anyone know these old pultec clones?

[salomonander]

Hey
im wondering if anyone knows these pultecc clones. they do use very nice components (gardener trannsformers, marconi inducter. mullard tubes) but dont sound so hot at the moment. maybe just need some fresh caps. it looks like someone did a hack job inside at some point though. some caps have very different values than on the schematic. so i need to bring this back up to specs.
problem is that lots of cap values are not even in the schematic. does anybody know these units and can assist? cheers

 

[pucho812]

if they are pultec clones, why not just use the cap values in a pultec schematic or do some LC/RC math.

 

[salomonander]

if they are pultec clones, why not just use the cap values in a pultec schematic or do some LC/RC math.

they are not 100% clones. some frequencies are different and i guess lots more. the things are called Tripletone Neuvista 320. thanks though

 

[pucho812]

then some LC math it is then. If you know two out of 3 things can get the cap value you need. In this case you know the aprox frequency  based on the faceplate and you know the inductor value. easy enough to math out.

This should help
http://www.sengpielaudio.com/calculator-XLC.htm

 

[shabtek]

more pics?

 

[salomonander]

front

 

[salomonander]

top

 

[salomonander]

guts

 

[ruairioflaherty]

The caps in the filters will probably be film and not likely to be causing you issues.  Speaking of which what are your issues "don't sound so hot" is a pretty broad statement.

 

[salomonander]

The caps in the filters will probably be film and not likely to be causing you issues.  Speaking of which what are your issues "don't sound so hot" is a pretty broad statement.

hey
yes i think so too. the problem is that there are no values in the schematic. one poster suggested figuring them out from the freq points and inductor values. but i dont see any values for the inductor - unless im missing something. since lots of caps are wrong in the power supply im not sure if the right ones are in the filter network now. its a weired mix of caps on the rotary switches. silver mica and some very modern looking mkts. i dont think they are original.

by saying not so hot i mean that some frequencies sound nice - others very harsh. not depending on material. the low dip is totally unusable (i think it sits at the wrong frequency or a design flaw).  but i guess all that points towards the filter caps.
well, maybe someone will show up who knows these. mine are serial number 200 something so there are some out there...

 

[audiomixer]

I think you should start with some measurements of the unit as of now, so you have a reference for further tuning. Arta or Rightmark would do the trick....

- Michael

 

[pucho812]

with an LCR meter you can measure the inductor value if need be.

 

[salomonander]

ok i found another schematic. in another eq my friend had. it has the cap values but some are unreadable. i can make out all caps on the rotary switch to the far right on the schematic. the caps in the unit actually represent those values (more or less). hurray!

but im totally lost on the rotary to the left of it (low freq). cant really read anything and the values on the rotary switch seem way different. so i just wrote down what caps are actually connected on that switch in which position. maybe someone can make sense of it.

20hz  2,2uf - 68nf
30hz    1uf - 33nf
50hz 470nf - 15n
100hz  22nf - 6,8uf (am i reading this one wrong maybe nf?)
250hz  no caps connected at all

as i have said. im totally lost here. maybe someone is kind enough to help me out? none of these caps are original. im pretty sure. the 2,2uf and 1uf are actually 105 degree electrolytics - certainly not from 1965.... please help

 

[salomonander]

now the original seller wrote me an email. this is his interpretation of the low freq switch:

"The schematic is hard to read.......

from the Ecc83 top left in picture reading from left to right this would seem logical...
10nf
4n7
33nf
150 nf
10nf
2nf

bottom left switch .......
left to right
1.5uf
1uf
560nf
270nf
2nf

The other point is it says "select on test"    "SOT""

does this sound good to you guys?

 

[salomonander]

ok i found another schematic. in another eq my friend had. it has the cap values but some are unreadable. i can make out all caps on the rotary switch to the far right on the schematic. the caps in the unit actually represent those values (more or less). hurray!

but im totally lost on the rotary to the left of it (low freq). cant really read anything and the values on the rotary switch seem way different. so i just wrote down what caps are actually connected on that switch in which position. maybe someone can make sense of it.

20hz  2,2uf - 68nf
30hz    1uf - 33nf
50hz 470nf - 15n
100hz  22nf - 6,8uf (am i reading this one wrong maybe nf?)
250hz  no caps connected at all

as i have said. im totally lost here. maybe someone is kind enough to help me out? none of these caps are original. im pretty sure. the 2,2uf and 1uf are actually 105 degree electrolytics - certainly not from 1965.... please help

these values are so close to a pultec that i start to think that someone modded the neuvista towards a pultec schematic...