The T-Rex SET Amplifier DIY project

[VT67]

I'm also kinda interested in this project. For the last five years now I want to build me a 300B amp, got a lot of parts to do so but up til now I haven't deceided on which concept. I have two sets of 300B's, AVVT and Krone.

Regards

 

[kmtang]

Hi Peter,

Congratulations on your new born T-REX. That's something I want to build next.


Hi GeWa,

Suggest you to build Mono Blocs because it weighs less. The stereo one just way to heavy to flip over for service and modification.


Johnny

 

[sparkle]

no more pic's????

 

[IslandPink]

I recently finished building the shunt-regulated T-Rex power supply for my existing C3m/300B SE amp . I might as well mention it on this (old) thread, as I picked up this discussion on a search when checking comments on the circuit .

Here's my main thread -
audio-talk :: View topic - Future plan for 300B XLS amp

I did quite a bit of LT Spice analysis when deciding whether or not to build .
Starts here : ( long )
audio-talk :: View topic - Valve Shunt Regulator Design Walk-Through

Overall it's been well worth the effort . It definitely beats the Series-regulated supply I had before . This was a Verdier/Thorsten style circuit with 6080 pass tubes and EF86 error amp , but with a substantial cLC supply up-front . This in turn was better than the cLCLC passive supply I used to use pre-2008 .

The new TRex supply has slightly better midrange than the series-reg . It has signifcantly better bass tone and bass timing than the series-reg . The whole bottom-end now sounds more like Class A PP , although the fluid and natural SE tone is retained .

Spice sims confirm that most of the AC return current path is through the KT88 cathode by-pass cap : make sure if you build that you put in the best possible cap here - I've just changed to a combination of a 220uF Elna Cerafine, plus an Audyn 2.2uF/100 film-foil cap here . This seems to be the best so far .

 

[Bigun]

A couple of months ago me and a couple of audio friends have compared all of our 300B diy amps in one setup. they where al driven by a transformer coupled 5842 preamp and where driving a pair of diy horn speakers. I don't know exactly all the schematics of the amps but there where four different topology's
1) 5687 srpp / 300B
2) d3A/ecc99 mu-stage, cap coupled, we connected, grid chokes, all Black Gate WKZ, Jupiter wax coupling caps etc amorfe core output stage and chokes (my own ones, total cost about 2500 euro))
3) the biggest one, somewhat similar to the T-rex with massive tube regulated power supplies and d3A/#27 tubes input stage, silver amorfe core output stage etc (total cost about 4000 euro)
4) A monkey style 6N1P/300B with very cheap Italian transformers (don't know the brand name) (total cost about 700 euro)

and (sadly for me) the cheapest amp sounded clearly the best of all, had the best micro detail, the best micro and macro dynamics, the biggest soundstage and more power than all the others. The circuit was based on a monkey style 6N1P / 300B combination.

Do we know what the key feature of the Monkey amp is that makes it the winner, is it dc coupling ?