New C22 Vacuum Tube Preamplifier Mk V

[robfine]

Charles, I have a PrimaLuna integrated amp. PrimaLuna was designed to facilitate tube rolling. I am not suggesting any comparison between your MC 3500s and what I have. However, you may be interested in PrimaLuna’s website. There are a number of pages that discuss tube rolling, and tube rolling for beginners. I think looking at that would probably start to answer some of your questions. It even goes into certain suggested tube rolling combinations and what they would result in. Now all that is particular to the PrimaLuna equipment but I tink it gives a good idea of what you can accomplish with tube rolling and then you can apply that general knowledge to the particular equipment you have in mind. From what I’ve seen, the real tube rollers on AA can be found spending time on the Dennis Had Inspire Amps string. It’s probably worth a few minutes of your time looking there as well.

[Charles]

Thanks very much everybody about the sage knowledge. I'm sure that I missed it but this is a first for me on AA concerning basic tube knowledge. What is the recommendation concerning using gloves when handling the tubes? On YouTube I see folks handling their tubes with bare fingers but I have heard this is a no no. Obviously one should not handle their tubes with dirty hands but clean hands leave oils and fingerprints.

Best

Charles

[Formerly YB-2]

All of McIntosh tube amps (not sure about the two MC3500 models) use the Frank McIntosh/Gordon Gow designed 'unity' circuit. Such noted tube designers as Tim De Paravicini (may he RIP) have said things like, "I wish I would have invented that circuit." The design has several notable features. 1st, it does not require the user to make any bias adjustments. 2nd, tubes do not need to very closely matched (again, do not know about the EL509S tubes used in the current MC3500). Just plug in a pair of decent tubes per channel and the circuit takes care of the rest. 3rd, the power tubes are not driven as hard as they are in many competing designs and tend to last longer than in many other circuits. There are a couple of lesser details that I don't recall at the moment.
For me, the crowning glory is the sound.

[Antonmb]

Originally Posted by Charles

What is the recommendation concerning using gloves when handling the tubes?

Opinions will vary on this one. Some claim that the oil from your fingers can create a variation in the heating of the glass and lead to premature failure or glass breakage. Others claim that's an old wives tale, probably derived from the effect of oil and grease on halogen bulbs, which is quite real. I use gloves or a cloth or a tube grabber/holder when removing and inserting tubes because I like them clean and not with fingerprints on them, and also to protect my fingers just in case a tube is tough to remove and breaks in my hand. It only happened once in 20 or 30 years of playing with tubes, but once was enough.

[Antonmb]

Originally Posted by antonmb

opinions will vary on this one. Some claim that the oil from your fingers can create a variation in the heating of the glass and lead to premature failure or glass breakage. Others claim that's an old wives tale, probably derived from the effect of oil and grease on halogen bulbs, which is quite real. I use gloves or a cloth or a tube grabber/holder when removing and inserting tubes because i like them clean and not with fingerprints on them, and also to protect my fingers just in case a tube is tough to remove and breaks in my hand. It only happened once in 20 or 30 years of playing with tubes, but once was enough.

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[Formerly YB-2]

Originally Posted by Antonmb

Opinions will vary on this one. Some claim that the oil from your fingers can create a variation in the heating of the glass and lead to premature failure or glass breakage. Others claim that's an old wives tale, probably derived from the effect of oil and grease on halogen bulbs, which is quite real. I use gloves or a cloth or a tube grabber/holder when removing and inserting tubes because I like them clean and not with fingerprints on them, and also to protect my fingers just in case a tube is tough to remove and breaks in my hand. It only happened once in 20 or 30 years of playing with tubes, but once was enough.

I find a paper towel works fine. I do make the effort to not handle in such a manner as to remove the printing on the tube, which can be soft and marred by heavy handling.

[PeterMusic]

Yes on either gloves or paper towel. The oil from your fingerprints will increase heat. At least one well respected tube source ships gloves with tubes

[Charles]

Originally Posted by Formerly YB-2

All of McIntosh tube amps (not sure about the two MC3500 models) use the Frank McIntosh/Gordon Gow designed 'unity' circuit. Such noted tube designers as Tim De Paravicini (may he RIP) have said things like, "I wish I would have invented that circuit." The design has several notable features. 1st, it does not require the user to make any bias adjustments. 2nd, tubes do not need to very closely matched (again, do not know about the EL509S tubes used in the current MC3500). Just plug in a pair of decent tubes per channel and the circuit takes care of the rest. 3rd, the power tubes are not driven as hard as they are in many competing designs and tend to last longer than in many other circuits. There are a couple of lesser details that I don't recall at the moment.
For me, the crowning glory is the sound.

Glenn, You have answered all my questions. I had wondered about the bias.

Best

Charles

[Formerly YB-2]

Just rolled in a set of matched Tung-Sol gold-pin 12AX7, an EH 12AX7 and a Gold Lion 12AT7 in my C22. To my ears, a nice improvement in black/quiet background and deeper sound-stage with better location of instruments. All-in-all, a nice improvement which was worth the effort of pulling the top and tube-clamp, which is a bit of a pita. Glad it isn't needed very often.