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I just started fiddling with tubes in my DR504 head...just for fun and for learning's sake. I pulled the Ruby EL34BHT tubes and replaced them with matched JJ E34L's....and pulled the original Mullard 12ax7's and the Groove Tube in V1...replaced them with a high gain JJ ECC83S with a balanced tube in the slot furthest away from the input (assuming that's a phase inverter slot).

I wasn't too impressed to be honest. Feedback was far worse than the previous tube arrangement and the tone became a bit "tinny" sounding. It had guts for sure...but...just not right.

Going to swap preamps around a little...going back to an original Mullard in the V1 and going to try standard JJ ECC83S in the middle to slots....leaving the balanced in the last.

I also have some of the ECC803S from JJ available....lots of options for preamp tubes. In the power section I have these matched E34L's...the Ruby's...and of course my original Mullards...which I want to hear...but I want to save kinda...not sure why...resale value I guess if I decide to sell ever.

Tell me what you think...what would you be apt to try? What have you tried and liked or disliked?

E34L's run HOT...I don't have the a bias mod installed and don't really intend to. I put the Ruby's back in and they not only sound better to me but they don't run nearly as hot as the E34L's. So that part of the experiment done.

I replace the Mullard in the V1 with a long plate ECC803S and can't tell a significant difference. I'll probably run it like this and let my son play (he has the realy ear) for a while.

Anybody else have the same experience with the JJ E34L tubes in their Hiwatt? I was scared to keep em in there to be honest.

The Phase Inverter is the middle socket of the group of three. YMMV, but I prefer to use an ECC81/12AT7 in that position (with Mullard CV4024 being my favorite). Those who prefer more gain/drive will run ECC83/12AX7's there.

I haven't experienced the hot running issue you mentioned with JJ E34L's. Guess they aren't a good fit for your particular DR504 (or line voltage). I've run them in DR103/105's without issue. Not saying they're my all-time favorite tube, just a good cost-value proposition.

Haven't heard much about Ruby Tubes lately. Have you had those for awhile or did you just pick them up?

Interesting observation about the ECC803S in V1. If there truly isn't much difference between a Mullard ECC83, either your Mullard is worn out or we can all save a bunch of bucks by using those JJ's instead. Please post your son's impressions as well.

Dave

I have had good luck with JJ E34L's. I have avoided the JJ EL34. I haven't added adjustable bias to any of my vintage HIWATTs and those with the E34L's ahve stood up just fine.

I have also had good luck with the GT EL34M. these have alot more midrange emphasis than the JJ E34L

I have only had 2 sets of =C= EL34's and they have done well also.

I prefer a real Mullard 12ax7, or Brimar 12ax7 in V1 and Mullard cv4024 in the PI. In the other positions I use whatever is laying around.

The Ruby tubes were suggested and installed by the tech who went through the head complete after I got it so they're new....and I guess they get pretty darn warm too after another look whith my son playing.

To my son's ear: The Mullard in V1 provides a deeper, more rich sound...darker all around (my favorite)
JJ ECC803S in V1 brighter..."more trebley"...grittier with more bite (my least favorite but the kid liked this one the best)
JJ ECC83S in V1...something in the middle with good mids and more punch (this one was marked as a "high gain" tube from Eurotubes)

Does any of this follow any particular logic? Is that to be expected from these tubes in my amp?

Will any of the other preamp positions have as much effect on the tone?

Also, I'm contemplating giving the E34L's another run for a fair comparison. If they do indeed seem to be getting hotter...is this a real cause for concern? I don't mind smoking a tube, but don't want to jeapordize anything else in the amp.

jrsdws wrote:Will any of the other preamp positions have as much effect on the tone?

Also, I'm contemplating giving the E34L's another run for a fair comparison. If they do indeed seem to be getting hotter...is this a real cause for concern? I don't mind smoking a tube, but don't want to jeapordize anything else in the amp.

V1 and V4/PI are where you'll hear the most difference.

When you say hot do you mean the plates are glowing orange/red? That would be bad. Smoking a tube can cause other nastiness inside the amp. Arcing, burned resistors, etc.

If I hear a tube going bad (that background hum that gets louder and louder until -hopefully- a fuse blows) I'll shut 'er down before it has a chance to wreak havoc.

No the plates never glowed or changed color...it just seemed that the filament (or whatever it is that runs up through the center) glowed brighter and put off more heat.

Heat (as in too hot to touch) is fine and normal. As long as the plates aren't glowing you should be safe.

The other day,
I was lucky enough to have someone I know who gave me a box of nos tubes !
I told him that I will choose the ones I like and he could tell me how much it will cost!
He said it`s yours ,keep it !! He`s a very nice man a certain age and it was a gift!!
I still dont understand how this happened to me but thank god!

2X Mullard 12ax7 with BVA logo with different getters
1X Jan (the rest is gone)
1X BOGEN apparently Mullard made
1X Brymar 12ax7
1X Amperex Bugle Boy12ax7
1X Tungsram 12ax7
1X RCA 12au7
1X Amperex Bugle Boy 12au7

I was surprised of the difference in sound of each tubes !

The Brymar had the most gain
The Bogen was very warm and schewy
The Mullards ,warm and smooth
The Tungsram had something in the mids that the others did`nt have

and the RCA 12au7 that has 60% less gain than the AX7 was very round and woody in a good way!

So it`s all a matter of taste but we should`nt under estimate the importance of choosing
the right one for our own personal taste! ....but hey!....it`s not every day that someone drops a box full of nos tubes
on your door step.

Louis

Louis you dawg....you get all the good deals!!!

We're gonna run the E34L's through some paces today and watch closely...and compare them to the Rubys.....I might even get crazy and compare to the old Mullards!!! I haven't got to hear them yet.

Ok..some conclusions:

I must have been having hot flashes yesterday because I noticed very little difference heat wise between the JJ's and the Ruby's this morning.

Power tubes: Ruby EL34BHT vs JJ E34L - Ruby's maybe just a little louder but very nominal for the price difference Matched Pair Ruby's $40 vs Matched Pair JJ's $27....WINNER JJ E34L

Preamp tubes: The only thing that sounded bad was the high gain JJ ECC83S in the PI position. Going to run with current configuration of ECC803S in V1, balanced ECC83S in PI, and regular JJ ECC83S in other two positions.

It was a fun little experiment. Thanks for the input.

That little 12ax7 in V1 can do wonders if you pick the right one!


Louis

I stumbled across this article about 12ax7 and 12at7's and PI's. It's a good read!

http://www.guitaramplifierblueprinting. ... verter.pdf

It totally supports what Old School Dave (I wouldn't speak for Dave unless I was 100% sure about this.) and I have experienced with High Quality Mullard 12at7 or the military version CV4024 in the PI of Hylight HIWATTs.

Dr.HIWATT wrote: It totally supports what Old School Dave ...

You mean to say I was right about something ? Better buy a lottery ticket today!

That is an interesting article. I didn't know a lot of the technical stuff Myles Rose detailed, but it makes sense. To my tired old ears, Hiwatts just seem to "breathe" better with a CV4024 in the PI socket. And, I've never worried about lacking gain/drive.

Sit back kids - lemme tell you a story:

One of the best guitar players I personally knew was (is) Bobby Barth, then of the band "Babyface". He was the first guy I saw that had really mastered harmonics and hammer-on technique. Bobby played a Custom L5S with low impedence pickups. This was in the day when folks were ripping apart their Les Pauls and Strats to stick in DiMarzio Super Distortion pickups. Bobby told me - and, I'm paraphrasing here 'cause it was 1975 and, well, you know - "You can always dirty up clean, but you can't always clean up dirty.".

That's tided me over well (thanks, Bobby!).

Dave

I thought we could not change the rules with the valves ?



http://i73.photobucket.com/albums/i210/ ... 3_2jpg.jpg
http://i73.photobucket.com/albums/i210/ ... R103_1.jpg

Thanks

Gilles