marko
New Member
Posts: 16
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Post by marko on Jun 9, 2012 19:55:29 GMT -7
I recently purchased a '69 drip edge Pro Reverb and am really, really liking it.
I took a SA Brake Lite with me to the store to knock down 3-5 db while I tried out the amps.
The owner of the store let me use the Brake Lite but as I was about to leave the store, he politely asked if I was aware that some people think using attenuators can harm output transformers over the long run. He told me Eric Johnson--a regular at his store--is convinced that using an attenuator ruined a couple of transformers in his vintage Marshalls.
I've been using a Brake Lite with my Maz 18 for 3+ years without any issues but am now wondering if I can do the same with a vintage amp that has an underpowered, 44 year old transformer.
Do you think it would be safe to use the Brake Lite at 1-2 clicks if the Pro Reverb is never turned above 5-6?
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Post by benttop (Steve) on Jun 9, 2012 20:48:11 GMT -7
Well first off, Eric Johnson also believes that guitar cords are directional - and I'm not talking about ones that are only grounded on one end. He is not one who I would put all my faith in for technical matters. He has some other very strange beliefs, most of which are unprovable in any venue.
In my own experience, I've used attenuators every night that I've played, and every time I've practiced for the last fifteen years or more. Shoot, I even designed my own resistive attenuator in the '70's and used it for years back then. I've never seen any evidence at all that it caused any issue whatsoever. All of the amps responded just as I would expect, and they were all functioning perfectly at the end of my use of them.
The real issue is this: When people suggest that doing something in particular "might" have a deleterious effect on the life of the equipment, ask them what the scientific basis for that opinion is. My bet is that it is just a hunch based on a single event when a power tube may have failed, and they really don't know didly about the actual technical merit of their theory.
I think of it this way: If you like hearing your amp wide open, and you play it that way, attenuators do not change the wear on your amp at all, but they sure do change the wear on your ears.
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marko
New Member
Posts: 16
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Post by marko on Jun 9, 2012 23:35:48 GMT -7
Thank you Steve. I appreciate your input. My gut response was similar to yours but I wanted to check with folks more knowledgeable than me when I learned that Mercury Magnetic's transformer warranty is voided if you use an attenuator with their transformer. www.mercurymagnetics.com/pages/_misc/warranty.htm
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Post by benttop (Steve) on Jun 10, 2012 7:13:05 GMT -7
Isn't that fascinating? These are the relevant statements: The use of any type of attenuation device on any Mercury Magnetics transformer will void the 10-Year Warranty. Using "dummy load" or "power attenuators" damages transformers. These type of products wear out power tubes at an accelerated rate, and in some cases may cause RF to be generated in the output, which may destroy the output transformer. There is a clue built in to their statements there - the assertion that attenuators wear out power tubes at an accelerated rate. To just state that without regard for the circuit type.... They can have any terms in their warranty that they feel they need to have to protect themselves from idiots. Most companies do exactly the same thing. But to make a technical statement right in there that may or may not be factual depending on the specific details - well that's just not my idea of a good warranty nor is it actually correct in all circumstances or with every amp design. I can see why Dr. Z doesn't like using their products. It makes me wonder why they don't also have terms saying that playing your amp wide open can wear out the transformer, so the warranty is void if you do that. And frankly, applying power at all may also reduce the life of the transformer - just don't do that. HOWEVER! If your vintage amp has a Mercury Magnetics transformer in there, I would avoid the use of any attenuator. Their statements may be accurate or bunk, but they know more about what's going on inside their own product than anyone. Maybe their design has an inherently weak point, or there is some other reason that they make this statement. YMMV.
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marko
New Member
Posts: 16
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Post by marko on Jun 10, 2012 9:55:50 GMT -7
Thank you again Steve.
(The amp has its original set of 1969 Schumacher transformers.)
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Post by Michael Bartee on Jun 11, 2012 11:20:42 GMT -7
I know what transformers I WON'T be using.
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jeffh
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Posts: 40
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Post by jeffh on Jun 16, 2012 4:45:25 GMT -7
I've always heard the vintage Marshall transformers are not as robust as vintage Fender trannys. If using an attenuator allows the user to crank the amp, and the OT is a weak link due to age/whatever, it might cause problems just as if the amp was cranked without attenuation.
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Post by Sean on Jun 18, 2012 11:27:02 GMT -7
I have a brake lite and a power glide. Have tried them with my Z's as well as a Marshall 6100 i used to own and a matchless sc30.
Honestly the brake lite with my Z's is the only combo I have been able to really gig with. Never really liked the others. But I never was really concerned with the attenuator killing the amp!
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Post by zpilot on Jun 30, 2012 2:29:01 GMT -7
The whole purpose of using an attenuator is to be able to turn the amp up without killing you ears or getting fired from the gig. Running the amp hard is what will wear out or damage components. Having said that you still need to consider that with most attenuators as you increase the attenuation you are changing from a reactive load to a resistive load. Although the ohms may not change much the amp "sees" the load differently. That's why I don't like ANY attenuators past the the 6dB setting. Here is something I have used occasionally with success that I haven't seen or heard of anyone else doing. I will use a closed back extension cabinet with a combo amp and place the cabinet FACE DOWN on the stage. That way I have about a 5 to 6dB attenuation and the amp still has a real speaker load. I can even use the cabinet to set my combo amp on. If you are playing on a wood floor you can feel a little thump from the cabinet which can be kinda cool too. I came up with this before there were any commercially available attenuators like the Power Soak.
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Post by Maddog on Jun 30, 2012 6:34:50 GMT -7
I will use a closed back extension cabinet with a combo amp and place the cabinet FACE DOWN on the stage. ^^^^^Wow....never saw that one coming!!!! Very interesting!!!! Here's the little dude that got blamed for giving attenuators a bad rap. Actually I ran one of these without issue for years on a 50 watt JCM half stack. I think the problem comes from frequently running amps (especially old Marshalls) on 11 (or 12) for extended periods oftime with the attenuator cranked up to a very high setting. I have used Doc's Brakelites extensively since they came out, as have many of you, with absolutely no ill effects. No amp was built to run full tilt forever.......... (except my little Red Monza ).
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Post by prspastor on Jun 30, 2012 6:47:33 GMT -7
Wow, I'm really surprised at Mercury Magnetic's statements. It doesn't make sense from an Electrical Engineering perspective. Let me ask this simple question - "What does a transformer do?"
It converts voltage to a different value by using a ratio of windings. In the case of an OT, it also converts the high resistance of output tubes (say 5,500 ohms) to an appropriate level for a speaker. It changes a high voltage low current load from the tubes to a low voltage, high current load for the speaker.
In many ways, in my thoughts, transformers act as "windows" that components on either side of the window interact with one another. Transformers are facilitators. They don't "see" a reactive or resistive load - they pass that load on to the output tubes. So if you are using an attenuator at higher values with more resistance than reactance, then the output tubes are experiencing that resistive, non-reactive load.
This does wear out your output tubes faster because you are really working them hard - but this is no different than if you regularly play your amps hard anyway. As others have said above, you are just saving your ears.
Now, your tubes can fail catastrophically when being pushed that hard and can take other components with them - I wonder if this is why Mercury Magnetics has that clause in their warranty. That is not the attenuator's fault though. That is the tube's fault.
What zpilot said is true - running an amp hard wears out components. Time itself will wear out your output transformer - the paper between windings will eventually fail to be an insulator.
It might be helpful if Doc responded with his knowledge. However, I participate on a guitar amp builder's forum where high-level engineering discussion occurs on every aspect of guitar amp manufacture. Dr. Z participates in that board as well. The overwhelming consensus on that forum is that attenuators do nothing to harm your OT. Instead, they let you run your amp like a guitar amp is supposed to be run without damaging your hearing. Seems like a lot of amps have survived 50+ years of being run hard when maintained properly.
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Post by prspastor on Jun 30, 2012 6:58:19 GMT -7
I've always heard the vintage Marshall transformers are not as robust as vintage Fender trannys. If using an attenuator allows the user to crank the amp, and the OT is a weak link due to age/whatever, it might cause problems just as if the amp was cranked without attenuation. This is very true.
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Post by zpilot on Jul 1, 2012 15:56:13 GMT -7
I don't remember where but I think I read that Doc says the Break Lite was really meant to be run at the first two clicks. He said that if you need more reduction than that there are better circuits than a Break Lite to get it. Don't quote me on that. I agree with that but they are a lot more expensive. I have a Koch Loadbox that I use for that and it cost several hundred dollars. My Break Lite works fine at most gigs when I need just a little attenuation
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Post by Brian on Oct 6, 2012 6:30:31 GMT -7
I don't like the sound of my amp at all with the Brake Lite on 3 or 4.
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