Hi,

For some time, I've been working on a Preamp and DAC combined. The idea is to have a system all matched using the same cases from HiFi2000. I've already done a Beta22 headphone amp and now it's the turn of the preamp/DAC.

It has balanced and single-ended inputs as well as the dual mono Opus and has both balanced and single-ended outputs also. I'm hoping to include a balanced headphone output provided by an IVY board, when they become available. The IVY will also act as the SE output buffer.

Although it's not complete yet, this is the current state.

Edited by user Sunday, March 30, 2008 6:03:08 AM(UTC)  | Reason: Not specified

Impressive. For those of us in the planning stages, perhaps you could identify/describe some of the layout.
thanks,
Michael

Following on ........

In the Power Supply, the Left hand side is the usual TP supplies, giving 2 x 7.5v from 1 LCDPS and 15v-0v-15v from 1 LCBPS.

There's also a little 5v supply I made up on a bit of Veroboard.

On the Right is the Transformer for my Beta22 headphone amp.

The mains comes in through a filter and goes to 2 relays, 1 of which controls the Beta22 transformer and the other controls the

transformers for everything else. All the transformers are individually fused. The Board Bottom Right, allows me to use a momentary

switch to turn everything on (except the Beta22) from the preamp front panel.

Most of this is fed to a 15-way D plug on the back, to link into the preamp. The Beta22 has its own socket and lead.


The Back panels (need cleaning ) :

Edited by user Monday, March 31, 2008 1:10:13 AM(UTC)  | Reason: Not specified

Just thought I'd add a 'latest' pic. I've been doing the front panel and wiring ..........

Edited by user Tuesday, April 8, 2008 5:56:38 AM(UTC)  | Reason: Not specified

Hi flozano,

I get them from http://www.rapidonline.com, here in the UK.

They are 'professional' ones with Teflon insulators and Gold plating.

I chose those particular ones as they were clearance stock, being non-rohs.

They only had black vertical, though, so I painted over the black identifier

ring with red enamel paint for the right channel sockets

It was a big saving though, over full price. :)

Well, I've decided to call this one finished. :d/


I did a little back-pedaling wrt the input buffer idea. I tried 3 different S/E sources and they were all fine without a buffer.

I still have the 'YVI', though should it prove necessary to add it in the future. I ended up, though, tweaking the gain of the IVY

a little. I finally settled on 1.8k input and 3.01k feedback resistors with 330pF filter caps. I thought it sounded best with this

combination. The values were chosen because they were what I had in 0.1% :) I also ended up with 18 Ohm 0.1% load-balancing resistors.

I had to balance the requirements as a headphone amp with those of the balanced outputs, so had to be a little bit careful.

I also made another change - I decided to put the Headphone/Balanced switch on the front instead of the back.

For this I used a little LED light-pipe momentary switch, which I made a little controller for. I think it looks cool :).


Anyway, I think it sounds superb. I've tried several different S/E headphone amps (including my Stax 2050's and Beta22) and have

concluded that the IVY driving the HD580's balanced is the best of the lot ! I even built a balanced (4 board) Jisbo buffer to see

if I could improve it, but it sounded virtually identical to the output direct from the IVY. I suppose with low impedance 'phones

it might be a different story.


So, a big 'THANK YOU' to Russ and Brian, for producing such excellent kit and a special thank you to Brian for 'Services beyond the

Call of Duty' :) .


It's now time to move on to the other components of my DIY Hi-Fi; I intend to build a matching 'Music' PC, a sort of Squeezebox clone

and a matching Power Amp next. ( I'm waiting for the Sympatico, Russ :) ).


Here's a final pic of the finished box, entertaining me .....