EQN build thread

[haima]

my Sound generator will not go that far in terms of voltage, any tips on doing this in Lab without much fuss ???

if you signal generator is too weak you can try boosting on the EQN to get you up to the clipping point. the test waveform will look weird but you can still look for symmetrical clipping... just an idea.

 

[Grooveteer]

I like Jeff's knobs...    No, wait.. I mean..  ;D

 

[dandeurloo]

Here is what I came up with for knobs.  Found them at a surplus store.  ;D

 

[ultra-alex]

massive types for the greyhills, but definitely unique.

 

[tim-burns]

This is what I'm up to in the knob department at present.

Peter
i've got knob envy, whats the brand/part number for your knobs? I've had a look round but can't seem to get the right combo...
cheers
Tim

 

[zayance]

Just a little update for those who need that info, i've done clipping calibration following Briomusic's tip on that, thanks to him, pretty simple procedure, don't know why i couldn't figure out that by myself :, meaning using Compressor Make-up gain for boosting the signal on the way up to the EQN, well the figures were looking good without doing nothing, well my trimmers were at unity when received, i believe that's enough for getting to a quiescent point, i trimmed a tad to get it to be precise, so if you don't need precision, then i believe you can skip that part, well that's on my side, but wanted to inform those who don't want to bother and maybe don't have the tools etc....

 

[peter purpose]

i've got knob envy, whats the brand/part number for your knobs? I've had a look round but can't seem to get the right combo...
cheers
Tim

Tim,
The bigguns are actual BBC knobs and are made of unobtanium.
RS part 465-9886 is similar, but comes without any markings..!! So you'll have to engrave the lines.
The littleuns are RS part 465-9820. I leave the pot shaft length at max and slip a Hellerman sleeve on.

peter

Here's a pic of my bodged engraving job.

 

[tim-burns]

That's great thanks mate.
Unobtainium - that's genius!

 

[crisotop]

Another question about the Q switch: Peter, you said the higher R17 the sharper the bandwidth of the mid-band - right? But by flicking the Q switch in the "Hi" position R19 is in parallel with R17 thus making the Q of the band wider? Or have I overlooked something

Thanks
Christoph

 

[peter purpose]

Another question about the Q switch: Peter, you said the higher R17 the sharper the bandwidth of the mid-band - right?
Wrong
But by flicking the Q switch in the "Hi" position R19 is in parallel with R17 thus making the Q of the band wider?
Grab a pair of resistors of the same size and measure them in parallel... report back.
Or have I overlooked something.
See above.

 

[crisotop]

it doesn't matter how many resistors I stick in parallel, the length of the resistance remains approximately the same - I can only measure longer resistance if I put them in series? 

Damnit, I've read that post on page ten two times and still got it wrong - going to shut up for know until it's finished

cheers
Christoph

 

[dmp]

Page ten, Peter says LOWER resistance than 6.8k makes a sharper Q.
Adding a resistor in parallel to 6.8k will lower the resistance.
Thus: R19 || R17 lowers the resistance and makes a sharper Q

 

[crisotop]

yeah, yeah - rub it in my face

thanks for the double clarification, I got it after reading the post a third time

best, christoph

 

[dmp]

I got a request for my parts list... so here it is. If it is not here, it was either in the parts kit from Audio Maintenance, or I had it on the shelves already. Use at your own risk; I've only partially assembled mine.

Resistor 820 ohm 299-820-rc mouser
Resistor 4.7Meg miniature (1/8 watt) 299-4.7M-RC mouser
Resistor 6.2k 271-6.2k-rc mouser
Resistor 12 / 2w 594-5083NW12R00J mouser
Resistor 47 / 2w 97M4543 newark
Pot 50k linear small footprint 785-392C350K mouser
Q BC184c 512-BC184C mouser
Capacitor 470p 2.5mm 490-3656-ND digikey
Capacitor 680p 2.5mm 490-3755-ND digikey
Capacitor 1n COG 2.5mm 490-3674-ND digikey
Capacitor 220p COG 2.5mm 490-3638-ND digikey
Capacitor 330p COG 2.5mm 490-3723-ND digikey
Capacitor 470 pf cog 5mm 490-3738-ND digikey
Capacitor 10uf / 25v tant 74-199D25V10-E mouser
Capacitor 22uf / 16v tant 74-199D16V22-E3 mouser
Capacitor 47p 2.5mm 140-50N2-470J-TB-RC mouser
Capacitor 470p 2.5mm 490-3656-ND digikey
Capacitor 680p 2.5mm 490-3755-ND digikey
Capacitor 1n COG 2.5mm 490-3674-ND digikey
Capacitor 68uf/10v small electro 667-EEU-FM1C680 mouser
Capacitor 10pf COG 2.5mm 140-500N2-100J-RC mouser
Capacitor 180pf COG 5mm 140-50N5-181J-TB-RC mouser
Capacitor 220p COG 2.5mm 490-3638-ND digikey
Capacitor 330p COG 2.5mm 490-3723-ND digikey
Capacitor 470 pf cog 5mm 490-3738-ND digikey
Capacitor 4.7nf film, 5mm thin 505-MKP24700/630/5 mouser
Tr MJE3055 512-MJE3055TTU mouser

 

[canidoit]

I got a request for my parts list... so here it is. If it is not here, it was either in the parts kit from Audio Maintenance, or I had it on the shelves already. Use at your own risk; I've only partially assembled mine.

Resistor 820 ohm 299-820-rc mouser
Resistor 4.7Meg miniature (1/8 watt) 299-4.7M-RC mouser
Resistor 6.2k 271-6.2k-rc mouser
Resistor 12 / 2w 594-5083NW12R00J mouser
Resistor 47 / 2w 97M4543 newark
Pot 50k linear small footprint 785-392C350K mouser
Q BC184c 512-BC184C mouser
Capacitor 470p 2.5mm 490-3656-ND digikey
Capacitor 680p 2.5mm 490-3755-ND digikey
Capacitor 1n COG 2.5mm 490-3674-ND digikey
Capacitor 220p COG 2.5mm 490-3638-ND digikey
Capacitor 330p COG 2.5mm 490-3723-ND digikey
Capacitor 470 pf cog 5mm 490-3738-ND digikey
Capacitor 10uf / 25v tant 74-199D25V10-E mouser
Capacitor 22uf / 16v tant 74-199D16V22-E3 mouser
Capacitor 47p 2.5mm 140-50N2-470J-TB-RC mouser
Capacitor 470p 2.5mm 490-3656-ND digikey
Capacitor 680p 2.5mm 490-3755-ND digikey
Capacitor 1n COG 2.5mm 490-3674-ND digikey
Capacitor 68uf/10v small electro 667-EEU-FM1C680 mouser
Capacitor 10pf COG 2.5mm 140-500N2-100J-RC mouser
Capacitor 180pf COG 5mm 140-50N5-181J-TB-RC mouser
Capacitor 220p COG 2.5mm 490-3638-ND digikey
Capacitor 330p COG 2.5mm 490-3723-ND digikey
Capacitor 470 pf cog 5mm 490-3738-ND digikey
Capacitor 4.7nf film, 5mm thin 505-MKP24700/630/5 mouser
Tr MJE3055 512-MJE3055TTU mouser

Thanks dmp, when I have time, I will compare and update parts from my excel version BOM. Keep me posted on how your build goes and how it sounds.

 

[kato]

I got a request for my parts list... so here it is. If it is not here, it was either in the parts kit from Audio Maintenance, or I had it on the shelves already. Use at your own risk; I've only partially assembled mine.

I guess if we're all sharing parts lists, I've got this one with most of the parts sourced from mouser, complete with alternate sizes on the aml parts for the lead spacing nazis among us. Personally I'm more of a 'bend it to fit' kind of guy these days, but I remember when I thought it mattered on some level.

 

[canidoit]

I got a request for my parts list... so here it is. If it is not here, it was either in the parts kit from Audio Maintenance, or I had it on the shelves already. Use at your own risk; I've only partially assembled mine.

I guess if we're all sharing parts lists, I've got this one with most of the parts sourced from mouser, complete with alternate sizes on the aml parts for the lead spacing nazis among us. Personally I'm more of a 'bend it to fit' kind of guy these days, but I remember when I thought it mattered on some level.

Thanks Kato!

 

[MM1100]

I ended up using the knobs from http://classicapi.com/catalog/index.php?cPath=23_24_40

Here's the parts and cost:
Products
------------------------------------------------------
4 x Plain 5/8" Black Aluminum Knob 1/4" Shaft (1-62-2B-WTIW) = $22.48
3 x Plain 3/8" Black Aluminum Knob 1/8" Shaft (1-37-2A-WTIW) = $14.28
------------------------------------------------------
Sub-Total: $36.76
United States Postal Service (1 x 4oz) (First Class Mail: Estimated 1 - 5 Days): $2.23
Total: $38.99

 

[peter purpose]

Nice.. they give it a vintage look.

 

[Marcocet]

So I finally got to finish my second batch but I haven't really gotten to troubleshoot them yet so a few are having problems. The only one I'm really confused by is motorboating like crazy. It's passing signal and working fine but it's oscillating like crazy even with RV4 all the way out. Also, RV5 causes the pitch to change. Any ideas?

Thanks again everyone, especially you Peter! I can't work on them again until next weekend but as soon as they're all in the desk I'll have some photos.

Oh: As a side note I think the faceplates are a little too wide. The new batch seems fine, but the ones from my original batch start to squish everything together. I'm gonna upgrade a few parts to what I used on the second batch next weekend as well so I'll file down the plates then.