aright2 wrote: "The ultra-linear design is a Class A/B amplifier." Just to be clear - and I'm sure aright2 knows this and didn't mean to imply otherwise - the MV-60 would still run in Class A/B if rewired for triode.
I see that I made a mistaken statement when I posted here back on 2/18/03: Actually, VTL's run their output tubes in either triode or tetrode mode (switchable in many models) but *not* in pentode, even if the output tube used is a pentode type. Oops. |
It is not a question of which is better it is matter of preference. A triode valve has a more linear response than a Pentode valve. This leads to a lower harmonic distortion when the triode is set-up correctly. The ultra linear design is a class A/B amplifier. The configuration of the output valves is set-up to help over come the non-linear response of the valves. It is also worth pointing out it is the harmonic distortion that give a valve amp its "sound". A SS amp has a far lower harmonic distortion figure. The SS introduce mainly odd harmonics because when it is overdriven it clips quickly rather than gradually like a valve amp. A MOSFET amplifier is a good as it gets as far as Hi-Fi is concerned because they are far more linear than any valve however Hi-Fi is not what a valve amps are about. |
As as someone new to tubes, you made an excellent choice. I'm on my 4th c-j piece (Prem. 16LS II) and have found their stuff is reliable, well engineered, and made by a company with superb customer back-up.
My experience with Tab Sigs is that they can tend toward the bright and lean. I think it'd be worth trying the triode version (you'd still be push-pull in operation) which most likely would be cleaner but more natural in sound. I had a Mesa Barron which was switchable and found triode to be the most musical with my ProAc 2.5s. I now use SETs but did borrow a c-j 60 (triode version) about 1 1/2 yrs ago out of couriosity. It was wonderfully musical and if I ever leave SET land (fat chance) I'll buy one of them or whatever c-j has current. |
Gs5556: That was a very good basic description, and answered my question. Thank you. |
I posed a similar question to the folks at Rogue Audio concerning the set up of my Rogue Audio Magnum 88 amp. Here is the response I received, "with speakers that tend toward the bright side, the triode mode may sound smoother and more natural.For speakers that tend to be laid back, UL may give it a bit more dynamics and or punch. It depends on the characteristics of the speaker". |
Btrvalik -- as you are driving Tablettes, I wouldn't change to triode if I were you. Tablettes are not very sensitive (as you note) &, if I remember correctly, they're not the easiest of loads... |
The "ultra-linear" configuration was developed by Mullard to sell their EL34 pentode. It generally differs from a typical SET in that the SET usually has two tubes per channel - driver (eg 6SN7, 6922) and output (eg 2A3, 45, 300b). An ul amp will usually have four tubes per channel - an input pentode (EF86), a triode phase splitter (ECC83) and two output EL34 tubes - and it splits the signal. This is a push-pull type confuration whereas the SET is a straight-thru amplifier. The difference is that the SET sees fewer signal manipulation than the ul, similar to Class A transistor vs Class A/B push-pull ss amps. The "ultra-linear" name does not describe signal linearity but instead describes the way the EL34's are connected to the transformer (both the anode and the screen grid are connected - to stabilize the whole setup).
The trade off is power for the signal linearity of the SET (I agree with Marakanetz, SET signal path is usually shorter). Of course, it does not mean one is better than the other - there are excellent ultra-linear designs (Mullard 5-20) that can give the best of both worlds. |
Thanks for the info... Most of my question is just because I'm a EE geek and new to tubes. I to am interested in the circuit design. I have ProAc Tabletts which I think are somewhere in the 87 db range. I use these with a HGS-10 subwoofer which is not some peoples favorite but it's size solved a huge placement issue for me. I love the sound of this amp in ultralinear but I just gots to know.... |
Can someone give us the basic circuit design differences and theory behind ultra-linear and triode? I have heard the two and it is clearly a trade off, but what I do not know is the circuit operation and how it directly affects what I am hearing. (clearly tube amplification is not my area of expertise--but I do enjoy dabbling in tubes). |
Despite what you might imply from Marakanetz' post, the signal path will be no shorter in triode mode than it is in ultralinear, though there will be fewer engaged elements inside the power tubes. Unfortunately, with the C-J amps it's not as simple as flipping a 'triode' switch to do this experiment (unlike the VTL's, which BTW are not otherwise wired in ultralinear but regular pentode), as the amp needs to go back to the factory for the modification. Going triode will not be a panacea or unequivocal gain - what you pick up in purity you will probably lose in extension and drive. FWIW, as a MV-55 owner (who now uses VTL's) I once investigated this procedure (since I live about 25 minutes from the C-J factory), and learned that C-J estimates that at least half of the audiophiles who try this mod wind up getting their amp converted back to ultralinear operation in the end. This tells me that unless you have quite efficient speakers, a smaller room, and prefer to listen mostly to smaller-scale acoustic and/or vocal music, you'll probably be better off overall using your MV-60 the way it came. |
Not that simple a question - a lot depends on the speaker you are using as well as your listening preferences. Most generally speaking i think most feel that ultralinear is a bit less delicate, for example as ss is to tube, ultra linear would be to triode. Why don't you post your speakers and your preferences - perhaps someone has the same and can comment. |
the shorter the signal path the greater the sound. under this theory SET is the best with single- power tube and possibly directly coupled(OTL). there are not too many speakers that are efficient and full range and in cases otherwise the greater power is needed.
i use triode mode in my VTLs despite having low-efficient speakers on the following reasons:
1. i have a small listening distance
2. i can hear more notes and instruments where every part of instrument is so clearly heard that you can hear button switching noise even in big bands. |
