[Gopher]

I just received a Melody MK88 from Hugh and I must admit to it sounding and looking very nice out of the box, but this integrated was said in the reviews to use 6sn7 tubes.  On the amp itself, however, the tubes are labeled 6sj7... 

I acquired some very nice Ratheon tubes I'd hoped to use in this integrated, but am scared to even try them now.

Can anyone tell me if this is safe or if theres been a mistake?

[gooberdude]

I dont know much about tubes but have been studying the variants of certain tubes including the 6SN7 lately.  I don't see that they are compatible.  One is a pentode, the other dual triode.

There's a thread at DIY audio from a guy who bought a 2A3 amp kit & had the same dilemma.  Most responses warned against swapping, but i'd contact Melody just to be sure.

[decal]

  i'd contact Melody just to be sure.

Excellent advice.

[Gopher]

Thanks.  I'd written to Hugh yesterday who will follow up for me this weekend and let me know for sure.

EVERYTHING I've read online about it says 6sN7--other advertisements, professional reviews, etc.

http://angelcityaudio.com/products/melody-valve-hifi/mk88/
http://reviews.audioreview.com/melody-mk88-32w-kt88-tube-integrated-amplifier-review

[woofersus]

You should know that Hugh's access to his email may be sporadic over the next couple of weeks as he's out of the country.  He'll be meeting with the folks from Melody though, so he can ask the necessary technical questions for you assuming he gets the message.

At first glance, it would appear that a mistake has indeed been made.  I've never actually had an MK88 in stock here yet, so can't look for myself, but the specs listed on the websites (I manage both his and mine) were copied from info sent by Melody.  It's a brand new model and Melody has been known to tweak a bit before, so it's possible the spec got changed and Hugh just didn't notice when using the amp.  Obviously I didn't.  Melody does use 6SN7's extensively.

I don't believe a 6SJ7 and 6SN7 are interchangeable, as one is a pentode and the other is a double triode.  Can you check one of the tubes and make sure the labeling matches what it says on the amp?

[Gopher]

I've been told by an equipment designer that the 6sn7 may be substituted in many cases based on his experience with older amps and guitar amps, but mentions the that the two tubes do use different voltages.

I have also noticed the tube store says 5693s are a direct sub for 6sj7...



 

[woofersus]

Yes, I believe 5693's are equivalent.

[bunky]

the link to Angel City Audio for the MK88 says that the tubes are 6SJ7 and the photos in the link clearly show Chinese glass bottle 6SJ7 pentode tubes in the forward most positions on the MK88.i have a JAS Bravo 2.3 6C33-B powered set amp that uses the 6SJ7 and i use NOS RCA red 5693's in it. Angela instruments sells NOS Sylvania glass bottle 6SJ7's and i believe that the Tubeman sells them too.i would not plug a 6SN7 into the MK88 

[woofersus]

The website used to say 6SN7 as Gopher pointed out.  I fixed it already. (a close look at that picture confirmed it easily enough)

I'm still trying to sort out the source of my incorrect information, and why it happened, but ultimately we screwed up, because one of us did the web page and another actually had the inventory, and we didn't realize our lines were crossed.  It's a new model and Melody uses 6SN7's extensively, so I just never questioned it.

I'm glad at least he likes the sound of the amp.  As far as whatever else, we'll get him taken care of.

[Gopher]

Yeah, I'm confident things will get sorted soon.  I'm also holding onto hope that I can plug in these awesome raaytheons.