Thought someone had posted a link to a circuit board to do this conversion. I cant find it anyone remember or have a link?

TIA

Could you explain a little more the specifics of what you are trying to do? We might be able to make some other suggestions. My first guess is that you are trying to connect up some speakers to your bike radio (CD/tape/whatever).

If your radio can connect to a 4 ohm speaker then it will be able to drive an 8 ohm speaker load. The difference is that for a 4 ohm speaker load it will deliver more power. If you look carefully I would bet that the radio can drive 8 ohm load also. One option is to put two 8 ohm speakers connected in parallel and get a 4 ohm load. Most radios will work with a 4 ohm load.

 

I want to put some Polks or Kickers in my 05 Road Glide. I know someone had a link to a site that had the 4 to 8 ohm circuit board that did this. I just don't want to stress the amp as driving a 4ohm load on a 8ohm amp would.

 

there is no circuit board needed. The difference is 4 ohms? connect a 4 ohm resistor in series. Im sure someone sells a 4 ohm resistor on a circuit board and charges ten times as much though. However i totally agree with rides4fun.

 

Try www.partsexpress.com or call them. If it's available, they will know. They specialize in audio components. Most likely a small circuit board transformer from 8 to 4 ohms. That's what was used in the the old days and today with tube amplifiers. Transformers are impendance matching devices.

I do not recommend placing a resistor in series.

4 ohms will work but the potential of over driving the amp is likely when used in a motorcyle application. Ampliifiers in these applications are typically driven harder because to the ambient (motor and road) you must over come. At 4 ohms with the same volume setting, you're doubling the power (current) needed to drive the speakers. Hence the danager.

Best advice, get 8 ohm nominal speakers. Rememver that 4 or 8 are nominal values. Meaning that the value only represents the average and not DC resistance.

 

Try www.partsexpress.com or call them. If it's available, they will know. They specialize in audio components. Most likely a small circuit board transformer from 8 to 4 ohms. That's what was used in the the old days and today with tube amplifiers. Transformers are impendance matching devices.

I do not recommend placing a resistor in series.

4 ohms will work but the potential of over driving the amp is likely when used in a motorcyle application. Ampliifiers in these applications are typically driven harder because to the ambient (motor and road) you must over come. At 4 ohms with the same volume setting, you're doubling the power (current) needed to drive the speakers. Hence the danager.

Best advice, get 8 ohm nominal speakers. Rememver that 4 or 8 are nominal values. Meaning that the value only represents the average and not DC resistance.

Thank you, this is what I was trying to get through to all who were trying to help me.
I know there was a link to a board that was available. It was like 23.00 for each, kinda salty but not compared to a head unit.
I just ordered a set of Infinity Kappa 52.5i for the bike and an oil gage, want to open the RG's fairing one time only thank you. So i will check the link.
I KNOW someone posted it before but I cant find the damn thing.

 

This is what I am talking about!!!!!!!!!!!!!!!!


http://www.smarthome.com/8265.html

 

I did it the easy way and picked up JM speakers. They are made for the EG and sound a lot better then the stock ones and are a perfect fit. They are a little pricey but they are water resistant and they are just a few bucks more the the polks 525s and if you add the resister adapter you around the same cost. I just like the ease of plug and play.

 

Looks like this transformer will work, depending on your application needs. The transformer is designed to drive parallel speakers, if that's what your trying to do (...One matchit is required for each channel) . If your planning on a 4 speaker system like in an Ultra, then you're going to need 4 of them. The ultra radio has left/right balance and front/back fade. If your'e going 2 channel, then you will need 2 (left/right). If you go mono all around, then you'll only need one. Then you have to find a place to mount it.

Unfortunately, the "plug & play" solution is still the most elegant and the one I would recommend for long term happiness. I would be worried about the heavy transformer breaking off the circuit board due to vibration. Only way to prevent that would be to epoxy the unit.

Guess it depends on whether or not you already have the speakers. Seems the cost of making this solution work may be more than the cost of new speakers.

Good luck with whatever solution you choose.

 

Looks like this transformer will work, depending on your application needs. The transformer is designed to drive parallel speakers, if that's what your trying to do (...One matchit is required for each channel) . If your planning on a 4 speaker system like in an Ultra, then you're going to need 4 of them. The ultra radio has left/right balance and front/back fade. If your'e going 2 channel, then you will need 2 (left/right). If you go mono all around, then you'll only need one. Then you have to find a place to mount it.

Unfortunately, the "plug & play" solution is still the most elegant and the one I would recommend for long term happiness. I would be worried about the heavy transformer breaking off the circuit board due to vibration. Only way to prevent that would be to epoxy the unit.

Guess it depends on whether or not you already have the speakers. Seems the cost of making this solution work may be more than the cost of new speakers.

Good luck with whatever solution you choose.

The most elegant yes, the safest no, IMHO.

As far as the board, going to mount with wire ties. Lifetime warranty.

It has been debated and I think proven that running a 4ohm load on an 8 ohm amp is going to fry it at some point, or at least shorten its life span. I have seen reports of speaker change outs and balance and fade controls not working and front speakers not being heard. Sounds like a burnt amp to me. Do not want to do that.

Don’t want an aftermarket amp as I like the hand controls. And to realize hand controls on an aftermarket amp is very expensive.

Cost? Well got the Infinity Kappa on e-bay for 82.00 total, Crutchfield price 149.00, got the boards for 50.00, so for 132.00 to the door I have piece of mind.

Will try with and without the impedance amplifier in place to see what if any degradation it adds to the speakers. Just do not want to do any harm and this looks like a solution that all of us could use. Just trying to let others know what I have found.


Thanks for the reply

 

My J&M speakers were about $95 shipped double that if you want the Ultra Glide speakers (I understand the rears have a slightly odd size) which go right in place of the factory ones.

 

My J&M speakers were about $95 shipped double that if you want the Ultra Glide speakers (I understand the rears have a slightly odd size) which go right in place of the factory ones.

I keep hearing about the J&M speakers. If that is what I wanted, I could have done them. I wanted more! From what has been said here they are nowhere close to a Polk, or Kicker, or Infinity speaker in sound quality. And then you are still at 6 ohm. I know it is better than 4 ohm and not 8 ohm, but better.

My point to all this was there IS a solution to those desiring to run 4 ohm speakers safely.

Each to their own for sure............

Its your bike, your head unit, and your ears.

 

LAF, let me know how your installation works. I have no desire to mismatch the impedance between the amp and speakers so I have stayed away from all the after market speakers including the Polk and J&M. The stock speakers are okay for running down the road but if your plan works I'll have to consider it.

lowbar

 

The most elegant yes, the safest no, IMHO.

As far as the board, going to mount with wire ties. Lifetime warranty.

It has been debated and I think proven that running a 4ohm load on an 8 ohm amp is going to fry it at some point, or at least shorten its life span. I have seen reports of speaker change outs and balance and fade controls not working and front speakers not being heard. Sounds like a burnt amp to me. Do not want to do that.

Don’t want an aftermarket amp as I like the hand controls. And to realize hand controls on an aftermarket amp is very expensive.

Cost? Well got the Infinity Kappa on e-bay for 82.00 total, Crutchfield price 149.00, got the boards for 50.00, so for 132.00 to the door I have piece of mind.

Will try with and without the impedance amplifier in place to see what if any degradation it adds to the speakers. Just do not want to do any harm and this looks like a solution that all of us could use. Just trying to let others know what I have found.


Thanks for the reply

LAF,

You nailed it with a good solution. You shouldn't be able to notice any difference in sound quality with transformer impeadance matching. Perhaps there could be some power loss through the transformer but I would bet it will be just fine. If you want to try out the direct 4 ohm connection don't kick the volume up too much when playing with it. In your shoes I would forgo that test alltogether if it sounds good with the transformer. Let us know how it works out for you.

 

Thanks to all. I hope everything is here this weekend, if not as soon as as all parts get here I will snap pics as I go. I hope it works out and believe it will.

What started all this was a oil temp gage install in place of my not too accurate air temp gage. I will not ride a bike in the cold PA winter as I do without knowing the oil is up into the 150's or so before I go. and at hi 20's and very low 30's it takes a few for it to get to 150.

So while I was there I figured to do the speakers and thus it began..........

So will snap pics of both as I go and post the oil gage install in another area.

 

I will agree with LAF on one point. I put the polks in for a few days and they sounded really fine. On a scale of 1-10 I would give the polks a 10 and the J&Ms an 8. I changed them out because of the 4 vs 8 ohm issue and I didn't want to risk frying my radio while riding across the country. Had this option been available I might have stayed with the Polks and done the modification. I did speak with on company about the impedence issue (I don't remember who they were but they were out west) but they suggested that I use a "4 ohm sand resister" which they sell for a few dollers and that should work without much signal loss. For what it is worth, I called the radio manufacture and spoke with their tech guys at length about this issue. Not only were they very helpfull and enjoyed talking about their product but they were clear that running 4ohm speakers for a long period of time would overheat the amps. They also suggested the J&Ms even at 6 ohms. I guess that doesn't fry the amps. What I can't understand is why HD can't specify a radio made to drive 4 ohm speakers. After all, this company can make them to any specification. I guess it is a way to keep us from making changes without paying them a lot of money.

 

The following was sniped from the web:

"Methods for making a 4 ohm speaker to appear as 8 ohms:

• Wire a 4-ohm power resistor (10-20 watt) in series with each 4-ohm speaker. This makes the system to appear as 8-ohm load and is inexpensive. The cons are that the resistor wastes power, may cause frequency response go bad because speakers do not have constant resistance with frequency. When you play at high volumes the resistor may get hot and burn things or itself.

• Using 4 ohm to 8 ohm matching transformer will not waste much power, but the transformer will be heavy, expensive and hard to find. Transformer has also problems in playing back lowest frequencies (saturation causes distortion in high levels) and in higher frequencies the inductance in the transformer will cause phase shifts.

• You can wire two 4-ohm speakers in series if you have two identical speakers. Problem is that if the speakers are not identical type the frequency response and power distribution will be uneven.

• Most "8-ohm" amplifiers can drive a 4-ohm or 6-ohm load as long as you don't try to get full power out of the amp (if you do, it may overheat and shut down). "

 

The following was sniped from the web:

"Methods for making a 4 ohm speaker to appear as 8 ohms:

• Wire a 4-ohm power resistor (10-20 watt) in series with each 4-ohm speaker. This makes the system to appear as 8-ohm load and is inexpensive. The cons are that the resistor wastes power, may cause frequency response go bad because speakers do not have constant resistance with frequency. When you play at high volumes the resistor may get hot and burn things or itself.

It is adding a 4-ohm on the positive side or an 8-ohm resistor in line. I added the 8 to each Boston FX5. Picked up the resistors at Radio Shack for about 2.50 each. Sound much better than stock, and their off the wall with out the resistor!

Added an XM Roady2 as well.