As per the diagram here I need 12x 120 ohm 1W, 4x 330 ohm 1W and 4x 47 ohm 1W resistors.

I'm having trouble sourcing 1W resistors though!

I found a source on eBay but had an awful experience with them. They sent me the wrong items (1/4W) several days late and when I asked for them to send the correct parts I was told I was being too rude and that I had to open an eBay case. They also told me explicitly that "no one from this company will help you". Three weeks later I have my refund from eBay....

Apart from that seller though, I can't find what I need. Maplin don't have them, the girl at the desk said they go from 0.6W to 2W so no luck there.

I've looked at places like Farnell and RS Online but that's a bit of a minefield and the options are endless and somewhat confusing for someone who isn't too familiar with this stuff. I also don't really need to order them by the hundred but I'm not sure these are bulb-buy places only.

Anyone know of a simpler place to find what I need?

Report them to ebay.....

If there is a RS outlet near to you pop in and they will help you

However there loads of other alternatives on ebay too

eg. 362081041472; They have cheapish 330 and 15 ohms so you can then parallel/series up to make 110 ohms and 15 ohms...
Yes, That would take quite a few resistors but it is better than arguing with a bunch of numpties !!

Or just use 47 ohm 5W items etc... (?)
Note Ray A. has suggested not using wirewound as they have an inductance which may affect frequency response

Here you go
RS Online- order today, have them tomorrow, and you'll have spares of everything
£5.00 freepost

davew wrote:

Report them to ebay.....

If there is a RS outlet near to you pop in and they will help you

However there loads of other alternatives on ebay too

eg. 362081041472; They have cheapish 330 and 15 ohms so you can then parallel/series up to make 110 ohms and 15 ohms...
Yes, That would take quite a few resistors but it is better than arguing with a bunch of numpties !!

Or just use 47 ohm 5W items etc... (?)
Note Ray A. has suggested not using wirewound as they have an inductance which may affect frequency response

They have been reported to eBay, not to worry! It was eBay that gave me my refund in the end as the seller continued to be an utter tosser, wanting to charge me all kinds of postage fees, handling fees, restocking fees, admin fees etc. It sounds petty for a value of £2.50 or whatever it was but there was no I was letting them get away with their poor business practices!

I did look for others on eBay but it kept giving me different ratings to what I was searching for (0.1W, 120 mOhm etc) and having had one bad eBay experience with resistors didn't want to chance it!

Cheers Orangebean, I'll order some of those using the part numbers.

Wirewound won't make the tiniest bit of difference, even at lowish RF and certainly not at audio. The inductance is in the order of picoHenries.

gordonjcp wrote:

Wirewound won't make the tiniest bit of difference, even at lowish RF and certainly not at audio. The inductance is in the order of picoHenries.

In fact I agree but simply did not want to 'slight' the helpful author (and hence my 'may'... rather than a straight 'he's wrong').
He had stated: "....not wire wound or you will produce undesirable inductive loading"

Accordingly I would personally use a single wirewound 47 ohm / 5W in place of the three 120 ohm / 1W items, as implied.

For some reason folks do get their panties in a twist with ICE circuitry, particularly as far as expected 'hi fi' results are concerned
and I don't know where this particular issue originated from either but I suspect it might be from cross-over filters and the like (?)

For some reason folks do get their panties in a twist with ICE circuitry, particularly as far as expected 'hi fi' results are concerned
and I don't know where this particular issue originated from either but I suspect it might be from cross-over filters and the like (?)

Davew- there are literally hundreds of pages of debate out there around solving the problems of the P38s unique (ish) use of balanced lines to feed the door amps as opposed to the usual screened cables.
The Ambler circuit is intended to be an impedance matching circuit/ attenuator to drive the door amps from the speaker output of any old head unit.

" The Ambler circuit is intended to be an impedance matching circuit/ attenuator to drive the door amps from the speaker output of any old head unit. "
I realised that OB but it still does not really explain the whole 'not wirewound' issue in this case.... and I guess you could only prove all this with a (AF) Spectrum Analyser, too ! Similarly I am aware that ground loops etc as associated with screened wire can be an issue with (more) traditional systems. At risk of getting into (more) trouble with the purists the interior of a P38 is not exactly a (perfect) Anechoic Chamber either... not to mention our (at least probably for many of us now) 15K Hz (or less) upper range either.... aka "Hiss, what's that ??"... !!

You wouldn't need to use a spectrum analyser. Wirewound resistors are about as inductive as a straight piece of wire.

Sadly, as I have too many toys, I actually used a pink/ white noise generator signal fired into my DSP, and a spectrum analyser to view the results.
All I discovered is that my hearing is completely shot, with old age and a misspent youth playing in bands and racing two strokes taking its toll. My top end hearing is down to the region of 11KHz :(

gordonjcp wrote:

You wouldn't need to use a spectrum analyser. Wirewound resistors are about as inductive as a straight piece of wire.

Gordon: We are talking at cross-purposes (again) !..
I was actually saying with an Analyser you could prove that using wirewounds in that circuit would have NO discernible 'frequency' effect/s.

The main issue here is why so many appear to believe it would ! In fact I will also contact Ray A. and ask him that exact question....
and I fully expect I will get the reply 'somebody told me it was important...." !

OB: I blame Heavy Metal for my own hearing losses (and let's face it a P38 is pretty heavy metal too.....)

You're going about it all wrong. This is all you need for top notch in car entertainment.

Was good enough for George Harrison!

Points lost for the lack of sat nav though!

You'd definitely need air suspension for that to work 😀

You guys have rather lost me but the parts showed up today :D

Unsurprisingly, RS is much better than morons on eBay when it comes to service. I've even been sent the right parts!

Now I need to break out the soldering iron and get them in place. I'm guessing that there's no such thing as a T-piece heatshrink for the joints shown in the diagram, wrapping them well with electrical tape should do?

Course it will, you only need to insulate the bits of wire from ground and each other. If you were really brave you could leave them as a three dimensional birdsnest but I wouldn't advise it.