EQN build thread

[Marcocet]

as for the small format pots....having trouble finding the PRV6 series, but found RV6 instead:
will this one fit the bill?
http://uk.rs-online.com/web/search/searchBrowseAction.html?method=searchProducts&searchTerm=2508745105&x=0&y=0
or indeed this one?
http://www.banzaimusic.com/Alpha-9-PC-NUT-10k-lin.html?quantity=1

Anybody have an answer for this one? The first ones look good to me but I don't trust myself. Thanks!

 

[briomusic]

the second one is no good (6mm shaft), so I swapped it for this one:
http://www.banzaimusic.com/CTS-270-10k-LIN.html
which just about fits after I clipped off some of the pcb material.

ETA: these pots eventually broke after my 'customisation'. : I ended up buying the PRV6's that this kit was designed for.

 

[Denyle Guitars]

as for the small format pots....

I used Clarostat 308 series

 

[jsteiger]

Tom,

You saw about the output iron didn't you? Just making sure.

Jeff

 

[Denyle Guitars]

Tom,

You saw about the output iron didn't you? Just making sure.

Jeff

Yeah, I just measured 600+mv at the OT primary pad. I was mainly wondering about the ratio. I figured I could stick a cap on there for testing until Ed's are done.

 

[Marcocet]

Thanks guys. I have one more newbie sourcing question

The 1N400x diodes: will 1n4001's cut it? was it not specified because any of the series will do?

Can't wait to get a look at the schematic.

 

[peter purpose]

Thanks guys. I have one more newbie sourcing question

The 1N400x diodes: will 1n4001's cut it? was it not specified because any of the series will do?

Can't wait to get a look at the schematic.

1N4001 will do nicely.

 

[peter purpose]

I am especially puzzled by R3 and R4 in parallel...is this to get a particular value?
No, but R4 39K can be left out. The prototype was fine with it.
what's the jumper between the OT and the word 'london' for?
That is to switch the R37/604R resistor accross the output transformer secondaries should you so wish.
On the underside are some pads for adding a zobel if we need one.

 

[peter purpose]

The pins need to have a fairly close-up bend to the pcb.
The easiest way is to solder them in and then bend them.
Don't worry about roughing up the surface... it'll give extra grip in the sockets.

 

[briomusic]

I am especially puzzled by R3 and R4 in parallel...is this to get a particular value?
No, but R4 39K can be left out. The prototype was fine with it.
what's the jumper between the OT and the word 'london' for?
That is to switch the R37/604R resistor accross the output transformer secondaries should you so wish.
On the underside are some pads for adding a zobel if we need one.

ok I am still not at peace with the input stage. I have now taken my 2nd kit and just soldered in part-by-part starting from the input transformer, all the while monitoring the secondary side with a little guitar amp. as soon as either R3 and/or R4 are connected, the sound gets really thin and quiet in a way that makes me think this can't be right. all this without power connected, just using the passive components up to R5 and R7.

just to confirm: I have the primary and the secondary side of the VTB9076 wired in series for 2:1 turn ratio.

peter, could you re-check and confirm the input stage on your schematic, I now have the exact same thing happening on two pcbs...

all the more frustrating, as on the first kit, I can hear the EQ working 'well' on the weirdly hpf'd signal

 

[peter purpose]

As you can see... the input transformer needs to be wired 4:1... primaries in series and secondaries in para.
2 goes to IN+
5 goes to IN-
7&8 go to OUT+
9&10 go to OUT- Ground

 

[briomusic]

Result! ;D ;D

After rewiring the input transformer to 4:1 and still struggling with the tinny sound, I decided to try using a different output from my interface (Digidesign 96 i/o) and all of a sudden everything was ok. Later on I will try and figure out why output 1 wouldn't play ball with my EQN and output 9 would  ???, but for now, let's just enjoy the sweet eq-ness.  ;D

Apart from this problem (which has to be blamed on my studio's wiring) this was really a very straight-forward kit to build (super minor gripe: the replacement screws for the input transformer are a little too long and need to be shortened which sometimes damages the threading). Also, I still would like to see a schematic whenever peter gets round to it.

I can't wait to try this eq in place of a unit built by a company that shares its name with a character out of friends. 
especially with the added high frequencies. will report back later.....

 

[Slenderchap]

I can't wait to try this eq in place of a unit built by a company that shares its name with a character out of friends.

Must be Phoebe Audio, or Monica Acoustics...

 

[strangeandbouncy]

Hey Brio,


  Hope all is well with you!


  i have beeen having all kinds of trouble with our 192's, having made the assumption that they would drive an unbalanced input. They will, but only with one leg(cold) disconnected, and with an insertion loss of 6dB. They HATE having one leg shorted to ground. This might be your trouble(?). I'd check you wiring to see if that output is shorted/un-balanced somewhere.


    Kindest regards,



      ANdyP

 

[Holger]

I don't have a 68µF C8 for the amp boards. Is it possible to use a 47µF or 100 µF instead wihtout getting punished?

Regards

Holger

 

[briomusic]

my half-educated guess - this is not a pcb-bypass or decoupling cap, so I would be careful about simply changing that value to a larger one.

 

[briomusic]

just one more bit of advice: put the stop pins into the grayhill switches before soldering them in. you won't be able to open them afterwards, as the filter caps are in the way.

(got that one wrong, pins go in from the front)

otherwise: great sound, very comparable to my 'other' commercially obtained neve copy
that said, I find it hard to do the top end of a female vocal sound with just neve-eqing, I feel that I need an 'air eq' or some plugin to get the really hi stuff. this applies to all 1073/84 eqs I have encountered.
I patched the EQN on various channels of a multitrack I had handy, and it was most helpful on drums and guitars - again typical neve behaviour

I'll definitely get two more if there is another round. ;D

 

[Grooveteer]

Ok, time for one of my silly questions:  How are you insulating your MJE3055 from the heatsink? I usually use an insulation pad plus a grommet to insulate the bolt, but the screw that came with the heatsink is too large for the grommets I have.  Should the MJE3055 be insulated from the heatsink at all?

Thanks!
G

 

[Denyle Guitars]

The heatsink isn't connected to the chassis so I didn't use an insulator.

 

[briomusic]

me neither. the soldering is just to fix it in place, no electrical connection to anything.