Whistle Rock Audio API Style Mic Pres - Pics

[Nick Franklin]

Thought I'd share my latest DIY exploit...

Just finished up this 4-channel API style mic pre set using PCB's from Whistle Rock Audio. Transformers are the Ed Anderson vintage recreations from Classic API. Op-amps are the GAR2520 kit from the same place. Knobs from CAPI also. Used an Altronics case and had the front panel laser marked.

Altronics toroidal coupled with a JLM Audio (thanks Joe!) powerstation is taking care of the juice.

They sound really good, as you would expect with all that iron and discrete op-amps. Some friends at work and I did a thorough comparison to the preamps in our SSL Duality and to be honest it's really splitting hairs on most sound sources. I don't know if I buy in to preamps making that much difference once you get to a certain level of quality. Needless to say I won't hesitate to use them on anything! Very happy.

Enjoy.

[Jim Williams]

Nice build. Maybe try some differnt opamps to vary the pallette? The Jensen 990 is a good design with very good open loop gain. Their transformers are top-notch too, all I use here.

I hear very large differences between transformer coupled SS mic preamps with iron-less designs. If you don't, maybe up the monitoring chain quality?

I like the iron stuff for a euphonic tone, the iron-less designs for the reality thing.

YMMV.

[Snarl 12/8]

That looks gorgeous to me.

[Osumosan]

Props! API style.

[Nick Franklin]

Hey Jim, thanks. Maybe down the track I'll pop some different op-amps in. I've got the 2520's now so I'll use those for a while though.

I think our monitoring system is pretty good (Genelec 1034B's), I reckon your hearing is better than ours!

Nice build. Maybe try some differnt opamps to vary the pallette? The Jensen 990 is a good design with very good open loop gain. Their transformers are top-notch too, all I use here.

I hear very large differences between transformer coupled SS mic preamps with iron-less designs. If you don't, maybe up the monitoring chain quality?

I like the iron stuff for a euphonic tone, the iron-less designs for the reality thing.

YMMV.

[Nick Franklin]

That looks gorgeous to me.

Thanks!

[Jim Williams]

Hey Jim, thanks. Maybe down the track I'll pop some different op-amps in. I've got the 2520's now so I'll use those for a while though.

[/quote]

Maybe try some JLM opamps, made there in Oz. They also have some hybrid designs that use a traditional DIP IC opamp with current boost output drivers. They have a cool class A-class A/B select too.

[Nick Franklin]

Yeah absolutely, I know Joe quite well actually. His 99V's rule!

Hey Jim, thanks. Maybe down the track I'll pop some different op-amps in. I've got the 2520's now so I'll use those for a while though.

Maybe try some JLM opamps, made there in Oz. They also have some hybrid designs that use a traditional DIP IC opamp with current boost output drivers. They have a cool class A-class A/B select too.[/quote]

[frans_13]

JLMs 99v totally rule - there's an idea behind them, if I got the tech right: less gain, less negative feedback in the circuit = friendlier behaviour as you approach maximum level, just like with tubes.

[Randyman...]

Looks good!

OT - do you know if the front panel is available separately? I built the "3nity" 3124 with a chassis/panel from Dan @ Collective Cases (both from Group DIY forum), and the front panel has the controls evenly spaced - so I had to shoe-horn the PSU in there - a bit too close to CH3 and CH4 so I get a bit of hum (1 and 2 are dead silent!).

The way yours is laid out leaves much more room for the PSU over on the side.

Also, how does the front panel attach to the chassis? I can't tell by the pics.

Thanks for any info!

[mrc]

Very Nice, a tip of the hat to ya!

[Matt C.]

a few questions about some little details of this build, since I've been thinking of doing the same:

how deep is the case you used?
what are the specs on the power transformer (VA rating and secondary voltage)?
what tools and parts did you use for those Molex connectors?

[Nick Franklin]

Hi Randy,

Thanks for the kind words. This front panel is not an off-the-shelf one, but one I measured out, designed and had laser engraved myself using an altronics blank 1u case (black annodised). I then drilled the holes out.

I intentionally put the preamp boards quite close together to make room for the power supply.

So no, this panel isn't available, but I'd wholeheartedly encourage you to get into the metalwork/case side of DIY because not only does it give your stuff a unique look, but it's in the true spirit of DIY. At least that's what I reckon!

Looks good!

OT - do you know if the front panel is available separately? I built the "3nity" 3124 with a chassis/panel from Dan @ Collective Cases (both from Group DIY forum), and the front panel has the controls evenly spaced - so I had to shoe-horn the PSU in there - a bit too close to CH3 and CH4 so I get a bit of hum (1 and 2 are dead silent!).

The way yours is laid out leaves much more room for the PSU over on the side.

Also, how does the front panel attach to the chassis? I can't tell by the pics.

Thanks for any info!

[Nick Franklin]

Thank you!

Very Nice, a tip of the hat to ya!

[Nick Franklin]

Hi Matt,

The case is 255mm deep.
Transformer: 18+18V, 30VA
Molex connector part numbers are on the BOM for the preamp cards, the crimping tool I have no idea. Actually borrowed it off a mate. Ill ask him where he got it!

a few questions about some little details of this build, since I've been thinking of doing the same:

how deep is the case you used?
what are the specs on the power transformer (VA rating and secondary voltage)?
what tools and parts did you use for those Molex connectors?