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Post by kcatthedog on Nov 30, 2017 17:35:12 GMT -6
I bought 5 new mullards from Tube depot for my egnator tweaker, replacing the original tubes
3 12 ax7: one in pre, one in fx loop and one in power section adn 2 6v6gt both power tubes, 2 power tubes were supposedly burned in for 24 hours each
amp is unusable with these tubes super noisy, static, crackles pops yechhh,
I took them out and reinstalled the old ones, one by one and the only way the amp was back to normal was with the original tubes
I have read that the first pre tube is most critical so now I am cycling all 3 of the 12ax7 through that spot but first one is still very noisy.
So, with new tubes ,do you normally have to burn them in at all shouldn't they all be at least quiet >
Egnator states that my tweaker does not need any biasing.
So, are all these tubes crap or how long would you burn them in for ?
thx !
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Post by Bob Olhsson on Nov 30, 2017 17:46:56 GMT -6
I've had the same experience :-(
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Post by Tbone81 on Nov 30, 2017 18:01:07 GMT -6
Sounds like you got a bad tube, maybe damaged in shipping? I would cycle in each tube, individually to see which are causing problems. Burning in tubes won't change any noise/crackles:pops etc. they should work out the gate.
The pre amp tubes should be very straight forward as you can swap 12ax7's without much trouble. Power tubes imho can be much more troublesome. Your amp has a fixed bias, which while easier, isn't the best design because ideally you want to bias each set of new tubes to their specific currents/draw. Fixed bias is sort of a "one size fits all" which delivers current based on specs, not on the actual measured draw from the tube. Make sense?
Now, I've had tube amps that did just didn't like certain tubes, for no apparent reason (that I could figure out anyway). I one time swapped some 6l6's with another brand 6l6 and the amp sounded really shitty. However those same new 6l6's worked in every other amp i had perfectly....so....I guess the moral is sometimes amps react in unexpected ways.
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Post by svart on Nov 30, 2017 18:17:18 GMT -6
I've had single tubes be bad but never whole sets. I've also had marginal stability with modern tubes in some designs since those times back then had limited bandwidth and no oscillation protection was needed.. (la2a I'm looking at you..)
Also never burned in guitar tubes for noise, never had to.
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Post by sozocaps on Nov 30, 2017 18:48:46 GMT -6
Seriously go to amplifiedparts.com or CEDIST.com they have the best tube matching I get 0 failures from them...
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Post by kcatthedog on Nov 30, 2017 18:51:20 GMT -6
thx guys. I may just re install them all (got 2 12ax7 back in now and its better) and just leave the amp on for a long time and see what happens ?
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Post by Martin John Butler on Nov 30, 2017 21:05:32 GMT -6
Tubes should work properly right away, break-in improves tone, but they should sound fine immediately. Something's wrong. I had a THD amp once that allowed any tube change without biasing. It worked perfectly, I had a half dozen expensive NOS tubes, and the new JJ's smoked them all, it was no contest..
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Post by johneppstein on Nov 30, 2017 21:15:43 GMT -6
Sounds like you got a bad tube, maybe damaged in shipping? I would cycle in each tube, individually to see which are causing problems. Burning in tubes won't change any noise/crackles:pops etc. they should work out the gate. The pre amp tubes should be very straight forward as you can swap 12ax7's without much trouble. Power tubes imho can be much more troublesome. Your amp has a fixed bias, which while easier, isn't the best design because ideally you want to bias each set of new tubes to their specific currents/draw. Fixed bias is sort of a "one size fits all" which delivers current based on specs, not on the actual measured draw from the tube. Make sense? Now, I've had tube amps that did just didn't like certain tubes, for no apparent reason (that I could figure out anyway). I one time swapped some 6l6's with another brand 6l6 and the amp sounded really shitty. However those same new 6l6's worked in every other amp i had perfectly....so....I guess the moral is sometimes amps react in unexpected ways. Not fixed bias. If you don't have to bias the tubes the amp is cathode bias. If you have to adjust the bias the amp is "fixed bias". Yes, I know it's confusing. Cathode bias is self adjusting but delivers less power, and also sounds a bit different. It's not "fixed bias" because the bias changes with the currenty draw through the cathode resistor. |
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Post by johneppstein on Nov 30, 2017 21:16:03 GMT -6
Get your tubes from Bowie.
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Post by kcatthedog on Nov 30, 2017 22:13:31 GMT -6
Ya I normally do ( always a first class experience),but a buddy recommended these other tubes: lesson learned!
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Post by Tbone81 on Nov 30, 2017 22:39:32 GMT -6
Sounds like you got a bad tube, maybe damaged in shipping? I would cycle in each tube, individually to see which are causing problems. Burning in tubes won't change any noise/crackles:pops etc. they should work out the gate. The pre amp tubes should be very straight forward as you can swap 12ax7's without much trouble. Power tubes imho can be much more troublesome. Your amp has a fixed bias, which while easier, isn't the best design because ideally you want to bias each set of new tubes to their specific currents/draw. Fixed bias is sort of a "one size fits all" which delivers current based on specs, not on the actual measured draw from the tube. Make sense? Now, I've had tube amps that did just didn't like certain tubes, for no apparent reason (that I could figure out anyway). I one time swapped some 6l6's with another brand 6l6 and the amp sounded really shitty. However those same new 6l6's worked in every other amp i had perfectly....so....I guess the moral is sometimes amps react in unexpected ways. Not fixed bias. If you don't have to bias the tubes the amp is cathode bias. If you have to adjust the bias the amp is "fixed bias". Yes, I know it's confusing. Cathode bias is self adjusting but delivers less power, and also sounds a bit different. It's not "fixed bias" because the bias changes with the currenty draw through the cathode resistor. Thx for the clear up. I have a decent understanding of electronics but I'm still mostly a laymen when it comes to Some of these things. And putting what I know into words is even harder. |
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Post by svart on Dec 1, 2017 9:18:32 GMT -6
I retubed 5 amps with both output and preamp tubes last year.. Triple rectifier, JCM800, Silvertone, Orange Rocker, 6505, and some preamp tubes in my SVT.. I had a single bad tube that red-plated, but the rest were fine. I've maybe had 3 tubes in my life show up bad/noisy and I've retubed dozens of amps over the years..
I don't buy fancy tubes, nor the cryo tubes, nor matched preamp tubes. The only thing I ever pay for is matched output tubes and I've never had an issue.
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Post by kcatthedog on Dec 1, 2017 9:53:41 GMT -6
Ya, I know this is weird, but I have replaced all the tubes one by one and the only time the amp is normal quiet is with all the original tubes in it.
Tube Depot is standing behind its warranty and has offered me a full refund, seeing how they also took two weeks to get here when I have number of good stores 10 minutes away I will just take the money back.
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Post by popmann on Dec 1, 2017 10:09:56 GMT -6
You know you can't replace power tubes one by one...?
I would put money on it being the power tubes...I had to go through a several of New Sensor Mullard 34s to find a pair that would operate without random garbled noises.
Preamp tubes TEND to go microphonic...so feedback at high gain....rumble at higher volume--fail a tap test...but, "noisy" on a "guitar amp scale*" IME, comes from bad power tubes. And Russia makes plenty of bad ones in "new" boxes.
I'm not sure what caused you to retube, but...try the new preamp tubes with the old power tubes. And yes-you need to set bia for power tubes, but....not for it to function noise free really. That's more a touch sensitivity thing at a certain volume...and to some degree (power) tube life. I have never been inside a Engnator, so I can't advise how stright forward it is....
*as opposed to pro audio scale which needs to be even lower noise
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Post by kcatthedog on Dec 1, 2017 11:23:18 GMT -6
I don't believe you can reset the bias with a tweaker ?
I was just trying to be thorough but it was still noisy with both the new mullard power tubes. I also tried keeping those in and all the old 12ax7, then the new 12ax7 and the old power tubes but that didn't work either.
I always came back to the original tubes working, Ruby 6v6 (matched) and the original 12ax7, branded egnator but actually are electro harmonex; anyway I got my return shipping label so back they go.
Original noise was some microphonics but inconsistent, current noise is consistent.
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Post by matt on Dec 1, 2017 11:59:20 GMT -6
I bought 5 new mullards from Tube depot for my egnator tweaker, The Tweaker is cathode bias. I have had 6V6 and EL34 in mine with no issues. One of the Egnater branded 6V6s went bad, which led to experimentation. Current Mullard production quality does not appear to be the same as the original brand. So, I would buy NOS only, or from a trusted seller. Here is an article about it: New Mullard versus old |
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Post by EmRR on Dec 1, 2017 12:01:44 GMT -6
Predominant noise is virtually always from the 1st gain stage. Got a schematic? Does noise change with the volume control? Output stage noise is rare, that's the least gain. Put all the new tubes in, rotate the 1st stage. Include old tubes in first stage analysis. Compare apples to apples. Burn in can be 40 hours for noise in preamp tubes. Burn in with output tubes is about stabilizing current for matching.
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Post by kcatthedog on Dec 1, 2017 12:49:08 GMT -6
The two 6v6 were burned in for 24 hours by the company,
so I could put the other 3 12ax7 back in and leave amp on for 3 days ?
v1 is pre
v2 is fx loop, and
v3 is power
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Post by johneppstein on Dec 2, 2017 3:15:38 GMT -6
I bought 5 new mullards from Tube depot for my egnator tweaker, The Tweaker is cathode bias. I have had 6V6 and EL34 in mine with no issues. One of the Egnater branded 6V6s went bad, which led to experimentation. Current Mullard production quality does not appear to be the same as the original brand. So, I would buy NOS only, or from a trusted seller. Here is an article about it: New Mullard versus oldThe new tubes have nothing to do with the old tubes but the name, which is not owned by the original owners. |
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Post by kcatthedog on Dec 2, 2017 6:02:55 GMT -6
Thx John yes I know about that but had heard some example on line and preferred the new Mullard tone to some others. I know the new are not the same as nos. I could hear the tone under the noise and I was liking that but the noise was unacceptable so tubes are shipped back:)
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Post by reddirt on Dec 2, 2017 7:05:47 GMT -6
Hey Kcatt and everyone else, I don't mean to be a smart arse as it's too late now but as JE said, get your tubes from Christian (Bowie) as he's super knowledgeable and very keen to be sure you are totally happy.
Cheers, Ross
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Post by kcatthedog on Dec 2, 2017 8:05:29 GMT -6
Thx: I know Christian and only bought these 5 tubes as they were a good price and to see if the new Mullards were worth buying. Although they are also a reputable company, it didn't work out well. I am wondering if the amp biasing may be part of the problem too ?
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Post by stormymondays on Dec 2, 2017 12:55:55 GMT -6
If your amp is cathode biased, then biasing is not a problem at all.
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Post by stormymondays on Dec 2, 2017 12:56:15 GMT -6
If your amp is cathode biased, then biasing is not a problem at all.
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Post by kcatthedog on Dec 2, 2017 15:28:53 GMT -6
At first when I reinstalled the old tubes it was working fine then it would power up and the tubes were lit but it stopped passing sound.
So now I have taken it to a local shop to get checked out my. Hopefully it’s nothing serious but so far trying these new tubes hasn’t worked out well at all:(
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