KT77s in Marshall DSL 100

[RichieB]

Hi,

Has anyone tried KT77s instead of the stock EL34s in the newer Marshalls like the DSL 100 -and if so, what was the difference in tone, headroom etc?

Cheers!

Rich.

[Denim n Leather]

Yes; KT77s are pretty bad. If you want a fuller sounding EL34, look into a 6CA7.

[HTH AMPS]

I was excited when the news of the JJ KT77 came out but they're a real let down imo - nothing like a proper NOS KT77.  Then again, nor are the EH 6CA7s, imo (sound flat and bland).

If you want a bigger bottle with more punch and headroom, go with the =C= 6550.

[Denim n Leather]

That's why you don't use the EH's!! They are rubbish!!

[RichieB]

Thanks guys, that's good to know -sounds like it should be the 6550s then. I've read about people like Zakk Wylde using them in their 2203s, but I've not heard about anyone putting them in a DSL, so wasn't sure. Anyone know if the DSL would need any mods to take the bigger valves?

Thanks again!

Rich.

[jpfamps]

I've had mixed results with JJ-KT77s, and would have to say to say it would be hard for me to give them an unequivocal recommendation.

Either 6550s or KT88s would probably be a better option.

[blue]

does this mean that various power valves can be easily substituted for each other?  my own amp has EL34's, with a switch for if you want to change to 6L6's.  are those two my only options, or would it be possible to try other valves without modification?  i've bought, but not yet tried, a set of thd yellowjackets with EL84's.  can other valves be used with the yellowjackets?

[jpfamps]

Power valves can be substituted if the following conditions are met:

1) The valves have the same pin out.

2) The sockets are wired to accommodate the valve (EL34s have virtually the same pinout as 6L6s for example, but pins 1 and 8 need to be connected externally. Many 6L6 amps don't have this connection).

3) The power transformer has the capacity to deliver enough filament current. For example EL34s require 1.4 A of current each, compared to a 6L6 which needs 0.9 A.

4) The B+ and screen voltages are within spec for the valve.

5) The bias can be adjusted appropriately. Often the bias supply will need modifying to accommodate different valves. That's what the 6L6/EL34 switch does on your amp.

Whether any such swaps improve the sound is really down to personal preference, although often running the "wrong" valves in an amp mean that the amp is not optimized for that valve.

It is fairly straight forward to design an amp that will take the most popular octal socket valves.

Yellow jackets convert an octal socket to a cathode biased noval (9-pin socket) for use with EL84s. Realistically this is the only common valve you can use with the Yellow Jacket.

Bottom line is if you are not sure what you are doing, don't try it.........

[blue]

thanks for the clarification, and i think your last piece of advice is the one to take!  curiosity is all well and good, but i'd prefer not to fry my amp.  or myself for that matter!

i will be trying the yellow jackets soon, and at some point i may try the 6L6's. i think i'll leave anything more to people with more expertise.

[hunter]

There's a lot of fuss about KT77s used to beefen up the VHT2502, which is my poweramp right now. I might get a pair and try them on one side to A/B with the Mullard EL34s that are in there as stock and see what it does sound wise.

[Denim n Leather]

There's a lot of fuss about KT77s used to beefen up the VHT2502, which is my poweramp right now. I might get a pair and try them on one side to A/B with the Mullard EL34s that are in there as stock and see what it does sound wise.

6CA7 :)

[HTH AMPS]

Most amps using EL34s should be fine to use 6550s unless the mains transformer is really tiny and right on the edge of specs for EL34s already.  6550s draw an extra 0.1A of heater current over EL34s, so in a 100w amp you're asking another 400mA which ain't too much really.  I've presonally never had a problem in this respect when putting 6550s in an EL34 amp.

Check the heater voltages when you pop the 6550s in - if they've dropped below 6v at idle, you'll probably not want to risk it.

Alternatively, run just two 6550s and you'll be fine - just set the amp's impedance to half the cab's impedance.

[TheDev01dOne]

I've never done much tube swapping or comparing so can't really say my opinion is hugely valid. Not exactly what you're asking but I swapped out EL34s in my Laney TT50 for a pair of KT77s...

To my ears it's noticeably louder and needs to be pushed a bit louder for useable practice sounds. Sounds wayyy smoother at gig levels though, especially the clean channel opened up a bit more, sounds more airy and natural IMO.

Might help you.

[hunter]

I was excited when the news of the JJ KT77 came out but they're a real let down imo - nothing like a proper NOS KT77.  Then again, nor are the EH 6CA7s, imo (sound flat and bland).

If you want a bigger bottle with more punch and headroom, go with the =C= 6550.

Did anyone have a chance to try the new Gold Lion KT77s?

I had a pair of their KT66s and they were amazing...