Twin Servo Sweetness!

Yep J99.

They're fitted with Lundahl 1538XL mic transformers which are a higher headroom version of the Lundahl 1538 mic transformer fitted to the original Focusrite ISA 110.

Sonic Imagery 990 style discrete opamps and a high nickel Cinemag output transformer.

No capacitors in the signal path and it runs on +24v/-24v rails so has plenty of headroom.

I initially bought two kits about 12 months ago but had got around to building one.

I decided to buy another two as I have a few acoustic sessions coming up and nothing much beats a KM84 through a Twin Servo style pre. I also will use them on drum overheads and vocals.

I tested out my recently acquired Bock 251 through the J99 and sounds incredibly detailed, big and lush without any harshness.

I just finished building three at the same time and they all worked thankfully with the exception of one which cuts out only on the highest gain setting so I'll need to fix that tomorrow.

I also have 4x SCA C84's (Millenia style) and 4x N72's (Neve Style).

Each module has its own custom onboard supply regulation and filtering and the SCA rack power supply doesn't confirm to API lunchbox standards so supply voltage and current availability are less compromised as in there's more of both.

Radial recently released a 500 Series version of the Jensen Twin Servo fitted with Hardy 990 op amps.
EDIT: According to a post on GS John Hardy said he has had no involvement in Radial's 500 series Twin Servo.

John's 500 Twin Servo has been vaporware for about the past 8 years and although he published some pics of a prototype last year and said it was 30 days from release it still hasn't materialised.

This dates back to 2009 and as of 2016 still nothing...
www.johnhardyco.com/pdf/JensenTwinServo500Preliminary.pdf

I reckon he would sell plenty of 500 series twin servos if he could get them to market but it seems he needs to expand from his apparent one man operation if he's going to able to maintain any kind of reliable supply and meet deadlines which appears to be his biggest downfall. Great products, not so great in delivering.

I tried to order four JH 990 opamps for my initial pair of J99's from John but after a couple of months of delays I cancelled my order and went with the Sonic Imagery 990 which are probably amongst the best 990 style opamps available.

I gave up after nearly 3 months as I had a J99 built and waiting for the opamps along with a customer wanting to use it.

I realise John probably has permanent big backlog of orders but he kept telling me "next week" so I waited until I could wait no more.

He initially told me when I first enquired that he had a batch of 990's that would be ready at the end of the week and he would ship the following week.

I kept hearing "next week" for months.

Anyway he makes a good product... if you can get it!

rowmat thanks for sharing! I've been browsing SCA a bit now, checking BOMs and build docs, but don't get what's included in the kits. Are these complete kits except the stuff that is clearly indicated as separate orders (like in the case of the J99 the op amps and front panel)?

Also, how come all options on the 8 slot CH02 rack - DIY or assembled - all seem to cost the same ($499)?

Thanks rowmat!!

Although I've built plenty of gear including API opamps for my CAPI gear I initially tried to purchase some Hardy 990 opamps as discussed above, however I ended up cancelling my order as Mr Hardy was unable to deliver them after months for reasons I gave up trying to decipher.

I did look at a couple of DIY options (SCA had ceased offering DIY 990 op amps) and Hairball looked like candidate but I decided to do a bit more research first to see what else was out there.

I am extremely wary of anything that looks like it involves Hi Fi 'smoke and mirrors' as we know all about 'those' websites.

I then stumbled across Sonic Imagery Labs who specialise in manufacturing custom discrete op amps, adapters and VCA's for high end audio applications in the recording and broadcast industry and nowhere did I see any references to magic power cables

They make a 990 style opamp...

www.sonicimagerylabs.com/products/Model990Enh-Ticha.html

QUOTE:
"The all-discrete SMT design is similar to the JE990 basic topology but has been completely redesigned to use an ultra-precision differential super-matched transistor pair specifically designed to meet the requirements of ultra-low noise, ultra-low THD, highly linear uncolored audio systems. In addition to the enhanced input stage, the 990Enh-Ticha uses high precision temperature stable power supply independent current sources. Supply independent current sources allow the bias to remain locked at the optimum operating point regardless of power supply voltage.

Dual matched pair temperature stable current mirrors, dual matched pair active current loads give the Model 990Enh it's outstanding power supply rejection performance. The enhanced low distortion Class-A output driver stage can sink or source 250mA allowing this module to drive transformers easily."

The super matched input transistor pair is a standard 990 design feature but the onboard power regulation and stabilisation looked interesting.

Anyway I decided to give them a shot and ordered 4 for a pair of SCA J99's.

Postage from the US to Australia was about 12 days from memory and I have had no issues and the preamps sound great. I cannot compare them with any other 990 opamps as I don't have different versions.

However I would think the Hairballs should be fine and I would have bought the 990 kits from them if I had gone the DIY route.

I may even buy a couple of Hairball kits and compare them to the Sonic Imagery Lab 990 but I suspect I would struggle to hear much of a difference.