Wiring resistors together

VR3

If you want to make a value with resistors - all you do is put two in line together correct?

Like if I wanted to get 3 ohm - I could take two 1.5 ohm resistors and attach the middle connection together then the end connections of each resistor go to the connection point...

Right?

Thanks

Face

http://www.sengpielaudio.com/calculator-paralresist.htm

dorokusai

Piggyback.

VR3

awesome - thanks!

inspiredsports

2 diametrically opposed answers above, but I vote "series" as you properly described in your post #1.

If you parallel (piggyback) them you get .75.

VR3

Yeah - I used their calculator and your right - running them together does give .75 ohms - that would be a no go...

3 ohms is the target

inspiredsports

Vr3MxStyler2k3 wrote: »

Yeah - I used their calculator and your right - running them together does give .75 ohms - that would be a no go...

3 ohms is the target

It depends upon what you want to accomplish.

In series it is simple addition (additive), but in parallel it is 1 divided by the first value plus 1 divided by the second value.

TECHNOKID

Face wrote: »

http://www.sengpielaudio.com/calculator-paralresist.htm

dorokusai wrote: »

Piggyback.

Exactly!

inspiredsports wrote: »

2 diametrically opposed answers above, but I vote "series" as you properly described in your post #1.

If you parallel (piggyback) them you get .75.

I'd never put them is series, when I was working in manufacturing and calibrating circuit boards we always picky back same value resistors in parallel. In the OP's case 2 6 ohms in parallel will give him his 3 ohm resitor.

VR3

Hey Techno - that makes sense.

dorokusai

inspiredsports wrote: »

2 diametrically opposed answers above, but I vote "series" as you properly described in your post #1.

If you parallel (piggyback) them you get .75.

Not sure what you're reading but you might want to order another copy.

cristo

I was waiting for someone to suggest adding a 4.7 Meg bypass resistor in parallel to even out the
phase response anomalies of a simple network of resistors and thereby markedly improve the sound,
but in an extremely subtle manner.
Works even better than with capacitors!

TECHNOKID

dorokusai wrote: »

Not sure what you're reading but you might want to order another copy.

He is talking about paralleling the 1.5 ohms Vr3MxStyler2k3 mentioned (which is correct).

inspiredsports

Vr3MxStyler2k3; Why not just use a single 3?

Does anyone know why series is technically a bad way to do it?

dorokusai

TECHNOKID wrote: »

He is talking about paralleling the 1.5 ohms Vr3MxStyler2k3 mentioned (which is correct).

I'm aware but Face and I didn't have diametrically opposing viewpoints to the best of my knowledge.

inspiredsports

dorokusai wrote: »

I'm aware but Face and I didn't have diametrically opposing viewpoints to the best of my knowledge.

I think I was typing when you posted and was looking at posts 1 and 2.

VR3

Some places I order from dont have values I need and when you order from two places the shipping cost doubles - so I try to avoid that

inspiredsports

dorokusai wrote: »

I'm aware but Face and I didn't have diametrically opposing viewpoints to the best of my knowledge.

Sorry for the confusion. I was referring to OP's idea versus both yours and Face's as OP said two 1.5's in his example.

TECHNOKID

inspiredsports wrote: »

Vr3MxStyler2k3; Why not just use a single 3?

Does anyone know why series is technically a bad way to do it?

In series you drop voltage at each resistor which IMHO is a bad thing the current is however constant. In parallel it is the opposite the voltage is constant across the load while the current is split (but does not matter as the current remains the same at either side of the resistor). Also, piggy backing the resistors make for a much cleaner job as it uses the exact same thrugh holes with the resistors on top of each other. In the series format, one would usually have to install the resistors standing up which does not make as clean of a job not counting that such arrangement is also more vulnerable.

inspiredsports

TECHNOKID wrote: »

In series you drop voltage at each resistor which IMHO is a bad thing the current is however constant. In parallel it is the opposite the voltage is constant across the load while the current is split (but does not matter as the current remains the same at either side of the resistor). Also, piggy backing the resistors make for a much cleaner job as it uses the exact same thrugh holes with the resistors on top of each other. In the series format, one would usually have to install the resistors standing up which does not make as clean of a job not counting that such arrangement is also more vulnerable.

Thanks!

I'm curious about this in terms of our crossover mods when we remove polyswitches (typically .5 ohm).

So technically speaking, can we say a 2.7 ohm + .5 ohm resistor in series (replicating the architecture of a 2.7 ohm resistor + .5 ohm polyswitch which were in series from Polk) would have a different VOLTAGE "signature" versus replacing both components straight through with a 3.2 ohm resistor ??

TECHNOKID

Vr3MxStyler2k3 wrote: »

Some places I order from dont have values I need and when you order from two places the shipping cost doubles - so I try to avoid that

BTW, the value does not have to be 6 ohms both ways if that creates and issue with your supplier. As an example if you piggy back 4 ohm and 12 ohm, you still get your 3 ohm average. The main thing is to make sure the wattage of value of all resistor used are the same. Also make sure they match the original wattage.

I have a story on the above. When I operated my repair shop, my so called technican had used a 15 watts ceramic resistor in lieu of the 1/4 watt original resistor.:eek: I think I had a heart attack on that day.:rolleyes: Unfortunately, it took all of my courage a while after this incident to fire this poor man as if not, he would have sinked the business into a hell hole. :frown:

dorokusai

inspiredsports wrote: »

Sorry for the confusion. I was referring to OP's idea versus both yours and Face's as OP said two 1.5's in his example.

Got ya' Inspired Sports and you're spot on in that regards.

TECHNOKID

inspiredsports wrote: »

Thanks!

I'm curious about this in terms of our crossover mods when we remove polyswitches (typically .5 ohm).

So technically speaking, can we say a 2.7 ohm + .5 ohm resistor in series (replicating the architecture of a 2.7 ohm resistor + .5 ohm polyswitch which were in series from Polk) would have a different VOLTAGE "signature" versus replacing both components straight through with a 3.2 ohm resistor ??

In a case like this, this is very insignificant and shouldn't have much effect when you consider the accepted tolerance in consumer goods is between 10 - 20% meaning that your 3 ohms resistor could vary from 2.7 to 3.3 ohms with 10% tolerance and between 2.4 to 3.6 ohms if the tolerance is 20%.

The situation you are talking about is not of a big concern as IMHO, I see the polyswitch as a short in such a circuit (that would be very different in a small active circuit). If you are to change value of any type of components (be resistor, coil, capacitor) in a crossover you then may affect the sound reproduction of the speaker (either in a good or bad way). This is how I view/understand sound signature of a specific speaker, due to the Xo circuitry you may affect the original sound as intended and thus creating a specific signature for the speaker. Resistors on their own IMHO will not create signature but simply affect circuit voltage but when used in conjunctions with other components such as coils and capacitors you can then create time delays, resonnant circuits and so no.

As far as I am concerned, I try to stick to original parts rating and arrangement as I am not an engineer and am not sure in which way a mod can affect the equipment.

BTW, when you remove that polyswitch if you really insist in replacing the resistor (which is not a must IMHO) you could simply go with a 2.7 or 3 ohms resistor with tighter tolerance such as 1 or 2% (military specs) and be done with it. Installing a resistor of 3.2 ohms at 10 - 20% tolerance will not garantee you 3.2 as it can go as low as 2.88 and as high as high as 3.52 at 10% and as low as 2.56 and as high as 3.84 so what is the point of replacing for a higher value cause of the switch value when the tolerance variation factor is just as bad.

Esreuter

learning opportunity.

What is a poly switch and what does it do?

i briefly read some things about they cut out and protect the tweeter, then i have read some things where people remove them entirely.

so yeah, please explain to me about them.

ESR

dorokusai

It's just like a circuit breaker that resets itself. They protect the tweeter from being blown by going into a protect mode when a certain tolerance is reached, namely heat, and reset when that threshold is returned to normal.

I remove them as I find them uneccesary in the signal path.

TECHNOKID

Esreuter wrote: »

learning opportunity.

What is a poly switch and what does it do?

i briefly read some things about they cut out and protect the tweeter, then i have read some things where people remove them entirely.

so yeah, please explain to me about them.

ESR

I guess they must create problem/issues? In this case I would be tempted to remove the polyswitch and resistor to replace them with a resistor fuse which would still match and protect the tweeter.

VR3

I have had some extremely negative results replacing resistors 10% in spec... like 9 to 8.2

Resistors can make or break a loudspeaker in my experience (as far as values go)

dorokusai

Vr3MxStyler2k3 wrote: »

I have had some extremely negative results replacing resistors 10% in spec... like 9 to 8.2

Resistors can make or break a loudspeaker in my experience (as far as values go)

Really? Ya' think so Trey? :redface:

VR3

Mark - I was commenting this

The situation you are talking about is not of a big concern as IMHO, I see the polyswitch as a short in such a circuit (that would be very different in a small active circuit). If you are to change value of any type of components (be resistor, coil, capacitor) in a crossover you then may affect the sound reproduction of the speaker (either in a good or bad way). This is how I view/understand sound signature of a specific speaker, due to the Xo circuitry you may affect the original sound as intended and thus creating a specific signature for the speaker. Resistors on their own IMHO will not create signature but simply affect circuit voltage but when used in conjunctions with other components such as coils and capacitors you can then create time delays, resonnant circuits and so no.

As far as I am concerned, I try to stick to original parts rating and arrangement as I am not an engineer and am not sure in which way a mod can affect the equipment.

BTW, when you remove that polyswitch if you really insist in replacing the resistor (which is not a must IMHO) you could simply go with a 2.7 or 3 ohms resistor with tighter tolerance such as 1 or 2% (military specs) and be done with it. Installing a resistor of 3.2 ohms at 10 - 20% tolerance will not garantee you 3.2 as it can go as low as 2.88 and as high as high as 3.52 at 10% and as low as 2.56 and as high as 3.84 so what is the point of replacing for a higher value cause of the switch value when the tolerance variation factor is just as bad.

dorokusai

Dude, just trying to lighten the mood....have some fun, relax....enjoy my evening.

VR3

The mood is lightened - I expect assless chaps when I go to MD

FTGV

Esreuter wrote: »

What is a poly switch and what does it do?

It's basically a resettable fuse.Like fuses they have different current ratings and when that rating is exceeded the contacts open until the unsafe current level is removed.Then it resets.