advertisement


Arkless 640P "Dr T Mode"/current input version interest check

Darren said:
Oh? Interested in this. Any details? Or even a rough outline of design objectives?
Click to expand...

I'll put a thread on DIY when I have it up and running and have had a listen to it but briefly.... Capacitor coupled and single voltage rail (like Quad 303, Sansui AU101 and countless others) but with modern techniques and components... such as the mosfet output devices. Output capacitor included in feedback loop to kinda "take it out of the equation",
class A monoblocks and about 14-15W but can be scaled to much higher powers and built as class A/B or anywhere in between or built as stereo amp etc. Designed to drive awkward loads no problem and to be largely "user proof" and very reliable and to not be able to "go DC" and take out speakers if the worst came to the worst (capacitor coupled).
Computer simulation suggests very good measured performance... proof of the pudding yet to come from test bench and lug 'oles.
Basically if the brief was to design an amp kinda like a Quad 303 (it's 100% Jez though) but class A (and lower power than the 303 in this incarnation of it), can drive any sensible load, do the frequency extremes much better, and you can use modern components that PJ Walker didn't have access to combined to some circuit techniques that hadn't been thought of back then.... then this would be one way of doing it. It was intended as just an Xmas present to myself type little side project to be done over xmas and new year but looks like it's going to be more a birthday present for early next week! As you may gather from the design objectives though it was also done with a weather eye to it being a potential product but many fish to fry before that.... it may sound shite any way!:rolleyes:
 
I currently have the GTi on loan, and it is sounding superb in my system, Technics sl1200gr with Denon DL 103R and Sansui Au 717 amplification, playing through Russel k speakers.
I have just purchased a 640p for Jez to convert, but it sounds as if i am at the end of a long queue!
Jez currently repairing my original Arkless phono stage.
 
A GTi (recapped, non-turbo) has been with me for a week now, replacing a P75 mark II on the end of a WTL Amadeus GTAa and AT PTG33/II. And I think it's a stonker. More detail and dynamics, with less noise. Music makes more sense, if that makes sense. It outputs at a higher volume too, so now is pretty close in level to my Rega DAC.

These are the only phono stages I have any experience of so don't know how a four figure one might stack up against it, but right now I don't care cos I have albums to play. Nice one Jez.
 
A GTi, recapped and turbo-charged, has now been with me for about a month and is everything I remembered and more (being a Turbo) from the extended period for which I had Jez's dem unit!

As before, switching from the DV-P-75ii in Dr T mode there is something in common in that neither imposes its own character on things in the same way some phono stages do. I assume that this is an inherent strength of any current input design as the cartridge isn't affected or effected by the load it sees as in other approaches. So there is a similarity in the overall sound with the same cartridge between the P75 and the GTi Turbo, but that is where the similarity ends. Before even playing anything the GTi has a massively lower noise floor generally and does not seem to have any of the P75's sensitivity to nearby power supplies or mobile phones. Although more subtle with a record playing it is still noticeably quieter, with my cleanest records it is almost earie, but even with some well used and abused old favourites contributing surface noise the difference is still detectable! The extra detail it resolves over the P75 is staggering, but is very natural, this is not detail being etched on your ear bones with brutal precision and whilst I have heard some things I didn't know were there, what is more noticeable is that the things you did know were there sound much more like they should and this is very uniform across the range. Cymbals sound more like real cymbals and less like a splash, drums sound more like sticks and beaters hitting drums, bass strings sound more distinctly like the instrument and less like a more simple bass note, there are dynamics, harmonics and timbre to voices and instruments that are obvious where they were previously blurred. It is actually staggeringly good even with some pretty crap records because this extra information seemingly comes without exaggerating their deficiencies, indeed it seems more forgiving of common surface noise and pops & clicks than the P75. The days when I thought I understood what Naim and Linn meant about musicality and PRaT have long since passed, but as when I switched from Naim to Avondale and MiniDSP, and Linn to Technics, I'm pretty confident I haven't lost any and it does everything else better. My old Stageline and power supply would cost you about the same as a GTi Turbo and Jez's creation sounds a lot more like real music to me, you can very definitely still tap your foot along with the music, but it's a lot less muddled!
 
djftw said:
A GTi, recapped and turbo-charged, has now been with me for about a month and is everything I remembered and more (being a Turbo) from the extended period for which I had Jez's dem unit!

As before, switching from the DV-P-75ii in Dr T mode there is something in common in that neither imposes its own character on things in the same way some phono stages do. I assume that this is an inherent strength of any current input design as the cartridge isn't affected or effected by the load it sees as in other approaches. So there is a similarity in the overall sound with the same cartridge between the P75 and the GTi Turbo, but that is where the similarity ends. Before even playing anything the GTi has a massively lower noise floor generally and does not seem to have any of the P75's sensitivity to nearby power supplies or mobile phones. Although more subtle with a record playing it is still noticeably quieter, with my cleanest records it is almost earie, but even with some well used and abused old favourites contributing surface noise the difference is still detectable! The extra detail it resolves over the P75 is staggering, but is very natural, this is not detail being etched on your ear bones with brutal precision and whilst I have heard some things I didn't know were there, what is more noticeable is that the things you did know were there sound much more like they should and this is very uniform across the range. Cymbals sound more like real cymbals and less like a splash, drums sound more like sticks and beaters hitting drums, bass strings sound more distinctly like the instrument and less like a more simple bass note, there are dynamics, harmonics and timbre to voices and instruments that are obvious where they were previously blurred. It is actually staggeringly good even with some pretty crap records because this extra information seemingly comes without exaggerating their deficiencies, indeed it seems more forgiving of common surface noise and pops & clicks than the P75. The days when I thought I understood what Naim and Linn meant about musicality and PRaT have long since passed, but as when I switched from Naim to Avondale and MiniDSP, and Linn to Technics, I'm pretty confident I haven't lost any and it does everything else better. My old Stageline and power supply would cost you about the same as a GTi Turbo and Jez's creation sounds a lot more like real music to me, you can very definitely still tap your foot along with the music, but it's a lot less muddled!
Click to expand...

All achieved without hexed fuses, magic wires or enchanted capacitors... just good engineering;)
 
Arkless Electronics said:
All achieved without hexed fuses, magic wires or enchanted capacitors... just good engineering;)
Click to expand...
NMRH8LD.jpg

Don't believe you Jez, you're obviously low-key a warlock! ;):rolleyes::D:D:D
 
Due to a cancelled order I have immediate capacity to make 1 more GTi Turbo with re-cap and as the cancelee said "keep the donor unit" I can supply donor unit and have it here right now. "ETA" about a month and £450 all in including delivery in UK.
 
Looking forward to the DIY version of your amp.
Or did I miss the said thread?
A modern 303 is a nice perspective indeed, I can’t wait to build one ;)
Will it suit the old ESL’s?
 
You must log in or register to reply here.


advertisement


Back
Top