TL Audio VP-1 - Manual (Page 20)

A rear panel Wordclock Input is provided for connecting the VP-1 to an external
master clock source. An associated switch on the rear panel selects between external
synchronisation and internal clock. In external mode the front panel sample rate
selection switch is still active and needs to be set to match the frequency of the
incoming wordclock source.
The Wordclock input connector is a BNC-type terminated in 75 ohms.
5
USER TIPS AND FAQs
Q: Why have both Class A and Valve preamp stages?
A: The Valve preamp stage combines an input transformer with
pentode and triode valve stages to offer supreme warmth, while the Class A
input stage replaces the valve stages with a discrete transistor design, yielding
a cleaner, harder sound. Class A circuitry involves special voltage biasing of
the transistors to minimise crossover distortion, contributing to its clean
sound.
Q:
How many valve stages are in the VP-1?
A: Seven. One EF86 pentode valve stage is located in the preamp section, as is
one triode valve stage. One triode valve stage is in the compressor gain make-
up circuit, and four triode valve stages are utilised in the EQ stage - one per
band. All the triodes are ECC83/12AX7A types, and all the valve stages are
run from a 250V DC power supply.
Q:
Is it better to leave the unit switched on all the time?
A: Doing this will avoid the typical 30 minutes warming up period that the unit
would normally require to settle, but will reduce the lifespan of the valves
since the valve heater will be on constantly. Most users would power off
between sessions but leave a suitable warming up period before use.
Q:
How long will the valves last before they need replacing?
A: This very much depends on whether the unit is left powered up all the time
(see above) and whether the unit is moved around and subject to vibration.
We’d say the average lifespan in a static set-up would be three to four years.
Ageing valves will typically result in a loss of HF brightness and a lack of
definition in the sound.
Q:
How do the two VP-1 insert points differ?
A: One insert point is positioned just after the preamp stage, but ahead of the
processing sections. This enables a clean feed to be taken directly from the
preamp output, and also allows another processing unit to be patched into the
signal path if required, much like a mixer insert point.
The sidechain insert point acts in an entirely different way, by permitting an
EQ to be patched into the compressor sidechain, allowing frequency conscious
compression to take place. Once the EQ is patched into the sidechain insert,
boosting a particular frequency on the EQ will effectively lower the
compressor threshold in that part of the spectrum, making it more sensitive at