Members bengerm77 Posted September 29, 2011 Members Share Posted September 29, 2011 I've seen it in a couple of different places, JCA20 mods adding a choke and the PRS amp has an adjustable choke apparently. What does an amp choke do? Where is it in the amp, and what kind of sound does it produce? Link to comment Share on other sites More sharing options...
Members teemuk Posted September 29, 2011 Members Share Posted September 29, 2011 http://en.wikipedia.org/wiki/Choke_(electronics)http://ken-gilbert.com/power-supply-design-henry-pasternackhttp://www.aikenamps.com/Chokes.html Link to comment Share on other sites More sharing options...
Members BerkleeBill Posted September 29, 2011 Members Share Posted September 29, 2011 Thanks. I'd like to know more about what it does, technically-speaking. I know I installed a choke in my 5150, and holy fuck! Did it ever "open" that amp up, like BIG time!! Would do it again Link to comment Share on other sites More sharing options...
Members guitarcapo Posted September 29, 2011 Members Share Posted September 29, 2011 I always assumed that they helped smooth out some of the ripple in the AC supply because of their location in the filter caps Link to comment Share on other sites More sharing options...
Members skaaks Posted September 29, 2011 Members Share Posted September 29, 2011 Similar to how a capacitor acts as a voltage reservoir, a choke (inductor) acts as a current reservoir. It stores current and releases it when needed. This is helpful in amps because signals like low frequency notes require more power, and therefore more current. Having an extra reservoir of current allows the amp to release that extra bit of current which would otherwise not be available. Without this current reservoir, the amp doesn't have that power immediately available, which leads to a 'sag' in the sound where the response is not immediate. That's my understanding of it, at least. Feel free to correct me if I'm wrong. Link to comment Share on other sites More sharing options...
Members Weathered Posted September 29, 2011 Members Share Posted September 29, 2011 Similar to how a capacitor acts as a voltage reservoir, a choke (inductor) acts as a current reservoir. It stores current and releases it when needed. This is helpful in amps because signals like low frequency notes require more power, and therefore more current. Having an extra reservoir of current allows the amp to release that extra bit of current which would otherwise not be available. Without this current reservoir, the amp doesn't have that power immediately available, which leads to a 'sag' in the sound where the response is not immediate. That's my understanding of it, at least. Feel free to correct me if I'm wrong. This is pretty much right on. Generally, a choke will have a higher inductance and a lower resistance than a resistor in the same spot of the power supply (usually after the power tube plate B+ and before the screen B+). Here's a good document on more generic power supply design, which addresses chokes: http://www.freewebs.com/valvewizard1/smoothing.html Link to comment Share on other sites More sharing options...
Members soundgardener75 Posted September 29, 2011 Members Share Posted September 29, 2011 Ask Latrell Sprewell. Link to comment Share on other sites More sharing options...
Members Weathered Posted September 29, 2011 Members Share Posted September 29, 2011 Ask Latrell Sprewell. One from the archives there.... Link to comment Share on other sites More sharing options...
Members Cirrus Posted September 29, 2011 Members Share Posted September 29, 2011 I always think of it like a fly wheel. Link to comment Share on other sites More sharing options...
Members TheRymanChu Posted September 29, 2011 Members Share Posted September 29, 2011 I've heard that when you add the choke, your amp has a more intense orgasmic tone. This can be very dangerous for the life expectancy of your...um...jack, head vent, strain relief, nuts and your tube. You wouldn't want your family to come home and find you all enmeshed in the wiring harness. Link to comment Share on other sites More sharing options...
Members Kap'n Posted September 30, 2011 Members Share Posted September 30, 2011 The big thing you get with a choke in its typical placement betwen the plates and screens is the stabilization of the voltage on the screens in the power tubes. The usual alternative is to use a resistor between the plates and screens to isolate them. When the amp is pushed, the screens draw more current = more voltage dropped across the resistor, giving a spongier feel. Tweed Fenders, with the exception of the Bassman and high power Tweed Twin have a dropping resistor in this location* as do brown/black/silver Princetons and Princeton Reverbs. Push one of those hard, and you will know the difference. Not only does the choke have a low DC resistance = less voltage drop, but it stores energy that picks up the slop when the screens start drawing power. They, along with filter caps act as "shock absorbers" in the power supply as well as filtering DC ripple that sounds especially nasty when you push the amp. *Yes, I know the late Super/Pro/Bandmaster/low-power tweed twin and a few of the champs have a choke. The location however is not in the location mentioned, and do nothing to prevent screen voltage sag. Link to comment Share on other sites More sharing options...
Members knucklefux Posted September 30, 2011 Members Share Posted September 30, 2011 Capacitors oppose a change in voltage, and inductors (chokes are giant inductors) oppose a change in current. If voltage drops, capacitors discharge to keep the voltage constant. If current flow drops, inductors discharge to keep the current constant. The effect of a choke OS to stabilize the current supply to any components downstream from it. Power tubes shouldn't be run off the choke. Link to comment Share on other sites More sharing options...
Members Kap'n Posted September 30, 2011 Members Share Posted September 30, 2011 Capacitors oppose a change in voltage, and inductors (chokes are giant inductors) oppose a change in current. If voltage drops, capacitors discharge to keep the voltage constant. If current flow drops, inductors discharge to keep the current constant.The effect of a choke OS to stabilize the current supply to any components downstream from it. Power tubes shouldn't be run off the choke. One way of looking at it. I think of it more as caps passing AC and blocking DC, and chokes vice-versa. But the choke is in line blocking ripple, wheras the filter caps are bleeding it to ground. Power tubes are run off the choke in some of the amps I mentioned above. Not great from a design standpoint for a few reasons, but they do give a characteristic sound. Link to comment Share on other sites More sharing options...
Members Y0UNGBL00D Posted September 30, 2011 Members Share Posted September 30, 2011 i choke bitches. end of story. (i was curious about these too actually. good info! i love when hcaf is actually informative) Link to comment Share on other sites More sharing options...
Members knucklefux Posted September 30, 2011 Members Share Posted September 30, 2011 One way of looking at it. I think of it more as caps passing AC and blocking DC, and chokes vice-versa. But the choke is in line blocking ripple, wheras the filter caps are bleeding it to ground.Power tubes are run off the choke in some of the amps I mentioned above. Not great from a design standpoint for a few reasons, but they do give a characteristic sound. If chokes blocked DC, they wouldn't be very good in DC power supplies... Link to comment Share on other sites More sharing options...
Members mhr74 Posted September 30, 2011 Members Share Posted September 30, 2011 One from the archives there.... yup Link to comment Share on other sites More sharing options...
Members skaaks Posted September 30, 2011 Members Share Posted September 30, 2011 I think that's what he meant by 'vice-versa', meaning chokes pass DC and block AC. Link to comment Share on other sites More sharing options...
Members NeloAngelo Posted September 30, 2011 Members Share Posted September 30, 2011 Ask Latrell Sprewell. ask david carradine. Link to comment Share on other sites More sharing options...
Members knucklefux Posted September 30, 2011 Members Share Posted September 30, 2011 Reading comprehension fail on my part. I blame old age Link to comment Share on other sites More sharing options...
Members Y0UNGBL00D Posted September 30, 2011 Members Share Posted September 30, 2011 i choke. bitches. did yall not get that? Link to comment Share on other sites More sharing options...
Members futurism Posted September 30, 2011 Members Share Posted September 30, 2011 i choke. bitches. did yall not get that? needs a bit more effort as you are doing it wronghow about it sits between the imma input and abitch output sections to constrain airflow Link to comment Share on other sites More sharing options...
Members Y0UNGBL00D Posted September 30, 2011 Members Share Posted September 30, 2011 i dont know why you can't fathom that i forcefully asphyxiate women on a regular basis. Link to comment Share on other sites More sharing options...
Members ShaneV2 Posted September 30, 2011 Members Share Posted September 30, 2011 I don't know, but I know that Wayne Brady sometimes has to use one on a bitch. Link to comment Share on other sites More sharing options...
Members Slaymoar Posted September 30, 2011 Members Share Posted September 30, 2011 1. Chokes prevent sag in the screen grids of power tubes, and of the preamp section. So cranking the amp will have little effect on anything but the power tube plates of the amp. This results in minimal voltage/current sag effect in the sound, so a cleaner output - to some extent. Power tubes will still drain enough voltage to sag the power supply when fully driven, but not as much as if there were no choke. The voltage change in the preamp is so minimal, that it won't affect the "gain structure" nearly as much as without a choke. Some people will describe the sound as "more open", more clarity etc.. 2. NOISE. This is, IMO, the other main reason for getting a choke. It filters down the AC ripple so much, it virtually kills it. AC ripple sucks in a high gain amp. It WILL leak through especially if the voltage drop resistors are of small value between preamp supplies. A 5150, a noisy ass amp, would greatly benefit from a choke for example; which will reduce the noise floor at high gain settings. Just my input. Link to comment Share on other sites More sharing options...
Members FastRedPonyCar Posted September 30, 2011 Members Share Posted September 30, 2011 i choke. bitches. did yall not get that? Wayne Brady did it first [video=youtube;8pklq_ShnbA] Link to comment Share on other sites More sharing options...
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