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View Full Version : For Sale: Passive pre-amp.



Filterlab
28-01-2008, 19:47
My gorgeous transformer based passive pre-amp as featured in the DIY thread.

Wonderful natural and clean sound, nice heavy control, one in one out. Simply not needed anymore.

http://s560.photobucket.com/albums/ss49/aos_images/random_stuff/PP17.jpg

http://s560.photobucket.com/albums/ss49/aos_images/random_stuff/PP16.jpg

http://s560.photobucket.com/albums/ss49/aos_images/random_stuff/PP18.jpg


PM me.

Gromit
29-01-2008, 13:53
Looks gorgeous! :)

I'm being a typical technophobe here (please bear with me!) but how does a transformer-based passive pre work? I notice NVA are now building their pre's with transformer volume controls and wondered how they work.

Sorry for the thread hijack! :o

Filterlab
29-01-2008, 14:12
Looks gorgeous! :)

I'm being a typical technophobe here (please bear with me!) but how does a transformer-based passive pre work? I notice NVA are now building their pre's with transformer volume controls and wondered how they work.

Sorry for the thread hijack! :o

Cheers!

Very basically:

At varying points of the transformer windings there are different attenuation values (increasing with the number of windings) and are accessed by the pins on the transformer housing.

http://www.intactaudio.com/images/Atten_images/AVC_Lg.jpg

These points are spurred off to the volume switch which is usually a 24 position switch and as each position is selected the attenuation is reduced and the volume increases.

http://www.intactaudio.com/images/Atten_images/Lg-switch-2.jpg

This one certainly works very well indeed and is very natural and transparent. Its only requirement is a low impedance input (say 50 ohms from a source) and a high impedance input on the power amp (say 50 Kohms). The ratio should really be no lower than 100:1 but preferably closer to 1000:1.

Gromit
29-01-2008, 15:16
Thanks for that - looks like a very elegant and clever way of doing things (and even I understood it). :)

Makes sense that it would sound good. :)

Filterlab
31-01-2008, 21:44
http://s560.photobucket.com/albums/ss49/aos_images/random_stuff/passive.jpg

Filterlab
31-01-2008, 22:51
Any offer considered - no matter how daft!

Go on, have a go with it. You'll be amazed! :D

Filterlab
06-02-2008, 14:21
Well I paid £350 for it last year, obviously I'm not looking for that much, around a couple of hundred-ish?

pure sound
06-02-2008, 19:12
sounded considerably better than the MFA (silver) to my ears. Didn't ring either! (I borrowed briefly before Rob had it)


Sastus,

The original metal case was RS part No. 364-1632

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=3641632

Filterlab
06-02-2008, 21:38
Cheers matey! Sounds like you know more about it than me. LOL! :D

Filterlab
13-02-2008, 12:22
Going up on eBay this weekend.

Mike
28-03-2008, 16:21
Nice box! :)

Where d'you get it?

:eyebrows:

Filterlab
28-03-2008, 16:48
I made it with my own fair hands. :)

Mike
28-03-2008, 17:01
Hmmm.... nice, looks just about the right size for this 'ere NVA phono board. ;)

What wood is that middle box part made from. I like it. :)

WikiBoy
28-03-2008, 17:06
I made it with my own fair hands. :)

It obviously didn't sell on ebay :eyebrows:

If I were you I would take the transformers out and sell them seperately and throw away the used chopping boards. :mental::lolsign:

Mike
28-03-2008, 17:30
Yeah!... and give me the bit in the middle! :)

Filterlab
29-03-2008, 09:49
Hmmm.... nice, looks just about the right size for this 'ere NVA phono board. ;)

What wood is that middle box part made from. I like it. :)

Cherry. :)


It obviously didn't sell on ebay :eyebrows:

I never listed it, couldn't be bothered and it looks quite nice just sitting on the rack. Will just keep it knocking about until I stash it deep in a cupboard somewhere and then discover it in ten years time or when I next move.

Filterlab
12-05-2008, 10:48
Now sold. :)

Phil Bishop
23-12-2008, 21:58
I bought this off Rob earlier in the year and was mightly impressed. However, Rob introduced me to computer audio and now I no longer need the passive so it is for sale again @ £175 - a bargain.

I have fitted a silver volume control, but will also supply the original brass knob.

e-mail me if interested - bishopfamily@ntlworld.com or phone me on 07747 642586

Thanks

Filterlab
24-12-2008, 08:54
LOL! Nice one Phil, it's a great piece of kit. Maybe you could sell it to i_should_coco, it's his kind of thing. ;)

Phil Bishop
24-12-2008, 09:58
Rob,

Thanks, who is i_should_coco? A member of AOS? I have had some interest already via other contacts, but given the economic situation and Christmas people are a bit short of cash. Funny, I am now exactly in the same position as you were a year or so ago - this is a graet bit of kit, but totally redundant in my present set up. Gone are the days when I would hoard stuff in the loft - it goes straight out for sale now.

I will probably put in on ebay in the new year, but for more than I am asking here.

Best wishes - have a great Christmas

Phil

Filterlab
24-12-2008, 10:59
Hehehehe, I was being a bit cheeky Phil. i_should_coco (Pete) is on here and the Wam - he built that passive, I then bought it from him and recased it. :)

Ebay might be the way to go, but with a BIN and offer rather than an auction (as I did) or you may end us losing a load of cash.

It's a lovely passive though, I'm glad you enjoyed it as much as I did - but like you I didn't have a real use for it and I also sell stuff as soon as it becomes spurious to requirement.

Mike
24-12-2008, 11:14
spurious to requirement.

Come again? :scratch:

Filterlab
24-12-2008, 11:45
Ooops, I meant superfluous. Tut, this beer and Baileys combination does nobody any favours! :lol:

Ali Tait
24-12-2008, 20:11
Try a BMW!

Mike
24-12-2008, 20:24
I've tried three.... they were very difficult to swallow!

anubisgrau
25-12-2008, 15:36
what trannies are inside?

Phil Bishop
26-12-2008, 20:54
I think if you go back to the beginning of this post, Rob describes the transformers - Intact Audio I believe.

Phil

Spectral Morn
10-10-2009, 17:03
Hi,

About a year or so ago, someone bought this from me, but has never arranged collection! I have lost their e-mail details. Please get in touch if you still want it! E-mail me at.........

Phil


HI Phil

Its not a good idea to leave your E-Mail address out in the open so I have removed it. However if the person who bought the item of Phil wants to contact Phil PM me and I will give you the Email address .


Regards D S D L

Phil Bishop
10-10-2009, 17:49
Cheers Neil.

Phil

anubisgrau
11-10-2009, 22:55
Here I am:)

Cheers

Spectral Morn
12-10-2009, 08:42
Here I am:)

Cheers


This is a bit vague. Are you the person Phil was talking about? If so confirm with me via PM and I will give you Phils E-Mail details.


Regards D S D L

anubisgrau
12-10-2009, 09:09
This is a bit vague. Are you the person Phil was talking about? If so confirm with me via PM and I will give you Phils E-Mail details.


Regards D S D L

no worries, i've contacted phil already - i do have his details of course

thanks for helping

cheers g.