Different sound from "same" tubes.

[flappycars]

Hello,

I have had a new set of tubes put in my amp earlier this year and I was never as pleased with the sound as the old ones. They were all Edicron EL 34 but the new ones had a different identification number to the old and look different inside. As I have got a suspect valve in the new set I refitted the old ones and it sounds better.

I have since ordered another new set this time Unison Research branded ones which are in fact made by JJ in Slovakia, so it will be interesting to see what the difference is when they turn up.

Can I just plug them in and play or should the amp be "biased" and what does that mean?

Hope somebody can tell me as I am fairly new to valves

[flappycars]

Yes I know it came up3 times.I have no explanation

[Mike Lindsey]

Stop hitting the return key.

Mike

[mike stehr]

I'd Email Unison Research for those questions.

Do you have the manual?

If the amplifier has a biasing feature, the manual should state where the bias should be set, for a given tube/valve.

Does the unit have a built in bias meter? If not, it should explain how to use a VOM for biasing.

Or you can look on the net for the specifications from the sites for the particular tubes that you have, and check to see if they match up.

Some makes of tubes are designated as a certain type, but do not necessarily match up spec wise.

Mullard EL-34?

[artto]

John, I see you've discovered why amplifier manufacturers tried to dump tube designs 30 years ago.

The all sound different to me. And many times in the past, even though you bought an RCA EL34 for instance, didn't necessarily mean that all RCA EL34 came from the same factory. Actually, I don't think any major "tube manufacturer" has actually made tubes in their own plants for decades. They usually sub-contract it to smaller more specialized OEM (Original Equipment Manufacturer) & label them with their own brand name. Some companies even specialize just in the re-labeling/testing/matching of these delightful glowing objects.

As far as biasing goes, that all depends on your amp's design. Some, like many of the Audio Research amps are self-biasing, but then they also require the use of "matched pairs or "quads", etc. Some like the Luxman MB3045 are a total pain-in-the-*** to bias & seem to need biasing more frequently especially if used with speakers that lack efficiency. Some amps also need to be rebiased even if a driver tube is replaced.

[mobile homeless]

Welcome to the World of Tube rolling and the various sounds and properties of tubes(and all depending on how run in circuit to boot)! It is both the positive and negative (depending on viewpoint) rolled into one as you can have a variety of sounds/presentations at your fingertips based on the make, vintage, and type of tube you go with.

The more you learn and the deeper you delve into the whole affair, the more you realize what you don't know with the propensity to contradict something you held as "truth" before. Believe me, it will come... heh.

I personally would not make a habit of buying tubes from the manufacturer as they tend to mark the tubes up, and many times you don't know exactly what is in place depending on the company you're dealing with. It is generally good advice to get amp manufacturer recommendations, however.

In general, most NOS (New Old Stock) tubes sound better than the majority of newly manufactured makes although there are some exceptions. Certain tubes are WORTH getting NOS from dealers, many online if you do the research, as the difference in sonics is WELL worth the cost. This holds true for driver/input tubes as well as power tubes (probably even more so with the driver/input/signal tubes). Unfortunately, the EL-34 in NOS is a VERY expensive beast and hard to locate. The most famous EL-34 generally speaking is the Mullard (from Great Britain) but the prices are beyond many. In the case of the EL-34, you will probably be dealing with modern equivalents.

Of these, the most popular are Svetlana, JJ/Tesla, Electro Harmonix(Sovtek), Chinese, and Ei. You will actually find that some tubes work better in certain designs/amps over others. Over the last five years or so, the Svetlana EL-34 received mostly praise as an upgrade over most EL-34 alternates. The JJ has come on recently as some people have preferred this tube in certain designs. Electro-Harmonix and Sovtek share building and the Electro-Harmonix have gained a following lately. The Chinese EL-34 has been much maligned but actually isn't that bad. I have had a number of Svetlana EL-34 and have generally liked them more often than not, and in a variety of amplifiers. That being said, I have had a failure with one but this is certainly more rare.

The Unison Research Simply Four is AUTO BIASING meaning you don't have to bias the tubes yourself. On the other hand, it is important to get matched pairs or a matched Quad of EL-34 so the auto-biasing feature will work as designed (some tubes are more matched than others if you get my drift).

Your input tubes are the 12AU7 which will do MUCH BETTER if heading to the NOS bin! There are a ton of choices and info here and some research(and listening) needs to be done. Some good 12AU7 include Mullard Long Plates, Amperex - Bugle Boy, Dumont, Telefunken, RCA Clear Tops, etc. Some "ok" modern 12AU7 are the JJ but these don't equal the best NOS.

What are in your amps now? It's a lot to learn, I know but there is no rush. The great thing is the INTERNET makes it much easier than in the past. Like a record store, however, you have to sift through the garbage. Other forums have much more tube action going on such as the Tube Asylum etc.

It's a fun journey...just remember to enjoy the music.

kh

Note - Edicron tubes are simply Ei tubes... Edicron handles the "Ei" brand. Perhaps you did get a different version. I know Ei makes a big bottle and small bottle EL-34. Did the glass look different as well with one bigger than other?