EQP1 Dual Pultec *finished* with *Purusha Case and PCBs*

[hotbaby]

for all who build an extern psu supply this are great 8-pole jacks.
http://sommercable.de/1__produkte/1__060_steckverbinder/137_tourlock/tourlock.htm

 

[dagoose]

Radiance said earlier that a DAO-c PSU will do a good job and it will, i know because i tried it
A good friend wanted a pultec type EQ which i actually finished today and it is a lot more quiet them ny own pultec.

It has:
extended range filters with iaudio inductors (620r resistor instead of 10k on input tranny)
stepped switches all over (lorlins 12 steps)
xs1100 edcor in/output tranny's
gyraf tube stage
last but not least DAOC psu  ;D

You can see some more pics here: http://www.dagoosemusic.nl/temp/dexter/

So.. it can be done.

 

[radiance]

Nice one!!

...620r resistor instead of 10k on input tranny...

So, how is the EQ response compared to your own one (which has a 10K on the input right?)
...does it give a little more boost?

 

[dagoose]

Thanks! It's for dextah from Synthforum, he's a really good friend which i know since i was like 12 or so.

I haven't really tested the difference, i heard some difference when i had 1 channel with 10k and the other with 620r load but not sure what was different. I tested it in my workshop with el cheapo behringer monitors (the cheapest they have, more like PC speakers).
RMAA does not work on the computer in my studio right now, i recently updated soundcard and DA converter (lucid) and it didn't work with RMAA at the moment and didn't have time to get it running.
I will probably test it later on or compare it with my own pultec which is basically the same, it has lundahls instead of edcors but the rest is the same.

About the DAOC psu, it might be a bit overkill since it only has to light up 2 tubes instead of 4 in the DAOC but it's a nice psu for sure.

 

[hotbaby]

thats the way it goes!
very good dagoose. Thank you for sharing the pics. it really helps me seeing other solutions.
The DAOCpsu design is much better designed. no compromise. On the original DAOCpcb the
elcos are shielding the ac section very good.

i ordered a 6a 600v rectiver today and will build a small powersupply near the toroid. would be better if id have more space than but i will try this first with what i already have...
you have so much space if you build it without comercial pcbs... im a little bit arguing about the g-powerpcbs are not really useful for paralleling in one case.
fo the next eq ill do it better 

 

[keefaz]

Nice build dagoose!
The sandwiched filter boards is a nice way to save place in the chassis, congrats 

 

[1954U1]

Yes, big congrats!

Veroboards & saving space & no hum/noise..
DIY in its max power!

Like hotbaby said, your build really helps we all with EQP1 on the tofinish list.

 

[hotbaby]

@radiance

inspirated of dagoose i will desolder my power supplys and do it myself for getting more distance to the toroid.
The idea was using just one gyrafpultec-powersupply (just those parts) to feed both tubes and the input output trannys.

- I will put the elcos and rectiver from one "g-psu board" to a stand-alone perfo board like this:


Do it really works with just the one 220uf 400v elco pair of one g-pultec psu (like on the skizzy i did)?
Doesnt the tubes sucks so much that the 250v elcos or the one 6,3v heaterrectiver (317AT) getting damaged?
For the AD/DC 250v rectivers i already got the 6a 600v bigger one that i will use.

aaron

 

[radiance]

Do it really works with just the one 220uf 400v elco pair of one g-pultec psu (like on the skizzy i did)?
Doesnt the tubes sucks so much that the 250v elcos or the one 6,3v heaterrectiver (317AT) getting damaged?
For the AD/DC 250v rectivers i already got the 6a 600v bigger one that i will use.

aaron

Well, I have not seen the schematic of the PSU you're using, so I can only guess.

Here goes....I guess it will work...
Also, do some reading on capacitors connected parallel or in series....

 

[skal1]

Hey dagoose  , what values did you use for your  boost ,cut and bandwidth controls , did you wire the resistors in series around the switch ?

And what pins  did you wire from  the secondary of the  transformer to the unbalanced filter board ?

regards

skal1

 

[hotbaby]

****!!!!!!!!!!!  ;D ;D ;D ;D ;D ;D ;D
I FIGURED IT OUT!!!!!! YIPPIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII

 

[hotbaby]

I AM AT -80 DB HUM. I cant hear anything!!!!!!!!!!!
Heres the point to point list i did.

-63,4 db
normal connection and 0v to star point ground
------------------------------------------

extern rectiviering (only with the 350v wires)
- 63,6 fb

grounding the eq filters to starpoint
-71.4

grounding the eq filter to starpoint AND Starpoint the psu "Filter Ground"
-75db

Distancing the 0v StarGround from the toroid...
-75,7

0v StarGround cable under the potentiometer - front section.
-76,5

Rotating the toroid vertical to the right site of the inside chassi.
-81 db
Hum is gone!

- Rotating The toroid did a hum difference of -76 to -95db on one channel. This was the most hum.

_____________________________________
puhh I can save working out a new psu

Problem: the toroid cant be installed to the side cause the diameter of the toroid is to large HMMM 

 

[hotbaby]

dagoose, rotate your toroid vertical to a site of the chassi inside and see if your hum is gone too, all troubles must be the cause of the electromagnetic radiance of the toroid...

 

[1954U1]

So, no ripple from PSUs using these PCBs, instead magnetic noise from toroidal..

Great to know, and thanks a lot for reporting all the steps and noise figures,
Very precious infos here! 

P.S. your noise measurements are unweighted, right?

 

[radiance]

Hum is gone!

Way to go!

...Still, it would be interesting to know if the hum will be even lower when making an external PSU 

 

[hotbaby]

>> if the hum will be even lower when making an external PSU
: : :


....
If the unit is off i have
-82db
and on on
-81,8db

i cant hear the hum as it has the same gain like the noisefloor... i dont need additional moddings yet, its very good now.
Will upload a picture later, now i am rewiring the machine cause i cut a lot of cables

I found out that i can just rotate the toroid horizontal, unbeliefable but this was the hum. just 2cm rotating 

 

[hotbaby]

now it looks like this:

Left -91db high frequences hum
Right -85db low/mid frequences hum

The Power cables are twisted and as you see i replaced the rectiver for the 250v cables for paralleling the psus only dc wires. As there was no wirehum problem anymore with i did not need more on the psu, than i had expect first...

All other hum comes JUST from the Toroid!
If i move it to a right position i can get -96db hum one ONE channel... but the other one is than -76db...
I will try mu-metall if i can get it cheap on ebay or do the extern toroid way. but this is not cheap too as i need a good power 7-8 Pol jack and a good chassi.
extern is the only best solution if mu-metall doesnt help...

anyone who did experienc with mumetall or shielding a toroid effective (just tryed a steel shield which didnt work)?

 

[hotbaby]

Great to know, and thanks a lot for reporting all the steps and noise figures,
Very precious infos here! 

P.S. your noise measurements are unweighted, right?

Hey 1954u1,

sorry i didn´t see you question. Thanks!
I measured the noise at the input on my rme mixer in RMS +3db measuring mode (all +4dBu standard) .I think it can tell more than measuring the peaks.
My system RME AES with aurora converters.

Im so happy now and as more i play around with this eq the more i love it! Look, a Massive p a s s i v e has a noise gain around -85 db. I get it down to -92db on the left channel. I will buy mumetall to get the right channel to the same value too with shielding the electromagnetiv field of the toroid. For the MEQ i ordered a extern small case and a 8plug and jack and a 8 multicore cable. I just do the ac/dc and toroid in this "power-transformer-case" and will let the elcos in the eq case. this will work at all and i think i m shure i will get very good results around -94db. For an tube eq unbeliefable but i really played many houres around with the grounding and could solve those loop problems completely i have had before. Working with DC cable on the 350v is a must. The 9v AC will not do any hum. you can simply parallel it without being angry for hum there. Think a litle bit about the star point too. if the star point is to near to the toroid you will get hum problems cause of that... The xlrs i simply connect all 1 to chassi and not to the sigmal ground thats.
The signal ground of both pcbs goes on ONE cable (each psu) to the star point (the lila cables). The cables are as close to the pots as possible and faar eway from the toroid. The filter pcb GRND is connected to the psu on the filter GRND (right side). The filteroutput cable shield(/ground)  is only connected to the filter board and cutted on the other site to avoid ground loops. The output of the filter boad is NOT connected to the GRND of the PSU. All power cables need to be twisted for a better radiance behaviour. thats all.
aaron

 

[1954U1]

Aaron,
thanks a lot for the photo and details.

Acquiring -94dB noise figure would be fantastic..
keep us informed of course.

So, you're using only 1, bigger than the speced "stock" one, 250V rectifier, outside of PCBs,
paralleled for both channels, seen in the photo on the left of toroidal.
That, with your starpoint groundings and cables twisting, makes sense to me, in reducing hum/noise.

I've your same case and PCBs, so will use your build as reference..  ;D
When you will have the mu-metal toroidal's shield in place, remember to put here some other photos of the inside 

Thanks again for your infos!

 

[hotbaby]

Thanks I am glad to read it  .
i used a 6a 600v and it works fine.
http://de.farnell.com/vishay-general-semiconductor/gsib660/bruckengleichrichter-6a-600v/dp/9549820
i did not use the 250v rectiver and i prever using a bigger one if you are going to feed both psus with only one rectiver like me.
the standard 250v rectivers i had before on the left and right psu are removed. The wires are going direct into the + and - of both psus from the
one big rectiver near the toroid.

I talked to a metal factory, they have a shielding metal for electromagnetic radiation which i can get for testing. i will try this first and i think it will solve the other 5db on the right channel. I will see and take one pic...
sourced mu metall today and recognized that it is very expensive. Much cheaper building an extern PSU than buying this expensive metal... so the best solution is still extern yet but i will
see... perhaps the toroid shield is much better than i expect  

[edit]
The grain oriented steel i got from the factory is amazing. It solved the 5db problem and now i have -95db on both channels.
Maybe you have the same Problem. I got some more sheets for selling off in my private thread: http://www.groupdiy.com/index.php?topic=34296.0