stay at home type 69 project

[craigmorris74]

Right, I've attached images showing what I'm talking about. If I install the pins according to Twentytrees's instructions, when I put the knob on the switch, the indicator points in the wrong direction, because of where the flatted side is the switch. Is there a specific type of knob I should be using?
View attachment 127141

The answer to my question is I needed collet knobs.

 

[dogears]

not necessarily. you can also use a knob with a set screw.

 

[elie Pak]

View attachment 124278

In lieu of trying to mod the full pre/eq PCB to just use the pre section, matt was kind enough to send over a modified pre-only version. Finished up 4 channels last night, all seem to have fired up no problem, just need to get myself sorted out with the panels and away we go.

Just testing them out with a 635A at home, they have a tonne of gain and turn into distortion boxes quite nicely, Should be a really fun set of affordable pres for tracking drums. Taking out the stepped gain switch and the inductors brings the cost per channel down to about $150CAD each, plus whatever you spend on panels.

Thanks again to Matt/dogears for being so generous with his time and expertise on this project!

Hi im interested in building these ! Could you share the link ? Thanks

 

[elie Pak]

@dogears @mdcmdcmdc Hi im interested in building the preamp only version ! Il will use Oep 1:6.45 input tranies. I was wondering what is the second potentiometer doing in the preamp. Only version ? Thanks

 

[TwentyTrees]

@dogears @mdcmdcmdc Hi im interested in building the preamp only version ! Il will use Oep 1:6.45 input tranies. I was wondering what is the second potentiometer doing in the preamp. Only version ? Thanks

Just to let you know the original Helios preamp circuit is optimised for a 1:10 input transformer - when I've tried using a lower ratio, I have encountered increased noise at higher gain. It may or may not be an issue at more usual gain levels, but worth testing before you commit to the OEP.

 

[elie Pak]

Just to let you know the original Helios preamp circuit is optimised for a 1:10 input transformer - when I've tried using a lower ratio, I have encountered increased noise at higher gain. It may or may not be an issue at more usual gain levels, but worth testing before you commit to the OEP.

Thanks for letting me know! I just bought 12 oep 262a3c (1:6,45) for 300 cad so if it work it's gonna make a lot of cheap preamp for me to track drums. Wouldn't the ratio of these have just a 4db difference from 1:10 TX? I'm a bit of of noob but I don't understand how it could be deal breaker in term of noise ? Anyway! Do you have tips and trick to contact Matt or Mdcmdcmdc because they didn't respond to me yet.
Cheers from Québec, Élie

 

[dogears]

@dogears @mdcmdcmdc Hi im interested in building the preamp only version ! Il will use Oep 1:6.45 input tranies. I was wondering what is the second potentiometer doing in the preamp. Only version ? Thanks

hi - it is an output trim.

you can use the existing board and just populate it with fewer items as described on this thread. easy peasy.

https://groupdiy.com/threads/stay-at-home-type-69-project.74779/post-1127482

 

[D.M.N.]

View attachment 124278

In lieu of trying to mod the full pre/eq PCB to just use the pre section, matt was kind enough to send over a modified pre-only version. Finished up 4 channels last night, all seem to have fired up no problem, just need to get myself sorted out with the panels and away we go.

Just testing them out with a 635A at home, they have a tonne of gain and turn into distortion boxes quite nicely, Should be a really fun set of affordable pres for tracking drums. Taking out the stepped gain switch and the inductors brings the cost per channel down to about $150CAD each, plus whatever you spend on panels.

Thanks again to Matt/dogears for being so generous with his time and expertise on this project!

Really love this idea of simply the preamp! Is there a gerber file for the simplified version, and a schematic? Want to take a look and see about adding in a DI to the front, more affordable and better suits my needs than the Pre+EQ, putting a few of the pre's in a 1U rack unit.

Speaking of the Pre+EQ, what are people seeing as roughly the price per channel on their builds?