So - if you were interested with the opportunity ---

[richieb]

Which would you choose - McIntosh Mc30's or Mc60's. Both pair are near mint quality and have been DeWicked. Have never heard either but I am buying one or the other. 30 watts vs. 60 watts really of no consequence with KHorns. $$$ will be same for either.

[Ceptorman]

Might as well go for the MC60, no replacement for displacement.

[richieb]

The 30's use the 6L6 output tube, the 60's use 6550. Research tells me a restored 30 has some of the best mid-range you could ask for, a little soft both top and bottom. The 60's with more controlled bass, extended top end and not as lush mids as the 30's. Seller is a great fellow and hasn't decided which or both pair to sell. Either way I will most likely own one or the other, or both.

[Fjd]

If you look at the curves of the 6L6 and 6550 you will find that they are very similar; however, the 6550 has more plate dissipation. Both the MC30 and MC60 seem to basically use the same circuit with the MC60 modified with an appropriate power supply for the 6550.  Of course, the output transformer will be different as the MC60 will be wound to handle more power output,  Now from a MC30 to MC40 there are more substantial differences as the MC40 has a solid state power supply, cathode feedback to driver stage, and a filter choke all of which are different from the MC30.

 

It has been a few years now since I bought mine in 2007, but the thing that attracted me to the MC30 was a much greater selection of "cool" tubes that can be obtained and rolled in place of the 6L6 as opposed to the selection to roll in place of the 6550.  For example, there is the metal 1614, the British Genalex KT-66, the 5781A, and Tung-Sol 5881, among several others.  Most of the 6550/KT-88 are new production or the NOS tubes are rare or priced out of range such as the solid black plate Tung-Sol 6550 or the British Genalex Gold Lion KT-88s.  Of course, there is the new production EAT KT-88s for about $1,600 a quad.  

 

If you decide upon the MC60 and the venerable 6550/KT-88 series tubes, if it were me, I would probably have just kept the VRDs and looked into this MagneQuest transformer upgrade for the VRDs. 

 

http://magnequest.blogspot.com/2016/01/nos-valves-vrd-amplifier-with.html

Edited April 6, 2016 by Fjd

[richieb]

Thanks Fjd - your point on the 60's and VRD's is well taken. While the VRD's sounded mighty fine I finally gave in that I favored lower power single ended. Which is why I tilt heavily to the 30's and its supposed "mellowed" presentation as compared. And aside from sonics is the iconic nature of the Mc's. Pairing the 30's with KHorns would make for a True Heritage system.

[jimjimbo]

May I have (purchase) whichever ones you decide against?  Seriously....

[jimjimbo]

but the thing that attracted me to the MC30 was a much greater selection of "cool" tubes that can be obtained and rolled in place of the 6L6 as opposed to the selection to roll in place of the 6550.  For example, there is the metal 1614, the British Genalex KT-66, the 5781A, and Tung-Sol 5881, among several others.

 

 

Is this really the case?  Can the 30's support (correctly) those tubes other than the 6L6GC?  Aren't some of the voltages required for those tubes different than the 6L6GC?

 

And if this is true, do you know if this is also the case with the MC240?

[Fjd]

 

but the thing that attracted me to the MC30 was a much greater selection of "cool" tubes that can be obtained and rolled in place of the 6L6 as opposed to the selection to roll in place of the 6550.  For example, there is the metal 1614, the British Genalex KT-66, the 5781A, and Tung-Sol 5881, among several others.

 

 

Is this really the case?  Can the 30's support (correctly) those tubes other than the 6L6GC?  Aren't some of the voltages required for those tubes different than the 6L6GC?

 

And if this is true, do you know if this is also the case with the MC240?

 

 

 

 

It is always good to check or know the specific voltages of the specific amplifier; however, if your circuit calls specifically for the latest version of the 6L6GC, it is probably designed to run the tube harder and you probably cannot use the earlier 6L6 models that were rated much lower.  My Harman Kardon Citation V would run the 7581 tubes pretty hard and it ran the 6L6GC tubes just fine but if just plugging in something like a 5881 the tube would have a much shorter life span.

 

My MC30 circuit used the 1614 metal tube which is similar to the 6L6; however, if I'm remembering correctly, there may have been a circuit designed for the 6L6GC toward the end of the MC30 life.  I don't have any experience with the MC240 design other than identifying the differences with the MC30 and wanting to go with the more classic tube rectification.

 

Edit: Brent Jessee does a good job of outlining when the various tubes can be substituted in what situation at the link below.

 

http://www.audiotubes.com/6l6.htm

 

 

 

Edited April 6, 2016 by Fjd

[Dr Morbius]

Pairing the 30's with KHorns would make for a True Heritage system.

 

​Truer words were never spoken……Thats something I would dearly love to hear!