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In my SCA-35, RCA's came out on top, followed by GE 7189's. The Sylvania's came in *just* slightly behind the others, but not enough of a difference to be bothersome.
Hi,Since I have own a Manley Stingray and Jolida 302b I found only Telefunken EL84s and Mullard or Lorenz (Blackburn) EL84s are the among the best EL84s with superior sound. I have never liked any of American EL84s which do not sound right to my ears.I still own these tubes an very little used since I bought them (3 months ago). Believe me they are worth the money you buy. Cheers,Tan
I think this particular choice just *might* have a lot to do with the particular amplifier being "tubed." I come at this from a "Dynaco" perspective. In my SCA-35, RCA's came out on top, followed by GE 7189's. The Sylvania's came in *just* slightly behind the others, but not enough of a difference to be bothersome. I have nothing against the Mullards, but the RCA's seemed to offer just a *touch* more clarity. In other applications, I'm quite sure the order could *easily* be different. I suppose that's what "tube rolling" is all about, isn't it?Sincerely,Bill
Hi Jon L ~Your tube choices are very interesting... I deeply appreciate your being specific in giving the characteristics of the tubes you like in the application you used them. Thanks so much!Hi Bill ~I have read your awe-inspiring from-ground-up restoration project-posts on the aging Dynaco products you love so much and I can only marvel at your dedication, thoroughness, clarity of your writing and accompanying photographic illustrations, and generosity in your willingness to share your penetrating journey into the mysteries and formidable challenges of bringing back to life the very soul of these excellent previously affordable vintage state-of-the-art beauties.Thanks also for your carefully thought out list and the characteristics you feel work for your Dynaco applications.As a reference I am using a "restored" Heathkit 151A... kinda looks like a 1957 Chevy design-wise. As a teenager I would look at these fascinating designs and wonder what it would be like to live with one... now 50 years later I know!!!! and it is a delightful experience.Hi ltr317 ~You could be quite right about no "best" output tubes for all applications... but this is a place to start to get-to-know what more experienced and astute listeners of vintage amplifiers think about EL 84 tubes according to their use of them.These NOS tubes have become quite expensive... some shared insights are a prudent way of establishing a demystification and reality-check of which tubes can serve our sonic pleasures.Warmest Regards ~ Richard
Hi ltr317 ~Yes... I see exactly what you mean... your description of moving the same EL 84 tubes from one kind of application and amplifier to another and getting different "results" based on the "personality" of the equipment you are using makes a great deal of sense. Thanks for clarifying your insights... I deeply appreciate it.Hi Ericus Rex ~Unfortunately I am not well versed in the actual circuit topology of this particular Heathkit 151A rebuild... it was created by Sam Kim who lives and works in Toronto, Canada... and apparently except for the transformers and chassis it seems to be a from-the-ground-up restoration. The Heathkit has a quad... actually 2 pairs of similar EL84 tubes. A pair of Westinghouse and a pair of Mullard. The Mullard's hardly light up... one of the Westinghouse EL 84 tubes glows brightly and the other one is not as bright... I don't know if that is because of the biasing of the amp or peculiar to each of the tubes' plate current values.The sound I am now hearing is quite compelling. But I am interested in obtaining at least one extra quad or perhaps 2 in case these tubes end their serviceable life in the near future. That is what prompted me to ask my original questions about different EL 84 tube characteristics... not necessarily because I wanted to change the sound. I have only been listening to the Heathkit for 3 weeks... so I am still learning to understand what it is doing that is so deeply satisfying. Admittedly, it takes me a bit of time to "hear" what an amplifier is actually doing that makes it so special. Deborah and I listen to a great deal of small ensemble classical and jazz... a great deal of voice, from Dufay to Cassandra Wilson... Baroque... the music of other cultures including native musical forms.I hope that information helps in some way.Warmest Regards ~ Richard
Paul, There are all sorts of "qualifiers" involved in my "quick and dirty" tube testing method. For example, you need some way to measure the Cathode Current, so if the tubes are connected directly to ground, it becomes "difficult" at best. If the amplifier has user adjustable bias, then you need a "reference tube" in order to know what "normal" is. But, it is one of the BEST ways to check tubes to see if they are reasonably closely matched for push-pull operation. You DO have to make sure the Power Supply can handle increased Voltage because most of the Output load is removed from the Power Supply. In a nutshell, here's the routine, using Richard's AA-151 as an example. As I mentioned, the circuit ties all four Cathodes together and runs them through a 100 Ohm resistor to ground. Pull all the Output tubes (with Power off, of course) and insert just ONE of them. With no audio applied, Power-up and measure the Voltage at the Cathode. Write down the result. Power down and remove the first tube. Insert another tube into the SAME socket. Power up and measure the Cathode Voltage again. Write down the result. If the two tubes have close or identical Voltage readings, they are *obviously* closely *statically* matched. In the case of Richard's amplifier, the reading should be close to 3.75 Volts (although the increased Plate supply Voltage will probably cause an increase in the Voltage measured at the Cathode as well.) Go through all four tubes and write down the Voltage readings. Now, simply match up the closest pairs. It is MUCH more "honest" than a standard tube tester because we are dealing with "real world" operation where the tube is operating at Voltage and Current levels that are near normal operating conditions. Of course, this is no guarantee that they are "dynamically" matched. That takes a bit more work to check and for BEST results an oscilloscope is necessary. It is well beyond the scope of what we are talking about here. It WILL work with almost any amplifier in order to match pairs, but ALWAYS use the same tube socket, don't apply audio and if you don't have a "reference tube", you *could* wind up matching two closely-matched nearly DEAD tubes. It also pays to make sure there is no leakage from the coupling capacitor that supplies audio from the driver/phase inverter stage. Simple and quick. *Reasonably* accurate and quite reliable. (And a LOT cheaper than buying an old Hickok tube tester and having it calibrated!)Hope this helps.Sincerely,Bill Thomas
