guy sergeant wrote:

I have heard Lamm ML2's in a couple of different people's home systems. Did they know how to use them properly? Well either they didn't (quite possible) or the amplifiers simply lacked the virtues I would prefer.

Well, I never heard any credible and rational critics of Lamm ML2 performance from anyone and I know quite a lot of ML2 users. Since I publish my personal unsatisfactory comments about ML2 I begin to hear here and there that some people do not like that ML2’s Sound or some of the fools have it for sale. I always follow up those comments and in some cases I visited the people and familiarized myself the context of the actual results that people achieved in their rooms before the Lamm ML2 was “not good enough”. What I have witnessed that NONE of them even remotely reach the point where was reasonably to talk about the Lamm’s limitations. People juts ran their lips, nothing else…

guy sergeant wrote:

Tommy Horning is the guy who makes those speakers but he wasn't using Lamms. His speakers are very enjoyable though.

It would be fun to combine a highpassed at 500Hz Hornins as MF channel with something that would be real bass and real upperbass capable, without stressing that flimsy rice-paper Hornings’ driver. The Hornings’ MF is very interesting though….

I do not really believe in the ultimate ability of SET amplifiers to drive loudspeakers, at least any loudspeakers. I am not talking about the impedance fluctuations or the inappropriately low impedance dives. Those are well know issues. The people who use 4R loudspeakers, that dive to 2.3R, drive them with SETs and then bitch that “the amp has no bass” are juts the Morons. There is another big problem with SETs that from my point of view make them not suitable for full range operation.

Genn wrote:

load for full range amp should be 1200 Ohm - that is very good for the tube and provides good damping.

The good damping for what? It is very very very frequently, practically always, that the MF and LF drivers (combined with the way how they implemented) would require different loading of the output tube. In my case the 6C33C loaded to 1200 Ohm and it is fine for my MF channels but I drive 6C33C much harder for LF channels (approximately 700R). It is not necessary has a lot of to do with 6C33C but with many other parameters that are external to amplifier. (For instant my LF speakers are superbly sensitive for damping and 50R of plate loading is quite auditable)

The point is that when people use SET for a full range then the by default introduce a huge compromise because the LF and MD simultaneously load the plate of the output stage. This is why I do not really believe that a SET might drive a full range inhalation. Usually SET does fine above 60Hz (with minimum capacitance in PS, and no compromise in transformer to accommodate the LF) and to go lower it needs another SET optimized for LF (with max capacitance in PC, oversized inductance on primary and exact LF loading of anode). This is where my rule of DSET (dedicated SET) was bourn…. A simple SET is just a MF amplifier….

The caT

Romy the Cat wrote:

I do not really believe in the ultimate ability of SET amplifiers to drive loudspeakers, at least any loudspeakers.

It is completely irrelevant how frequently an amp switched off and on if a soft start is made properly. A few years ago my friend and I, having the 6C33C based Lamms ML2 (where I do not like how the soft was working) , noted that we both change the output tubes once a year despite that I turned it on and of dally but the friend of mine ran it all year long, practically without shutting it down.

Cooling the 6C33C? The original Melquiades was running with natural convention and it was fine. The Super Melquiades quite packed inside and with all that it has in this chassis it getting too hot. The Super Melq uses a fan that outputs approximately 75% of its flow to the LF tube. It is, 1300 rotations @12DC with 26dB fan sitting at 9V. The fan is well decoupled from the chassis but still with a stethoscope it is auditable on the chassis. The way in which this fan works in the Super Melq’s enclosure make me happy, I initially though to put a thermostat in there but then realized that it is good keep running the fan all time.

The use external leaves on 6C33C is kind of completed. The 6C33C is not flat and has two diameters. It is not clean what diameters should be cooled, even with a forced convention. The Pearl coolers are fine but Bill’s cooler are half ass coolers and the type of the coolers that Pearl has very limited thermal conductively between the glass and the cooler. I had an idea a few years ago to press the 6C33C into a form and after it solidify to fill it with copper. So, what I would have is a flat contact (without the “nipples” that should be omitted and enlarged) between a copper sarcophagus and the glass. Then too the sarcophagus it might be attached any conventional cooling devise. This head-sarcophagus might be completely removable and might just “condom” the 6C33C.  When I designed the Super Melq holes around the 6C33C I thought that I might try to do it sometimes. I think it will be $300-$400 per single cooler… kind of pricey and not really necessary….

The Cat

Yes, Jim, you put it very well. Still in case of the 6C33C it only possible to cool the glass and I made experiments blowing a strong flow to the glass and it did cool down the plates. The problem is that it is not a good idea to apply a strong flow juts to one side of the tube and the entire balloon should be cooled down. To do it with sufficient flow it would need a very powerful blower and consequentially a lot of noise. It would be possible to engineer something effective for the 6C33C cooling but the real question that I always ask myself: why would I need it? It the end, leaving aside my foolish desire to deal with imaginary problems, the 6C33C does not need cooling…. In the case of the 3 tubes in a relatively small chassis (the Super Melq’s gain chassis is 14x20), and considering that the chassis is staffed the forced airflow to the tubes socket is really necessary, at least in my case.

Genn wrote:

Another issue of the 6C33C - short lifetime of the socket.  I think, that ventilation will help to extend their lifetime as well.

Johnson’s sockets for 6C33C (it was Johnson’s $236 or Johnson’s #237 if I am not mistaken) have no problems to hold the 6C33C and they do not burn itself. They have a contact surface as a short cylinder instead of triangle and when the “leaves” open up the pins are hold not by a single point but by a certain "height of metal".

I have a post last year when I found even some RCA socket for the 6C33C, although I thing it was made by Johnson and then rebranded

http://www.goodsoundclub.com/TreeItem.aspx?PostID=1093

Rgs,
The caT

Here is an interesting article by Dmitry Nizhegorodov about his experiences to use 6C33C. (I do not know who Dmitry is) I disagree with Dmitry’s amplifier. Also, I very much disagree with his vision that an amplifier is juts a machinery where voltages and currents simply propagated according to the circuit’s rules. Of course all these things are important I did not see in the Dmitry’s article how it all realties to Sound.

http://www.geocities.com/dmitrynizh/ecc99-6c33c-se.htm

After all we do not built amplifiers for sake of amplifier but to serve the interest of Sound not the interest of the applied scientific theories. The theories of science just describe the events of Realty but they are not the Realty itself. In order an amplifier were able to operate by the language of Realty (instead of the language of Reality's description) the different design methods should be used. Anyhow, I feel that the Dmitry’s article and the Dmitry’s affords are very much worth attention as it electronically-mature written.

Rgs,
Romy the caT

Paragon wrote:

Romy,any information out there for a set of Power / Audio output Trans/ for a Single-Ended 6336B Monoblock project?   Thanks, The Paragons

N-set wrote:

Risking that the topic has already been discussed and that I post in a wrong category (Romy feel free to (re)move this post: Is there any sense in trying 6C33 at higher volatges and lower currents? More precisely, I've been wondering if  1/2 6C33 @ 300-320V, 30-40mA is worth a try or the tube is bad non-linear there? The amp I'm contemplating is a Romy-style-but-Push-Pull amp for electrostatic headphones: something for the input - 6E5P - DC -  1/2 6C33 Push-Pull stacked PSU's, the driver and the output PP choke loaded. The load in a rough approximation is a 100pF cap (stator-stator).

N-set wrote:

BTW, how stable 6E5P is? I'm asking as I was contemplating biasing the output by the voltage drop on 6E5P's plate choke (DCR is say around 1k), with only some minimal autobias on the output. The drawback is that any drift in the driver will rebias the output (I'm all the time assuming DC coupling with stacked PS).

the question about the 6E5P/6E6P stability I asked myself as well, what I was constructing with DHT version for MF. If you look MF channel of 6ch-Milq

http://www.RomyTheCat.com/TreeItem.aspx?PostID=10915

… then you will see that DHT tube is direct compiled and failure of driver tube will burn out  the output tube, in my case the rare and expensive 4V DH tubes. Yes, I put 100mA fast blow fuse on B+, just in case, but so far I did not have it blowing because a catastrophic failure of  driver tube. As you might see I use 6E5P/6E6P everywhere and since 2004 I went over I think 2-3 dozens of them. Some of them were very severely abused by a Moron with soldering gun (means me), I made many mistakes while I was experiencing with Melquiades and there were events when  6E5P/6E6P were running with no bias and as the result had anode with the temperature nears of Sun surface. Surprisingly, after cooling the tubes still forking fine, even though I did not put them in amps after that.

Uselessly what I take a new 6E5P/6E6P I test them.

I uselessly go the second posts of this thread

http://www.romythecat.com/Forums/ShowPost.aspx?postID=4805

…where the test data is located.

I usually test them at 4V bias, not the 3.4V as I wrote in the post. The 4V is how they run in Melquiades.  The good new tubes have GM around 19000, the well works tubes, after one year, have around 17000. The tube that approach 16000 are candidates for replacement but I sometimes replace tubes with 17000 GM. I look if the tube is old and if it has too much darkness built up on the glass. It might be not right way to do but I have many of those tubes – so why do I need to collect them? Live of high-end audio person is about who accumulate more tube before then die – I do not want to be a winner in this competition. I will be very comfortable if at the time of my final hart attack I will not have any tubes left….

Now, about the rejection rate. For all time I had one or two 6E5P/6E6P that I trashed right from beginning as they were not useable.  Another one or two tube did not give sufficient current. I generally would like to have 35Ma at 4V bias, if tune do not give it then I use it in A, B, C, D channels of 6ch-Milq. I need a full 35mA for single-stage amps of Melquiades. The 6E5P/6E6P are Russian tubes and as any Russian tubes they have notoriously wide parameters. The 6E6P-DR shall be military tube and shall have much less spin off the parameters but it is not what I see. What is good about those tube is that if you get one that operate as you want then it will most like to maintain this operation mode very stable. At least I did not have any single 6E5P/6E6P that failed on me after it was accepted on duty.

It might be no a lot but this is all data that I have. The tube is not used widely for a long time. The history of it’s use in high-end audio started in 1999 what Dima “discovered” it for audio. There is no known to me motioning of this tube in audio before.  If you plan to use 6E5P/6E6P then a tube tester (I am sure you have)  and it will be sufficient for initial filtering out the bad tubes, then they shall be working fine.

manisandher wrote:

Hi Dima, Do you know if this is similar to the approach Tim de Paravicini took in his direct-coupled amp placed inside a Quad? I'm currently using Quad speakers (I gave up on the horn approach through sheer frustration) and it seems to me that this is a great way to go... Mani.