[BUILD] GIX-51X tube preamp

[Toure14]

Very nice Toure
i´m was not sure about the phase switch, i guess toures version is right.
I guess you can raise the DI-Input or mount it on the plate and connect it with short wires, but better let Rodney confirm this...
Chris

I don't have a version up at least not yet but gunpoint version which is all black is sort of the direction I'm heading in. I was hoping he/she would be willing to share the faceplate

 

[qmp audio]

I don't have a version up at least not yet but gunpoint version which is all black is sort of the direction I'm heading in. I was hoping he/she would be willing to share the faceplate

Sure thing.  Not really finished yet... still need to make sure my added mounting screws line up.  Also haven't finalized knob choices yet so i may move the markings around once i find out the final knob diameters.    The holes for the 2 mounting screws are for http://www.amazon.com/gp/product/B000FN1EJS/ref=oh_details_o00_s00_i01?ie=UTF8&psc=1

zipped the fpd file here:
http://gunpointrecording.com/gdiy/qmp-GIX.fpd.zip

 

[gemini86]

Just to jump in here and offer my two bits;

The 3 toggle switches were never meant to be mounted to the faceplate. I built mine so they are just about flush with the front. The faceplate is bolted to the bracket via the gain switch, output pot and instrument jack. It's quite solid.

 

[qmp audio]

Just to jump in here and offer my two bits;

The 3 toggle switches were never meant to be mounted to the faceplate. I built mine so they are just about flush with the front. The faceplate is bolted to the bracket via the gain switch, output pot and instrument jack. It's quite solid.

My plan is to mount faceplate with 2 added mounting screws ( they're visible in the design I posted ) and instrument jack.  I have 2mm counter bored on the back for the gain and output.  This is so I can use a knob style that sits flush w the faceplate.  Since those nuts will be behind the faceplate and not securing it... I decided to add the 2 holes for small mounting screws. 

 

[gemini86]

ah, okay I understand now... I misread your earlier post and thought you said you added blind pockets on the backside to allow for a nut behind the toggles, when there's no need for that.

Carry on.

PS, here's a pic of the oxblood chicken heads on my second unit. The chicken heads are too big for this design, but I think they're fun and retro.

http://i.imgur.com/qEyZspH.jpg

 

[Brolik]

Hey guys, C6 68pf ceramic is spec'd 250v or greater in the BOM, but the one in Toure14's Mouser cart is 50v. Was this a revision that I missed or just a mistake in cart?

Thanks

 

[gemini86]

It's not actually blocking any DC, just passing bypassing HF signal around R10 (47K), so the voltage is not important. I spec'd at 250V to ensure it could handle a large signal swing. 50V should be fine.

 

[mhuss]

PS, here's a pic of the oxblood chicken heads on my second unit. The chicken heads are too big for this design, but I think they're fun and retro.

http://i.imgur.com/qEyZspH.jpg

The smaller chicken heads work fine, and they are available in oxblood from CE, etc. I only have black ones handy:

--mark

 

[mulletchuck]

Link to those?

 

[irfrench]

Link to those?

+1


I'm looking at getting my second built up - can anyone recommend a mouser alternative to the 330uH (652-SRR1210-331M)?  I'm not entirely sure what the specs of the inductor need to be (Max. current, Max. DC resistance etc.)  :-[

Thanks,
Ian

8)

 

[mhuss]

I guess I misspoke. :-[ They don't seem to have maroon/oxblood:

http://www.tubesandmore.com/products/P-K900
http://www.smallbearelec.com/servlet/Detail?no=1190

--mark

 

[gemini86]

Yeah I was looking around last night. If you really had to have that color, it would be hard to paint them. I'm not sure if I'm keeping them or not. I might grab some rca knock offs.

 

[Makofoed]

Received my kits, thanks Rodney!

Stuffed the pcbs tonight, just waiting for the transformers now.
Of course I ordered too thick caps for 100nf and 10nf so it looks a little clumsy.
Also I had to bend C3 slightly in order to make room for the tubepcb. 
Tested them both with the DI input, and directly out from the 4.7uf cap and they both work great.

Went for Lundahls all the way and the ll1538 is currently out of stock, should ship 16 july, cant wait!
Also, Mouser has gotten the Inductor back in stock.

Magnus

 

[Winetree]

I have 4 unbuilt kits. Not enough time.
Would you mind sharing the Parts Cart?

 

[qmp audio]

I have 4 unbuilt kits. Not enough time.
Would you mind sharing the Parts Cart?

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=be0cfb162d

Here's mine.  I haven't built yet so i can't verify all the parts. You may want to double check.  I'm still waiting on the rectifiers which should come within the next week or two.  I have everything else though.  Using lundahls and aux7's, which i've already acquired.  I'm Looking forward to starting the build.

 

[Toure14]

Heu Rodney quick question.

In regards to the Lundahl transformers would the 38XL or the 78Xl fit with the added 3.5 mm in height each add? I want to really max out this pre and I haven't ordered my Transformers yet. Also wouldn't I get more out of the 1578 since its 1:10 or 1:5 in this case better?

Thanx

 

[gemini86]

I think the XL has a much larger core and wider pin spacing. Regarding the step up, you could use whatever you wanted but the higher the step up, the more you could overload v1. A lot of legacy valve preamps use a 1:10.

 

[Toure14]

pin spacing is the same its just a smidgen taller by 3.5mm than the regulare which is 17mm. And yes the core is 45% larger...so would the added height of the XL transformer be too much or would I still clearance? also can V1 be changed to safe guard overloading?

 

[gemini86]

Well if the pin spacing and pinout is the same and the core will fit in the space, no problem. No need to change v1, but you might be using the input pad a bit more. (Except that you can't use the pad and phantom power at the same time, so either use external power if needed it external pad, if needed.) Nothing wrong with a little tube overdrive, it comes on pretty soft.

 

[gemini86]

Now that I'm finally home from work, looks like the XL should fit just fine. The bracket is .75mm thick, then 5mm spacer, then 1.5mm pcb, then 20.5mm for the 1538xl puts everything at 27.75mm or 1.1 inches about. That's actually a lot shorter than the OEP transformers I have in mine right now.