HF to sound the same in context of one installation. Still, I think the experiment is very worth to undertake.

Rgs,
Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-14-2012 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,216
Joined on 10-12-2006

Post #: 68
Post ID: 17973
Reply to: 17971
Giant Transformer
fiogf49gjkf0d
KOT, as you may know, the ML2 has a BIG transformer to make "36 Watts" at clipping; but even with this and the trick feedback it is not the first choice for large dynamic/OB drivers.  Of course I mention this because of your remarks about the 6C33C, big transformers and LF.  OTOH, if you give the 6C33C suitable input and a reasonable load, then it will not mess up what what it is presented with, including the amazing-to-me ability to not screw with any Tone that comes its way.  In this way (and in its "directness") it reminds me somewhat of the 2A3.

For many years I also used the RTR HF modules (6/side), but paralleled with XXXXXXXX dynamic tweeters, as far as they would go.  IOW, I agree with Romy about exploring the 6C33C with parallel "tone drivers", if only to also enjoy the 6C33C's "gift" to Tone.

Not to go too far, but I also like the "6C33C SET LF" very much...  as far as it goes...  In fact, one problem I'm having now is getting "more LF" that is anywhere as good as what I got from my 6C33C SET!

Maybe Class A SET input/drivers into Class A 6C33C PP...

Best regards,
Paul 
03-15-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 69
Post ID: 17974
Reply to: 17973
New 6C33C mono block amp coming.
fiogf49gjkf0d
Ok, I will try to lower the primary impedance like you suggested, but it will be on the new 6C33C mono block amplifier that I am building. The custom made chassis will be finished by next week and I have the better components waiting to get installled in these new amps. It's unfair to compare the stereo 6C33C with the mono block 845 with top grade parts.Now the thing about the dynamic tweeters, I would be very interested to see your suggestion as I always want to look for the best tweeters to match my systems and finally settle on these RTR, so Romy, please send me an email regarding these tweeters. Thanks in advance.
03-15-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 70
Post ID: 17975
Reply to: 17974
Would you like to try the Milq’s basing?
fiogf49gjkf0d
 KOTriode wrote:
Ok, I will try to lower the primary impedance like you suggested, but it will be on the new 6C33C mono block amplifier that I am building. The custom made chassis will be finished by next week and I have the better components waiting to get installled in these new amps. It's unfair to compare the stereo 6C33C with the mono block 845 with top grade parts.Now the thing about the dynamic tweeters, I would be very interested to see your suggestion as I always want to look for the best tweeters to match my systems and finally settle on these RTR, so Romy, please send me an email regarding these tweeters. Thanks in advance.

I do not see if any why it would be unfair to compare the stereo 6C33C with the 845 monoblocks. But to me more important for “compare” bass is to assure the both 6C33C and 845 has the same lower cut of full power. If one amp has -3dB at 20Hz and another -3dB at 26Hz then we do not compare bass but rather the amount of inductance of OPT for a given tube. if both amps have the same cut off (difficult to do) THAN whatever difference is will be the true difference in the tube bass character. The PS and other things let presume are the same.

Anyhow, KOTriode,if you build new 6C33C monoblockd and as I underrated you render some kind if your version then can you juts as a prototype try my Milq basing schema with Milq driver. You might very much like it but I would be very interested to see you feedback posted. I do find that the 6E5-6C33C amps are very brutal and not interesting but the Milq’s basing make sound truly magical, at last in my view. If you have your 6C33C power then to make a few voltage dividers from B+ or whatever driver you use, fast power two gas tubes and put Milq driver in temporary test would be a couple hours for you. You can make it only with one amp, something that I call “maket” and see what happens.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-16-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 71
Post ID: 17976
Reply to: 17975
Further thoughts
fiogf49gjkf0d
Romy, in the contrary, it is very unfair to compare my 845 amp with the 6C33C. The main reason is the 845 amp used the best output/interstage transformer available, while the 6C33C's output xformer is pretty good but far from being best for the 6C33C. I can see sine wave distortion on the 6C33C at full power (15W) below 30Hz, while the 845 has no problem down to 20Hz (limit of my audio analyzer). Since there are not much 6C33C transformer availability out there, I just have to settle with what I have, but that's in the amplifier department. 
Now, the main reason that I built the 6C33C preamp is to experience the pure sound of 6C33C, with one cathode bias resistor/cap and a transformer load , it is as pure as it can be. It even have double output, one is through the output transformer, the second output using the transformer primary as choke load and output through a capacitor. It's output is pretty flat from 20Hz-20Khz with low distortion, sine wave looked pretty good at 20Hz, this is what I compared with a 845 preamp (even though with different output transformer), both do not have any other inoput/driver tube to inject their own sound. And it was these two preamp that lead me to compare the bass of the two tubes.
When I described the 6C33C sound in the bass, I think you might have misunderstood that I criticized in a bad way. " On dynamic, the 6C33C tube showed its ability to go deep in the bass on Ray Brown trio recording of Soular Energy which is excellent for a 15W SE , the 845 amp can do better, but not by much, but probably because of its 25W output give it more headroom than the 6C33C"
After living with 845 tubes over 20 years, with no less than 7 845 amplifier built, including 2 pair of push pull class a 50W and 100W(to satisfy my curiosity, I made a Parallel push pull with 4 845 tube per side to get 100w), I can say thay 845 is king in the bass area that no other tube can approach, now if the 6C33C being second best in the bass department at my first shot at it, I would say this tube is a miracle, I was so ecstatic adding this tubes to my stable and racing toward implementing it in a mono block version. I wish there are more output transformer available for the 6C33C, the Tango is too small to be serious, that leave Sowter and Lundahl, I might have left some others but if anybody know something I dont then I am all ears.
Regarding the Milq, it's not easy to modify my amp to the Milq cricuit, my amp was designed with DC coupled, therefore the B+ is pretty high, at about 500V it has twice the voltage of the Milq, the regulator cant regulate down to 220V without problem (too much voltage and current for the pass tube). To duplicate the Milq, it would  require different power transformer, but that can be done and I will put some thought into it.
03-16-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 72
Post ID: 17977
Reply to: 17976
Bias with attitude, bass and transformers...
fiogf49gjkf0d
 KOTriode wrote:
Romy, in the contrary, it is very unfair to compare my 845 amp with the 6C33C. The main reason is the 845 amp used the best output/interstage transformer available, while the 6C33C's output xformer is pretty good but far from being best for the 6C33C. I can see sine wave distortion on the 6C33C at full power (15W) below 30Hz, while the 845 has no problem down to 20Hz (limit of my audio analyzer). Since there are not much 6C33C transformer availability out there, I just have to settle with what I have, but that's in the amplifier department.

Well, if you saw sine wave distortion at full power at 30Hz than whatever bass you heard from that amp was nothing to do with bass of 6C33C but it was just the inadequate quality of your output transformer. I hope you understand it.
 KOTriode wrote:
Now, the main reason that I built the 6C33C preamp is to experience the pure sound of 6C33C, with one cathode bias resistor/cap and a transformer load , it is as pure as it can be. It even have double output, one is through the output transformer, the second output using the transformer primary as choke load and output through a capacitor. It's output is pretty flat from 20Hz-20Khz with low distortion, sine wave looked pretty good at 20Hz, this is what I compared with a 845 preamp (even though with different output transformer), both do not have any other inoput/driver tube to inject their own sound. And it was these two preamp that lead me to compare the bass of the two tubes.

Yes. I do understand it but I have absolutely no experience with 6C33C in preamp. I know very well how 6C33C act as current buffer in power SET but I have no idea what the 6C33C needs at line level. It might have very different needed about wish I am not informed.
 KOTriode wrote:
When I described the 6C33C sound in the bass, I think you might have misunderstood that I criticized in a bad way. " On dynamic, the 6C33C tube showed its ability to go deep in the bass on Ray Brown trio recording of Soular Energy which is excellent for a 15W SE , the 845 amp can do better, but not by much, but probably because of its 25W output give it more headroom than the 6C33C"

Possibly it was your observation but it might be skewed by the specifics of your implementation. To have a common denominator for talking we need to talk about the publicly available 6C33C implementations. So, the only thing that I personally can testify is that I heard quite a few power amps with 845. I myself prefer amps around 211 as I feel it is softer sounding tube then 845 but it is not the point. The point is that any single power amp that I heard with 845/211 was absolutely no context in lower bass department to Lamm ML2.0. It is laughable how much ML2.0’s bass is better then pretty much any other SZET out there with 845/211 or pretty much with any other tube. The Lamm ML2.0 bass is better then any SS amp out there as well and in my view the Lamm ML2.0’s bass is the textbook bass as it has to be in audio, of cause if the amp has enough power to drive whatever it drives. That was my introduction to 6C33C bass and in my estimation the 6C33C still hold own, again, in my estimation.
 KOTriode wrote:
After living with 845 tubes over 20 years, with no less than 7 845 amplifier built, including 2 pair of push pull class a 50W and 100W(to satisfy my curiosity, I made a Parallel push pull with 4 845 tube per side to get 100w), I can say thay 845 is king in the bass area that no other tube can approach, now if the 6C33C being second best in the bass department at my first shot at it, I would say this tube is a miracle, I was so ecstatic adding this tubes to my stable and racing toward implementing it in a mono block version. I wish there are more output transformer available for the 6C33C, the Tango is too small to be serious, that leave Sowter and Lundahl, I might have left some others but if anybody know something I dont then I am all ears.

There are no good ready to go transformer for 6C33C. Tangos are garbage.  The 20 years back Tangos were OK for small tubes but Tango is long gone and whatever crap they label by Tango in fact Chinese transformers agglomerate production. Lundahl, with glass core, are very good in my view but they have small core size. At 200mA gap you will have 20Hz but if you build a full bloom 6C33C then you do not want to stop at 200mA. Your voltage is 200V, at 200mA you will have 40W on plate – way to little power, particularly for bass. I do not know the Sowter but generally I would advise to find somebody who would make for you your own custom transformer. Go for 350-400mA gap and for inductance to support 12-15Hz at 20W. There was a guy at my site who ordered one in Europe, I do not know if he like the results – he did not post any feedback. I guess you are American, so you might want o talk with somebody like David Slagle from NY. He is kind of “project guy” and he might be a good source for not cookie-cutter transformers with fast cores. Anyhow, the sound of nay SET is made at 85% by the sound of OPT. If you used any temp OPT to test your 6C33C then you get temp results and temp bass. I do not insist but I think that it is possible that as you get better and deserving OPT for your 6C33C then your view about the 6C33C bass will change.
 KOTriode wrote:
Regarding the Milq, it's not easy to modify my amp to the Milq cricuit, my amp was designed with DC coupled, therefore the B+ is pretty high, at about 500V it has twice the voltage of the Milq, the regulator cant regulate down to 220V without problem (too much voltage and current for the pass tube). To duplicate the Milq, it would  require different power transformer, but that can be done and I will put some thought into it.

I see, you use 6C33C as DC coupled with driver setting the bias – a dangers game for THIS tube. Anyhow, the idea of Milq is not the output tube but the driver tube and the way to bias the driver tube. Of your use the Milq’s driver tube with cathode bias or fixed bias then it will be very different sound that I very much do not endorse. Only with the bias as Milq has it the amp shows the sound that I like. Ironically, when I used the same Milq-style bias on the output tube then6C33C sounded like shit. The Milq driver and the way to bias THIS driver is very lucky combination in my view. BTW, if you use fixed bias on 6E5P and compare it with Milq bias then you will see that Milq bias show much much much more interesting bass…
Rgs, Romy the Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-17-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 73
Post ID: 17978
Reply to: 17977
Milq Driver tube bias
fiogf49gjkf0d
Romy,I looked at your Melq schematic : http://www.goodsoundclub.com/PDF/Melquiades_SET.pdf  regarding the 6E5P bias. Would it be simpler to use two alkaline battery in place of R5 to provide 3V , or 3 Rechargeable for 3.6V in place of R5 ? Did you tried that?
03-17-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 74
Post ID: 17979
Reply to: 17978
It is about Sound, stupid.
fiogf49gjkf0d

 KOTriode wrote:
Romy,I looked at your Melq schematic : http://www.goodsoundclub.com/PDF/Melquiades_SET.pdf  regarding the 6E5P bias. Would it be simpler to use two alkaline battery in place of R5 to provide 3V , or 3 Rechargeable for 3.6V in place of R5 ? Did you tried that?

I for sure do NOT call you stupid but rather improvise upon the celebrated Bill Clinton’s 1992 presidential campaign slogan against George Bush. KOTriode, I think you are NOT understand my whole adventure with Melquiades. If all that is necessary is to supply right voltage to the 6E5P drip then it would be so much simpler and any amp with right voltage would sound “right”. I did explain at this site a lot about the motivation and reasoning to use this type of bias instead of just “voltage supply”. I do not insist that my explanations are correct but I feel that my findings are very much accurate.  BTW, if you have 6E5P with min 15K plate resistor driving 6C33C then to convert the 6E5P to battery, cathode or fixed bias will be for you the matter of a few minutes. So you will be able to make your judgment.  The Melq’s idea was to engage the 6E5P in two-stage operation and among what I have seen the use of the 6E5P in the way how Milq does it provide the most interesting sonic result. There are many other ways to drive 6C33C, including multiple stages but if you attempt to use 6E5P (and I do not know if you do) than I do advise my version, at least to try and to fitness what will happen with Sound.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-17-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 75
Post ID: 17980
Reply to: 17979
Just have to build one to hear.
fiogf49gjkf0d
Ok, I just read your "Melquides Remote biasing". This technic can not be duplicate in my amp due to DC coupling, the C3G (I dont use 6E5P) driver stage basically adjust the 6C33C current in the output stage. Just for curiosity, I will build a mono block version Melquiades and compare with my version, I believe I have extra chassis for it.
03-17-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 76
Post ID: 17981
Reply to: 17980
Convince me.
fiogf49gjkf0d
 KOTriode wrote:
Ok, I just read your "Melquides Remote biasing". This technic can not be duplicate in my amp due to DC coupling, the C3G (I dont use 6E5P) driver stage basically adjust the 6C33C current in the output stage. Just for curiosity, I will build a mono block version Melquiades and compare with my version, I believe I have extra chassis for it.
The Melquides Remote biasing is not the Melquides but the idea to use the positive side of biasing to pressurize interconnects with voltage, thus the Remote past comes from. To try the Melquides biasing feel free to discard the biasing PS. You would need 400V to drive the 6E5P, so use the very same supply as you use for driver tube, juts drop voltage to ~ 190v to light up the 150V gas tubes. Evrything after the points B and C on the schematic is important. Do not change the value of C4 and C5 and keep R4 and R6 as high as you can.  By biasing with grid resistor we eliminate the cathode bypass cap (always horrible for sound) in case of cathode biasing, the grid cap in case of fix biasing or grid battery that has a whole array of own problems. The miller capacitance of 6E5P is low as it looks like the grid impedance do not form filter with it that too auditable. The 6E5P has own unique sound that I happens to like but the key in there the gas tube biasing. The gas tubes damp reflections of currents from the 6E5P grid and make the tube sound very luxurious and pliable, it also create very different bass.

The reason I do encourage you to assembled a prototype of Melquides and to give it some listening test is because I find it would be interesting to have some reality check and to see how the my version of 6E5P-6C33C would stand against alternative to drive 6C33C. I do not mind somebody find better single-stage driver 6C33C and I do not mind to use the efforts and time of others to propel the journey. I do feel that anybody who would like to drive 6C33C with one stage have to listen what Melquides. I might be wrong, convince me.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-30-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 77
Post ID: 18023
Reply to: 17977
Tango Made in China? Any proof in this rumor?
fiogf49gjkf0d
 Romy the Cat wrote:


There are no good ready to go transformer for 6C33C. Tangos are garbage.  The 20 years back Tangos were OK for small tubes but Tango is long gone and whatever crap they label by Tango in fact Chinese transformers agglomerate production. Lundahl, with glass core, are very good in my view but they have small core size. At 200mA gap you will have 20Hz but if you build a full bloom 6C33C then you do not want to stop at 200mA. Your voltage is 200V, at 200mA you will have 40W on plate – way to little power, particularly for bass. I do not know the Sowter but generally I would advise to find somebody who would make for you your own custom transformer. Go for 350-400mA gap and for inductance to support 12-15Hz at 20W. There was a guy at my site who ordered one in Europe, I do not know if he like the results – he did not post any feedback. I guess you are American, so you might want o talk with somebody like David Slagle from NY. He is kind of “project guy” and he might be a good source for not cookie-cutter transformers with fast cores. Anyhow, the sound of nay SET is made at 85% by the sound of OPT. If you used any temp OPT to test your 6C33C then you get temp results and temp bass. I do not insist but I think that it is possible that as you get better and deserving OPT for your 6C33C then your view about the 6C33C bass will change.


Regarding Tango, the one they build for 6C33C, (the XE-20-600) is the economical XE-20 lines, so I do not feel that they are up to the task that I am looking for. I am not convinced the larger Tango X, XE-60 series are garbage like you said, I have used them for years and compared with many other brand.  There are lots of talk over the net regarding qualities of old Tangos versus the (post 2000) new ISO, and things like Tango are Chinese made transformers (without any proof). Now, I can put all these rumors to test in the next few months since that I have on hand these Tango to test in my new amplifier be it 845, 211 or GM70. What I got is Tango X10S dated 1990, 1998, The Tango ISO X10SF dated 2004 and 2008 that I would be able to test them electrically in one of the industrial standard HP/Agilent LCR Meter and in amplifier.... we shall see! 
03-30-2012 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,650
Joined on 05-27-2004

Post #: 78
Post ID: 18025
Reply to: 18023
The proof to rumor?
fiogf49gjkf0d
Nope, I do not have any proof to the rumor as I do not use the Japanese transformers. I heard them many times, was not liking the entire sound of the playbacks (do not blame only transformers for that) but since I never myself dealt with Japanese transformers my opinion is leas relevant on the subject. The source for rumors is probably come from me but it is not my invention. A few years back I was talking for a famed US transformer maker. He is very knowledgeable guy who is in business for many dozen years and he knows his field. so, he told me that some years back a large Chinese or Taiwanis corporation did buy all those Tamura, Tango, Hashimoto and etc. they still operate independently and a separate brands (like all companies that under umbrella of Harman International) but they all owned that that huge Chinese conglomerate that makes all possible cheap power, switching, signal and many other transformers. So, according to him: as the conglomerate’s cost-effective nature begun to penetrate the production discipline of former small Japanese makers their transformer stopped to be what they were famed for in past and nowadays they all sound “nothing special”. I can’t corroborate with it as I have no personal experience but to be the story sound very believable. He did named the name of the conglomerate and even I knew it but I can’t recall it now. Ironically that many US makers: Plitron, Torpid of Maryland do not make transformer in US but outsource it to the very same Chinese conglomerate. So, today if you buy a Tamura, or Tango, or Plitron, or Amplimo or a $5 transformer in Radio Shake you might very much but the very same transformer only with different labels. I do not know if the Partridge, MagneQuest, Sowter, Stevens & Billington, Bartolucci, Lindberg, One Electron, Audio Note, Hammond and other still do the transformers themselves. I personally prefer to deal directly with one-person type of company, somebody like Intact Audio, Tribute, Elektra-Print and others – who will do my own custom transformer. It is not the most cost effective way and not the assurance of quality but it is an assurance that it will be no indifference in the results. I do like that personal touch….

The caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-06-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 79
Post ID: 18039
Reply to: 18025
New 6C33C SE mono block
fiogf49gjkf0d


Just finished one mono block 6C33C SE amp.To keep things simple (power supply only need 220V), I used a single driver tube (the second tube is there for backup if not going as planned) through an interstage transformer. Power supply is still regulated but used 6080 instead 6C33C. There are two tube rectifier, one for B+, one for negative bias. This amp used oil cap everywhere except two electrolytic for the heaters for the driver and output tubes. The amp measured better than I planned on the bench, power is a whopping 22Watts with 5% distortion, with 10% distortion it is up to 27W, this put the amp power in 845 territory. The level of distortion across the audio band is also much lower. Can't wait to finish the second one to hear them!

IMG_7950a.JPG
04-06-2012 Post does not mapped to Knowledge Tree
KOTriode
Posts 40
Joined on 07-19-2010

Post #: 80
Post ID: 18040
Reply to: 18039
New 6C33C SE amp at clipping.
fiogf49gjkf0d
Amp at close to clipping level 20.4W, I am surprised that sine wave looked pretty symmetrical. Still has couple chassis left for the Melquiades, the problem is the 400V supplies which required extra power supplies. This interstage amp is so much simpler and easy to build at the expense of the interstage cost.


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