Wanted 36ohm 1/4 Watt 1% Metal Film Resistors

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04-09-2026, 09:21
isobarik

Wanted 36ohm 1/4 Watt 1% Metal Film Resistors

I need just 2. I know you can buy them online but I only need two and I don't want to be left with loads I'm not going to use just to be thrown in a drawer.
Anyone help me out? Obviously I'll pay for the components and postage.
Thanks.

It's times like this that I miss Maplin's. Only a short bus ride from me!
Thanks for looking.
Regards,
Ray

P.S. Could Mods please move this post if it's not in the right category.
04-09-2026, 10:15
Barry

I'll have a look in my spares box. All of my electronic components are stored in my garage, along with a whole load of other stuff which needs sorting out, so it might be some time. What are the resistors for Raymond?
04-09-2026, 10:45
isobarik

Quote:

Originally Posted by Barry

I'll have a look in my spares box. All of my electronic components are stored in my garage, along with a whole load of other stuff which needs sorting out, so it might be some time. What are the resistors for Raymond?

Hi Barry,
I'm in the process of buying a Quad 306 to partner it with my Hafler DH 101 (I think you know the 101) Lol
As you know the 101 delivers 3 volts where the Quad only needs 375mv for full output.
The 27 ohm resistor will increase the Quads input to 1 volt to a far more satisfactory level

Regards,
Ray
04-09-2026, 10:56
isobarik

Hi Barry, having a senior moment, it's 27ohm I need.
Sorry about that.

P.S. Any chance you could amend the title so it reads 27ohms.
04-09-2026, 13:25
mik_rik

Hi Ray
I have a couple of 27ohm and a couple of 22ohm also if you want ,can post thm today if you want (f.o.c)
04-09-2026, 13:32
isobarik

Hi Mick,
It's a small World! Thank you so much Mick, that would be brilliant!
I think you've got my address lol.
I think you know what I want them for?

Cheers,
Ray
04-09-2026, 15:09
Barry

How do you derive a figure of 27ohm, and where will the resistors be fitted?
04-09-2026, 15:46
isobarik

Hi Barry, from this:

9.1 Ω (Stock): Gives standard 0.375V sensitivity.18 Ω: Lowers gain, raising sensitivity to 0.775V.27 Ω: Lowers gain further, raising sensitivity to 1.0V.36 Ω: Lowers gain to the ideal level for a 1.25V target sensitivity.

Resistor 13 on the Quad 306.
04-09-2026, 16:44
isobarik

Thanks to Mick, I've obtained the parts I need.
Thank you too Barry for your help, much appreciated
04-09-2026, 16:53
mik_rik

Checked on the 2 digi meters I have,readings were 26.9 ohms for each
04-09-2026, 17:33
isobarik

Perfect!!!
04-09-2026, 19:17
Barry

Quote:

Originally Posted by isobarik

Hi Barry, from this:

9.1 Ω (Stock): Gives standard 0.375V sensitivity.18 Ω: Lowers gain, raising sensitivity to 0.775V.27 Ω: Lowers gain further, raising sensitivity to 1.0V.36 Ω: Lowers gain to the ideal level for a 1.25V target sensitivity.

Resistor 13 on the Quad 306.

Well it's not the way I would have done it. But then I don't understand how you calculate the various values of R13 for a given sensitivity. Good luck with the modifications.
05-09-2026, 08:59
isobarik

How would you do it Barry?
05-09-2026, 17:07
Barry

As I said, I don't understand how you calculate the new value or R13 for a given input sensitivity; perhaps you could explain as it would appear to be an elegant solution.

My approach would be less sophisticated. The full output from the DH101 is 3V. The input voltage required by the 306 is 0.375V for full output; which is 1/8 of the Hafler output. Thus we need an 8:1 voltage divider (or an attenuation of 16dB), so with a Quad 306 input impedance of 22Kohm, we need a series resistance of 7 x 22K = 154K (or 150K in round figures).
05-09-2026, 17:32
isobarik

Hi Barry,
I followed this but it has been documented on other sites i.e. diyAudio https://dadaelectronics.com.au/doc/A...anual-V1.4.pdf

I'm not going to do the full DADA upgrades as I want to leave it stock. Just the R13 change.

Regards,
Ray
05-09-2026, 17:39
Firebottle

Ray is altering the gain, not attenuating the input Barry.
05-09-2026, 17:44
Barry

Quote:

Originally Posted by Firebottle

Ray is altering the gain, not attenuating the input Barry.

Yes, I realise that, but how are the new values of R19 calculated?
05-09-2026, 17:45
isobarik

Quote:

Originally Posted by Firebottle

Ray is altering the gain, not attenuating the input Barry.

Thanks Alan, I'm hopeless at explanation sometimes.
05-09-2026, 18:14
isobarik

Hoping this sheds new light. Change R13 to modify the overall sensitivity of the amplifier,

The Mathematical RelationshipThe core AC voltage gain (\(A_{v}\)) of the Quad 306 input feedback loop behaves roughly proportionally to the ratio of the feedback resistor (R22, which is 330 Ω) and the gain-setting resistor (R13, originally 9.1 Ω or 9R1):)Because it is an inverse relationship, increasing the value of R13 lowers the amplifier's internal gain, thereby requiring a higher input voltage (lower sensitivity) to achieve the same full output wattage

Regards,
Ray
05-09-2026, 19:53
Barry

Thanks Roy,

Now that I understand, even though I would not be able to derive the mathematical relationship from first principles. Despite working in the research department for a major UK electronics company for thirty years, my speciality, amongst other things, was microwave technology and radar, not electronic circuitry.

So the voltage gain is 330/9.1 = 36.26, for that to tally with an output voltage of 20V for an input voltage of 0.375V (the gain being 53.3) the constant of proportionality is 0.68.