User's Manual

Thank you for purchasing the HA540. We spent a consider-
able amount of time designing and developing the HA540.
Hundreds of hours listening and improving the design. We
hope you enjoy using the HA540, and that it makes listening
to your music collection rewarding. We sincerely appreciate
the opportunity to build a product for you and participate in
your love of quality music and sound. We love what we do
and we’re happy to help. All Bellari products are hand built in
Salt Lake City, Utah by people who care about high quality
music.
What's in the box?
1 - Made in USA HA540
1 - 15V power supply PN PS27s
1 - This owners manual
1 - Love for great audio
CONNECTION:
1 - Connect your source to the HA540’s “in” RCA
jack or 1/8" stereo jack.
2 - Connect the supplied PS27s adapter to the
jack labeled “POWER.” Do not use any other
adapter, or the unit might not be happy and you would need
some repair work done. Reversed polarity adapters will
cause damage.
3 - Connect your headphones to the jack, marked “head-
phone”. You can use either the 1/8” or 1/4” jack or both at the
same time.
4 - Enjoy your music.
The HA540 uses one 12AX7 tube running at 150 volts. The
input signal is connected directly to the grid of the tube and
almost all of the gain of the HA540 is from the tube. The
output section is a pair of MOSFET's to drive headphones.
This is called a "hybrid circuit". The HA540 has no feedback
circuit or Integrated Circuits in the audio path, it is all analog.
FAQ:
Q:What is a N.O.S. tube?
A: N.O.S. refers to (new old stock) it is a tube that was man-
ufactured long ago and never used. These tubes are very
sought after. They may or may not sound any better, but it is
generally thought that most N.O.S. tubes are better in many
ways over new foreign manufactured tubes.
Q: What kind of tubes can I use in the HA540?
A: Tubes that can be used in the HA540 are:
12AX7 - The industry standard for preamp tubes.
12AX7A - Same as a 12AX7 but generally has a slightly
higher output.
7025 - This is the Military part number for a 12AX7.
ECC83 - This is the same as a 12AX7 it is the European part
number.
12AX7WA - This is a 12AX7 with slightly lower output.
5751 - This is a Military part number for a 12AX7WA.
There are many other tubes that can be used, but you get
where this is going they are essentially the same tube with
di󰀨erent part numbers doing almost exactly the same thing.
Q: What is the best sounding tube I can get for the HA540?
A: This is an unanswerable question. Everyone has di󰀨erent
tastes. It is up to the individual to decide as all tubes sound
slightly di󰀨erent. For me the best tube I have ever heard in a
HA540 was a N.O.S. 5751 Telefunken tube.
Q: Does the tube need time to warm up before use?
A: Yes, it will be usable in about 30 seconds. Longer warm
up times are not needed, there is no benet to warming the
tube up longer than 30 seconds. Warm up simply means
powering the unit on.