OK, here comes another big sandwich to digest over the weekend.
This is where I should have read GE's General Characteristics - and I do plan to do so - but I am just getting back to finishing my 2 channel rig after an audio hiatus (lack of working computer, other pressing issues, etc). Still listening, of course, but progress halted for a time. Since my wife has OK'd room in the budget for tube investments, I need to ask these questions....and since the crossover capacitor replacements have allowed me (and her) to hear more audible differences between channels, I wish to do the best I can based on what info you folks can give me.
Now that I've lived with my MC-30 pair for about a year with the given supplied tubes still in the amplifiers, I have begun investigating and collecting some tubes for these for trial. My amplifiers have mismatched (not electrically, but different branded tubes) as I received them almost one year ago. Since there is some room in our budget here - typically the case this time of year - I wish to begin collecting/selecting lifetime tube stocks for these amplifiers. I have obtained some used/fully tested and matched tubes for trials (12AX7 Tele smooth plates, 12AU7 Mullard and Amperex, 1950's RCA blackplate 12BH7A's and 1940's RCA 12BH7 single wings) - and am looking to purchase others (mainly rectifiers and outputs). I do, however, have some confusion as to what variants are actually proper in certain slots.
For the rectifiers (5U4's): I have been given some opinion from Mcintosh people that it is not recommended to vary to other rectifiers than the 5U4GB - 5U4G for example. I am well aware that many on this and other forums have gravitated to the 5U4G coke bottle rectifiers in these amps (instead of 5U4GB), with apparent success. I have a feeling that the Mc people are recommending 5U4GB's for safety and the fact that I am relatively new to tubes - and want me to make "safe choices" - which is understandable.
I figure, however, that if so many are using 5U4G's without smoking thier MC-30's, that something must be OK with this. I know these rectifiers spec differently, but am unaware of how to interpret the data in front of me.....and if they are inappropriate, what in the data should be telling me so.
I also want to know about "SLOW RISE" rectifiers - if they are desireable to an MC-30 owner for any reason, and if there are specific rectifiers I should be looking at in this regard.
I have a similar question regarding using the 12BH7 (RCA single winged black plates, 1940's version, in this case) vs. the RCA 12BH7A blackplate. Is there any electrical reason I should be aware of in regards to using the non "A" version in these amps? I know the "A" version specs differently, but am unsure if the non "A" version is OK by the manufacturer's specs on the 30's.
On the 350B: I read somewhere that the 350B doesn't give as much power output in 30's, and that the operating characteristics are different from a 6L6GC. In what way, and what long term effects could arise from using a 350B?
Also, would a WE 350A be an option here? I have access to a quad of these for (I think) a good price.
I looked at this page, the Duncan amps page for tube specs, to see the ratings for the 5U4G and GB variants:
http://tdsl.duncanamps.com/show.php?des=5U4G - 5U4G ratings
http://tdsl.duncanamps.com/show.php?des=5U4GB 5U4GB ratings
And the 12BH7 ratings:
http://tdsl.duncanamps.com/show.php?des=12BH7 12BH7 ratings
http://tdsl.duncanamps.com/show.php?des=12BH7A 12BH7A ratings
6L6CG ratings: http://tdsl.duncanamps.com/show.php?des=6L6GC 6L6GC ratings
350A or B ratings: Having a bit of trouble finding that info at the moment.
And finally, the manual for the MC-30 is this PDF file: http://www.berners.ch/McIntosh/Downloads/MC30_own.pdf MC-30 manual in PDF
The voltage spec info is on page three. I know what I need to know is in the links above, I am just unsure of how to interpret the data.
This is where I need to order "General Characteristics" by GE, I suppose - and I will get to that - but since my wife has approved a bit of fundage for the tube upgrades, and my amps have mismatched tube brands in them currently, I wanted to clarify these issues before I proceed
Thanks very much in advance.
This is where I should have read GE's General Characteristics - and I do plan to do so - but I am just getting back to finishing my 2 channel rig after an audio hiatus (lack of working computer, other pressing issues, etc). Still listening, of course, but progress halted for a time. Since my wife has OK'd room in the budget for tube investments, I need to ask these questions....and since the crossover capacitor replacements have allowed me (and her) to hear more audible differences between channels, I wish to do the best I can based on what info you folks can give me.
Now that I've lived with my MC-30 pair for about a year with the given supplied tubes still in the amplifiers, I have begun investigating and collecting some tubes for these for trial. My amplifiers have mismatched (not electrically, but different branded tubes) as I received them almost one year ago. Since there is some room in our budget here - typically the case this time of year - I wish to begin collecting/selecting lifetime tube stocks for these amplifiers. I have obtained some used/fully tested and matched tubes for trials (12AX7 Tele smooth plates, 12AU7 Mullard and Amperex, 1950's RCA blackplate 12BH7A's and 1940's RCA 12BH7 single wings) - and am looking to purchase others (mainly rectifiers and outputs). I do, however, have some confusion as to what variants are actually proper in certain slots.
For the rectifiers (5U4's): I have been given some opinion from Mcintosh people that it is not recommended to vary to other rectifiers than the 5U4GB - 5U4G for example. I am well aware that many on this and other forums have gravitated to the 5U4G coke bottle rectifiers in these amps (instead of 5U4GB), with apparent success. I have a feeling that the Mc people are recommending 5U4GB's for safety and the fact that I am relatively new to tubes - and want me to make "safe choices" - which is understandable.
I figure, however, that if so many are using 5U4G's without smoking thier MC-30's, that something must be OK with this. I know these rectifiers spec differently, but am unaware of how to interpret the data in front of me.....and if they are inappropriate, what in the data should be telling me so.
I also want to know about "SLOW RISE" rectifiers - if they are desireable to an MC-30 owner for any reason, and if there are specific rectifiers I should be looking at in this regard.
I have a similar question regarding using the 12BH7 (RCA single winged black plates, 1940's version, in this case) vs. the RCA 12BH7A blackplate. Is there any electrical reason I should be aware of in regards to using the non "A" version in these amps? I know the "A" version specs differently, but am unsure if the non "A" version is OK by the manufacturer's specs on the 30's.
On the 350B: I read somewhere that the 350B doesn't give as much power output in 30's, and that the operating characteristics are different from a 6L6GC. In what way, and what long term effects could arise from using a 350B?
Also, would a WE 350A be an option here? I have access to a quad of these for (I think) a good price.
I looked at this page, the Duncan amps page for tube specs, to see the ratings for the 5U4G and GB variants:
http://tdsl.duncanamps.com/show.php?des=5U4G - 5U4G ratings
http://tdsl.duncanamps.com/show.php?des=5U4GB 5U4GB ratings
And the 12BH7 ratings:
http://tdsl.duncanamps.com/show.php?des=12BH7 12BH7 ratings
http://tdsl.duncanamps.com/show.php?des=12BH7A 12BH7A ratings
6L6CG ratings: http://tdsl.duncanamps.com/show.php?des=6L6GC 6L6GC ratings
350A or B ratings: Having a bit of trouble finding that info at the moment.
And finally, the manual for the MC-30 is this PDF file: http://www.berners.ch/McIntosh/Downloads/MC30_own.pdf MC-30 manual in PDF
The voltage spec info is on page three. I know what I need to know is in the links above, I am just unsure of how to interpret the data.
This is where I need to order "General Characteristics" by GE, I suppose - and I will get to that - but since my wife has approved a bit of fundage for the tube upgrades, and my amps have mismatched tube brands in them currently, I wanted to clarify these issues before I proceed
Thanks very much in advance.
Last edited: