Passive Pre Amp Build.

[Pepperamip]

I've been through a few pre amps lately and the one I've enjoyed the most out of them was the tizzy ('was' meaning I foolishly sold it for some reason)

So before I make another pre amp mistake I'm going to to build a little passive Pre with a dale stepped attenuator.

I'm having no switch so just the one input but i want two outputs.

The case arrived from aliexpress today and it fits together perfectly. Was described as aluminium but the weight of it suggests otherwise. Either way it's a solid box now it's together and it should barely move during operations so that's a good thing in my eyes.

I was going to solder the rcas directly onto the Attenuator hence the cable glands inone of the pics but thinking about it, it's probably best to add rca sockets just in case I don't want to stick with it.

Can anyone recommend some decent quality UK based female rca sockets? Are gold plated ones best? And what about a good internal wire? I could use some left over sommer carbokab but not sure this is necessary inside the case. https://uploads.tapatalk-cdn.com/20190930/463e888668b9c12549036be3d10922da.jpghttps://uploads.tapatalk-cdn.com/20190930/911c6d692681c027ca0eb6dfab6ed0da.jpghttps://uploads.tapatalk-cdn.com/20190930/07a49ef13d4cb85864eaed3100b7c742.jpghttps://uploads.tapatalk-cdn.com/20190930/ba704cbb3dcd76b075c68c736980d45c.jpg

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[mikmas]

Built a few passives and usually use these as preferred:

https://cpc.farnell.com/rean/nys367-2/phono-socket-chassis-red/dp/AV11155?st=rca%20sockets

cpc are quick to deliver and prices are good - they do add a handling charge (not much) so best to order all you need at once.
They take Paypal and have 'guest' checkout,

[Pepperamip]

Thanks Mike ill check them out.

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[Bigman80]

Built a few passives and usually use these as preferred:

https://cpc.farnell.com/rean/nys367-2/phono-socket-chassis-red/dp/AV11155?st=rca%20sockets

cpc are quick to deliver and prices are good - they do add a handling charge (not much) so best to order all you need at once.
They take Paypal and have 'guest' checkout,I dislike these. Brass connection. No no imo

I'd go for the Valab everytime. Yes, they are in Asia somewhere but as its your lucky day, I have 3 pairs here that I'll sell you for cost as I'm in no rush for them.

Up to you but you won't do better for the money.

[Bigman80]

Thanks Mike ill check them out.

Sent from my CLT-L09 using TapatalkI've got these but they are bright gold rather than frosted looking.

Think they are about £10 per pair on ebay.

Here: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F 323853261876. https://uploads.tapatalk-cdn.com/20190930/84003d37980fc39add28de2eda5c7afd.jpg

[mikmas]

I dislike these. Brass connection. No no imo


Weird - Rean are gold plated ... not 'brass'. :scratch:

[Pepperamip]

Thanks for the offer Ollie but the Attenuator only cost me £18 so no point spending £30 on the rca sockets :)

I'll pick up some cheapies for this build but if I ever do something more substantial I'll defo consider the valabs.

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[Bigman80]

Weird - Rean are gold plated ... not 'brass'. :scratch:What do you think might be under the gold plating?

[Bigman80]

Thanks for the offer Ollie but the Attenuator only cost me £18 so no point spending £30 on the rca sockets :)

I'll pick up some cheapies for this build but if I ever do something more substantial I'll defo consider the valabs.

Sent from my CLT-L09 using TapatalkFair enough. Completely understand

[walpurgis]

What do you think might be under the gold plating?

More gold? :D

[User211]

I've got some CMC silver RCA you can have for £5 to cover postage and hassle factor, Ollie.

These.

https://www.hificollective.co.uk/phono_sockets/cmc-805-cu-ag-double-silver-plate-rca-sockets.html

If interested PM me.

They were in my Lampizator before I went for these:

https://www.hificollective.co.uk/phono_sockets/wbt-0210ag-topline-nextgen.html

Are the WBT any better? Prettier. But no idea really. Made too many changes at once.

However the CMCs are real quality. You can just feel it in your hand. Reassuringly heavy with a matt tarnish that you just don't usually see. Made of something nice, no question. Silver but not like you usually see.

[Lawrence001]

I've got some CMC silver RCA you can have for £5 to cover postage and hassle factor, Ollie.

These.

https://www.hificollective.co.uk/phono_sockets/cmc-805-cu-ag-double-silver-plate-rca-sockets.html

If interested PM me.

They were in my Lampizator before I went for these:

https://www.hificollective.co.uk/phono_sockets/wbt-0210ag-topline-nextgen.html

Are the WBT any better? Prettier. But no idea really. Made too many changes at once.

However the CMCs are real quality. You can just feel it in your hand. Reassuringly heavy with a matt tarnish that you just don't usually see. Made of something nice, no question. Silver but not like you usually see.It's Paul after them not Ollie [emoji23]

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[User211]

Same applies though I did think it was Ollie because I didn't read enough of the thread.

[User211]

TBH I just want to pass them on. They are nice items and I feel guilty hanging on to them with no current use for them.

[Bigman80]

TBH I just want to pass them on. They are nice items and I feel guilty hanging on to them with no current use for them.I'll have them if the op doesn't want them.

How many you got?

[User211]

Just the two.

[Bigman80]

Just the two.OK, cool. If the op doesn't want them, drop me a message.

[mikmas]

What do you think might be under the gold plating?

.... pixies in pink tutus?

[Bigman80]

.... pixies in pink tutus?That's the stuff.

[mikmas]

More gold? :D

:lol:

[Pepperamip]

Thanks Justin but I need 6 so Ollie can grab them if he wants them.

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[Pepperamip]

What suggestions for the internal wires? Copper / silver / Teflon coated :) Thickness?

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[Bigman80]

What suggestions for the internal wires? Copper / silver / Teflon coated :) Thickness?

Sent from my CLT-L09 using TapatalkWhy got for anything other than OFC copper if you're keeping it cheap and cheerful.

I think you have missed an opportunity to go "Balls out" and build a killer passive here.

Would have took longer and involved a bit of saving but it would have been worth it.

[User211]

Thanks Justin but I need 6 so Ollie can grab them if he wants them.

Sent from my CLT-L09 using TapatalkOK.

[Pepperamip]

Why got for anything other than OFC copper if you're keeping it cheap and cheerful.

I think you have missed an opportunity to go "Balls out" and build a killer passive here.

Would have took longer and involved a bit of saving but it would have been worth it.Yeah the prob is the one I've liked the most so far is has a cheaper SA in it than the one I'm building.

If I knew for sure that a dcb1 would work in my system I would have a go at bulding one but I don't so I'm not going to risk it

I couldve splashed out more on the SA I suppose but the last time I did that it didn't work out too well. Possibly picked the wrong type of khozmo there and didnt give it long enough burn in time.

I can always switch bits out of this pre once it's together.

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[Bigman80]

Yeah the prob is the one I've liked the most so far is has a cheaper SA in it than the one I'm building.

If I knew for sure that a dcb1 would work in my system I would have a go at bulding one but I don't so I'm not going to risk it

I couldve splashed out more on the SA I suppose but the last time I did that it didn't work out too well. Possibly picked the wrong type of khozmo there and didnt give it long enough burn in time.

I can always switch bits out of this pre once it's together.

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whats not to work?

If the passive works, a DCB1 will just give you impetus rather than affect your tonal balance.

It'll tighten the bass and add a bit of focus. You need to lend one.

[Pepperamip]

Oh go on then if you insist..... Sure you won't miss it? Ha ha

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[Bigman80]

Oh go on then if you insist..... Sure you won't miss it? Ha ha

Sent from my CLT-L09 using TapatalkHahaha, I'd love to but it's not cheap to post a DCB1 out and back. Looking at least £50

[Pepperamip]

Oliie I couldnt borrow your DCB1 off you even if you was happy for me to.

Anyway today my SA has turned up so just waiting on the rca sockets now and I'll be under way. https://uploads.tapatalk-cdn.com/20191003/f1e26528420b8bbf1ec28dc4e291871b.jpg

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[Pepperamip]

Rca sockets turned up too. Not solid gold like Ollies :) but 24c gold plated and should do the trick nicley..

Anyone after cheap gold plated rca sockets should take a look at 'that's audio' on ebay. Got 3 pairs for £8 delivered. Good value in my book. https://uploads.tapatalk-cdn.com/20191003/a300bf320d18efb190a1be4c8c78300e.jpg

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[Bigman80]

Rca sockets turned up too. Not solid gold like Ollies :) but 24c gold plated and should do the trick nicley..

Solid gold aint that great :lol

Anyone after cheap gold plated rca sockets should take a look at 'that's audio' on ebay. Got 3 pairs for £8 delivered. Good value in my book.

I have bought a lot of RCA sockets and sometimes (not in this case I presume) they are way off spec. The cheapies are usually undersize on the OD and oversized on the ID, giving the impression of a tight fit but they can be problematic. That's why I only buy from a trusted source who offer the tight tolerance build quality and the materials I want. It's not just because they sound better :mental:

[Pepperamip]

Totally agree about being fit for purpose. It don't matter matter how cheap they are if they don't work properly.

I'll check mine tonight actually before I start soldering.



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[Bigman80]

Totally agree about being fit for purpose. It don't matter matter how cheap they are if they don't work properly.

I'll check mine tonight actually before I start soldering.

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Always wise but I think I bought some of those a while back and they were OK.

[Firebottle]

Rca sockets turned up too. Not solid gold like Ollies :) but 24c gold plated and should do the trick nicley..

Anyone after cheap gold plated rca sockets should take a look at 'that's audio' on ebay. Got 3 pairs for £8 delivered. Good value in my book. https://uploads.tapatalk-cdn.com/20191003/a300bf320d18efb190a1be4c8c78300e.jpg

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I have used these a lot without any problems.

[Pepperamip]

Got it all wired up at the weekend and to say it wasn't easy would be an understatement!

The combination of the small back panel and my crappy little soldering iron (it just doesn't maintain a constant heat) = rough old joints that dont look too pretty but are at least strong.

Another thing I didnt consider was the mounting hole on the front panel. It was too small for the shaft of my attenuator so I had to drill a bigger one. No big deal but not having the right metal drill bit meant a trip to the DIY store.

A test outside the box showed it all worked with no hum, imbalance or cross talk I could detect. A longer and more thorough test is required though to be satisfied

A couple of things of note is how notchy (stiff) the steps are on the Attenuator. I think this is a good thing as this will only ever get loser over time.

I may have made my 2 coax lengths to and from the Attenuator 3 or 4cm too long which meant I had to shove it inside the box and made me feel I was stressing the joints more than I would like. This is where using standard hook up wire may be more to your liking if building one yourself. I may have to address this before it causes a problem.

Oh one final thought. The case from aliexpress can't be recommended enough it arrived quickly with parts you might not expect (iec socket, toggle switch, all screws and bolts and even some rubber feet)
https://uploads.tapatalk-cdn.com/20191009/204285f0252aa359434e3521b3a06f58.jpghttps://uploads.tapatalk-cdn.com/20191009/94e6b094c388665eea1170ab02a6f560.jpg

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[Bigman80]

Well, that soldering ain't pretty but if your iron isn't getting hit enough, it's understandable.

Invest in a decent one and redo at a later date.

What you don't want is a joint breaking and
That loud buzz blowing a driver.