MC30 tube rolling - how much difference?

[jgnagy]

Hi Folks,

I'm new here - stopped by to get the Steve Hoffman discography and started reading away. Hooked.

So, I have a pair of MC30s in my system, and I notice Steve praises the GE 6L6GC to no end. I use the Philips/Sylvania 7581A with good results. I picked that tube because I have a lifetime supply of them (bought a bunch back when they were drying up since I use them in my guitar amps). If you're unfamiliar with the tube, its an uprated 6L6GC with 35 watt plate dissipation. Very similar to the Sylvania 6L6GC.

Forking out for 4 GEs would be a bit of an expense, so I wanted to find out people's tube rolling experiences with this amp. I'd like to know if I should I expect a drastic or subtle difference? I'm guessing there will be subtle differences in certain tonal areas, but overall the MC30 will still sound like an MC30. Is this about right?

Pre-drivers are Teles for the 12ax7 and 12au7, RCA for the 12bh7, Philips/Sylvania for the 5u4. The preamp is a C22. I have recapped both amps and replaced a few resistors that had strayed.

Thanks for the input - great forum!

John

[Dean De Furia]

Hi and welcome!

MC30's are great aren't they? I also have a C22 with them and love the sound. I have tried RCA, GE, and Sventlana 6L6gc's in mine. All sounded good with the RCA and Sventlana having better bass than the GE's. The GE's, however, are THE tube to use with these. They are just unreal with the midrange. The singers just come alive in my listening room.

I tried 5UG and a NOS set of 5UGB rectifier tubes and again Steve was right with the GB's having quicker response (less "sag").

You might want to try different 12AU7's as Telefunkens tend to be a tad "slow". I'm using Mullards with nice results.

I'm sure others will chime in here.

Good luck!

[Steve Hoffman]

John,

Welcome, and a tip for finding GE 6L6GC's cheaply:

In the 1980's and early '90's, GE tubes were made in big quantity by Richardson. They sound like older GE's and they look pretty GE like, but (and here is the clincher), the boxes, while looking like they are from the 1950's say up in the top corner ("Made from recycled paper"). This is your clue that these are contemporary GE's and should only cost around $100.00 for the quad at the most. These were also branded "Groove Tubes, made in USA" as well. Try and find some of these; I use 'em and swear by them. They last forever and they make your MC-30's and Mac 240's really come alive with magic midrange palpability. It's uncanny. My Gold Lion Genelex KT-66's and my Amperex EL-37's are just sitting around gathering dust!

I use Sylvania 6L6GC's in my 1954 Fender Concert amp and they are perfect for that application.

[jgnagy]

Thanks for the tip Steve - any hints on where to find the later Richardson/GE tubes?

Also, saw this:

http://groovetubes.com/assets/1713_GT6L6GE%20PR%204_02.pdf

Looks like GT bought the GE machines from Richardson. At $180/quad, you might as well by NOS. Nice to know someone's making them though.

John