Front speakers - replacement with Infinity Ref 6510CS

[p64]

I think it is kind of a placebo effect with the Infinitys. I compared them with the stock, two cars side by side, same cd and all and there was nearly no difference. And, the stock setup is actually balanced, as the 6510 tweeter is just too loud and sharp.
In my opinion, sound deadening is a must.

In fact, I replaced them with DLS C6A in front, and put them in the rear doors. The result was, the tweeters were so loud, I could almost listen to the music with the fader all the way back. Rear system is for the passengers in the back, IMO.

So, I installed a 4-channel Blaupunkt amp, insulated the doors with 2 square meters of buttyflex and attentuated the Infinity tweeters with a L-pad. I'll post the DIY soon.

Andrej

ps: Don't forget, the sky's the limit with car audio.

[Munro]

Originally Posted by p64

I think it is kind of a placebo effect with the Infinitys. I compared them with the stock, two cars side by side, same cd and all and there was nearly no difference. And, the stock setup is actually balanced, as the 6510 tweeter is just too loud and sharp.
In my opinion, sound deadening is a must.

In fact, I replaced them with DLS C6A in front, and put them in the rear doors. The result was, the tweeters were so loud, I could almost listen to the music with the fader all the way back. Rear system is for the passengers in the back, IMO.

So, I installed a 4-channel Blaupunkt amp, insulated the doors with 2 square meters of buttyflex and attentuated the Infinity tweeters with a L-pad. I'll post the DIY soon.

Andrej

ps: Don't forget, the sky's the limit with car audio.

I am very happy with my set up with the infinitys, but still have the bass at +3 and the trebble at -3 to get the sound as I like it. The sound has improved dramatically since the speakers were first installed, how much is down to running in the speakers I don't know

What is an L Pad and how do you attenuate the tweeters with it ? .
Thanks
.

[p64]

Google for it, but actualy it's two resistors, one in parallel and one in series with the tweeter. The one in parallel takes some of the current of the tweeter, hence less power, and the one in series keeps the whole setup's resistance the same (4ohms in our case). Actually, the -3db setup uses only one 2ohm resistor in series, which also changes the frequency cut.

I added 4ohms in parallel, which produce final -6db, but hadn't had time to install it yet. Will post some pictures in future for clarification.

But don't forget, I'm an amateur, maybe I'm wrong in some details.

Andrej

[Munro]

Google came up with this ( it looks a bit complicated !):

Link:
eBay.co.uk Guides - Tweeter Attenuator Resistor Guide

Tweeter Attenuator Resistor Guide

by: mgc200( 2424)

14 out of 14 people found this guide helpful.

Guide viewed: 706 times Tags: Tweeter | Attenuator | L Pad Resistor | Resistor Crossover | Matching

Here is a short guide to help when selecting resistors to attenuate (reduce the level) of a tweeter in a loudspeaker system. Especially useful if you cant find an original type replacement and have to fit a unit of greater sensitivity.

Tweeter Attenuation Chart.

Attenuation is needed to match the output levels of midrange and tweeter drive units to match the output of a woofer. This is especially true when using horn loaded midrange and tweeter units, which can be 15 to 20 dB higher in sensitivity than the woofer.

The most common way to match the levels of the drivers is to add an ‘L’ pad to the output of the tweeter and midrange sections of the crossover, which allows the ‘volume’ to be turned down, while maintaining a proper load to the crossover. An ‘L’ pad is designed with 2 resistive elements controlled by a single shaft, and they look similar to the diagram shown below.

The crossover side has a resistive element of 8 ohms (for an 8 ohm ‘L’ pad), and the driver side has an element of about 80 ohms. The point is, as you adjust the level, the ‘series’ portion of the 8 ohm element, when added to the parallel value created by the 8 ohm driver in parallel with the driver side element, always adds up to 8 ohms. The purpose of keeping a constant 8 ohms is because the capacitor and inductor values that make up the crossover were all chosen based upon them ‘seeing’ an 8 ohm load. If the load changed, then the crossover point would also change….

Many people in the audio field do not like any variable units in the signal path, although they are very useful for testing purposes and can help

determining the values required for a high quality fixed resistor network to be used permanently in place of the ‘L’ pad.

The chart below gives you a quick look up table to create a voltage divider to give you the desired attenuation. Attenuation in dB for the above circuit R1 R2 (value in ohms) assuming an 8 Ohm crossover design and an 8 Ohm driver. Please note that these are values for resistance, and as with all things loudspeaker the impedance of the actual systems components may subtly alter the attenuation achieved in any particular system combination….

Attenuation in dB R1 in Ohms R2 in Ohms

1 0.87 65.56

2 1.65 30.90

3 2.34 19.39

4 2.95 13.68

5 3.50 10.28

6 4.00 8.00

7 4.43 6.46

8 4.82 5.29

9 5.16 4.40

10 5.47 3.70

11 5.75 3.14

12 5.99 2.68

You don’t have to have ‘exactly’ the listed value, although do try to be pretty close!. (within @10 %) For resistors in series simply add the values together for the total resistance.

Resistors in parallel are calculated differently. If all of the parallel resistors are the same value, then simply divide the resistor value by the

number of resistors. For instance, say you had three 10 ohm resistors in parallel, the total resistance would be 10 divided by 3, or 3.3333…For two 8 ohm resistors in parallel, the total would be 4 ohms, and so on Resistance of parallel resistors is ALWAYS less than the lowest value resistor in the parallel circuit. For parallel resistors of different values, this formula is the one to use:

How to calculate resistance for resistors in parallel:

Where Rt = total resistance

R1= value of resistor 1

R2= value of resistor 2, etc

An example. We have 3 resistors, one of which is 2.7 ohms, one is 5 ohms, and

one is 12 ohms. Solve 1/R for each resistor, and then add them together, like

this:

1 / 2.7 = 0.37037037

1 / 5 = 0.2

1 / 12 = 0.0833333…

So you add 0.37037037 + 0.2 + 0.0833333, and you get 0.6537…, and now 1 / 0.6537 gives you 1.529 ohms total. By paralleling resistors, you can get to almost any value……Always be sure to check power ratings of resistors for such networks, we recommend at least 7W ceramic units are chosen.

Chris Cooper

Connect Audio Ltd

[p64]

Try this one:

L-Pad (Driver Attenuation Circuit) Designer / Calculator

R1 is already there, all you have to add is R2.

Andrej

[Munro]

Originally Posted by p64

Try this one:

L-Pad (Driver Attenuation Circuit) Designer / Calculator

R1 is already there, all you have to add is R2.

Andrej

Thanks, But I think I will stick to just having my trebble set to -3, it seems to work fine for me. Electrics are a bit of a black art and I would probably end up frying my tweeters or something !

Here is the explanation from your link for those that are interested:

L-Pad (Driver Attenuation Circuit) Designer / Calculator Help

L-Pads (Loss Pads) are used to decrease the output level of a driver. This is useful in a multiple driver system where the drivers do not have the same sensitivity. A L-Pad, or driver attenuation circuit, can be used to decrease the output levels of the louder driver to match, or attenuate, the sensitivity of the less sensitive driver.

A L-Pad is simply 2 resistors, one in series (R1), and one in parallel (R2) with the driver.

Z = Total Driver Impedance in Ohms

A = Required Attenuation in -db

Example: Say you have a two way system with a 8 Ohm horn tweeter with a sensitivity of 97 db and 100 Watt power handling and a mid with a sensitivity of 91 db. You need to lower the output of the horn by 97 - 91 = 6 db. Using the above formulas where Z = 8 Ohms and A = -6 db you get results of R1 = 3.99 Ohms and R2 = 8.04 Ohms.

Important: Please read the end of the RCL electronics page for information on required wattage ratings of resistors.

[NickG]

Thanks for the detailed info Munro! If anyone tests this setup and finds the best value resistors to use and whether it affects sound quality or not, can you please post the solution here.

[p64]

Maybe you should read more carefully before you post. The above mentioned calculator gives you resistor values, I followed those values and ended up with a 6db attentuation.

The simplest way to test it, buy a 4 ohm 5W (I used 2 2ohm resistors in series) resistor and screw it on the crossover, between TW- and TW-3db. I eventualy disassembled it and soldered them directly on the PCB.

Andrej

[GHGH]

Sorry, but you need to throw in a new amp to get decent sound.
I also replaced my speakers, but it didn't help me much.
The built in amp just couldn't run a pair of Polks (my replacement).
And yes - Merry Christmas!

[Munro]

Originally Posted by p64

Maybe you should read more carefully before you post. The above mentioned calculator gives you resistor values, I followed those values and ended up with a 6db attentuation.

The simplest way to test it, buy a 4 ohm 5W (I used 2 2ohm resistors in series) resistor and screw it on the crossover, between TW- and TW-3db. I eventualy disassembled it and soldered them directly on the PCB.

Andrej

Did it work ? What settings do you have on the stereo bass / trebble now? Was the sound impoved over just simply turning down the trebble on the stereo?

Thanks

[p64]

I did the tweak and bench tested it, but did not instal the panels, and I won't be able to judge exactly the difference because of the newly applied buttyflex inside the doors. But opposite of the -3 output, which is a joke, those 4ohms make a difference, and by the theory the sound quality should be superior to setting just the treble down.

And since I'm three days from home and a completely different continent, this is all for now.

Greetings, A

[Munro]

Originally Posted by p64

Maybe you should read more carefully before you post. The above mentioned calculator gives you resistor values, I followed those values and ended up with a 6db attentuation.

The simplest way to test it, buy a 4 ohm 5W (I used 2 2ohm resistors in series) resistor and screw it on the crossover, between TW- and TW-3db. I eventualy disassembled it and soldered them directly on the PCB.

Andrej

I am not having much luck sourcing 4 ohm 5 watt resistors, having tried several component suppliers.

The best I could find was 2.2 Ohm 0.25W metal film resistors from Maplin. I bought 4 for @ 20p and will try in series. (4 ohm out of stock). I suspect these will be overloaded.

The only ones I could find of the correct rating were from the USA with £16 postage !!
CW0054R000JE12 | VISHAY DALE | Resistors, Thermistors & Potentiometers | Passive Components | Farnell

Advice welcome !

[Koen]

Finding 5W resistors should'n be a problem, finding a 4 ohms resistor however is not that easy. Closest standard values are 3.9 and 4.7 ohms. Taking in account tolerances to both the tweeters and the resistors, 3.9 will do fine. The 5 watt rating is important, though. Smaller ones will just burn.
Be carefull when soldering them to the tweeters, because especially in a door, the have to withstand quite some vibrations. It's best to, after soldering them, glue them also to the tweeter casing.

K.

[Munro]

Originally Posted by Koen

Finding 5W resistors should'n be a problem, finding a 4 ohms resistor however is not that easy. Closest standard values are 3.9 and 4.7 ohms. Taking in account tolerances to both the tweeters and the resistors, 3.9 will do fine. The 5 watt rating is important, though. Smaller ones will just burn.
Be carefull when soldering them to the tweeters, because especially in a door, the have to withstand quite some vibrations. It's best to, after soldering them, glue them also to the tweeter casing.

K.

Thanks, but also struggling to find anything close to 4 ohms. Maplin sell 3.9 ohm 0.25W but were temporarily out of stock. I suspect these don't have a high enough power rating as you say. Where can you get the 5W ones?

[FWH]

Try ELFA -- Electronics supplier of Northern Europe

Part number 60-036-93

[Munro]

Originally Posted by FWH

Try ELFA -- Electronics supplier of Northern Europe

Part number 60-036-93

Thanks FWH , the resistor spec was spot on and I nearly ordered them. However postage was a bit steep at 46 euro from Sweden to Scotland.

I managed to pick up some 3.9 Ohm 7W items mail order from the
UK (Maplin). Not quite the ideal spec but I hope it will do the job.

You wouldn't believe how many different types and specs of resistor there are. One thing I found out was a resistance of 3.9 Ohm is the same as 3R9 and 3.9R (I hope).

[p64]

As promised.

Andrej

[Koen]

Originally Posted by Munro

Thanks FWH , the resistor spec was spot and I nearly ordered them. However postage was a bit steep at 46 euro from Sweden to Scotland.

I managed to pick up some 3.9 Ohm 7W items mail order from the
UK (Maplin). Not quite the ideal spec but I hope it will do the job.

You wouldn't believe how many different types and specs of resistor there are. One thing I found out was a resistance of 3.9 Ohm is the same as 3R9 and 3.9R (I hope).

Yep, 3R9 or 3.9R is the same as 3.9 Ohm. "R" is often used because the ohm-sign is not always available in a standard character set, and "Ohm" is sometimes to long/expensive to print.

7W is more than good. 5W is a minimum, so 7 is even better. And don't worry about 3.9 not being 4, since the tweeters won't be 4.0 spot-on, the resistors won't be exact 3.9 either, the speaker leads will have some resistance which will make the overall calculation even worse...

For best results, order some extra resistors (but I figure it's to late for that), and measure each individual resistor so you can make 2 identical L-pad filters/attenuators by matching the values for left and right.
If you don't have a tester (we call it "multimeter") it's wise to get one. Pretty good ones for general purposes are available from £15 on. After a while you'll wonder how you ever did without.

K.

[Munro]

Originally Posted by Koen

Yep, 3R9 or 3.9R is the same as 3.9 Ohm. "R" is often used because the ohm-sign is not always available in a standard character set, and "Ohm" is sometimes to long/expensive to print.

7W is more than good. 5W is a minimum, so 7 is even better. And don't worry about 3.9 not being 4, since the tweeters won't be 4.0 spot-on, the resistors won't be exact 3.9 either, the speaker leads will have some resistance which will make the overall calculation even worse...

For best results, order some extra resistors (but I figure it's to late for that), and measure each individual resistor so you can make 2 identical L-pad filters/attenuators by matching the values for left and right.
If you don't have a tester (we call it "multimeter") it's wise to get one. Pretty good ones for general purposes are available from £15 on. After a while you'll wonder how you ever did without.

K.

Thanks - I do have a multimeter and will check the resistance. When I bought the metal film resistors last week I checked them with a shop multimeter. The first ones offered incorrectly by the shop were k ohm so 1000 times out!! The second ones were slightly higher resistance than spec @ 10%. The metal film ones are useless in any case as they are only 0.25W rated, but at £0.20 for 4 I took them to try anyway.

It should be an interesting experiment before and after with the L Pad. I am not overly optimistic about any improvement, but for £3.40 it is worth trying. When My "power resistors" are delivered I will install and let you know how I get on.

For anyone who doesn't already have a multimeter - they have a basic one on sale at Maplins for £5 - unbelievable.