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Post by tipper74 on Apr 27, 2020 3:07:18 GMT -7
Hi guys,new to the world of Z amps in the U.K.! I recently purchased a maz 18 head with reverb with 2x10 cab off eBay,for a good price,very,very happy so far. 2009 model I believe. I absolutely love it,but Ive had a swap around of a few valves,as I wasn’t sure of the history of it,I’ve changed the power tubes out,putting matched sovtek EL84/6b5q in,out the tube in v6 is overheating,I’ve let it cool down,and swapped the positions over,but position 6 is still overheating the tube,I’ve put the Tung-sols back that we’re in it when I bought and so far seems to be ok,I’ve also swapped out the v1 and v5,cos these looked dead. Tubes currently in are
V1 sovtek 12ax7lps V2 Jj ecc83s V3 jjecc81 V4tung sol 12ax7 V5 Tung sol 12ax7 lps
I’m planning on getting it serviced soon,when the lockdown has eased a bit. Can anyone shed any light on this?
Thanks Simon.
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Post by pcns on Apr 27, 2020 5:20:07 GMT -7
Welcome to the forum. Lots of great information on the forum and some really great people and knowledge. Are you saying that V6 gets hot no matter the tube you've put in? or just when you swapped tubes? Stay safe, God bless, Todd
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Post by headshrinker (Marc) on Apr 27, 2020 8:36:08 GMT -7
Often preamp tubes "look dead" even when they are good. You don't get a big glow from them like power tubes. Long plate tubes have a reputation for rattling and going microphonic, so they generally don't do well in V1 or V2. Looking at your tube assortment and from what I have heard out of the tube types, I would arrange them like this. Before you try, be sure to note how they are now, so in case it sounds a lot worse you can get things back. I also would play the amp for an extended amount of time and watch V6 with the Tungsols in and see if V6 starts to red plate. If not, your new tubes may be bad. It's been known to happen. If it does, you may have a screen resistor or another component attached to V6 that went out when a power tube blew. V1 tungsol 12AX7 V2 jj 12AX7/83 V3 jj 81 v4 tungsol lps (though I would get something other than a lps) v5 sovtec lps You might also try swapping where I have the tungsol in v1 and jj in v2 and see if you like that better. You could do the same with what I suggest in V4 and v5. If you are fine with how everything sounds as you have it, feel free to ignore this.
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Post by tipper74 on Apr 27, 2020 9:23:10 GMT -7
Hi,thanks for the replies,I’ve ran the amp for a few hours today with the original Tung sols in and it’s been fine,but whichever of the new sovteks are in v6,the sound fizzes out and I can see the tube is overheated. I’m taking in for a service on Wednesday,so I’ll mention it then,great amp though,I’m after a back up now,maybe a wreck jr.
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Post by headshrinker (Marc) on Apr 27, 2020 10:24:58 GMT -7
I'm guessing the amp is fine and the problem is the new EL-84s. They could both be bad or one may be way out of specs compared to the other. Were they supposed to be matched? Your tech should be able to figure it out.
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