Update: Simple 5687-based preamp

Update: Simple 5687-based preamp




Since the day I put up the Simple 5687 preamp on my website, I have been
overwhelmed by the response! So many have approached me and so many have
initiated their rites to tube DIY! Some of their baptism of fire was easy, while
some had a bit more trouble, but overall, no one has yet written to me claiming
they don’t like the preamp. This is great!

Well, if you have built your 5687 preamp, write to me and I’ll put your work


Waily, Ang Mo Kio, Singapore



Well done, Waily!

Waily is using Marantz CD63, Roksan solid
state power amp and Paradigm Studio Reference speakers.

Waily can be reached at waily at yahoo dot com.

Hi Yeo,After weeks of tweaking, I
finally concluded that
those values that U used in
the project is very very
near to ideal(best) what a
5687 should sound. Maybe my
preference for good
sound is quite similar to yours,
in expecting what a
good, neutral sound on system
should have. Or maybe
my gear should match with this
of sound.


Here I would like to kow tow to you as I
that u’ve
probably tried up quite a number of
values/ config before concluding and
sharing this
project with us and other diy’ers.


Initially I thought that this
humble preamp has’nt
reach the full potential yet,
hence the word TWEAK
comes into my mind. But then,
those original values
definately has to stay in
order for me to really enjoy
all my favourite
albums/cd. Of course, there is room
for improvement,
but does it really justify the total
cost of the
project, or the degree of improvement-
coupling caps (hovland, multicaps, etc), black
skz/wkz sound of music power caps, dact stepped
pure thicko silver hook up cable, lundahl
or other
expensive choke/ transformer, and much more
Ok, I might do that when I am very loaded and
feel the pain of thrashing/ keeping those that
unsuitable to me.;-)


Remember the 100u+100u, I just took it off
and in
place back
the 50u+50u. The smoothness, creamy voice
has came
back, dynamic is a bit slower – u can get to
the singer voice extension very well. The 100u
sound much dynamic with Mohamad Ali punches in
fancy footwork and that of course, will very soon
u to K.O. (definately ngam those ah beng in honda
with the windscreen wind down). One words, I
take it anymore. Out u go. The opposite of
happen with the 25u+25u, it makes everything
motion and dull, lifeless.


Anyway, the 390ohm dubilier has found some
use in
preamp..I put it in the grid resistor for fun and
it sound much better than the Riken but
values that I’ve tried (100,150,1K). I can
said that this resistor ngam ngam roll off
tiring highs and the loss in sonic clarity is
(of course, it cure my power amp shutdown


To summarise, the only difference my circuit
to you
is only
this grid resistor, 250K ohm alps pot, some
thick solid core copper hookup cable, S$15 per
bronze female RCA from Well Audio, pair of Welwyn
for the plate(well), others is riken (well) and
cerafine cathode caps that i found it brings
mid and lower bass than the 470u (who knows I
revert bacck to 470 in future??;-), and of
this will varies from system to system.


    Thanks for your input Waily! Well, the circuit has
been optimized by vt4c. I just muck around with the power supply. : ) That said,
glad you like it! I hope you’ll be encouraged to try more DIY projects in



Mike, Johor Bahru, Malaysia. 

Mike here has done a fabulous job! Congrats! Big endbells to cover
those butt naked ugly 30H Hammond chokes.

Mike could be reached at bina_tang at yahoo dot com.


Verdict –
DIYParadise’s 5687 Preamp on Echoloft

« on: 03/25/03 at 12:15:37 »

I’ve just completed Yeo’s 5687 preamp.
It sounds great. Very extended high end with nice firm bass.
A definite improvement over my tube buffer running Mullards.
A greater degree of clarity & depth.
Plugged it into my AV amp CD-In as it didn’t have a Pre-In. My amp
didn’t complain & there wasn’t any complication in regards to gain.
The 5687 preamp can go very loud but more importantly it goes very clean
as well.

Followed Yeo’s instructions to a T … & there was no audible hum or
hiss at all on my Diamond 8.1s. I was initailly worried as I felt my
Hammond chassis was a little on the small side.

I hope you guys don’t mind the shameless plug … anyone keen on tubes
but have no idea (like me )
should give this project a try. Can be very cheap to build depending on
your choice of parts. Check it out at  http://www.diyparadise.com/simplepreamp.html

Thanks to Yeo & Waily for their help … very much obliged.


Thanks Mike for your endorsement! 



Xavier Goh, Petaling Jaya, Malaysia


Ha! Another Simple 5687 comes to the fore!
I like this. Non-boutique parts at all! Okay, just one Black Gate cap but cheap/common parts everywhere. Well, you can still hear its beauty. This, to me, is the mark of a good design. Kudos to vt4c again. Congrats on a successful project!

Hi Yeo,

All parts are non-audiophiles grade except cathode cap (blackgate). I will
upgrade it with adding in another choke with FT cap (awaiting your supply).
The sound was transparent & the mid was good compared with my existing SS
preamp. Source from Marantz CD6000OSE, 5687 preamp, JVC 4-channel power amp
& out from Revolver floor standing speaker. I would expect better sound with
additional 10H choke & FT cap. The holes beside the transformer & choke are
for this purposes. I am using DC filament supply for 5687 tubes & with
additional resistor at the grid input.








Billy Florentino, a Filipino lost in Singapore


Well, well, well. This Simple 5687 has a more “modern” aesthetic feel.
The handles and plumbing bobs do add a touch of “IKEA” to it. Ha ha! Well done Billy! Well done!

Hi Yeo,
Finally, I finished my first ever project 5687 preamp.
It’s pretty lovely sound. The look that matches the

The Look :
Those cabinet handles makes it look very cool. The
chokes, I sprayed black to match the chasis. The blue
light makes it very high end.

The Sound :
First, I was bothered about the hummm although it
can’t be heard when listening. It did improved when I
did the star gounding.
It’s true that this machine is very dynamic and fast.
The vocal is also great after changing the cathode cap
to 1000uF (thanks to Wally for this). The extension of
the highs are amazing. There are a lot of little
sounds that brings out with this preamp.

Further Improvements :
I know there still a lot of room for improvement like
finding the right value for the grid resistor, DC
filament supply, trying tung-sol 5687 etc…
Thanks man for all your help.. More power to you..




Come on! If you have built this project, send your pics to me!




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