Hey all, just a quick rundown of the services I offer (or plan to in the near future)..
Replacing & Biasing Power Tubes - This is something everyone with a tube amp should have done when they replace their power tubes, and that should be every year or two, depending on how often you play and how hard you play the amp. This kind of job isn't too difficult, and once the parts are in, can be done rather quickly. Bring me your amp, we'll fire it up, I'll help you pick the best tubes for the amp (and at the most reasonable prices), and when they arrive, bias them properly and send you on your way.
$50 + cost of the tubes. I can help you pick a good pair of tubes if you need me to, as a free service.
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Minor troubleshooting: blown lights, power cable disintegrating? need new knobs? I can do that stuff easy, with discounted bench rate.
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CUSTOM AMP DESIGN AND CONSTRUCTION - You want a real vintage hand wired custom amp for less than those exorbitant name-brand prices? Let's talk. Right now I specialize in Tweed Fender era amps - great for blues & classic rock - great for indie rock. Looking forward to adding BF era and classic Marshall's to my list once i have a reason to, though, and a custom order would be just the excuse. big discount for the first order i get of a specific model. Email me for more details.
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Interested parties email me at tjwark@gmail.com for pricing information and details. I've currently got one deluxe built now (which i would be happy to demo) and plan on building another and a 59 Bassman in short order...
I'm conveniently located right behind the cherry hill mall in Cherry Hill, NJ
Showing posts with label biasing. Show all posts
Showing posts with label biasing. Show all posts
Thursday, March 26, 2009
Wednesday, January 14, 2009
biasing your amp
...or rebiasing, depending on your point of view.
anyway - this is something that you should only do if you KNOW WHAT YOU'RE DOING. Your amp has big capacitors in it like old TVs that can hold a charge long after you've unplugged your amp, and that charge is enough to KILL you if you're unlucky. so don't do it unless you've been shown how to properly discharge them. if you don't want to do it yourself, i can do it for you ;-) if you're brave enough to think about trying it though, read on...
that being said - most of what i can say about it has already been said here, but i can add a few additional pointers.
#1 - if you check the amp's bias current several times over the first 15 or 20 minutes it's been on, it'll continue to creep up - so to avoid biasing too hot, you're probably better off letting it warm up that long before taking a measurement.
#2 - the ted weber bias-rite is a handy little device, especially if your amp doesn't have a bias point built into it - but i've found that the reading coming off of a single "head only" bias-rite (the thing that just has leads coming off to plug into a stand alone multimeter) seems to be a little low - at least when dealing with an amp with more than one power tube. My guess is probably that the value at the plates doesn't quite sum to the value at the bias point, at least in the case of my deville - but it's something to keep in mind. Not sure how that compares to the actual 2 & 4 head bias-rite device...just keep this in mind - although you shouldn't be biasing at the absolute limit of the tubes anyway.
#3 - biasing too cold causes the amp to buzz and give you flabby lows. biasing to hot causes you to distort quick. both are bad for the tubes, and possibly the transformer. too hot is probably worse than too cold, though.
#4 - replace your power tubes after about 2 years of use if you use the amp 'regularly'. you'll be amazed at the difference in the sound. replace the preamp tubes every 4-5 years, or when they start to go microphonic. if you hear weird rattling when you play the amp, or weird out-of-key harmonics, that's microphony. chances are this is how your preamp tubes will go. they're relatively cheap, and don't need to be biased, so this is always a good first thing to do.
#5 - speaking of microphony, DON'T ROLL YOUR AMP ON BUMPY CEMENT if you have coasters on it. this is the quickest way to develop microphony and ruin otherwise good tubes. this is why 50-pound tube combos don't come with coasters on them.
anyway - this is something that you should only do if you KNOW WHAT YOU'RE DOING. Your amp has big capacitors in it like old TVs that can hold a charge long after you've unplugged your amp, and that charge is enough to KILL you if you're unlucky. so don't do it unless you've been shown how to properly discharge them. if you don't want to do it yourself, i can do it for you ;-) if you're brave enough to think about trying it though, read on...
that being said - most of what i can say about it has already been said here, but i can add a few additional pointers.
#1 - if you check the amp's bias current several times over the first 15 or 20 minutes it's been on, it'll continue to creep up - so to avoid biasing too hot, you're probably better off letting it warm up that long before taking a measurement.
#2 - the ted weber bias-rite is a handy little device, especially if your amp doesn't have a bias point built into it - but i've found that the reading coming off of a single "head only" bias-rite (the thing that just has leads coming off to plug into a stand alone multimeter) seems to be a little low - at least when dealing with an amp with more than one power tube. My guess is probably that the value at the plates doesn't quite sum to the value at the bias point, at least in the case of my deville - but it's something to keep in mind. Not sure how that compares to the actual 2 & 4 head bias-rite device...just keep this in mind - although you shouldn't be biasing at the absolute limit of the tubes anyway.
#3 - biasing too cold causes the amp to buzz and give you flabby lows. biasing to hot causes you to distort quick. both are bad for the tubes, and possibly the transformer. too hot is probably worse than too cold, though.
#4 - replace your power tubes after about 2 years of use if you use the amp 'regularly'. you'll be amazed at the difference in the sound. replace the preamp tubes every 4-5 years, or when they start to go microphonic. if you hear weird rattling when you play the amp, or weird out-of-key harmonics, that's microphony. chances are this is how your preamp tubes will go. they're relatively cheap, and don't need to be biased, so this is always a good first thing to do.
#5 - speaking of microphony, DON'T ROLL YOUR AMP ON BUMPY CEMENT if you have coasters on it. this is the quickest way to develop microphony and ruin otherwise good tubes. this is why 50-pound tube combos don't come with coasters on them.
Tuesday, January 6, 2009
I rebiased my amp tonight.
So currently my main amp is still my Deville 4x10, and lately it's been sounding not so fresh. Well, now that I know how amps work, I figured rebiasing it wouldn't hurt. Well, sure enough, it was biased a little cold - I couldn't really crank it to get a feel for how it sounds now because i'm doing this in my apartment, but from what i could tell it sounds a lot warmer, which makes sense. Next practice will tell...
anyway, this brings up another point - when i had the tubes replaced on this amp, i took it to a prominent local tube amp repair place to have the work done. Now I won't name names, but the place is in south jersey. when i got the amp back, one of the speakers was blown. Now i'm not saying they did it, but they definitely should have caught it. Anyway, one of the things I paid for at the time was for them to put high-quality tubes in the amp - and i paid $100 extra for this.
The tubes in my amps are regular Sovteks. Nothing special, and $24/pair tubes. So not only was this guy incompetent, but also dishonest.
Let this be a lesson! Know your amp tech, and get some background information on them if you can! If you're replacing your power tubes, you DO need to have the amp rebiased. This is NOT something you should do if you don't know what you're doing because we're talking about serious voltages that can kill, but if you want to here's a link that explains how to do it.
Of course, I'll be happy to install your tubes and bias them for a nominal fee, and I also won't rip you off on the tubes. I'll even give you a link to a place to check the prices on them.
anyway, this brings up another point - when i had the tubes replaced on this amp, i took it to a prominent local tube amp repair place to have the work done. Now I won't name names, but the place is in south jersey. when i got the amp back, one of the speakers was blown. Now i'm not saying they did it, but they definitely should have caught it. Anyway, one of the things I paid for at the time was for them to put high-quality tubes in the amp - and i paid $100 extra for this.
The tubes in my amps are regular Sovteks. Nothing special, and $24/pair tubes. So not only was this guy incompetent, but also dishonest.
Let this be a lesson! Know your amp tech, and get some background information on them if you can! If you're replacing your power tubes, you DO need to have the amp rebiased. This is NOT something you should do if you don't know what you're doing because we're talking about serious voltages that can kill, but if you want to here's a link that explains how to do it.
Of course, I'll be happy to install your tubes and bias them for a nominal fee, and I also won't rip you off on the tubes. I'll even give you a link to a place to check the prices on them.
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