Duncan's Audio Repair and Restoration

08/11/2025

For the foreseeable future recaps/overhauls are the only level of service I will offer on the vintage 1970s amps and receivers. There are a couple reasons for this. First, I have a waitlist of 50+ units to do. Second, this is the level of service this gear ultimately needs to sound how it should and be reliable long term. Partial measures approaches are becoming increasingly tedious. I can spend a couple hours troubleshooting a problem that would be solved with no additional troubleshooting if I was overhauling the unit.
If anything slips through for the basic service it will be the simplest of units.I will still offer the basic service on most units from the 80s and later for now.
I will still be servicing turntables and speakers. I can take most of those jobs in right away but things will be decided on a case by case basis.
I turn more jobs away than I used to. I may turn jobs away if it is something I don't know well, if I know it to be a big time sink, or if odds of a successful repair aren't high enough. I aim to provide reliable service in a reasonable time frame. To maintain that commitment I need to be selective on what I take on.

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06/07/2025

I haven't posted anything here since 2022 but am very much still active.
I'm taking June off from accepting new work. I currently have a waitlist of 4-5 months for recap/overhaul jobs. I was taking smaller jobs in while working through that but need some time off to catch up on the list and maybe even take some time off. I will still add overhaul jobs to the list in this time but may be slower to reply if I'm at the cottage.

I keep the contact page on my website up to date with what I'm currently accepting.
https://duncansaudio.ca/contact/

I primarily work on 1970s-90s home HIFI gear. I also do older tube HIFI gear (but not standalone radios or big consoles) and sometimes I sometimes do newer high end but not those big computerized AVR receivers. Overhauls on the 1970s equipment is core of my business.

I also have a page where I talk about what I don't service. I turn a lot of jobs away if they are outside my specialty. It is easy to waste a LOT of time in this business trying to tackle the wrong jobs.
https://duncansaudio.ca/gear-i-dont-service/

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06/18/2022

I'm just finishing up a restoration on a Pioneer SX-1050.
You can find a rundown of what a restoration/overhaul includes here: https://duncansaudio.ca/restorations/

There were lots of visibly leaking capacitors in this one (and in most units this age).
Even the ones that haven't actually leaked yet will be well past their prime.

This unit will be brought back to its full potential. It might even sound a bit better than new because new capacitors are a higher quality than what was available in the 1970s.
I used Nichicon KL low leakage caps in the signal path and Rubycon ZL or Nichicon PW low impedance caps elsewhere.

05/26/2022

Power is back!
I'm a few days behind on work now. Please be patient if you have something here.

05/24/2022

Everything is okay but power still out.

04/24/2022

Here's a true monster amp for sale! $2900 after tax.
STILL AVAILABLE

This unit is in very very nice condition.
This is the ultimate amp for driving Bose 901 speakers. The 901s require a lot power and many this amp to power them. It will work great with lots of other speakers too of course. I'm currently playing with this beast in my main system while my Kenwood 700m is on the bench.

Comes with original box complete with packing material, and original documentation.

Here’s what was done during the overhaul:
All new electrolytic capacitors including main filter caps. Long life EU made Kemet caps were used for the main filter caps.
Replaced all carbon comp resistors on amp boards with new metal film resistors
Upgraded input opamps to new low noise TL071 opamps.
Upgraded all lamps to LED
Added speaker DC protection relay and circuit. The circuit is one of my own design, and the relay is a 10A Omron LY4F relay.
Replaced ¼” jacks for input 1 with RCA connectors
Replaced bias trimpots with new Bourns sealed parts and set bias
Added DC offset adjustment and set offset to

04/10/2022

I have three fully restored/recapped units for sale, with a couple more coming soon. Sony STR-7065($750), Kenwood KR-4070($450), and a Hitachi SR-903($600). The Sony and the Kenwood are in very nice condition. The Hitachi is in a bit lesser condition.

As this vintage 70s gear we love gets older and older, having gear properly restored becomes more and more critical to have it sounding and operating as it should. The electrolytic capacitors in all 70s gear have degraded audibly and will continue to degrade. Bass gets muddy and highs lose crispness and clarity.
When I recap a piece of gear, I don’t stop at caps. There are usually a few other updates that need to be done as well. Certain transistors cause issues with age. Higher wattage resistors maybe be showing wear. Assembly glue used to hold capacitors in place may be corroding components it touches. Bias and DC offset trimpots can be upgraded to much more reliable new parts, this upgrade can prevent expensive damage. I usually replace speaker relays as well. Solder is touched up as needed, I usually end up reflowing the power supply and power amp boards entirely.

03/27/2022

I haven't posted in a while but I should probably post to show things are very much still in full swing.
I finally put up a website last year but haven't done much to promote it. It contains general information on services, etc. And some troubleshooting aimed at helping people identify which component to bring me. I still have a lot to add/refine on the site.
www.duncansaudio.ca
Here's a bench picture of a McIntosh MA-6100 integrated amp being restored. I just changed all the RCA connectors because the originals don't age well.