Transcendent T16 OTL amplfier.
Copyright 2008 Troels Gravesen

Go to: Transcendent website

No output transformer, 15 wpc in 8 ohms, 8 wpc in 4 ohms.
Valves: 2 x ECC81, 2 x ECC82, 2 x ECC83, 16 x 6C19PI


The finished amp.

First of all: Buy the 6C19pi tubes from Russia. Much cheaper. I paid some 60 US $ for 20 tubes and it's nice to have a few spare tubes, although I only spent very little time swapping tubes to get the rid of DC off-set.

This amp is a very neutral sounding performer. Different from my Audio Mirror PSE mono-blocks and the 300B SE amp. By no means sterile. It is not. Allow some 20-40 hours of burn-in before making your final verdict because it gets smoother over time and I'm not even sure my amp is fully broken in yet. I haven't recorded how many hours I've used it, but my guess is some 30 hours.
Initially it didn't have the spacious presentation of my other amps, but this certainly changed after trying the
TRAM line stage. So, it appears the Transcendent line stage is not the final word in line amplification.

Like all low-wattage valve amps it's picky on the speakers attached. Don't go for something less than 93-95 dB/2.8 volts and 6 ohms minimum unless you never play very loud. I know you can find examples of people using this amp with something far less efficient, but it's not my recommendation. For some reason it does very well with my current DTQWT experiments. Supravox has been tried with good results too.

The T16OTL is an output-transformerless, push-pull design using negative feedback. Now, the Audio Mirror amps use negative feedback as well, where the 300B doesn't. But this may only be a small part of the explanation for these amps sounding different. Where both AM and 300B amps use the best coupling caps I can find, I have "only" tried the Solen FC caps (supplied) and the current Hovland caps. I think there are more to come from e.g. Mundorf Silver/Gold caps. According to Bruce Rosenblit, 0.1 uF is absolute minimum where bass will slightly suffer, so 0.22 uF is probably minimum. I'd go for 0.47 uF, ~200 US $ extra.

Construction pics


Left: Rigid stainless steel chassis. Right: Power supply board in middle.


Left: Filament supplies in place (twisted wires). Right: This amp contains a lot of wire!!

The coupling caps:


Left: Solen Fast Caps bypassed by polystyrene caps - not bad at all for a low-cost solution. Right: Hovland 1 uF/400 volts.