current projects

[Quirkaudio]

so a quick update on current projects:

Sugden A21 Mk3- a 20w per channel British (well Yorkshire actually) cap coupled class AB amplifier- doing a full restoration upgrade

McIntosh Mc754- great little 100w per channel power amp

Superphon- Just finished a pair of Superphon Basic preamps and currently working on a Superphon Revelation II preamp- The basics are dual mono using BJT transistors, the Revelation II uses FET's- both sound excellent and are one of my "go to" choices for $500 or less preamps- which then need to be upgraded/restored to realize their full potential.

I am also grateful to Audio Science Review, who reviewed one of the APT preamps I recently worked on for one of my customers (the APT/NAD 2200PE combination is a particularly good one)

here is the APT review

Apt Holman Preamplifier Review (vintage Audio)

This is a review and detailed measurements of the Apt Holman vintage preamplifier. It is on kind loan from a member and has been refurbished by QuirkAudio. The look is a cross between hifi and pro gear: Other than some scratches on top, the unit is a very good cosmetic shape. Rear...

www.audiosciencereview.com

and for those that may not have seen it- here is the NAD 2200PE review

NAD 2200 Vintage Amplifier Review

This is a review and detailed measurements of a refurbished and upgraded NAD 2200 stereo amplifier. It was bought by a member, sent to QuirkAudio to be fully updated and then loaned to me. The work that Peter has done is exemplary. The inside looks brand new! I have repaired hundreds of...

www.audiosciencereview.com

Peter

 

[Deli]

I have a trio of Apt preamps here- I’d like to hear your thoughts on them, and I’ll also read the Audio Science Review write-up.

Superphon gear- really great stuff.

 

[Quirkaudio]

I use an upgraded APT in my lab as the "reference" preamp- it is hard to beat as a neutral transparent source, and has an excellent set of inputs and outputs. Hard to beat on a value basis- you would need to spend a considerable amount to get anything significantly better.

 

[Quirkaudio]

So life has been busy

I have just finished a Sansui Au555A which came up very well and a Sugden A21 Mk3- both are cap coupled and have that "warmer" sound, but with the upgrades and refurbishment, a great deal more detail, better bass and overall enhanced fidelity. Both are great small amps.

On the larger side I have just completed a Proton D1200- a very cool looking evolution of the NAD 22XX series. There is much in common with the NAD's in terms of circuit design, though the Proton has ultra cool meters and a great deal larger reservoir capacitors. The upgrade included replacing the input IC, some additional decoupling and replacing all the small value electrolytics and some ceramics. The published circuit was not the same as the amp, with different component values and/or components removed or added- so a bit of a challenge. The reservoir capacitors seem to give a deeper and more defined bass response, especially under heavy load, though I do wonder if in a blind test there would be any difference between this and an upgraded NAD 2700 or NAD 2600A.

Next on the list is some Kenwood gear, including a KA600 and L07M mononblocks and a Bryston 4SST, plus a selection of NAD 2200's.

 

[Deli]

Great to see your posts!

Just last night I was checking out your restoration of a Superphon preamp.

Thanks for keeping these cool vintage pieces alive, and performing better than original. You are appreciated.