Abbey

Description: This is one of the original brand-name folders created for the site, and for almost three years it has been empty, just a distant memory. Suddenly, there is a nice picture and the circuit of the preamp. The preamp circuit was traced from my unit in the photo (forgive the haircut, but it was 1985). The power amp is pretty much a Fender type with a power rating of 100/50 W, utilizing four 6L6GC tubes, and includes features such as presence control, slave output, and impedance options of 4, 8, and 16 ohms. On the back of the unit is a small plate indicating Christchurch, NZ, which suggests it is a pre-80s build since Ross relocated to Melbourne, Australia, in the early 80s. The serial number is 045, indicating that at least 50 of these units were made around that time. I have never seen another one like it, so the total number produced is uncertain. This amplifier was purchased from Cash Converters in Parkdale for $300 in June 2008, after negotiating down from an asking price of $500 due to the perception that it was only half functional, with some controls not operating correctly. Upon further inspection, it was discovered that the amplifier is essentially fully functional, having been customized so that the controls no longer correspond to their original functions. This modification transformed a clean-voiced AC-50 clone into a high-gain amplifier with knobs controlling two gain stages, as well as an added master volume control. The original controls would have included (BRILLIANT) Volume, Treble, Bass, and (NORMAL) Volume, Treble, Bass, but now function as Gain 1, Gain 2, Bass, Middle, Treble, and Master Volume. Gain 1 and Gain 2 provide similar amounts of gain when used individually but have a cumulative effect when combined, allowing for high gain settings at low volume. The clean tone remains excellent, with a desirable level of overdrive achievable through careful adjustment of the gain controls and master volume. Notably, there are only three preamp tubes, which is typical for an AC-50, yet the chassis appears to have once accommodated five preamp tubes. The origin of this discrepancy is unknown. The circumstances surrounding how this amplifier ended up at Cash Converters for $500 remain unclear; it is likely that it was sold to them for around $200. This amplifier exhibits impressive handmade quality and components throughout. The transformers are substantial and heavy. It has been used as one of the main amplifiers for gigging and recording over the past few months, proving to be an exceptional instrument. It is remarkable to acquire such a high-quality, handcrafted amplifier for $300, while a custom shop equivalent would typically cost several thousand dollars.

The amplifier described is a modified version of the AC-50, which has undergone significant alterations to enhance its performance and versatility. The modifications include the addition of two gain stages that allow the user to achieve a wide range of tonal options, from clean to heavily overdriven sounds. The presence control adds an additional layer of tonal shaping, influencing the high-frequency response and overall brightness of the sound.

The power section, utilizing four 6L6GC tubes, is capable of delivering a substantial output power, adjustable between 100W and 50W, making it suitable for various performance settings, from intimate gigs to larger venues. The inclusion of a slave output allows for easy integration into larger sound systems or for recording purposes, providing flexibility in usage.

The impedance switch for 4, 8, and 16 ohms adds further versatility, allowing the amplifier to be matched with different speaker configurations. This feature is essential for optimizing performance and ensuring compatibility with various speaker cabinets.

The chassis design, which suggests the potential for additional preamp tubes, raises interesting questions about the amplifier's history and design evolution. This aspect may indicate that the original design was intended to accommodate more complex circuitry, perhaps for different tonal characteristics or additional features that were ultimately not realized.

Overall, the amplifier stands out not only for its sound quality and functionality but also for its craftsmanship, indicative of a bygone era of hand-built electronics. The ability to acquire such a unique piece of equipment at a reasonable price highlights the potential for discovering hidden gems in the used market, particularly for musicians and audiophiles seeking high-quality sound without the exorbitant costs associated with modern custom-built amplifiers.This is one of the original brand-name folders created for the site, and for almost three years it has been empty, just someone`s distant memory - suddenly we have a nice pic and the circuit of the preamp. Thanks Richard. I`ve only a pre amp cct I traced from my unit in photo (forgive the haircut but it was 1985) Power amp was pretty much Fender t

win: 100/50 W, 4x6l6GC, presence, slave out, 4, 8, 16ohm, Wicker trim. On the back of mine is a little plate that says Christchurch, NZ indicating that it`s a pre 80`s build as Ross relocated to Melbourne, Australia in the early 80`s. Serial number is 045, so I guess at least 50 of these were made around that time I`ve never seen another one like it, so I`m not sure how many would be out there.

I bought this amp from Cash Converters in Parkdale for $300 in June 2008. I bargained them down from their asking price of $500 as I thought the amp was only half functional, with half the controls not functioning correctly. When I came home and inspected it further I realised, with a bit more tweaking, that it`s actually essentially a fully functional amp and has simply been customised so that the controls are not doing what`s indicated on the panel anymore, but have other functions.

This conversion has basically involved turning a clean voiced AC-50 clone into a hot-rodded monster with a couple of knobs to control the two gain stages, and addition of a master volume control at the end. So, whilst the original controls would have been; (BRILLIANT) Volume, Treble, Bass, & (NORMAL) Volume, Treble, Bass, now the knobs function as Gain 1, Gain 2, Bass, Middle, Treble, and Master Volume.

Gain 1 and Gain 2 controls basically add the same amount of gain when used individually, but have a cumulative effect when used together, facilitating quite high gain settings at low volume - way too much gain for my usual style of playing - but the clean tone of this amp is also still great, and a nice level of overdrive can be dialed in at whatever volume with a little tweaking and balancing between the gain controls and the master volume. Another interesting point is that there are only 3 pre-amp tubes (which seems to be what your average AC-50 has) but the chasis looks like at some point it accommodated 5 pre-amp tubes.

Don`t know what`s the story there. I`d be interested if anyone knows the pre-history of this amp. How it ended up in Cash Converters for $500 I don`t know. That would normally indicate that someone`s sold it to them for $200 or so. Crazy. This is a fantastic amp with hand made quality and components throughout by the looks of it. I`m not sure what the transformers are but they`re big and heavy. I`ve been using this as one of my main amps for gigging and recording for the past few months and loving it. Amazing that it`s possible to pick something like this up for $300 whilst a hand built or custom shop amp of this calibre would set me back a few thousand dollars!