Marshall 100W OT replacing Twin OT in 100W Dumble

[David Root]

Anyone have any comparative notes on this change, other things equal? I am wondering how the Marshall would do in a #124 circuit?

[tubedogsmith]

I've built a couple amps with Marshall style iron and thought they came out real nice. I still find that I prefer 6L6's in these amps although I'm not done trying EL34's.

[ayan]

I've built a couple amps with Marshall style iron and thought they came out real nice. I still find that I prefer 6L6's in these amps although I'm not done trying EL34's.

That sounds good. This is bound to be like the argument about tomatoes, ie., "tuh-mey-toes" VS "tuh-mah-toes." As per my experience, the amps with EL34s and Marshall style iron tend to sound better.

Cheers,

Gil

[tubedogsmith]

well, I'm going to be trying EL34's again in a day or so along with a few other small circuit changes. Hope springs eternal!!

[mojotom]

I was thinking about using el34 for a 100W Bluesmaster using Marshall irons but didn't find good reports.
I like the 124 a lot and want to build something different (I prefer el34 to 6L6 in most amps).

EL34 and more voltage means more punch and attack to me, still lots of people here report a softer attack.

EL34 with Musicman PT might be the solution.

[talbany]

34's to me..

More touch sensitive..Faster
Crunch quicker
less low end response/Boxier
Slightly louder 3-5 db (in same amp)
also sound better to me w/Marshall Iron..Brings out more of the above qualities

I think of the 34's as a Ferrari and the 6L's as a Rolls.. Weird huh!!


Tony

[David Root]

I sort of expected this, opinions differ!

I had thought because the 100 Marshall OT is built on a 100W frame and the Twin OT on a 50W frame that there might be better low end performance, period, but I didn't hear that in your responses. I am considering putting a M-C 100W Marshall OT in my #124, currently equipped with a M-C Twin OT.

I like the Ferrari/Rolls comparison, unfortunately I don't think that extends to EL34s holding up in service like 6L6s do, from what I hear from regular EL34 users.

I would like to like EL34s but I generally don't. OTOH I have never heard old Mullard XFs either, but I know and love RCA 6L6GC blackplates.

[67plexi]

David, I’m not sure what you want to get out of your #124 build. From my observations the Dumble style amp
It’s about preamp gain not so much power tube gain or distortion. First off I know nothing about new production tubes the new tubes I have tried tested strong on my tube tester but sound harsh in use.
The black or gray plate USA made 6l6gc is a great power tube and long life @ 440v on the plates.
My all time favorite is the kt-66 GEC. Solid lows, mids ,and highs. The el-34 mullard xf dark sounding @ 440v on the plates will clean up @ 700v on the plates. The next one is the GEC kt-77 dual getter it is a cross between a 6l6 and an el-34 off the charts price wise for a NOS quad. On the output transformers
I recall could be wrong the fender twin iron is wound @ 2:1 ratio and the Marshall 100 watt iron is wound 1,7:1 ratio could be to clean up the top end on the Marshall not sure. Nice clean work on your #124 build I enjoyed the photos. My first #124 build I don’t care for it to much I have tweaked it to the max I can’t get a great clean sound out of it ABC it with my favorite amps and it falls short.
Working on the second #124 build with vintage iron I will leave it as is for reference.
“Oh” the KT-66 is a 1959 Rolls-Royce Silver Cloud and the KT-77 is a 1962 Ferrari 250 GTO.

Take care Steve.

[David Root]

Thanx for all the NOS tube experience 67plexi! I don't use new manufacture tubes in my amps either. GEC KT66s are too rich for me I think, don't they cost more than RCA blackplates?

My#124 sounds great clean but I have a fizz issue on the ODS. I need to scope it to find out where the parasitics are.

Vintage iron I'm sure will make a difference to a #124, or any other amp for that matter. I've done a '70s ODS with old Bassman iron that is the best 50W I ever built.

Dogears suggested changing some stages from 100K/1K5 to higher gain and some other changes, however I have mislaid that after I printed it out and have to go find it again.

Guess I should make those changes before I switch in the Marshall OT.