Strange Amp problem

[bigpony777]

Well they must have gone downhill quite a piece since I was using them ten years ago? We used to buy 50 ECC83s in at a time and 45 of them were perfectly fine in all positions but I used to select the ones with lowest noise and hum for front ends. Had no failures as I recall. Sovteks, TAD and other makes.

Dave.

so do you think its not the tube? and i should just test my connections?

 

[ecc83]

so do you think its not the tube? and i should just test my connections?

If the hum is still there with the valve out it cannot be the cause. If there is no hum with the pre amp bypassed (PA in jack) then it must be in the pre amp section and I strongly suspect that crude and archaic Zener LT supply. I think you need an amp tech.

Dave.

 

[SHEPPARDB.]

Well they must have gone downhill quite a piece since I was using them ten years ago? We used to buy 50 ECC83s in at a time and 45 of them were perfectly fine in all positions but I used to select the ones with lowest noise and hum for front ends. Had no failures as I recall. Sovteks, TAD and other makes.

Dave.

Some brands seem to be better than others. Brand is probably not the best word, as it is my understanding that they are only being manufactured in 2-3 factories these days. The trick is to buy from someone that has a good reputation for picking tubes, or find NOS.

 

[TalismanRich]

Some brands seem to be better than others. Brand is probably not the best word, as it is my understanding that they are only being manufactured in 2-3 factories these days. The trick is to buy from someone that has a good reputation for picking tubes, or find NOS.

Personally, I'm not a fan of NOS tubes. 40 years ago, there were tons of tubes that were on shelves waiting in vain to be bought. There simply wasn't that much demand. Over the years, they have been picked over to the point that the majority of the good ones have been sold. Prices have gone insane, and now, everyone who finds old tubes of questionable provenance puts them on Ebay and Reverb as "NOS". I've run across old "NOS" tubes (6V6s) that were far more microphonic than the Ruby tubes that replaced them.

12AX7s made today (JJ, Tungsol, TAD) are good quality. I doubt that the circuit in the Crate is that stressful on the tube.

In any case, if the OP has pulled the tube and the noise is still there, then it's likely not the tube.

 

[RFR]

Save yourself the headaches, the guessing, the trial and error. Just take it to a competent amp tech. Have him fix it, pay him and bring home a working amp

 

[ecc83]

Save yourself the headaches, the guessing, the trial and error. Just take it to a competent amp tech. Have him fix it, pay him and bring home a working amp

Absolutely! The amp stands you in no money and the most awkward and expensive parts to fix, the sstate PA and its power supply seem to be in good order.Fork! The speaker has to be worth 25 of anybodies bucks!

Having said that ^! The stock speaker appears to be the Celestion G12M-70, a speaker that seems to be reviled only second to the Rocket 50! Nonetheless a new one is about £100 here, so 20quidish for the lot is bloody good. The speaker seems to be rather disliked for being "meh", bland rather than having any intrinsically bad tone? Ideal for a modeller? Amp techs might be interested in one because it is rated at 70W and so safe in a 30W valve amp and even some 50W valve jobs and amp techs often get peeps that need a cheap S/H speaker to fix an amp that has suffered a boot.

Dave.