I was able to audition two different tube tape preamps, borrowing them from a friend. They were the Bottlehead Tube Repro, and the DeHavilland Amplifier 222 tape preamp, also a tube unit.
After installing your beautifully-made direct-out cards into my Studer A80RC Mk II, replacing its internal solid-state amplifier cards, I noticed a hum emanating from the A80 bridge monitor speaker. After contacting Peter Sedlak, he informed me that the origin of this sound was due to an “open” circuit to the monitor when the tape machine’s amplifier cards are not present, but that this sound would not be present at the card’s output or into my audio system. That is exactly right. To eliminate the sound from the tape machine, I simply disconnected the cable to the bridge which was not a problem since the VU meters no longer function anyway when the direct-out cards are installed.
I chose the Bottlehead Tube Repro first. My first impression was it produced a very pleasant sound, but the more Iistened, the more I realized the sound to be overly ripe. the bass frequencies even appeared to be bit “smeared” compared to the stock electronics of the A80. So, off to the next unit…
The Dehavilland tape preamp is not as physically attractive as the Bottlehead in my opinion, but has more facility to adjust the signal. Even so, I felt the high frequencies were a bit too forward with this preamp compared to the stock A80 which seems very neutral and balanced. The bass was tighter than the Bottlehead, perhaps due to the tube complement differences between the two units, but I don't really know why.
I spoke with a friend who has tired other tape preamps as well, like the King/Cello, solid-state unit, and the discontinued Manley professional studio tape preamp. he felt my impressions were quite accurate. In fact, he felt the ONLY way to produce a superior sound to the stock electronics of the A80 was to take two steps: First, replace the factory heads with ones from Flux Magnetics, the ensure they are precisely aligned and EQ’ed. Next, invest in the Doshi tube tape preamp, but at $17,900 USD, this is not a possibility for me.
This experiment, all made possible by the installation of Peter Sedlak’s direct-out cards, was fascinating and illuminating. I now know that for me, at least, keeping my Studer A80RC Mk II stock will be the best choice.
Kip
