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Post by briman on Nov 14, 2011 3:02:45 GMT -5
I finally received my biaspro tools in the mail last week and re-tubed my Comp and biased it. Like I told Ayton in another thread, I had 2 new JJ's and 2 new Electro Harmonix...... both pairs matched. I bought them on ebay. One of the electro's red plated when I installed it to bias. It would go up to 68 Ma while the other one was like 18 Ma. Turned amp off right away and switched them around and the same thing happended again! So I got screwed by someone on ebay.
So I put in the JJ's and my plate voltage was 506 V. I biased them to 32 Ma which roughly 65% dissip. They sound awsome! Nice tight and smooth. The one's in it before were Tung Sols and they were dying. Anyways... I then put in 3 Sovtek's for the pre amp and I found it lost a bit of bite and felt colder. I put the 3 Tung Sols back in and I am in heaven again.
This was my first time re tubing my splawn and everything went well and boy this is a well built amp! It was written John 2:16 inside the shell. I have to go look that passage up!
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Post by Ayton(e) on Nov 14, 2011 13:32:54 GMT -5
Hooray!
Now, where do you live, because I'm still too scared to do mine. ;D
Can you remember the character of the Tung Sols before they started fading, how they differ from the JJs? Choosing tubes is a shot in the dark now that I'm looking outside Mullard.
Glad it went well for ya. Hope the eBay guy takes returns as some of the tube websites do.
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Post by briman on Nov 14, 2011 15:59:45 GMT -5
The JJ el34's and the Tung Sol el34's sound very identical. My tone is back to the same it was before before the Tung's started fading.
But when I put in the Sovteks pre amp tubes, they definetely sound colder.......kinda like you turned down the gain knob a quarter way with the tung sols in there. I have switched them in and out about 5 times to see the differences and I like the sovteks but I like the Tungs better. The tungs just have more gain and a slight tad more warmth.
I have used Ruby's, electro hamonix and Svletana's EL34's before with my old Marshall and I found the Ruby and electro sounded similar and the Svletana's not as warm as them.
In conclusion, this is my firt re-tube with my Comp and the JJ and Tung EL 34's sounded the same but the sovtek and Tung pre amp tubes were different sounding.
My next re-tube will be all Tungs or JJ's. I really loved the electro's EL34's in my Marshall and would love to get some good ones to try in my Comp just to compare. I bought these defected ones 2 years ago on ebay so I can't really get refunded. I might shoot the guy an email if I can find the sale in my history listings.
As for taking the chassy out and all that....... it was easy as pie. Just stand the head on it's side and remove the screws and slide the chassy out by pushing on the front panel of the chassy and guide it with your other hand. I was focusing very hard on not grabbing it with my fingers going inside the chassy. I just grabbed the edges and sides carefully. Then I stood upside down on two boxes that I spread out 21 inches apart. I was even playing guitar and adjusting the bias at the same time which is a no no. I was just being very cautious with the screw driver (rubber handle!) as to not let the screwdriver slide off the brass screw and touch something! Just wear good shoes and go very slowly. It's really easy. Just don't touch anything but the bias screw...... that's all! Let me know when you do yours and tell me the results. I am sure your gonna be very happy if you haven't changed them in a while. If your questioning your amps tone..... then they are getting tired.
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Post by briman on Nov 16, 2011 19:54:35 GMT -5
Well well....... I was playing yesterday and the low E string's sound was bugging me. I played and played and finally decided that it was sounding too muddy when I palm muted it or even open. It had no crispy edge or bite. I was puzzled because the JJ tubes were supposed to be "new" that I got on ebay. So I went today and bought some electro harmonix from my local guitar shop and came home and plugged them in. Luckily the plate votage was roughly the same so I didn't need to change the bias. What a difference!! Sonic bliss! Highly detailed and rich and smooth is all I can say. My amp sounds the best I've ever heard it to date. I am now finally satisfied!
Be very careful buying tubes on ebay.
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Post by speedemon on Nov 17, 2011 13:15:57 GMT -5
Ja!
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Post by Ayton(e) on Nov 17, 2011 15:18:48 GMT -5
See, now I don't know whether JJs don't suit the amp or you just got a bad set. Gah!
Screw it, I'm putting lightbulbs in. GE. 2700k.
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Post by briman on Nov 17, 2011 19:51:27 GMT -5
I think you'll love the electro's. Smooth detailed and rich. I will post a sound clip when I get a chance but I only have a HD camera.
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Post by Ayton(e) on Mar 2, 2012 14:35:04 GMT -5
Finally did this last night. My excuse besides basic cowardice is the amount of work I've been doing on the house. Went smoothly enough! Opted for propped up sideways against a wall. Put on a pair of nitrile gloves so as not to explode my heart. My brother had sent me JJ E34Ls and I thought they sounded fantastic, to be honest. Smoother than the Mullards, less jagged in the mids. More vintage, in a brown way. I guess I now have JJs all the way around, except one ancient RCA in the phase inverter. Only problem is that my amp always tends to really get into the zone after about 45-60 minutes of playing, when it's really warmed up. With the new tubes/bias, it got a little too warm sounding at this point, you know, losing a bit of headroom and clarity, and I've no idea where to set the bias so that it only reaches my target at this point rather than overshoots. It sounded sensational until then, I've never heard it so warm and clear at the same time! I'm assuming just leaving it on for 45 mins before biasing won't help much, as the tubes are getting no work with the volume off and the guitar unplugged. My biaser warns about playing with the probes attached, saying you could fry them, so I ain't doing that. Plate voltage was 520 on both sockets. I shot for 67-68% as a starting point.  |
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Post by rocknrolla on Mar 2, 2012 15:41:44 GMT -5
Cool man. I do mine the same way by leaning it against a wall with the heavy side down. Next time I have to bias I'm taking my 1" hole saw to the bottom and installing a removable plug.
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Post by Ayton(e) on Mar 2, 2012 16:07:47 GMT -5
Yep, I wanted to do the camsdad mod too but I don't have any spade bits. Now I'm going to find out what a hole saw is.
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Post by rocknrolla on Mar 2, 2012 17:38:41 GMT -5
"camsdad mod"
That really caught on didn't it.
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Post by briman on Mar 3, 2012 1:51:09 GMT -5
I was playing the guitar for a bit with the probes still on and didn't have a problem. I wonder why they say not to do it? Will it damage the probes or your amp? Glad you got the courage to bias it Ayton...... I was a little nervous doing mine too. I've biased heads before but they didn't require taking the guts out. You never know, something can fall or you slip etc. I was super careful and slowly slowly doing it. I have a clip of the electro harmonix here: www.youtube.com/watch?v=A8pCOe0ZNtAI'll post one with a little more variety soon as I can. |
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Post by Ayton(e) on Mar 3, 2012 2:41:35 GMT -5
Well that sounds really good. Detailed but warm. Did you dial the Electros in at 65% like you did the JJs? I will have to dial mine back a bit this weekend to get more clarity back when it's really cookin', but don't want to go too far and end up with cold/stiff.
The probes are in danger (according to my instructions) if you play the amp with them installed because they're designed to measure idle current, and when you play the current spikes. I know they have resistors in there to reduce the current by x1000 for safe measuring, so my guess is these resistors are the components that could be damaged if they see more juice than they're rated for. It could be hogwash but for right now I'm following the guide to the letter!
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