Gyraf Pultec on my bench!!

[dukasound]

Hi
Same story from Lazy and Slowly Duka
After more than one year looking for boards, transformer, inductors and other parts I finished soldering.

In first moment it works. I used two 220V-12V (back to back) and I saw only 230VDC after 3,3K resistor. On 4,7uF i have 92VDC, on plate of second trieode (and grid of first) I have 88VDC and on cathode is 1,8VDC. On filament I have 6,08 (I think 1,8K have bad tolerance). SRPP stage works good. I have about 20db. I checked on bench and I havent any hum.
I put signal (pink noise) on input and first reception was all position on switch for low and hi freqency sounds different. Nice :grin:
Problems :?
-When I move pot for Low Boost on CCW there is no sound.
-Pot for Low Cut doesnt work.
-Hi Cut works only in bypass mode

And after you think: "what a clever guy" :grin: here is a stupid question
-If I switch EQ in On position what is a «flat» position of pots?
-How to use Low Booost and Low Cut when we have only one selector.

Thanks in advance for answers :thumb:
Duka

 

[chrissugar]

Hi Duka, nice work. :grin:

Question 1: All pots conterclockwise produce no boost or cut. Although it doesn't mater for this case the Q knob has the highest q counterclockwise.

Question 2: You should read the PDF manual of the Moonlee M@ss!ve P@ss!ve. You can download it from their page. It has a nice explanation about how the cut and boost interact and produce some interesting equalisation.

chrissugar

 

[dukasound]

[quote author="chrissugar"]Hi Duka, nice work. :grin:

Question 1: All pots conterclockwise produce no boost or cut. Although it doesn't mater for this case the Q knob has the highest q counterclockwise.

Question 2: You should read the PDF manual of the Moonlee M@ss!ve P@ss!ve. You can download it from their page. It has a nice explanation about how the cut and boost interact and produce some interesting equalisation.

chrissugar[/quote]
Thanks Chris
What about "Hi Cut works only in bypass mode"
and "When I move pot for Low Boost on CCW there is no sound"
Best
Duka

 

[chrissugar]

Check your Lorlin switches. They have those stopers.
Check the filter board.

chrissugar

 

[synthi]

hi duke,

I`m sorry I don`t have answers to your questions but in my experience with the pultec eq, all my problems goes away just checking every part/connection and resoldering suspect solder points, also check that the switches are all in the correct position, they can be mounted in 2 different positions in the pcb.

good luck!

Synthi

 

[dukasound]

[quote author="chrissugar"]Check your Lorlin switches. They have those stopers.
Check the filter board.

chrissugar[/quote]
Stopers are OK. Three on 6 and bypass on 2 positions.

 

[dukasound]

Hi
I solved problem :grin:
Two trace was shorts.

Everything works nice. I check noise, some music, kick and bas.

Does anyone knows frequencies of Low and High.
Also valuse of boost cut and cut.

Happy Duka :grin:

 

[dukasound]

Hi
About voltage :?
I used two 220V-12V (back to back) and I saw only 230VDC after 3,3K resistor.
Is it enough to work :?:
Duka

 

[dukasound]

Hi
It's finished :grin:

I got a few days and after I got chassis I put boards in. Because I make different position of selectors and pots on front panel I put board on the floor and made conections between Lorlins, pots and In-Out switch.

I put stereo jack on In and Out.
Sound :?: :?: :?:
Nice :!: :!: :!:
No hum and noise.
I check on vocal, bass and even if I put some music trought it sound nice.
Look at this with G9:

I have a little click when I turn bass selector.
Thanks Jakob and :!: to all who help me on any way
Duka

 

[radiance]

Wow Duka! Your Pultec looks very nice!
:thumb:

 

[jrmintz]

Very nice, Duka! :thumb: :thumb:

 

[louder]

alo duka
congratulations.
if they sound the way they look,.................(heaven).
best regards
pedro

 

[SonsOfThunder]

:thumb: :thumb: :thumb:

Peace!
Charlie

 

[Tekay]

Good lookin' units! I guess the sound is as good as the lookin' :thumb:

 

[synthi]

Nice :razz:

Good Job!

 

[dukasound]

Thanks guys :grin:
This make me happy and give me a reason to make another project.
Duka

 

[craigmorris74]

what model of inductor did you use?