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Post subject: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Tue May 15, 2012 3:24 am
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Has anyone run a Super Sonic Twin with 2 of the 4 6l6 tubes removed (correctly paired) to reduce the output volume? Can this amp be run in this configuration. I use it on the 25Watt setting and it is still @#$% loud.


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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Tue May 15, 2012 3:48 am
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Yes you can remove two tubes to try .


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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Tue May 15, 2012 7:33 am
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AaronK wrote:
I use it on the 25Watt setting and it is still @#$% loud.


Sounds like a situation tailor-made for a (drum roll please......) Deluxe Reverb.

:mrgreen:

Arjay

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Tue May 15, 2012 8:48 am
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Retroverbial wrote:
AaronK wrote:
I use it on the 25Watt setting and it is still @#$% loud.


Sounds like a situation tailor-made for a (drum roll please......) Deluxe Reverb.

:mrgreen:

Arjay


+1 or a Blues Jr..... Nah Just kidding. Deluxe Reverb
Pulling two tubes will lower the volume somewhat, but from my experience with my old Twin, it just made it sound bad.
Sounds like you need a lower wattage amp for some situations.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Tue May 15, 2012 9:18 am
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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Wed May 16, 2012 4:49 am
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No thanks on the Deluxe Reverb (no offence to anyone). I am completely in love with my SuperSonic Twin, and I need the 100Watt headroom for when I play outdoors. I was just wondering if pulling 2 tubes would give me the 12Watt bedroom level option (on 25Watt mode) for when I play at home so the volume knob is not so sensitive. I really am not looking to get a second amp. But thanks guys for the suggestions. Also if the fundamental sound is going to change or get muddy because of the output transformer missmatch with 2 tubes missing, then I will probably just leave them in and live with it.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Wed May 16, 2012 5:06 am
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With two remove the amp will stay very loud. Better to use some attenuator like Hotplate or Weber Mass .


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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Wed May 16, 2012 5:48 am
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stratele52 wrote:
With two remove the amp will stay very loud. Better to use some attenuator like Hotplate or Weber Mass .

+1, Just be sure to get one that will handle the amps wattage.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Wed May 16, 2012 7:47 am
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AaronK wrote:
...I was just wondering if pulling 2 tubes would give me the 12Watt bedroom level option (on 25Watt mode) for when I play at home so the volume knob is not so sensitive....


Yes, but you have to try it to know if the sound will be muddy. In this particular amp, the lower power is achieved by lowering the Plate voltage supply to the output tubes by half. So it won't be as clean on low power as it is on full power normally. Lowering the Plate voltage by half also lowers the Plate current by roughly half, resulting in 1/4 power with all four tubes. Pulling two tubes should give a little bit cleaner sound than with all four tubes set on low power, because the current will rise a little bit on the remaining two tubes, so you will have a little more than 12 watts. And, using only two tubes in full power setting should sound a little cleaner than four tubes in lower power setting. The impedance mismatch is within the two to one ratio with two tubes removed, so no problem there. The impedance mismatch isn't much of a factor with the much lower Plate voltage of the low power setting. If you really want to match the impedance while using only two output tubes, then use a 4 ohm speaker load. The amp will sound different with an 8 ohm speaker load as compared to using a 4 ohm speaker load, you might prefer the sound of one over the other.

Try it already and let us know your thoughts on the sound.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Wed May 16, 2012 12:59 pm
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Thanks Shimmilou, your insight has given me the confidence to give it a go. I will post my thoughts on the results of removing 2 tubes as soon as I get around to trying it. I will look into the attenuator option but probably not go that route anyway.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Thu May 17, 2012 5:30 am
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Just a side note. On my 76 100 watt Twin, I pulled either the two inside or two outside 6L6 power tubes, not a pair next to each other. I'd check the bias too just to be on the safe side. Not sure how the SS Twin works, but you may want to investigate it. Just remember, the less power you have the less headroom you'll have. :wink:

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Thu May 17, 2012 10:41 pm
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Ok, so for those of you who are interested to know, I removed 2 6L6's last night and this is what I found.

I used the Circuit Diagram provided to get the valve names of the push/pull pairs and decided to remove V11 & V12. I used the valve location diagram provided on the inside of the amp cabnet to physicaly locate that valve push/pull pair and found them to be the 2 inside valves of the power valves as 63supro had noted. I then powered up the amp in standby to see what the SS 'Auto Bias Unit' was going to do, but once warmed up and even once off standby the unit still indicated that all valves were ok (when they were obviously not) :? . However as soon as I started playing the 'Auto Bias Unit' started to re-calobrate and measured that V11/V12 was missing and then it shutdown those 2 valve sockets. I am guessing that it needed some sort of load on the valves to get a good feedback of whats happening on the valves biasing. Ok so with regards to Sound and Volume levels with 2 6L6's out, The volume level on 25Watt mode was still as loud as before when you are trying to play at bedroom levels, and my volume knob adjustment was only marginaly better, I could turn it up to 2.2 instead of 1.9 as before to get the same loudness at band practice, at low volumes for bedrooms it still is a hairtrigger response at 1. At the levels I was playing (2.2) the clean "Twin" channel was still very clean and bright, the "Burn" channel sounded the same in overdrive, but the clean "Bassman" channel sounded minutely slightly more "Gritty". Overall the sound and low volume levels did not really change with 2 tubes removed so I just turned off, put the other push/pull tube pair back in and powered back up. The "Auto Bias Unit" then recalobrated and everything was back to normal.

So to sum it all up, for low volume playing, removing 2 tubes is not really going to make much difference, but you may want to consider it if you want to squash the headroom of the amp while you are on stage playing much louder.

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Fri May 18, 2012 2:07 am
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stratele52 wrote:
With two remove the amp will stay very loud. Better to use some attenuator like Hotplate or Weber Mass .


Whith two TUBES removed.....


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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Fri May 18, 2012 4:09 am
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Yes, Stratele52, you nailed this one on the head, you were correct, but I still had to try it to believe it, and it gave me a chance to test the "Auto Bias Module".

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Post subject: Re: Removing 2 6L6 Power Tubes from a Supersonic Twin
Posted: Fri May 18, 2012 5:06 am
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+1 Aaronk


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