EuroDriver

<center><img src="http://pictureposter.audiworld.com/24943/aac_e.jpg"></center><p>I realy wanted to keep the OEM look of the Concert I and was happy with the functionality of the Phatbox. The sound was something else. Focal 130A in the front doors were good, but the amp was lacking. The first try was a Blaupunkt digital amp hooked up to the pre outs at the back of the concert. Total failure due to noise issues which were uncurable.

German car audio dealers told me that with Audi head units, the best way to go was with the High-Low adapter from Helix. I paid 49 Euros for the unit which also has a remote amp power up lead.

I have the Helix AAC driving Helix's B2 amp driving the Focal's and the sound is very good. Way better than my Soundstream and MB Quart system 10 years ago

avincar

...those preouts sound better than stepped-down speaker outs in my experience.

Pelican Pete

If I understand your post correctly, you are taking the speaker-level outputs into this Helix line-level converter.

Better yet, you can get a Blau adapter that plugs into the rear of your Concert radio and gives you two sets of RCA outputs for front &amp; rear control.

And it is line-level all the way. The adapter costs about $5 USD.

I've been running this setup for years, also with Focal 130 speakers in the front doors. But I have an Alpine amp.

Cheers,
Peter

EuroDriver

Your Alpine amp must be more tolerant of input impedance than the Blaupunkt I was using.

I was always extremely sceptical about hilo adapters, but several German audio installers said that the Helic AAC was the best solution for Audi heads such as the Concert

EuroDriver

I had a Blaupunkt passive hilo adapter that was rubbish !

avincar

And I blame either the Blau amp or the install on this one... it's not an input impedance thing, it's probably a DC offset thing.

But a preamp level common ground single-ended signal should work fine once the DC offset, if any, is removed.

The Helix probably lacks input bypass capacitors, which reduce its ability to work with DC-offset signals.

I'd be interested in running pink noise in your HU and measuring the output - most LOCs roll off in the bass region, especially at higher volumes. I would also expect the LOC to hurt your signal-to-noise ratio.

I'm glad it helped, really, but I don't believe it's a magic bullet, and I won't be convinced otherwise unless someone wants to get all theoretical on me

broke90

I've always suspected you have that ancestry. Now you've confirmed it!