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Post subject: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tubes?
Posted: Fri Jul 06, 2012 4:48 pm
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Hi, I own the following four amps, each with four power tubes:
1964 Fender Twin Reverb 85w 2x12 combo
1968 Fender Dual Showman Reverb 100w amp head
1984 Fender Twin Reverb II 105w amp head
1994 Fender Tone Master 100w amp head

Question:
Within an amp that has four power tubes, what are your thoughts about removing
two power tubes to reduce the wattage output for better home practice volumes?
or small club or show volumes?

Good idea or bad idea?

Which two to remove? Inner two? Outer two?
Any two? does it make a difference?
I've read that the inner or outer two would do the job.
To learn something here, why are some tubes not to be removed?

Also, I've purchased a Weber Mass 200 attenuator and it is great.
But, we've all read about how some of the older amps (I have several)
might have output transformer issues with attenuator!!! True or not,
would it be better to remove two of four tubes rather than attenuate all four?

Does the bias need to be constantly reset?
Say you are practicing at home in the morning
with 50w two tubes, then go to practice later, and re-install to 100w four tubes.
Does going back and forth require bias setting or not?

Thanks for your ideas, experiences and technical know-how :shock:
Toppscore 8)

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Fri Jul 06, 2012 4:58 pm
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The search function is your friend this has been discussed many times.


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Fri Jul 06, 2012 5:06 pm
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Toppscore wrote:


Question:
Within an amp that has four power tubes, what are your thoughts about removing
two power tubes to reduce the wattage output for better home practice volumes?
or small club or show volumes?


I doubt pulling two tubes will significantly reduce the volume. Maybe drop the overall level 6 dB.

I also have a Weber MASS and love it. I got the optional bypass footswitch, so I can use it as a "clean" boost; I use the MASS to attenuate 6-12 dB.


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Sat Jul 07, 2012 2:14 am
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Removing two tube don't reduce enough output power to room use. And there are a very small earing difference.

An attenuator is the best and only way to reduce power level. I have a Weber Mass attenuator. It matche any speaker impedance.


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Sat Jul 07, 2012 4:40 am
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See my post - It may answer half your questions as it did mine.

viewtopic.php?f=13&t=71021

I have yet to try an attenuator so I cannot give any input on that aspect.

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Sat Jul 07, 2012 6:49 am
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In the same vein as Arjay's post... if you have two GOOD 6V6GT lying about (like a pair of US made NOS 6V6GTA or 6V6GTY or selected JJ 6V6S), you can try this trick. Pull all 6L6GC and replace with the two GOOD 6V6GT (they have to be able to handle 425+ VDC on the anode plates).

Rebias to about 9-10 watts, idle dissipation per tube. Voila! El Cheapo, near DR amp! No worries, the 6L6GC OPT can easily handle the impedance difference.

Worth a try. I've done it with NOS 6V6GTY on a TR, with pretty good results.

See EDIT on biasing.


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Mon Jul 09, 2012 11:57 pm
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tbazzone wrote:
The search function is your friend this has been discussed many times.


Thanks for your valuable input. Much appreciated. I searched & found some glorious comments.
Fender Forum has over 100(+) new members join each day. I bet there is a lot of knowledge
and experiences and fresh thoughts and new ideas with the new.
Also, sometimes alternative view points and explanations on the same subject can be very helpful.

Tbazzone, you are right as the "search function" is the all-answer-machine :lol:
Is there a subject that has not been broached or discussed?
Toppscore 8)

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 12:12 am
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Guitarist1983 wrote:
Toppscore wrote:
Question: Within an amp that has four power tubes, what are your thoughts about removing two power tubes to reduce the wattage output for better home practice volumes? or small club or show volumes?
I doubt pulling two tubes will significantly reduce the volume. Maybe drop the overall level 6 dB. I also have a Weber MASS and love it. I got the optional bypass footswitch, so I can use it as a "clean" boost; I use the MASS to attenuate 6-12 dB.


Hi, Guitarist! Thank you for your response.
The Weber Mass 200 is a jewel.
But, in theory, say one buys an 100w-200w tube amp and loves the amp & it's tones, etc.
But, it is too loud. Therefore, the guitarist can get another amp or modifiy his "loud-but-dearly-great"
amp that does have that "special something" he likes. Let's say playing with an
attenuator all of the time is out of the question and pulling the tubes is the best option.

My question to you is: Based upon your's & MANY other statements that pulling two tubes
will only marginally reduce the overall amp volume, and that amps with the "Hi/Low"
switches/circuitry also have the same complaint, why is it that if four tubes produce 100w
of loudness, why is there not more reduction of volume/loudness when reducing down to
two tubes?

Will pulling two tubes from a 100w amp reduce the amp's wattage rating to 50w?

Also, why is removing two of four tubes OK, but what is the issue removing one tube
from a two tube 50w amp?

By the way, I do understand that attenuators and master volume amps do provide
a very good alternative solution. Just wondering about those loud Tweed-Silverface amps
that have four power tubes.
Thank you for any and all responses. Toppscore 8)

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 1:23 am
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Top, no offense, but too many questions. 100 to 50watts(removing tubes) would also be best served by increasing the output trans impedance, by disconnecting one speaker in a 2X12, 4ohm amp set-up. IE, the amp would be seeing a higher load(8ohms). If I'm not mistaken, the dcp level will be hard to discern. Pulling one tube out of a two power tube amp, just pushes it into a single-ended situation. Fun, but not healthy for an AB-push-pull, designed amp. JMHO Art

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 2:02 am
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+1 aclempoppi.

With two tubes removed, the amp won't play at half level, and 50 watts is a very loud too.


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 4:27 am
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I second that Stratele52.

The whole reason for pulling 2 tubes was to get acceptable bedroom levels. However 100 watt down to 50 watt or even 100 watt down to 25 watt is still way too loud for low volume bedroom playing. For bedrooms you may want 2 to 10 watt (valve amp power) which pulling 2 tubes on a 100 watter won't give you. I also find the volume control on valve amps to be non-linear and get loud realy quickly down around 1 & 2 and taper off around 5 and almost flat to 10. This may be the reason why you barely notice the volume difference when pulling 2 tubes on a 50 - 100 watt valve amp.

Also when removing 2 tubes from a 4 tube amp it is recomended removing 2 tubes of the same push-pull pair, so that you don't restrict the shape of the "sine wave" audio signal, which would happen when removing the "Push" or "Pull" partner tube of a pair. Hence in a 2 tube amp you only have 1 pair so removing 1 of the tubes defaults the amp to a "Push" or a "Pull" only, which distorts the effective audio "sine wave".

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 5:12 am
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Toppscore wrote:
tbazzone wrote:
The search function is your friend this has been discussed many times.


Thanks for your valuable input. Much appreciated. I searched & found some glorious comments.
Fender Forum has over 100(+) new members join each day. I bet there is a lot of knowledge
and experiences and fresh thoughts and new ideas with the new.
Also, sometimes alternative view points and explanations on the same subject can be very helpful.

Tbazzone, you are right as the "search function" is the all-answer-machine :lol:
Is there a subject that has not been broached or discussed?
Toppscore 8)

Do you think that if there are 1000 new members every day the answer will be different .


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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 11:38 am
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Posts: 2337
tbazzone wrote:
Toppscore wrote:
tbazzone wrote:
The search function is your friend this has been discussed many times.

Thanks for your valuable input. Much appreciated. I searched & found some glorious comments.
Fender Forum has over 100(+) new members join each day. I bet there is a lot of knowledge
and experiences and fresh thoughts and new ideas with the new.
Also, sometimes alternative view points and explanations on the same subject can be very helpful.
Tbazzone, you are right as the "search function" is the all-answer-machine :lol:
Is there a subject that has not been broached or discussed?
Toppscore 8)

Do you think that if there are 1000 new members every day the answer will be different .

Nope. Yes. Maybe.


Unless previous responses are incomplete or are missing ideas not discussed
or are missing experiences not shared or are missing interesting ways to explain
their concepts. Maybe responses are scattered over the website?
Never really know, do you?

Also, great way to meet, get to know and interract with new members. Don't cha think?
Maybe new members have not found the search button.
Maybe, just maybe, there are thoughts not thought or shared ever before.
Lot's of possibility.

Do you think if there are a 1000 new members, answers will be different?


Again, Tbazzone, thanks so much for pointing out the search button.
I got some answers to some of my questions. My inquiry has changed a bit.
Take care. Toppscore 8)

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 11:57 am
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AaronK wrote:
I second that Stratele52. The whole reason for pulling 2 tubes was to get acceptable bedroom levels. However 100 watt down to 50 watt or even 100 watt down to 25 watt is still way too loud for low volume bedroom playing. For bedrooms you may want 2 to 10 watt (valve amp power) which pulling 2 tubes on a 100 watter won't give you. I also find the volume control on valve amps to be non-linear and get loud realy quickly down around 1 & 2 and taper off around 5 and almost flat to 10. This may be the reason why you barely notice the volume difference when pulling 2 tubes on a 50 - 100 watt valve amp. Also when removing 2 tubes from a 4 tube amp it is recomended removing 2 tubes of the same push-pull pair, so that you don't restrict the shape of the "sine wave" audio signal, which would happen when removing the "Push" or "Pull" partner tube of a pair. Hence in a 2 tube amp you only have 1 pair so removing 1 of the tubes defaults the amp to a "Push" or a "Pull" only, which distorts the effective audio "sine wave".


Great answer, Aaron. I like the "non-linear" response, makes sense that when four
become two, the volume does not reduce in half as there are other factors involved.
Interesting subject, dont you think?

Would a two power tube amp actually work if one tube or the right tube was pulled?
"Hence in a 2 tube amp you only have 1 pair so removing 1 of the tubes defaults
the amp to a "Push" or a "Pull" only, which distorts the effective audio "sine wave".
Is it possible one tube would work and have interesting tones/sounds?
Or, would one tube ruin that tube and possibly ruin the amp? . . . . or get over heated?

Now, to let you know, I am not pulling any tubes, any time soon.
I have a new Weber Mass 200 and am looking for a smaller Weber attenuator
for my smaller amps. Apparently, the Mass 200 will handle loads down to 3w
(according to Weber). But, a Mass 50 or whatever might be good.


I have been looking at the Ed Jahns designed Fender 75 amp with a 75/15 Hi/Low
switch, and several amps with Master Volume control. I have a Twin Reverb II
amp head with the Master Volume. But, pulling tubes does not seem like the best
way to go, if a good attenuator can be used and does not harm the output transformer.
Thanks to some of the responses in this thread.

Take care, Aaron. Toppscore 8)

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Post subject: Re: 4-Power Tubes * 2-Power Tubes or Attenuate All Power Tub
Posted: Tue Jul 10, 2012 1:11 pm
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Toppscore wrote:
tbazzone wrote:
The search function is your friend this has been discussed many times.


Thanks for your valuable input. Much appreciated. I searched & found some glorious comments.
Fender Forum has over 100(+) new members join each day. I bet there is a lot of knowledge
and experiences and fresh thoughts and new ideas with the new.
Also, sometimes alternative view points and explanations on the same subject can be very helpful.

Tbazzone, you are right as the "search function" is the all-answer-machine :lol:
Is there a subject that has not been broached or discussed?
Toppscore 8)
.

No . This is a very basic subject ; removing 2 tubes or attenuator ......


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