[GROUP BUY] G9 in 51X format (CLOSED, ALL STOCK GONE)

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gemini86

Well-known member
Joined
Sep 22, 2008
Messages
2,477
Location
Eugene, OR USA
------READ ME!--------
The group buy is closed and PCB sets/brackets/faceplates are being shipped out asap, there are limited leftovers/extras. PLEASE PM OR EMAIL ME BEFORE SENDING ME MONEY.
Unless you're just sending me free money, then do that.

So here's what I've been working on:

-Jakob's original G9 circuit
-Adapted for use in 51X format.
-Heaters run off -24 rail in series. (only drawback is the christmas light effect, one goes out, they both go out)
-Boost converter runs off +24V. Relays off the +16V rail, using individual dropping resistors which must be adjusted to your specific coil R.

Big thanks to Peter Purpose. He put a lot of work into his G9 rendition, and I took a couple ideas from him- using 1mm pin sockets as tube sockets and switching my converter IC to the mc34063, rather than an old fashioned 555 timer circuit. (HV controller is now the Maxim1771CPA+)

Also, big thanks to Jakob, of course, for designing the circuit to begin with. I've played around with guitar amp circuits for years, but I could never design such a simple, great performing mic premap.

Schematic attached-

--UPDATES--
Added LL5402 option on output.
Added CM-75101APC and LL1528 option to input.
Added boost converter input filtering
11/20/2012 - Schematic updated, converter controller IC change, layout tweaks.

---PRICES AND PAYPAL INFO---

- PCB sets are 18USD each, shipped in the USA.

- Metalwork and faceplate are 16 per set.
(0.125"/3mm white PCB board with black silkscreen)-no additional shipping if you're buying pcbs already.

If you're buying 4 or more boards, things start getting heavy, so maybe throw a couple extra bones in, if you can.
International guys (there are a lot of you, it seems) you are going to need to chip in a bit for shipping. Since it varies to widely, I would like to just set it at 4USD per package for up to 4 boards. This should cover everyone along with the likely medical bills I will incur after hours of filling out customs forms at the post office.

If you are ready to pre-order, please send payment to roddycluff AT hotmail DOT com and in the notes please include your forum name and how many you're ordering. Please include proper shipping as stated above, and if you're exchanging currency, please include an additional 3.5% for paypal fees.

Example: 2 PCB sets sent to germany - send 41.40USD. That's 36USD + 4USD for shipping + 3.5%
Example 2: 4 PCB sets sent to Kansas - send 72USD

You can send paypal to roddycluff AT hotmail DOT com ****PLEASE remember to add a note with your forum name****
 

Attachments

  • G9-51X-SCHEM.pdf
    104.5 KB · Views: 390
PCB artwork and overlay:

The gain switching is the original lorlin/alpha type that Jakob originally implemented. Ingenious. The phase and input switches are now on-on toggles.

HPF/low-cut is now on-off-on. Down is off, middle is high, up is low. Backwards, I know, but the only way to implement it in one toggle switch.

Input iron options:
OEP A262A3E, Lundahl LL1538, Cinemag CM-75101APC, EA2622, Jensen JT-110K-HPC, Jensen JT-115K-EPC (pin spacing is slightly different, may be made to fit *UNTESTED*)
Higher ratio Lundahls can also be used such as LL1576 (1:7), LL1578(1:10), which are the same pinout as LL1538
Output:
OEP A262A2E, Lundahl LL5402,

The boost converter is on it's own little board, which connects to the main pcb with SIL pins. The bottom of the converter has a copper ground plane, as does the top of the main pcb. Together they should provide a good amount of shielding (better than nothing). You could also hot-glue a small RF shield (like the ones your IC chips come in from mouser) to the main pcb between the two to add more shielding there. Some ferrite beads in the audio path would be a last resort, but I don't think it should be needed.

Artwork attached.

--UPDATES--

Added LL5402 option on output.
Added CM-75101APC and LL1528 option to input.
Added boost converter input filtering
Moved output pot- now 1.25" below gain switch, for more space between controls.
11/20/2012 - Update PCB file
 

Attachments

  • G9-51X-PCB.pdf
    273.5 KB · Views: 255
How it all fits together:

This was the big challenge, getting it all to fit, and making it simple to build, without a lot of hand wiring.

Here is a Google sketchup model, which is what aided me in the design: https://docs.google.com/leaf?id=0B6s_klsk9wMDYWM0YmQxNjgtODU5ZC00OGY4LWEyMDktNzNhMGM4OGU5MTM1&hl=en_US

Some things to note;
-The lorlin switch is over half an inch tall from pcb surface to mounting surface, and it's on the same control pcb as the input, hpf, and phase switches.
-The control board connects to the main board via a 12 pin header. The pins will go on the main board at a right angle, the header connector on the control board. This will likely need to be fine-tuned. I'm fairly confident that it should all line up as is, but not 100% certain until I make a prototype. (update: yes it works quite nicely)
 
Anyway, I open the thread up for suggestions/comments. I'll be adding more transformer options soon.

So this is a feel, I guess. I'd like to do a group buy, if there's enough interest to send it out to be made.
 
consider putting an LC filter on the input of the mc34063 or you may be dirtying up the rail with HF trash.

if you could move the high voltage boost away from the input circuitry, that would probably be good.

i know you want to eliminate as much wiring as possible, but i would put in headers and just run the filament using a pair of wires if you are going to go straight from the -24 rail. 

i would not run the relays from a rail to ground -- better to go from rail to rail to avoid bouncing your ground with switching transients.

your gain and your output controls look a little close together.  try drawing in some knobs to get an idea of how much space you'll want.

ed
 
Ed, thanks for your input.

edanderson said:
i know you want to eliminate as much wiring as possible, but i would put in headers and just run the filament using a pair of wires if you are going to go straight from the -24 rail. 

I actually had already done that, forgot to mention it. The heaters terminate to 2 pads on the daughter board, then hand wire to a set of pads near the card edge.

edanderson said:
i would not run the relays from a rail to ground -- better to go from rail to rail to avoid bouncing your ground with switching transients.

Well, unless you plan on clicking around while recording, I don't see the problem. Unless you think the pops induced into the ground rail could be loud enough to pop some speakers (like unplugging a hot phantom mic?).

edanderson said:
consider putting an LC filter on the input of the mc34063 or you may be dirtying up the rail with HF trash.

if you could move the high voltage boost away from the input circuitry, that would probably be good.

Done and done, I'll revise the first posts with updated files.

edanderson said:
your gain and your output controls look a little close together.  try drawing in some knobs to get an idea of how much space you'll want.

I'll do that and see what I come up with, kindof limited there too. I had planned on using 1" mxr type knob for the gain and 3/4" for the output.

Thanks again.

PS...spent literaly two days straight on this so far, and looks like all night tonight adding in alternative transformer options. Added CM-75101APC and LL1528 to input and LL5402 to output. That's 5 lbs of shit in a .5lb bag, people. ;)
 
Hi Rodney,

I am just creating a PCB footprint for the 1mm pins version of a B9A socket and I would just like to check I have not made any serious mistakes before committing to a PCB.

The holes for the pins are 75 mil diameter and I have used 100 mil diameter pads.

The pads are arranged at 36 degree intervals on a  468 mil diameter circle.

OK so far?

Cheers

Ian
 
Ian,

Sorry, been a long day at work. I just used the stock 9pin footprint I had and changed the pads to fit this:
http://www.harwin.com/include/downloads/drawings/H3161.PDF

I use Kicad, otherwise I'd send you the module. Everyone else in the world seems to use eagle.
 
gemini86 said:
Anyway, I open the thread up for suggestions/comments. I'll be adding more transformer options soon.

So this is a feel, I guess. I'd like to do a group buy, if there's enough interest to send it out to be made.

I could go for cinemag on the input. And count me in for 4 of these if the group buy happens.
 
gemini86 said:
Ian,

Sorry, been a long day at work. I just used the stock 9pin footprint I had and changed the pads to fit this:
http://www.harwin.com/include/downloads/drawings/H3161.PDF

I use Kicad, otherwise I'd send you the module. Everyone else in the world seems to use eagle.

Thanks for that Rodney. That's a different drawing to the one I have for the same part but yours is much more comprehensive. Their recommended mounting hole is 75 to 77 mil so I think I'll go with 76.

I have used Kicad in the past because I run Linux and wanted a free PCB layout package. In fact I liked it so much I started the yahoo group for it. That said, for my simple tube layouts I now use freePCB which, although a windows app, runs fine under Wine. Might be time to try Kicad again.

Cheers

Ian
 
I think 8 of them would look good in your rack...  ;D seriously though, are you in for 2? I'm trying to get pricing together. The setup cost will kill for the first batch. I'm trying to get the quantity up so they can be more affordable.
 
haha.
Well, Thats the case here too. Definite interest in this but I guess it depends how many others jump on.
Think I need some ballparks(cost and contents) to have a better idea.
On first impression it looks like it will be economic (only few parts and budget oeps) and a great excuse to have a couple G9s!

is it just boards you're planning or the metal too?
 
I was just planning on boards. I can design an FPE file, but other than them, I don't know where to get fronts made in small quantities. The good news is that Jeff at classicapi has blank front plates with screw holes already in them. I could make a drill template you could print out and just drill away.

Price... well. It still depends on quantity, and I have to finalize some dimensions, etc., but it's looking like 18USD.

Not bad for the whole shebang.

Of course, all the documents I've posted are all you need to self-etch.
 
sounds good.
2 for me then :)

its awesome you put the etch file up, and the right time for this project.
looks a bit complex for my etching skills, would need to get some bigger clad and other stuff too so i think this is a good plan.
 
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