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SlagJones

Weber MiniMass attenuator

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I used to use a 100 watt MASS with a 50 watt amp. It worked well, but, like any attentuator, the more you choke down, the more the amp tone gets mangled. I ultimately opted for a Hotplate, which I found slightly more transparent than the MASS.

 

Not that it's necessarily a "bad thing," mind you. It's not a bad sound, it's just not what I was looking for. I wanted something more "open." Some like added compression. It'll make the amp seem gainier and smoother than it is, and that's something that is appealing to some.

 

If this is for Jr., pick up a mini (or micro)-MASS and a load dump, and try them both to see what you like best.

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Well, I got a 25W MiniMass for my Crate V18. I guess it does ok. It just seems like if you have the volume on the Weber all the way down to 0 it's quiet but it seems real sensitive as you up the volume and all of the sudden it's real loud again before you even pass 2 , I guess I was expecting a smoother transition as you up the volume on the attuenuator.

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I read somewhere that a attenuator was hard on your tubes?

 

Not so. Life of the tube might be shorten, just as if you ran your rig wide open all the time, but not due to the use of an attenuator it self.

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Anyone use the Weber MiniMass? How do you like it?

 

I bought an older, used 25W MiniMass a while back. The rheostat was flaky so I emailed Ted Weber to see if I could buy a new one. He sent me a new 50W rheostat free of charge, great customer service. My unit is now a 50w MiniMass.

 

As said in previous posts, they are good for knocking off a few dBs but when turned all the way down, it sounds like a blanket over your speaker cabinet. Mine lacks the treble switch as it is an older unit, and it could sure use one.

 

Here is a schematic:

 

http://freestompboxes.org/members/soulsonic/schematic/WeberMiniMASS.gif

 

tung

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I read somewhere that a attenuator was hard on your tubes?

 

Yes, that's correct. You will absolutely burn through more tubes if you run your amp with volume up, vs. down, no question about it.

 

It just seems like if you have the volume on the Weber all the way down to 0 it's quiet but it seems real sensitive as you up the volume and all of the sudden it's real loud again before you even pass 2

 

Sounds like your rheostat has some dead spots. That's a bit under-rated for that particular amp, too. Power rating is measured BEFORE distortion.

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Yes' date=' that's correct. You will absolutely burn through more tubes if you run your amp with volume up, vs. down, no question about it.[/quote']

 

But not as a direct result from just using an attenuator. I'm comprehending his question as if the use of an attenuator alone would be the cause of hardship on tube life which it is not.

 

If you run your amp at full volume all the time the results in tube life will be the same with or without an attenuator....wouldn't you agree m?

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Yes' date=' that's correct. You will absolutely burn through more tubes if you run your amp with volume up, vs. down, no question about it.

 

 

 

Sounds like your rheostat has some dead spots. That's a bit under-rated for that particular amp, too. Power rating is measured BEFORE distortion. [/quote']

 

That's interesting. I got an e-mail before I bought it that said that the 25W MiniMass would be OK for my 18W Crate V18.

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But not as a direct result from just using an attenuator.

 

Cranking a tube amp will chew through output tubes much faster than running the throttle low, whether there's an attenuator on the amp or not. It has nothing to do with the attenuator, other than that an attenuator is often used to allow cranking the amp at a reasonable output threshold.

 

I think some of the confusion might come from the fact that there HAVE been incidences in which improperly matched attenuator devices have destroyed output transformers. Often, I see the question posed as "Will an attenuator hurt my amp?" In this case, the question has morphed a bit to only discuss tubes, but I suspect that it still derives from that original question.

 

And, to that, yes indeed, running an improperly matched attenuator device can most definitely melt down an OT. The key is to make sure that the device and the speaker load match what your amp wants to see. No 16 ohm attenuators on 4 ohm amps, etc.

 

Another point worth consideration is the heat that's generated by running a tube amp at full throttle. While you might very well find the amp barely warm to the touch after an hour of low volume play, you'd likely find a much different story after an hour of full volume play.

 

I personally find the stock Vjr. inadequate for ventilation, when the amp is run at full volume. I'm in the process of flipping the amp, so that the tubes ride on top, venting heat away from the chassis (why wasn't this amp built like this originally?), but in the meantime, I've been running it with the back cover completely off, and it seems to stay cool enough that way.

 

On my main stage amp, I use a small clip on fan, directed towards the transformers. It really doesn't take much airflow to make a tremendous difference. Does it really matter? I believe it does. Sure, the amp will run the next day after running it wide open all night the night before, but heat and vibration are the two biggest causes of failure, so why not take steps to minimize at least one of them?

 

And again, this is another effect of running the amp at full throttle, with or without an attenuator.

 

That's interesting. I got an e-mail before I bought it that said that the 25W MiniMass would be OK for my 18W Crate V18.

 

It might well be. I'm just saying that you're pushing it, if you crank that amp. I literally smoked a MASS with an amp that was supposedly rated for it. Overdriven tube output can be significantly higher than the amp's posted rating, and power resistors and rheostats have rather wide tolerances (20%, I believe), which means that a 25w device might actually only be good to 20 watts or less (or more, for that matter, but you don't know). I'd go with a 50 watt attenuator on an 18 watt amp, personally.

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It might well be. I'm just saying that you're pushing it' date=' if you crank that amp. I literally smoked a MASS with an amp that was supposedly rated for it. Overdriven tube output can be significantly higher than the amp's posted rating, and power resistors and rheostats have rather wide tolerances (20%, I believe), which means that a 25w device might actually only be good to 20 watts or less (or more, for that matter, but you don't know). I'd go with a 50 watt attenuator on an 18 watt amp, personally.[/quote']

 

Oh I hear you. You got me thinking now. I'm not into blowing up my stuff. All I know is the info that was given to me. I have no prior experience.

So with the 25W MiniMass on my amp, is it more a risk to destroying the MiniMass or to the amp? Or I guess both.

 

I'm generally not going any farther than 8 on the gain and level. Only occasionally do I go full thottle. The sound gets a little too dirty for me when it's all out. When you smoked your MASS was it instantaneous or did it die a gradual death?

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Cranking a tube amp will chew through output tubes much faster than running the throttle low' date=' whether there's an attenuator on the amp or not. It has nothing to do with the attenuator, other than that an attenuator is often used to allow cranking the amp at a reasonable output threshold.

 

I think some of the confusion might come from the fact that there HAVE been incidences in which improperly matched attenuator devices have destroyed output transformers. Often, I see the question posed as "Will an attenuator hurt my amp?" In this case, the question has morphed a bit to only discuss tubes, but I suspect that it still derives from that original question.

 

And, to that, yes indeed, running an improperly matched attenuator device can most definitely melt down an OT. The key is to make sure that the device and the speaker load match what your amp wants to see. No 16 ohm attenuators on 4 ohm amps, etc.

 

Another point worth consideration is the heat that's generated by running a tube amp at full throttle. While you might very well find the amp barely warm to the touch after an hour of low volume play, you'd likely find a much different story after an hour of full volume play.

 

I personally find the stock Vjr. inadequate for ventilation, when the amp is run at full volume. I'm in the process of flipping the amp, so that the tubes ride on top, venting heat away from the chassis (why wasn't this amp built like this originally?), but in the meantime, I've been running it with the back cover completely off, and it seems to stay cool enough that way.

 

On my main stage amp, I use a small clip on fan, directed towards the transformers. It really doesn't take much airflow to make a tremendous difference. Does it really matter? I believe it does. Sure, the amp will run the next day after running it wide open all night the night before, but heat and vibration are the two biggest causes of failure, so why not take steps to minimize at least one of them?

 

And again, this is another effect of running the amp at full throttle, with or without an attenuator.

 

 

 

It might well be. I'm just saying that you're pushing it, if you crank that amp. I literally smoked a MASS with an amp that was supposedly rated for it. Overdriven tube output can be significantly higher than the amp's posted rating, and power resistors and rheostats have rather wide tolerances (20%, I believe), which means that a 25w device might actually only be good to 20 watts or less (or more, for that matter, but you don't know). I'd go with a 50 watt attenuator on an 18 watt amp, personally.[/quote']

 

That's good advice m-theory.......infact Weber recommends 100watt attenuator for 50 watt amps as well because of the peak power those amps can produce. I have a 50 watt mini-mass and it works great with my 5 watters. All attenuators sound their weakest at full attenuation from L-pad's right on up to the $200+ models....it's just the nature of the beast. If you want or need that much attenuation you'll get better results with a pedal in front IMO...but if you just need to knock off a few db's the attenuators work great.

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When you smoked your MASS was it instantaneous or did it die a gradual death?

 

It worked for a while, and then smoke literally came curling out the vents. I couldn't find anything actually "burned out" when I opened it up, but I suspect it was either the rheostat itself that was cooking, or some of the varnish on that device burned off. Ted (Weber) made it into a 100 watter (at no charge to me...the guy is unbelieable at customer service), and shortly after that, began recommending 100 watt devices for 50 watt amps. :)

 

Looking back, I can see how naive it was of me to assume that a 50 watt attenuator would survive being pounded by a cranked 50 watt amp, but I figured 50 watts for 50 watts. Unbeknownst to me at the time, that amp probably pushes close to 60 watts when it's cranked, just as your 18 watter probably pushes in the low 20's when cranked.

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Cranking a tube amp will chew through output tubes much faster than running the throttle low' date=' whether there's an attenuator on the amp or not. It has nothing to do with the attenuator, other than that an attenuator is often used to allow cranking the amp at a reasonable output threshold. [/quote']

 

OK...thanks, we're both saying the same thing then......you just as always put it so much better

 

Another point worth consideration is the heat that's generated by running a tube amp at full throttle. While you might very well find the amp barely warm to the touch after an hour of low volume play' date=' you'd likely find a much different story after an hour of full volume play. [/quote']

 

This reminds me of something I read a while back. Don't know how much truth or bunk there is to it, but to me it kind of made sense at the time and to a point....in other words not as the only cause but in some cases maybe? Throw it at you and see what your views are.

 

Anyhow what I've read is some folks now where able to crank their OLD amps at much higher volume because of adding an attenuator.....or running the amp at higher volumes longer. Which now the amp is dissipating(?spelling) allot more heat than the amp was use to in the past. In turn causing the glue, or whatever, from the paper around the transformer to melt into the windings gumming it up and causing failures....or something of that nature IIRC.

 

Sounds more like Science Fiction to me now that I've typed it, or maybe more so the way I've word it, than actual fact....what yous think?

 

 

 

I've used a Power Brake in the past many times with no issues...then again I only used it for stage volume control and only knocking of a few dbs.

 

However I read all the time where allot of folks try to get their 100watt, 50watt, or whatever large size amps down to TV volumes sort of speak and complain about the attenuator being the cause of making the amp sound bad....or sucking the life out off the amp.

 

IMO that's just due to misuse of the equipment. The higher you attenuate the more you take out the speaker from the equation....which is pretty much already been said. Anyhow some folks attenuate so high that you might as well be listening through a little 4" speaker IMO. Kind of like listening to your stereo through headphones, but not have them on your head...just sitting on a table or somewhere else.

 

At any rate I don't use mine anymore, it sits in my gear cemetery....just cause I don't need one, and not because they aren't any good. Properly used however I think they're great tools.

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Well, I was originally going to get the 50W MiniMass but after a couple of e-mails, one responded by Ted himself saying the 25W would be OK, I figured I'd save $25 and got the $25 watt version. Now, I'm wishing I should have just gotten the 50W version and my mind would be at rest. I hate when I start overthinking things...:)

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Well I from what I understand about SE style amp’s like the Valve Jr is that they are running full throttle all the time.

At full volume they actually conduct less current.

So I couldn’t see a VJ burning through the tubes any faster a high volume than low.

 

Now the other hand to this; the Crate V18 spoken of here or the other 50+watt amp’s you are talking about would be push-pull amp’s that have a different duty cycle and would increase the load as the volume is turned up.

Thus burning out your tubes faster at high volume vs low

 

From what I understand in my limited knowledge of tube amp's.

 

(p.s. yes I would probably double the attenuator wattage to my amp's wattage for a safety margin)

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In turn causing the glue, or whatever, from the paper around the transformer to melt into the windings gumming it up and causing failures

 

Yes, this can happen, as can any number of other heat-related failures. Pushing any tube amp, old or new, to the extreme, will put everything in the amp under stress, which means that eventually, some weak link will appear, whether it be a resistor, cap, tube, or transformer. You can relieve a great deal of stress by simply getting some air moving across the transformers. Also, as a rule, my main stage amp visits the amp doctor every now and then for a checkup. I don't need a weak link showing its ugly self on stage.

 

The odd thing is that a lot of people don't trust and won't use old amps, just because they've undoubtedly heard the numerous horror stories of catastrophic failures at the worst possible moments. Yet, if the amp was fully serviced before being pushed into hard work, the chances of it failing under load are no greater than that of a brand new amp pushed the same way, and in fact, could be significantly less, since modern amps utilize PCB construction for the most part, and that board is always going to be susceptible to heat damage that wouldn't necessarily affect PTP wiring.

 

Now, I'm wishing I should have just gotten the 50W version and my mind would be at rest.

 

I'm sure you'll be fine. I'm quite comfortable with Ted's advice, and if it hasn't smoked by now, it's not likely to. The thing is, there's nothing wrong with having extra cushion, imo. Based upon my own personal past experience, I'd go with a 50w attenuator on an 18w amp.

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Yes' date=' this can happen,....[/quote']

HA....so I can belive some of the stuff I read out there:)

 

You can relieve a great deal of stress by simply getting some air moving across the transformers.

 

I do the same' date=' or rather always carry a small portable fan with me....even so I still worry about the heat. I do outdoor gigs from time to time and it gets pretty hot down here in Florida.

 

 

Also' date=' as a rule, my main stage amp visits the amp doctor every now and then for a checkup. I don't need a weak link showing its ugly self on stage.[/quote']

 

Ditto!! Depending on how much use as to how often, but treat it just like my vehicles. I get the oil changed and tires rotated every 3k miles or 3 months. No need to go that over board with my amps, but they do get a checking often enough for the same reasons.....don't need no surprises. Not to mention the obvious in that I'd like to keep them around for a long time.

 

The odd thing is that a lot of people don't trust and won't use old amps' date=' just because they've undoubtedly heard the numerous horror stories of catastrophic failures at the worst possible moments. Yet, if the amp was fully serviced before being pushed into hard work, the chances of it failing under load are no greater than that of a brand new amp pushed the same way, and in fact, could be significantly less, since modern amps utilize PCB construction for the most part, and that board is always going to be susceptible to heat damage that wouldn't necessarily affect PTP wiring.[/quote']

 

Once again we are on the same page...totally agree. As a matter of fact I treat my newer amps, or modern ones, more gentler than my older ones as far as pushing them.....actually trust the old ones more than the modern, or newer, ones I have just for that very reason you mention.

 

Got nothing against PCB at all, nothing in the least wrong with them IMO, but I feel as you, from what I'm understanding any ways, in that they are much less tolerant to heat. The newer ones get checked by my tech allot more than my older ones. Then again the only old ones I have left are my Red Knob Twin and my Princeton, and both are build like tanks anyways.

 

Anyhow totally agree, just keep them up and they'll perform for ever I think...watch me just jinxed my sheet.

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Thanks for all the input. I have been messing around with it and learning how it works with my amp and how to tweak dials and knobs to get what I want out of it. I'm happy with it. I'll just be aware to avoid pushing the thing past it's limits.

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