ebay preamp kits

[glennjarrett]

Hi
would like to make a valve buffer / pre would either of these be any good
being a Blackburn lad born and bread would replace china crap with Mullard valves
or would the build on pfm be better ?​

https://www.ebay.co.uk/itm/Assembel...359277?hash=item2128f97aad:g:jvEAAOSw9OFZIxjb
https://www.ebay.co.uk/itm/Assembled-12AX7-12AU7-tube-pream-board-Pre-amplifier-Board-AMP-Classic-circuit/272753534330?ssPageName=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649
https://www.ebay.co.uk/itm/6N4-x3-6...m=251331195733&_trksid=p2047675.c100005.m1851

 

[316a]

None of these appear to be valve buffers

'The board is copied by Maratz 7 schematic.

Used 6N4 3pcs and 6Z4 1pc.

It is with 7 color flash LED light.'

Taken from the description . I would suggest avoiding all these products...

cheers

316a

 

[Eli Duttman]

I 2nd the notion of avoiding Chinese guano off of Ebone.

Glenn, what is the goal you have in mind? Do you want to drive long cables or a low I/P impedance amp? A correctly functioning buffer will do that. OTOH, are you after an effects machine? Euphony may be pleasing, but it's not HIFI.

 

[JZatopa]

I'm not sure everything from China is bad but if they don't have a schematic of the circuit you should probably pass.

That being said, it looks like the second link has a schematic, you may have better luck posting a copy and asking for feedback on the design.

 

[Lingwendil]

I'm not sure everything from China is bad but if they don't have a schematic of the circuit you should probably pass.

That being said, it looks like the second link has a schematic, you may have better luck posting a copy and asking for feedback on the design.

First link simply states "grounded grid" with no real details. A grounded grid can be a tricky to use design, depending on implementation...

That second link has a schematic included, and appears to be cascaded gain stages, feeding into white cathode followers.

Third link is a copy of the Marantz 7, which is basicalliy cascaded gain stages feeding a cathode follower.


Unless building a phono stage or maybe repurposing them for something for instrument amplification I would pass on all of those. The second two will give much too high of gain if what you want is a buffer.