Will the real slim shady please stand up, and bring the right Pultec schemo!

[jwhmca]

So what is the deal with the at least 2 different versions of the EQP-1A?

Version 1 = http://gyraf.dk/gy_pd/pultec/pultech.gif

Version 2 = http://www.recproaudio.com/diy_pro_audio/diy_files/eqp_1a/eqp1a_filter_schematic.jpg

???

There seems to be some capacitors and inductor differences?

Anyone have the "REAL" one ? I know... NOT! otherwise it would be out there... Maybe EveAnna will share?

Seriously, can't we all just get along and settle on the defacto?

 

[pucho812]

revisions perhaps? 

 

[ruffrecords]

Well, I guess the second is the 'original' and the first is simply Gyraf's version of it.

Cheers

Ian

 

[edanderson]

the first schem is jakob erland's (gyraf) reverse engineered schematic of the tubetech version of the pultec.

the second schem is joe malone's (jlm audio) reverse engineered schematic of the filter section of a vintage eqp-1a.

if you look at the recproaudio.com site (which is where it looks like you got the second file) you can pretty easily find the original schematic:

http://www.recproaudio.com/diy_pro_audio/diy_files/eqp_1a/eqp-1a_schem.jpg

for the "passive equalizer circuits" block you can use the jlm circuit.  you can get inductors and transformers that will work from sowter... very high quality, though they aren't exactly like the original parts.  all the info you need is on the recproaudio site.

ed

 

[okgb]

I've never seen what looks like an " official " or real version of the filter network , just the
rest of the circuit with the block  " filter network "  and  reasonable working schematics of the filter
Story go's it was licenced from western electric and [ not patented ? ] and hidden not because
it was so special but more so straight forward ?
Someone correct me if i'm wrong , or anyone has ever seen a filter schematic from the time

 

[atxt]

Pictures from pultec manual
http://s2.ipicture.ru/uploads/20110913/EUUH3Pxc.jpg
http://s2.ipicture.ru/uploads/20110913/2gNpU3VZ.jpg
http://s2.ipicture.ru/uploads/20110913/38x5Rkzu.jpg

 

[okgb]

Is that first filter diagram , really from the manual ?
i've seen that before but it's not the multi tap inductor version
and doesn't look like it matches the amp schematic , drawing style

 

[jwhmca]

No, I don't think it is... hence my problem.