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Looking for tube selection advice

S

shipman5

New Member
One of my 7025 / 12ax7 tubes stopped working the other day. Everything was playing just hunky dory the day before. Swapped the two around and the problem is definitely the tube. Any advice on manufacturers to replace it? Should I get a matched set?
 
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Matched pairs are best. For vintage tubes the ones that are good in about everything are RCA black plates and they cost less than Mullards or Telefunkens. Buying used, test new is a good way to go. There is a good list of tube dealers in a sticky at the top of the tube forum page.
 
Matched sets aren't really necessary with preamp tubes. There are plenty of nice cheap 12AX7's available too. If price is no object then I'd look for Tele's or Mullards. If it was me, I'd just buy some new EH's and be done with it. :yes:

Mike
 
Thanks guys, I was looking at tubedepot.com and was trying to narrow the field. I had a small question related to this. Should I still get some sound out of that channel even thought the tube is bad or is something leaking through the mono switch?
 
Tubedepot.com is a great place. I bought four Ei 12ax7a and four EH 12ax7a and I've had two of the four EI ones go bad and the other two test low on a TV-7 and a 600a.
Tubedepot was very understanding and offered to replace all four of the Ei's with no questions asked.
 
Glad to hear they're a reputable source. I ordered a set of 12ax7 EH's today. Got home and deoxit'd the pins and socket and everything works again. Good to have backups thought. Guess I'll start rolling :scratch2:
 
I don't have a balance control in my amp, so matched tubes are important. I think it is always a good idea to use the same brand if you are using pairs.

Glad to hear that it was just a bit of dirt and the EH probably cost about as much to ship as to buy so having back ups that don't cost a lot is nice.
I have had only one piece of gear with Ei tubes (preamp, 1 12AX7, 2 12AY7) and I thought they sucked.
 
I'll keep your comments on EI in memory. I was looking at availability for the rest of my tubes and the only ones which are hard to find are the 7199's. I'm considering "investing" in a spare set.

FYI my amp has:

2 12ax7's
2 7199's
4 6v6gt
1 ez81

oh yeah almost forgot, i promised new pics a while back. I'll start a new thread......
 
shipman5 said:
I'll keep your comments on EI in memory. I was looking at availability for the rest of my tubes and the only ones which are hard to find are the 7199's. I'm considering "investing" in a spare set.

FYI my amp has:

2 12ax7's
2 7199's
4 6v6gt
1 ez81

oh yeah almost forgot, i promised new pics a while back. I'll start a new thread......
Click to expand...
The unusual part is that they look very well made. Long plates. almost double the length of the EH's plus they have gold pins. I think it's more a yield problem with other members stating that they have a high failure rate even though they're tested.
I'll give em another try in a few weeks. I was running them in a Dynaco PASIII that was stock I thought it could be a circuit problem but my Mullards are working like a champ.
Kudos to tubedepot.com for standing by their product.
 
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