![]() ![]() ![]() So for this build the amplifier modules are the excellent Avondale NCC200 amplifiers built using Dale RN60 resistors throughout except for resistors in the signal path which are Audio Note tantalum resistors, matched transistors are used throughout and Capacitors are all high quality Polypropylene, polystyrene, silver Mica and military spec wet tantalum types. My own preference is to use a Military spec Wet tantalum capacitor bye passed with either a 100nf polypropylene or polystyrene capacitor this retains all the speed and dynamics of the solid tant but sweetens the treble and still retains the excellent bass performance but also with a 3 dimensional image. Its a tried an tested design that provides an excellent solid state power amplifier that sounds fast clean with high transient performance, the sound can be tailored to your taste particularly by the choice of components with the feedback and input cap having a significant effect on the voicing of the amplifier., NAIM chose solid tantalum capacitors for these caps and that gave their amps that fast clean sound with an upfront presentation, some find their sound initially impressive but fatiguing in the long term, if you use film caps the sound will be a lot smoother and sweeter but can lack the excellent bass impact of the tantalums. I have been using the NCC200 amplifers for a few years now and also builts some voyager clones by Hacker ( the Hackernap amplifirer).Īll of these amps are based on the 1960s RCA power amplifier circuit that NAIM also used in all of their Chrome Bumper amplifiers The first stage is just a buffer it has no real gain to it and technically you can just add the eq part of the jcm preamp and take the output off of the cathode of v1a after removing the cathode capacitor c4 and in that case, I would change R4 to 220K, R5 to 470K so there is more drive to the el34īut of course I would be hand wiring an amp like this so I could try different things.Finally got round to starting my build of a pair of monoblock amplifiers based on the Avondale Voyagers If I was going to stick an eq on this thing I would discontinue the first stage entirely (V1a, c1, r8, r7, and vr1 of the valve Jr) and maybe throw some negative feedback on it from the output transformer to new preamp after getting rid of the noise by adding hand selected grid stoppers where there are none on the jcm800 clone preamp (this is design flaw to your circuit you are adding btw). I don't know why you would need that much gain other than trying to insert the eq. Provided I do the modifications to the valve junior as you have listed above, should it be all good to come straight out of the jcm800 preamp's line out and into the valve junior's effects return?now if you are inserting an effects loop, R7 would have to be there to load the previous stage. ![]() ![]() The schematic i'm currently looking at can be seen here: I've seen a couple of standalone preamp builds where guys are plugging the output of the preamp straight into the FX return / power amp section of another amp and was wondering if this kind of setup was possible if I were to install an effects loop on the Valve Junior and run the JCM800 preamp into the valve junior's power amp or if further circuit modifications were necessary to make the two compatible? Instead of diving right into the deep end I thought a good introductory project would be to build a relatively simple standalone tube preamp - in this case, the JCM800 - which I could then run through an external power amp.Īs i'm only able to play at bedroom volumes for the time being I don't have the need for a big power amp. I have a little bit of electronics experience (building fx pedals / doing a couple of mods on the valve junior) and have recently been looking at getting into building a tube amp. My current guitar amp is a somewhat modded Epiphone Valve Junior stack which now has a 15w output transformer. ![]()
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