G-PULTEC problems, please help!

[gyraf]

You would need a gain stage for each filter - they both attenuate the signal quite a lot.

Jakob E.

 

[juanjovincenzo]

Thanks Jacobs.

You would need a gain stage for each filter - they both attenuate the signal quite a lot.
Jakob E.

So I need to use two stage for each filter, but if I put both EQs inside a box, the correct way to link these are connecting the output  of PEQ1 to input of MEQ?
Regards

 

[RYM]

Hi,

i build 4 units of the G-pultec 2 with Edcor and two with Lundahl! The units with the eddies works great, but the other two units with the LL´s are have less gain (-8db or more) and are sounding a little bit thin. The Tube Voltages are 6.3V and 375V could it be that the 375V create the problem?

Best

Stefan

 

[gyraf]

Yes - you absolutely NEED to keep the operating high-voltage (when tubes fully heated) below 250V by increasing the series resistor. Otherwise you'll probably kill the tubes too soon - they are only designed for 120V max (we split ht voltage between the two triode systems by running srpp).

Gain should be more or less unity with Lundall's - I haven't tried the Edcor equivalents (are you sure they are the same ratios?)

Jakob E.

 

[RYM]

Hi Jakob,

thx for reply i will try! The Edco´s are the equivalent!! I will give a try and let you know !!

best

Stefan

 

[RYM]

Hi Jakob,

i fixed the voltages but there´s still the same problem .... i also changed the filter board from the working unit but nothing happend ....
any idea ?

best

Stefan

 

[gyraf]

swap amplifiers between the working and non-working units to find if problem is in amp or filter? Then recheck wireing and component values (such as tube types and resistor values)?

 

[RYM]

Hi Jakob,

i changed the filter boards and now it works fine! now i tried to figure out whats wrong on the not working filter board:

and one thing is at the hi boost the signal lost a lot of gain. If  I put out the poti and short all 3 pins I have Unity gain. I´ve changed the poti but there is still the problem .....

Thx

Stefan

 

[gyraf]

Stefan,

check and re-check. compare with schematic.
from description, it's hard to tell where fault could be.

Jakob E.

 

[frazzman]

Sorry if this is an obvious question but are Greencap Metalised Polyestor capacitors ok to use in the filter section, rather than the usual WIMA poly film caps? These are the caps i'm talking about: http://www.jaycar.com.au/productView.asp?ID=RG5222
The reason being is that i'm having an issue finding the wider 15mm lead spacing caps without a large minimum order quantity. The Greencap cap's I can get individually but they are different to the small WIMAs i've been using so I just want to know if the Greencaps are OK to use also

 

[gyraf]

No problem in using different brand polyester caps.

But it's also easy enough to solder extension-leads to whatever caps you have at hand.

Jakob E.

 

[spase]

where did you find those 2k2 lin pots in europe?

 

[audiophreak]

I got them here 

http://www.audiomaintenance.com/acatalog/potentiometers_carbon_20mm_diameter_single_gang.html

 

[gyraf]

2K or 2K5 will do fine as well - should be easy to find..

e.g.: http://www.musikding.de/Passive-parts/Potentiometers/Alpha-Pots-16mm/Mono/Alpha-Potentiometer-16mm-2-5k-lin::2886.html

Jakob E.

 

[jordan s]

Greetings esteemed DIY'ers. I got this bad boy nearly all wired up and ready to go but the transformer wiring has me stumped at the moment. I'm using two Antek AN-0212 http://www.antekinc.com/pdf/AN-0212.pdf. I'm getting a 6.7V heater which makes me think that the first transformer is wired properly but my HT readings are a bit funky (11V) so I could really use some help with configuring the reverse transformer.

 

[gyraf]

The Antek AN-0212 is a 115v-primary-only transformer - you'll need a 230V type (at least for trafo2)

 

[jordan s]

Hm, I read this and thought it would work, "They are specially designed to work on all standard 115V or 230V at 50Hz or 60Hz."
I also thought I read of others on this board using Antek transformers for their G-pultecs.

 

[jordan s]

I want to note that I did successfully complete the build with the mentioned Antek transformers. I tested the reversed 115 sides of the second transformer with a light bulb and then put them in series to get 230V. I had to increase the value of the 2W resistor to 13K, now I've got around 235V for HT. Sounds great!

 

[gyraf]

 

[jordan s]

Here's some shots of my build: