2. amps-preamps
  3. 1146886860

My Little EL-84 Amp Has Problems And Needs Fixin'

Greetings fellow audiophiles-
I bought a 18wpc EL-84 integrated amp from a very nice Chinese eBay seller.I went around eBay and offered him $250 shipping included from China.It was a very nice price.
Its called a Aria Minip-1 and was built to 110V.
Its a heavy little guy at 22lbs,point to point wiring,ceramic tube sockets and looks very well made.
My rig was down for cleaning,adjustments and tweaks when the amp arrived.
I put the amp on a table and ran it ~48 hours with the stock tubes.
Dead quite trannies and the tubes were issue free.
I then turned it off for ~30 seconds then installed some NOS tubes I bought for this amp that was suggest to me from a friend who once owned this same amp and NOS tubes.He never had a issue.
The stock input tubes for this amp are 2 6N3's
My NOS input tubes are 2 matched G.E. 5670/2C5i Western Elecric 396A mil.spec.
The NOS EL-84's are a matched quad of General Rohren.
Upon fire up of the amp, the 2 left EL-84's flashed and glowed a white color.The other tubes were a nice steady yellow.
I shut the amp off and waited a few minutes.
I then turned the amp back on with the same results but this time after a couple of
seconds a light colored,small amount of smoke came out from under the left EL-84 socket.
I switched back to the stock tubes and they glowed without a problem.
I then switched the NOS tubes back in and they glowed without a problem.
I then put my rig back together enough so I could test it.
The Right channel is dead,but all tubes glow a pretty yellow :~)
Im not going to bother the eBay seller over this.
The local,excellent tech. is out of town and I'm planning on having him repair this amp.
My question is,whats up with this amp?
Im eager to aquire the most information I can on the failure of this amp before the tech.returns in a week.
Thank you for any infomation anyone can share.
dave


david99
4 responses Add your response
studio1
99 posts
 
If you know of someone else who has the same amp but did not experience the same fate when changing out the EXACT same type of tubes - I would then point out revisions in these amplifiers. It could very well be that there was a revision. Golden Tube went through this with the SE40. It went through numerous revisions. These re signified by markings on the circuit board.

Another explanation could be life cycle for whatever resistor you blew....another could be that the amplifier when you open it and compare - does not have the same parts as the other person's amp. With this type of scenario - there are quite a few possibilities.

If you like the EL84 - move forward to a better amp and do not look back.

God Bless
s23chang
619 posts
 
You might have bad tubes which shorted the amp
Have you checked your NOS tube before put them in your amp?
david99 OP
1,467 posts
 
Studio1-
Thank you for your detailed answer.
I have to add this though.
The amp is the same amp with the same tubes that my EL-84 amp lover/friend once owned and he never had a problem with this amp or the NOS tubes.
I cant figure out how this could be.

Studio1,maybe you can add some insight on how this coulg be.
Thank you again for your time and your excellent knowledge.
dave
studio1
99 posts
 
Friend

The simple explanation is that it sounds like you plugged a tube in that was not compatible. Now for a technical explanation. If I had to call it from where I sit - I would say that the incompatible tubes that you inserted either did not match the pinout of the original tubes, or had totally different operating parameters.

An example of latter would be an amplifier built specifically for the 6L6GC. Well, the 6L6GC can operate at higher voltages than the 6L6. Therefore, inserting a 6L6 could result in blushing tubes that will eventually self-destruct. This is a mild exmple. In more severe cases the NOS tube is hit with so much voltage that it simply blows upon turn-on of the unit taking a resistor with it - which would cause smoke.

When you spoke of smoke, that immediately lead me to think that you have blown a resistor of some type. Maybe bias. It will be interesting to find out if that is actually what happened.

Now, if you have the budget and time - please find a dealer that sells tube gear and listen to a 45, 2A3, and 300B. Between these tube types - I am sure that you could be very happy. Just keep in mind that as refinement goes up - you get less power. I currently use a homebrew SET that keeps me involved with the performance.

About Asian amplifiers. ASL, and www.diyhifisupply.com are among the best. Japan has some very well built amplifiers also, but they can be expensive. Anyway, I hope this helps.

Studio1
Log in to respond
More to discover
80x80
Audio Research Reference Phono 3SE
80x80
EAR (Esoteric Audio Research) 890
80x80
Audio Research LS28SE