Power Attenuator
- Thread starter pooo
- Start date
brundisium
New member
yup, power attenuator does work with combo amp. The attenuator will be connected in between the speaker output and the speaker cab.
Only attenuator that i know of that is available locally is the THD hotplate. Only downside is that the price is not cheap($600-$700+ brand new). But for attenuator, the hotplate is one of the best for product of this kind. Some other attenuators are marshall powerbrake and weber mass attenuator which are much more cheaper in price than the THD one.
Thru a attenuator, the crank tone of the amp can be achieve at a lower vollume, but it will change the tone to a certain extend and with some tubes, the crank tone would sound fuzzy.
Only attenuator that i know of that is available locally is the THD hotplate. Only downside is that the price is not cheap($600-$700+ brand new). But for attenuator, the hotplate is one of the best for product of this kind. Some other attenuators are marshall powerbrake and weber mass attenuator which are much more cheaper in price than the THD one.
Thru a attenuator, the crank tone of the amp can be achieve at a lower vollume, but it will change the tone to a certain extend and with some tubes, the crank tone would sound fuzzy.
marshall_law
New member
I think it will colour the tone... not very sure, i never got one anyway.
brundisium
New member
brundisium
New member
fretless6 said:Do try to keep in mind, however, although u are stepping down the power to the speakers, u are still cranking up ur poweramp section. U will significantly shorten the life of ur powertubes and might even blow a couple of resistors if you are to run it at 10 all the time.
Running the tubes hotter but shortening the lifespan does give a good tone most of the time. As for blowing resistors, that i couldnt agree more. It was definitely a painful situation to hear the amp go dead in such manner. Pain for the amp and the pocket :lol:
This website is pretty cool for addressing myths about amps...
http://www.guitarnuts.com/amps/myths.php
I don't personally own a preamp, but has anyone here had experience using attenuators? I quote advice given from the above website:
Have a reputable tech "cool off" your amp. Explain to the tech that you are going to be driving the amp very hard into an attenuator and you want it biased a bit cold to save the tubes. This will cost a bit in tone (chances are you won't notice this because you probably never drove the amp so hard anyway) but will make the tubes last a lot longer and reduce the chances of damage to other components such as the expensive output transformer. A knowledgeable tech can also tell you if the model of amp you are using is known for blowing transformers and what have you (many guitar amps have output transformers that are not rated anywhere near the amp's max output).
Has anyone had a tech "bias the amp a bit cold"?? Also, wouldn't mind if someone explain that term....
http://www.guitarnuts.com/amps/myths.php
I don't personally own a preamp, but has anyone here had experience using attenuators? I quote advice given from the above website:
Have a reputable tech "cool off" your amp. Explain to the tech that you are going to be driving the amp very hard into an attenuator and you want it biased a bit cold to save the tubes. This will cost a bit in tone (chances are you won't notice this because you probably never drove the amp so hard anyway) but will make the tubes last a lot longer and reduce the chances of damage to other components such as the expensive output transformer. A knowledgeable tech can also tell you if the model of amp you are using is known for blowing transformers and what have you (many guitar amps have output transformers that are not rated anywhere near the amp's max output).
Has anyone had a tech "bias the amp a bit cold"?? Also, wouldn't mind if someone explain that term....
brundisium
New member
most tube amp bought brand new are bias lower than the best operating spec that the amp is supposed to be if not wrong. There is a calculation which can be done to find out the average value for biasing. Some of the guitar player would bias the amp a bit hotter to get the so called "warm tube" tone. Although its pushing the tube harder, it does get a good tone.
As for what is biasing, in simple term, its adjusting a pot in the amp circuit to varies the current flowing through the power tube(EL-34/84 etc). Preamp tube(12ax7/ecc83, 12 at7 atc) need no biasing on replacement.
Biasing of amp will also depend on the design of amp, some tube amp does not require biasing even when changing the power tube. Most tube amps do require biasing though
here is a good page for faq of tube amp, including the biasing part and various class of amp. http://www.geofex.com/tubeampfaq/taffram.htm
As for what is biasing, in simple term, its adjusting a pot in the amp circuit to varies the current flowing through the power tube(EL-34/84 etc). Preamp tube(12ax7/ecc83, 12 at7 atc) need no biasing on replacement.
Biasing of amp will also depend on the design of amp, some tube amp does not require biasing even when changing the power tube. Most tube amps do require biasing though
here is a good page for faq of tube amp, including the biasing part and various class of amp. http://www.geofex.com/tubeampfaq/taffram.htm
marshall_law
New member
Does my marshall DSL 401 needs biasing? I thinking of changing to EH tubes. And if it needs to be bias, do i bring it to a shop to do it or the technican comes to my house.
brundisium
New member
yeah, most of marshall tube amp will need biasing on changing the power tube.
I do believe that most amp tech would request the owner to bring the amp down to them for biasing.
Another way is to learn how to do your own biasing. There are sites over the net which has the info. But to do that, you will have to know what you are doing, if not, it might be fatal. Some components in the amp circuit contain voltage(unless being discharged) even though the power is switch off. Most would suggest use one hand at a time to chk the circuit, just in case of electic shock, you wont be the path for the electricity to flow through
I do believe that most amp tech would request the owner to bring the amp down to them for biasing.
Another way is to learn how to do your own biasing. There are sites over the net which has the info. But to do that, you will have to know what you are doing, if not, it might be fatal. Some components in the amp circuit contain voltage(unless being discharged) even though the power is switch off. Most would suggest use one hand at a time to chk the circuit, just in case of electic shock, you wont be the path for the electricity to flow through
JMguitars
New member
pooo said:
Poo,
As Brundisium mentioned, I sell THD Hotplates here for the price of SGD 640.
The price is inclusive of shipping and GST.
Let me know if you're interested. I can be reached at sales@jmguitars.com if you have further queries.
Mark L.
J&M Guitars
www.jmguitars.com
Hi Mark (JMGuitars),
Remember me, you brought the blown Univalve to me (Mike, Roy Music Studio) before to check out. How's things?
Well, 2 months ago, your customer brought that replacement you had to me, same complaint. Luckily this time round, no burnt stuff around, thus I could get measurements and sucessfully fixed it. So any new stuffys?? Your site not updated for a while already.
We should catch up a bit and share some ideas sometime.
Regards,
Mike
To Tread Posts:
My personal opinions is most important to choose an amp that suits you. Don't buy a 100Watt 2X12, to put in your bedroom. You can't crank it up enough to get any decent tone it's meant to drive, because if you do, you'll have policeman taking a report on your disturbance.
On adding attenuators, I'd suggest against it, because you don't know what kind of stress you are putting on your amp and wheather your amp can take it. Once blown, you might not be able to get back the tone you amp is supposed to produce, even after repairs by an experienced amp guru. This is because the general tolerance of components will be affected by a major blow, eg. like a person recover from a stroke, will never be like before.
I haven't being repairing amps for long, but I can fix and advise on most if not all problems with faulty amps. I have dabbled hands-on in electronics since young, so I'd have what you'd say, more feel than knowledge on these stuffs. I have done quite a nos of amps already, both trans and tubeys type. If anyone out there need to fix theirs, you can simply contact me at 97337161, Mike. Thanks.
Remember me, you brought the blown Univalve to me (Mike, Roy Music Studio) before to check out. How's things?
Well, 2 months ago, your customer brought that replacement you had to me, same complaint. Luckily this time round, no burnt stuff around, thus I could get measurements and sucessfully fixed it. So any new stuffys?? Your site not updated for a while already.
We should catch up a bit and share some ideas sometime.
Regards,
Mike
To Tread Posts:
My personal opinions is most important to choose an amp that suits you. Don't buy a 100Watt 2X12, to put in your bedroom. You can't crank it up enough to get any decent tone it's meant to drive, because if you do, you'll have policeman taking a report on your disturbance.
On adding attenuators, I'd suggest against it, because you don't know what kind of stress you are putting on your amp and wheather your amp can take it. Once blown, you might not be able to get back the tone you amp is supposed to produce, even after repairs by an experienced amp guru. This is because the general tolerance of components will be affected by a major blow, eg. like a person recover from a stroke, will never be like before.
I haven't being repairing amps for long, but I can fix and advise on most if not all problems with faulty amps. I have dabbled hands-on in electronics since young, so I'd have what you'd say, more feel than knowledge on these stuffs. I have done quite a nos of amps already, both trans and tubeys type. If anyone out there need to fix theirs, you can simply contact me at 97337161, Mike. Thanks.
JMguitars
New member
Hi Mike,
Yes, I heard from the client that after the component was replaced, the amp has been in good shape since.
Regards.
Ps - Been a bit busy so updating the site will have to be done somewhere in July earliest. I'll be uploading my Winter NAMM 2004 videos about that time as well so drop in for a look then.
Mark
J&M Guitars
Yes, I heard from the client that after the component was replaced, the amp has been in good shape since.
Regards.
Ps - Been a bit busy so updating the site will have to be done somewhere in July earliest. I'll be uploading my Winter NAMM 2004 videos about that time as well so drop in for a look then.
Mark
J&M Guitars
JMguitars
New member
mikemann said:
Just a small clarification Mike, ...
The attenuator acts as a load in the place of a speaker i.e. the amp recognises the Hotplate as the speaker.
It permits the amp to be turned up most or all the way while absorbing most of the power generated by the amplifier and turning this power into heat. It then passes a small amount of power onto the speaker.
The danger to the amp, if any, is similar to when no attenuator is used ....
The ohmage of the load, be it the speaker(s) or power attenuator, must be the same as the ohmage setting (4,8,16 ohms) on the amp (see link for full explanation).
http://www.thdelectronics.com/products/hotplate.htm
"Will it hurt my amp?"
The THD Hot Plate® will not damage your amplifier. When you play continuously at full output, you cause your tubes to age more quickly than they would at lower volumes. Using a Hot Plate® will maintain the life of your tubes at exactly the same rate, no more or less, as when you play straight through the speaker.
Using a Hot Plate® will also not hurt your transformer any more than playing through a speaker, as long as the impedances are matched (i.e. 8 ohm setting on the amp, 8 ohm speakers and an 8 ohm attenuator). If you are using a well-made amp, then the transformer should last indefinitely, regardless of whether you are driving a speaker or attenuator. If you are using an inferior amp and the transformer blows, it would have done this whether you play through a speaker or an attenuator. The Hot Plate® puts the same load on the transformer as a speaker (which is why it makes such a good dummy load).
Mark
J&M Guitars
JMguitars
New member
this link shows a test as done by a Hotplate user on the effects on attenuators on tonal frequencies ....
http://acapella.harmony-central.com/forums/showthread.php?s=&threadid=641405&perpage=20&pagenumber=1
http://acapella.harmony-central.com/forums/showthread.php?s=&threadid=641405&perpage=20&pagenumber=1
Err...Mark,
Let me just put it in another way:
There is a 5yr old car, engine never overhaul before, in original state, works great, and will give many years more of good service.
It's sold to another person who modded it, add turbo kit, exhaust system.....and what not. Then he keeps pushing the engine beyond it's max rpm. Within 3days, he ends up with a blown engine, and hefty repair bills.
So, the story is similar here. If you have something modded, tendency is that you'll want to experience the max. Which is what that device is meant to do, push the output circuit to overdrive.
Moral: Power is nothing without control
I'm not putting down the product or anything, I think it gives the user more options for sound possibilities and output. Just giving friendly advice and opinions to potential buyer of it.
Praises and tech specs are just what the manufacturer uses to promote his products. Who will advertise bad things about their stuff. Thus I hope that when you sell this device, you'll explain the downside possibilities to the customers. Else he will come knocking on your door if it causes his amp to blow. At least you disclaim this responsibility to the customer already.
Regards,
Mike
Let me just put it in another way:
There is a 5yr old car, engine never overhaul before, in original state, works great, and will give many years more of good service.
It's sold to another person who modded it, add turbo kit, exhaust system.....and what not. Then he keeps pushing the engine beyond it's max rpm. Within 3days, he ends up with a blown engine, and hefty repair bills.
So, the story is similar here. If you have something modded, tendency is that you'll want to experience the max. Which is what that device is meant to do, push the output circuit to overdrive.
Moral: Power is nothing without control
I'm not putting down the product or anything, I think it gives the user more options for sound possibilities and output. Just giving friendly advice and opinions to potential buyer of it.
Praises and tech specs are just what the manufacturer uses to promote his products. Who will advertise bad things about their stuff. Thus I hope that when you sell this device, you'll explain the downside possibilities to the customers. Else he will come knocking on your door if it causes his amp to blow. At least you disclaim this responsibility to the customer already.
Regards,
Mike
JMguitars
New member
Mike,
Definitely know where you're coming from and thats good; to pinpoint potential problem causing issues before they surface.
Perhaps I should have left mention of the THD Hotplate off ....
But answering purely as a guitar player myself, ...... I remain an advocate of using power attenuators in order to achieve the overdriven tone of a tube amp (be it whichever brand).
I've been doing this for the last few years and as a personal user of power attenuators, its been great to crank the tube amp and hear it come alive at low volumes.
Therefore, just like you, I'll be here to lend a voice to share my own experiences as a guitarist and maybe once in a while, help answer any direct questions on the products I support.
Regards.
Mark
J&M Guitars
Definitely know where you're coming from and thats good; to pinpoint potential problem causing issues before they surface.
Perhaps I should have left mention of the THD Hotplate off ....
But answering purely as a guitar player myself, ...... I remain an advocate of using power attenuators in order to achieve the overdriven tone of a tube amp (be it whichever brand).
I've been doing this for the last few years and as a personal user of power attenuators, its been great to crank the tube amp and hear it come alive at low volumes.
Therefore, just like you, I'll be here to lend a voice to share my own experiences as a guitarist and maybe once in a while, help answer any direct questions on the products I support.
Regards.
Mark
J&M Guitars
