Need help ordering components for Passive

Somebody please reply. I need to get the passive ready before I get my amp.

1. Dual is stereo pot
2. Black Inner panelmount RCA socket is the female part of the RCA phono system , the one you see at the back of your equipments.

Black Ring plug is the male part of RCA ssytem, this is fixed at the end of your cables.

Thanks Me dumbo. Didn't realise I'll order the pot and the panel sockets

Eeeks! I can't figire out their site The order form has a section called "Quotation Ref" What do I put in there? I send them an email with this query, but no reply yet

You register at RS site and then follow the menu.

Quotation ref is your ref no or name you put eg. "Passive pre components"

They are very fast and efficient, never had any problem in procuring from RS.

Regards
Anil

Ohh.....so "quotation ref" is for my reference? Never thought of that

Ok, I've ordered. But they didn't ask me for payment (I've selected credit card). This is quite confusing

I paid cash on delivery.

THe reference number is only for frequent customers.
You will have a reference number after this order and this will be on your invoice. RS is very fast in shipping and excellent packaging. However you pay a hefty price for the components. They are worth sometimes though as i found out.

Yes, I got a RS Ref Number. But, I haven't got the shipping cost yet, nor have I paid them. I assume they'll contact me after calculating shipping cost, and then I'll be asked to pay.

Wheeeeeeeeeeee I'll get the components today. And I thought they'd forgotten me :p

Now, what wire do I use for soldering? Standard copper wire or something different? My friend suggested getting thick copper wire gold plated and using that.

Got them



But how do I tell which pin is for what?

Edit: Found a nice explanation here - http://tangentsoft.net/audio/pancomp.html

Hi Zhopudey,

How much shipping did u pay for them?

Thanks,
Vijay

None! Shipping was free Only had to pay 4% tax.


Hey guys, which wire do I use for this?

Hey Zhopudey:
Having a look at your choice of passive components, you could have ordered the Luminous Audio Axiom Single-input / Single-output passive using high quality Noble Dual pot with a choice of Holco resistors as Standard or the Caddock as an upgrade and nice RCAs. Not too expensive at USD 160 + shipping for the Caddock resistors which sound much, much better than the Standard Holcos.

link: http://luminousaudio.com/axiomrca.html

Well - its too late now. Maybe next time.....

zhopudey schrieb:

Wheeeeeeeeeeee I'll get the components today. And I thought they'd forgotten me :p Now, what wire do I use for soldering? Standard copper wire or something different? My friend suggested getting thick copper wire gold plated and using that.

Go for basic teflon coated copper wire with about 14 to 20 strands for each conductor.
basically look for a shielded 2+1 wire. should be thin and flexible.
u are pushing very little current through these wires..a fraction of an amp..
so a wire rated at 1 amp is way more than enough.

Here is a pic of the ALPS in my amplifier.

@audio_engr, I'll keep the axiom in mind when I feel the need to upgrade

@saachi, could you please post a bigger pic? And where would I get this wire? Local electric shop?

zhopudey schrieb:

@saachi, could you please post a bigger pic? And where would I get this wire? Local electric shop?

Here you go.
http://img440.imageshack.us/img440/5158/ampiw0.jpg

Don't know how well you can make it out.

You should be able to find the wire in any cable shop.

Here is a pic of the ALPS in my amplifier.

I am not sure that the wiring is correct ...

Amp_Nut schrieb:

Here is a pic of the ALPS in my amplifier. I am not sure that the wiring is correct ...

He's got me all confused as well Saachi, does your wiring follow this - http://tangentsoft.net/audio/pancomp.html ??

The farthest part is the ground and you can see that the shielding from the two wires are shorted.
the middle two are the output for left and right channels and the nearest wires(in the pic) is the input.

The wiring is perfect. What makes you think the wiring is not correct amp nut?

zhopudey schrieb:

Amp_Nut schrieb: Here is a pic of the ALPS in my amplifier. I am not sure that the wiring is correct ... He's got me all confused as well Saachi, does your wiring follow this - http://tangentsoft.net/audio/pancomp.html ??

looking at the link, it is the same as my wiring. I have no issues whatsoever with my setup. runs flawlessly and even the shielding works like a charm, especially considering that the wires run right next to a 650VA EI core transformer.

Savyasaachi said:

What makes you think the wiring is not correct amp nut?

It appears that you have 2 separate shielded cables.

These are best deployed so that each cable ( each cable consists of a shield + Black + red conductor ) carries the signals ( To & return ) of the same channel.

This will avoid Cross Talk ( ie signal of 1 channel intefering with the other channel. )

You have however shared each cable with both channels.

Ofcourse will work, but what i have mentioned above would be better practice IMHO.

I was thinking of keeping all 8 cables separate. Would that be ok?

Ohh and btw, what is the easiest method of testing this preamp, without connecting it to my amp and speakers? Can I use a dmm to test it?

Amp_Nut schrieb:

Savyasaachi said: What makes you think the wiring is not correct amp nut? It appears that you have 2 separate shielded cables. These are best deployed so that each cable ( each cable consists of a shield + Black + red conductor ) carries the signals ( To & return ) of the same channel. This will avoid Cross Talk ( ie signal of 1 channel intefering with the other channel. ) You have however shared each cable with both channels. Ofcourse will work, but what i have mentioned above would be better practice IMHO.

aaah...u mena the ground cable right?

hmm..yes..but that innvolved running another cable or rather even a 4 core and the cable thickness would have been too much and unwieldly to route. Like you say, this works pretty well. Ultimately, the two channels would have to share the ground pin on the pot so that nullifies the extra cable run.

Or do you mean that i should have used one cable(ground+red and black) for one channel. red for input
black for output and the ground to one of the ground pins and repeat the same for the other.

Hmm..yes, that might work.
But then again. at the input side, meaning the RCA, they share the same ground and as well on the crosover board, so how much of a difference that would make is questionable.

Saachi

The purpose of twisted pair shielded wire is to reduce cross talk between channels and to reduce the EMI pick up by the wires plus cancellation of any picked up signals.

For twisted pair to function the pair should carry the balanced signal ie signal of the same channel, one wire carrries the opposite of the other


By using one wire each from both the cables you have made the life difficult for the twisted pair and cross talk due to induction will be maximum, one may get better result by using unshielded hookup wires.

the common ground has no effect on cross talk in this case, provided the connection to ground is not very resistive.

Regards
Ani

You mean to use the twisted pair for one channel like in red to signal and black to ground?

Just a thought.

To truly avoid crosstalk, shouldn't you have a dual mono(in one chassis) or two monos?

Can use the red for the wiper, black for the input and shield for earth or common.

In a passive pre the weakest link is th pot where maximum cross talk can occur.. The second culprit can be the cables and sockets. So dual mono or mono might be an overkill.

Regards
Anil

Then i would noty be able to use twisted pair in such a config.
I would have had to use individual wires..single core.

Else the input and output RCAs should be very close to each other.
Since my input to the pot is coming from a 2pole 6 way switch there is no way to cooncet it in the fashion that you suggest by using a twisted pair.

Will the concept in mind though.

Besides, i thought twisted pair were used to isolate crostalk between other twisted pairs.

Since we only have one single pair of twisted pair, i still don't get how the signal gets affected.

Cross talk between two channels (L & R) is what we are trying to reduce by going in for mono dual mono etc.

Input to output you can have leakage which is negligible compared to the direct path you are creating through the pot.

Hey guys, here how I plan to do it.



Is this correct? Will shorting the two ground pins help?

If i understood correctly, that kinda wiring is what ani meant.

You are right Sachi

Presenting the

UBER GHETTO PRE-AMP




I have to get a proper box (and better wires), and heat-shrink sleeving. This was just for testing purposes I did manage to get it wrong, despite checking with a dmm Will have to reverse the connections next time.

BTW, for the sockets, the center pin is +ve, and the side pin is -ve, right?