The BA-3 as preamp build guide

[Dudeisms]

I have not used the baseplates or risers, and probably wouldn't with a 2U chassis. Just drill through the bottom plate.

Typically standoffs (is that what you mean?) are 1/4 or so. So you would probably be fine.

You definitely don't want the heatsink to touch the chassis unless it's isolated electrically with a mica or silicone insulator.

Honestly, it doesn't matter much. You can buy a 2" heatsink from Mouser or Digikey and use that instead if it's a deal breaker for you.

Yes... standoffs (Told you guys I was newbie)!

 

[6L6]

how does it sound, you know musicality, bass, gain, soundstage, etc..

Yes, it has all those things.

Build it, you’ll love it. It’s a wonderful preamp.

 

[6L6]

I would say it’s pinched at the top end, bass is a little weak and loose...soundstage is big and diffuse. ... Dynamics a bit soft.

This is exactly why I don’t describe the sound of these projects. I would never describe the sound as any of those... I’d the bass is right, tuneful and powerful, the soundstage focused and the overall presentation punchy. Very musical, very nice to listen to.

But, that’s what I hear. You will certainly hear differently.

 

[Hikari1]

Yes... standoffs (Told you guys I was newbie)!

I think you mean:

Baseplate = pcb
Risers = standoffs

Standoffs come in lots of sizes...you will need at least 1/4 or so. I have found it’s cheapest to buy a “kit” of them on eBay....usually you can get a range of sizes in like a 200pc set for 7 bucks or something.

The pcb should just be a few mm thick.

But 1.5” heatsinks will be fine. No problem. Just buy some bigger sinks down the road if you them.

 

[Hikari1]

This is exactly why I don’t describe the sound of these projects. I would never describe the sound as any of those... I’d the bass is right, tuneful and powerful, the soundstage focused and the overall presentation punchy. Very musical, very nice to listen to.

But, that’s what I hear. You will certainly hear differently.

We'll, he or she asked for an opinion.

But I agree, everyone has preferences and the room is probably a bigger factor than anything. But this is my assessment when comparing between the different preamps I have. A lot is power amp dependent as well. I am more of a "spatial" than tonal listener. So keep that in mind.

Currently Iam listening to B1 Rev 2 which is definitely the detail king but doesn't have enough gain for me.

 

[Dudeisms]

I think you mean:

Baseplate = pcb
Risers = standoffs

Standoffs come in lots of sizes...you will need at least 1/4 or so. I have found it’s cheapest to buy a “kit” of them on eBay....usually you can get a range of sizes in like a 200pc set for 7 bucks or something.

The pcb should just be a few mm thick.

But 1.5” heatsinks will be fine. No problem. Just buy some bigger sinks down the road if you them.

Thats fair, in this case I was thinking about getting the actual baseplate so as not to have to drill so many holes....

so pub's plus baseplate, plus what ever necessary risers. I will look for some risers, I have some last few items to procure.

 

[Hikari1]

These riser panels?

They are 10mm tall.

 

[Russellc]

Yes its back in stock

I have also used their off/On switch, as well as their selector switch. Thinking I picked these parts from 6L6's BA3 build ?

Russellc

 

[Dudeisms]

These riser panels?

They are 10mm tall.

Chassis Baseplate – diyAudio Store

Baseplate

 

[Dudeisms]

for riser I mean those little round like tall washer (spacer) things I see in all your photos to slightly raise up the pcb's when you screw them in to the base or baseplate.

 

[silasmellor]

Those are the standoffs you can get them in different heights, but 5-10mm is common.

 

[Zen Mod]

use two or 3 stacked nuts as standoffs

 

[Russellc]

This is exactly why I don’t describe the sound of these projects. I would never describe the sound as any of those... I’d the bass is right, tuneful and powerful, the soundstage focused and the overall presentation punchy. Very musical, very nice to listen to.

But, that’s what I hear. You will certainly hear differently.

I have to agree. I have 2 of these preamps, used mainly for large scale music and rock. I find their performance excellent, and I have had a mountain of preamps over the years. That said, everyone's ears and preferences are different.

If I hadn't been thrilled with it, I certainly would not have built 2.


Russellc

 

[budwiser]

Almost finished.

 

[Manolo47]

P and N mosfets

I do not see any package options for these to order in the store.. Is this so?
Thanks,

 

[6L6]

Mosfets? Just order IRF610/9610 or FQP3N30/3P20. No matching required.

 

[Todd Mills]

I have my BA3 line stage mostly finished. Just have to wire it up and make a few mechanical adjustments to the chassis. I used an ELMA selector switch and a TKD2P65CS stepped attenuator. I may(probably will) have a few questions regarding setting bias.I hope to have it up and running in the next few weeks. Could I just run a wire and a resistor from V+, on the preamp board, to make a front panel LED power indicator?

Thanks

 

[6L6]

Looks fantastic!!!!

Could I just run a wire and a resistor from V+, on the preamp board, to make a front panel LED power indicator?

Yes, of course.

 

[Zen Mod]

don't forget appropriate series resistor

rule of thumb - 1K to 1k5 for every Volt from PSU

 

[Eric]

Wow - awesome build, Todd! You don't see too many dual-chassis preamps floating around...