Attenuator

[Stryder5]

Hi guys,

I want to make some 10dB attenuators, I'm told I need 1/4w metal film resistors in 6.9k and 4.7k.

Are there metal film resistors and metal film resistors i.e. Is there a quality or sound issue, if so watts (sorry) best to use.

Where's best to get them (long live Maplin), or will somebody throw me some.

I know it's not a complete scenario, but let's just assume I'm right in these values.

Gary

[Bigman80]

Just get accurate values and make sure the match per channel. Simples

I'll have a look at what I've got.

[Light Dependant Resistor]

Hi Gary
Resistor values easily available are 6k8 and 4k7 , but if you need a 6k9 you could use formula R1xR2 / R1+ R2 to
arrive at 6k9 with two parallels - 6k8 is probably close enough for the purpose.

For any attenuator there are known Pad types the L pad being very common, comprised of a series and shunt resistor
for each channel.

Metal film is good for the purpose., but would be remiss of me not to mention a LDR being much better.... which is variable :)

[Barry]

What do you want the attenuator for? What are the source and load impedances? 0.25W rated resistors will be fine.

[Stryder5]

What do you want the attenuator for? What are the source and load impedances? 0.25W rated resistors will be fine.

Sorry, I knew someone would ask but I don't have that info. not ideal I know but let's assume as I said above that these values are true, it's just a test.

Gary

[Barry]

Sorry, I knew someone would ask but I don't have that info. not ideal I know but let's assume as I said above that these values are true, it's just a test.

Gary

Where will the attenuator be used - between which two items will it be placed? For example between a CD player and a preamp?

[Stryder5]

Yes source and preamp

[Barry]

What is the source: pick up or CDP?

[Stryder5]

CD

[Barry]

Well assuming the CD player has a low source impedance (most likely to be < 100R), and the line-level input of your preamp presents a typical load impedance of 10k, then with a 6k8 series resistor and 4k7 shunt resistor your L-pad attenuator will offer an attenuation of 9.9dB, so the values suggested are quite correct.

[Stryder5]

Well assuming the CD player has a low source impedance (most likely to be < 100R), and the line-level input of your preamp presents a typical load impedance of 10k, then with a 6k8 series resistor and 4k7 shunt resistor your L-pad attenuator will offer an attenuation of 9.9dB, so the values suggested are quite correct.

Many thanks for your input, I wasn't trying to be evasive to your questions but this was over my head.

Now....where can I get the above value resistors? Any ideas?

Tried looking in all sorts of places, but to no avail.

Gary

[Barry]

Try https://www.cricklewoodelectronics.com/0.25-Watt-1-Metal-Film-Resistors.html?page=3 You can order on-line or by phone.

[Stryder5]

Many thanks for your help, just ordered.

Gary


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[Barry]

You're welcome Gary.

Let us know how you get on. :)