PRS ARCHON 50 (head)
Hello and welcome back to the blog. We are now offering world-class (non-warranty) service & repairs to the range of valve (tube) guitar amplifiers from PRS Guitars, of Maryland, USA. We should point out that we have no official relationship with PRS, so we cannot accept any warranty repair claims without the endorsement of their Australian distributor.
PRS Archon 50
Our very first PRS amp repair was brought to us by new customer, Luke Denniss, from Central Coast NSW. This particular model is the Archon 50 in ‘head’ format. The Archon series of amps follows the tradition of offering a Fender inspired clean channel and a higher gain British voiced channel, footswitchable, plus a valve (tube) driven FX Loop as a bonus inclusion. PRS have chosen to employ a pair of the 6L6/5881 family of output valves for the 50 watt power amp.
PRS chassis interior
The clean channel offers one gain stage before the EQ and two gain stages after. The is before the signal path continues to the (series) FX Loop, and the PI (phase-inverter) stages. The lead (British) channel offers five gain stages prior to the 3-band passive EQ and master-volume. The end result for the lead channel is a very smooth, well controlled overdrive, with good decay characteristics. In order to keep the overdrive nice & tight, a fair amount of bottom end is sacrificed. If you are not looking for a high-gain preamp, then this amp is probably not for you.
output transformer is USA sourced ClassicTone
The assembly of the Archon employs a combination of boards and hand-wiring. Compared to the many production amps we have seen lately, this is a very practical and serviceable approach. This amp is very serviceable, and we heartily endorse that. The component layout on the boards very much follows the signal path, and for any experienced tech this is very easy to follow. What a contrast with some of the competition !
rebiasing the PRS is relatively straightforward
As you can see, whilst the power transformer is fairly nondescript, the output transformer is the ClassicTone model 40-18025, ie a 50 watt ‘plexi’ voiced transformer made in Chicago, USA. Luke’s amp was delivered to the workshop for a revalve. We removed & tested all valves, and only the output valve pair required replacement. Rebiasing this amp was straightforward, the power amp runs off a very healthy +475V, with no bias drift after our customary power output test & burn-in test.
PRS Archon 50
Many thanks to Luke for providing the subject matter for this week’s blog. IR.
ivanrichards 
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