Moreplay Upgrade Kit - Bottlehead

Moreplay Upgrade Kit

$289.00

This kit incorporates our tried and true power supply upgrades as well as upgrading the stock potentiometers to the great sounding Alps Blue series. The result is a more quiet background, about 6dB more gain and improved resolution.

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While the stock Moreplay circuit offers exceptional performance with a simple circuit and straightforward build, we felt improvements could be made with some upgrades. Where we have traditionally modularized these upgrades to allow individual modules to be compatible with other kits, the Moreplay instead receives its own set of customized PC boards optimized for this specific application.

The first portion of the upgrade features a PC board with a Schottky rectified low voltage DC supply feeding a pair of individual DC regulators to heat each 6V6, a high voltage regulator, and a pair of C4S current source loads. The regulated DC heater supplies remove the 60Hz heater hum and harmonics from the 6V6 tubes for a quieter background. Likewise, the high voltage DC regulator provides substantial power supply ripple rejection as well as isolating the large electrolytic capacitors from handling signal current. The pair of C4S constant current source loads provide twice the impedance to the 6V6 tube plates compared to the stock plate loading resistors, which reduces distortion and provides a slight (2-3dB estimated) increase in gain.

The second portion of the upgrade replaces the volume and balance pots with a pair of Alps RK27 Blue Velvet potentiometers. These have been a popular upgrade choice with our builders for many years, though they require PC board mounting. The substitution of the Alps balance pot removes 4dB of insertion loss present in the stock balance control design.

As with all of our upgrade kits this one is intended to be installed into a completed and fully functional basic version of the kit.

Product specifications

Gain: Adds 6dB of gain to the stock Moreplay circuit for a total of about 15dB

Perfecting imperfection

Some people may not realize that a tube preamplifier's signature warmth is a result of distortion. The trick becomes reining in bad distortion and making the most of good distortion (also known as second harmonic distortion).

The stock Moreplay amplifier already produces a pleasing, tubey warmth. On the graph, you can see the fundamental as the biggest peak toward the middle, and a series of smaller peaks to the right. That first peak around 2 kHz is second harmonic distortion, and it's higher than the less-desirable harmonics that follow.

When you upgrade the Moreplay, you're getting three benefits: you're adding higher quality potentiometers for volume and balance, you're increasing gain, and you're reducing the amplitude of the peaks beyond the second harmonic. What does that mean? More of the tubey warmth you love available for your amplification stage with even less of the distortion you don't want.

Person using a screwdriver to attach hardware to a Bottlehead amplifier kit chassis plate.

Yes, you can do it!

Bottleheads have been assembling our kits for over thirty years. Every kit includes the parts and components you need to build the kit plus an incredibly detailed manual with step-by-step instructions and close-up photos. Check out this sneak peek into what every manual includes. We've also put together a handy list of the tools you'll need to bring along.

Need some assistance or inspiration? Check our user forums.

Just add tools

Bottlehead kits come complete with everything you need to assemble. We provide the wood base, chassis plate, tubes, hardware, wire, circuit boards, and electronic components. You just provide the tools and solder.

Check out this blog post to see what comes in every kit, and this handy list of tools and equipment you should gather before you begin.

FAQs

Please read our FAQs page to find out more.

What does the Moreplay Upgrade provide?

The Moreplay Upgrade replaces the stock potentiometers with higher-quality Alps potentiometers, improves gain, and reduces higher order harmonics while retaining a pleasing and warm tone.

Can this upgrade be done in phases?

Yes, you can install just the potentiometer upgrades first. From there you can install the rest of the upgrade when you're ready, or just leave it as-is.

Will this upgrade affect the sound?

Changes to the circuit will almost always result in some change to the sound. In this case, we see lower higher order harmonics while retaining the desirable second harmonic. This means you're getting that signature, warm Bottlehead sound while reducing some of the (already low) harsher distortion.

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