mixer with 5 tubes

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hooman

Well-known member
Joined
Aug 31, 2018
Messages
54
hi
this is my first post .  analog tube mixer Simple, But Not Easy .  my plane  :4 mono  input just control by  one switch.2 mono  input  with mix  pot  and  pan control . 3 mono  input with  mix pot .and  2 stereo input  with  mix pot .used  1 x 12au7 in mono  section for best stereo  signal . .2x12av7 for  EQ amp  and main  process  of  stereo  signal .2x12fq7 for out put in low impedance.


mix_mono.png
 
mix_1.jpg


.for  best result in hum  i used  dc  for  all  filaments .  ac  transformer  fixed in back of  box .
 
mix_2.jpg


i  don't  use  audio  transformer  in  this project . when i start  to  build  this mixer  first searching  for  good circuit with  no transformer  in input and output and  simple  in EQ.
 
mix_3.jpg

test  10 khz  in  sum  mixer ....... EQ  circuit  can check  by osiloscop  for best result .
 
mix_new.png


EQ  circuit  can  change  frequency  of  all in put  in main mixer  amp .there is 4 separate  sections by  keys and pots for  control frequency  , user    can  cancel eq  circuit  and signal  receive to output without any  change .
this is very  simple  .  :)
 
  we can meet  world class engineers in mixers  and analog record gear  like  mr Ian Thompson-Bell  in this nice  place . so i am waiting for  good advise  before  complete my  project . :) :)
 
20 hz to 45  khz  in stereo and  30 t0 25 khz in mono  ,,,,,,,,,,  i used  small tube amp pcl86  for monitoring . i  found this kind of tube mixer in internet .never  found  circuit diagram ....  just  2  low resolution inside pictures  of new  made mixer .it was not  so easy to understand  which topology  that designer used  for eq ?
 
ruffrecords said:
I think you have done very well to extract all this information from a couple of pictures. Well done.

Cheers

Ian
Thank you for showing  the  art of    tubes  in audio    . This is most  important....when i saw your  pages in inter net  i  understand  why  analog tube mixer is alive?......why modern  circuit  with  vacuum tubes  can  improve quality  in  studio ...?
simple but  not so easy . in my country we  don't have  easy  access to    all parts  like other in world. :(  but  love  the tubes  magic .10 years before  i started to  buy  tubes . i have  more audio tubes  ..some times  buy  audio transformer  for  tube mic preamp.
again thanks  to you  :) :)
 
i was member of  famous  diy  forums  sins 2008 ...but to day find this place with professional peoples  :)  this  forum is very strong but  very  friendly and easy  to use for members and visitors!!!!!!!!!!! .before our king  buy best of any product  for  us .

so  to day i have more than 1000 of tubes liks rca 2a3 .....u52 from uk .....6550 tung sol  ..12ax7 tele . 211 of usa ......gz32 mullard ...and ...and
i have experience with  tubes in  high gain circuit in guitar amp ....  tube mic  preamps ...hifi amps ....
i am working in  panasonic  service as technical manager for 10 years .and  10 years  in sony as technical center in audio .
noting  dangerous for other people . ;)


 
mix_33.jpg

most important  point for tube mixer  project  is hum  ::)  in project s  without pcb  ... can  test  and find best grounds point , for  removing hum .i used  amps with  gain to hearing hum  when all pots in max  position . ::)
 
mix_31.jpg


2x12fq7  in parallel  triodes for  low out put impedance.nice tubes  good sound.
 
mix_88.gif


this analog tube mixer  is simple but very useful and sound is amazing .
no inexpensive audio transformers ...good  eq circuit.....harmonic
The EQ section :low  boost- hi  boost -low  cut -
hi  cut.
The harmonic  control increases gain and harmonic
tube  sound ... :) for  tube lovers .
12fq7  good for out put ....12av7  has enough  gain for  eq circuit ;)....12au7  good for mono mixing in stereo mixer . 

 
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