advertisement


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

slawekt said:
Paradise if I remember has a 0.6-0.8dB @20Hz obviously depending on accuracy of RIAA components
Click to expand...

I believe this is deliberate to give a bit more bass "oomph" than is strictly accurate. I have worked out VERY accurate networks for the Paradise... subject to the possible small discrepancy between measured and simulated output impedance of transconductance section of course.

The Arkless 640P in all variants uses very high quality op amps and hence computer simulation and real life are the same to within the tolerance of the components:)
 
Arkless Electronics said:
I believe this is deliberate to give a bit more bass "oomph" than is strictly accurate. I have worked out VERY accurate networks for the Paradise... subject to the possible small discrepancy between measured and simulated output impedance of transconductance section of course.

The Arkless 640P in all variants uses very high quality op amps and hence computer simulation and real life are the same to within the tolerance of the components:)
Click to expand...

Joachim was quite clear about his "funky" RIAA approach , little rise in high and low to make 80's records sound listenable ,
Sorry about derailing you thread a bit , good work and if your phonostage available at some point I'd love to have a listen .
 
I build them for customers according to Joachims 0.4db funky house curve.

My own is 9k9, 73k7, 32.1nF, 11.05nF which is pretty damn flat, and I have two sets of loading plugs which I swap according to taste, 120r and 220r.

It's pointless talking about riaa accuracy when every paradise user uses plug in loading to suit their taste. I'm not going to dictate how they should enjoy their music, I'm happy to serve them up what they like.

Obviously with no loading or adjustment in a DrT circuit one should shoot for nominally flat in the design as jez has.

Comparing cd to vinyl on the paradise theres nowt in the bass on the tracks I have that appear to be the same mastering. With jezs stage vs cd there a decent roll off on the vinyl. No doubt that's just an artifact of the Benz LPs crazy high impedance.
 
sq225917 said:
I build them for customers according to Joachims 0.4db funky house curve.

My own is 9k9, 73k7, 32.1nF, 11.05nF which is pretty damn flat, and I have two sets of loading plugs which I swap according to taste, 120r and 220r.

It's pointless talking about riaa accuracy when every paradise user uses plug in loading to suit their taste. I'm not going to dictate how they should enjoy their music, I'm happy to serve them up what they like.

Obviously with no loading or adjustment in a DrT circuit one should shoot for nominally flat in the design as jez has.

Comparing cd to vinyl on the paradise theres nowt in the bass on the tracks I have that appear to be the same mastering. With jezs stage vs cd there a decent roll off on the vinyl. No doubt that's just an artifact of the Benz LPs crazy high impedance.
Click to expand...
Looks almost flat to me ,with parallel 147k would be even closer , is that Benz LPS? with 38ohm impedance damping with 120R or 220R loading would explain bit more bass .
Do not agree about importance of RIAA accuracy though , MC carts exhibit at best 2-3% THD above 10kHz does it mean we shouldn't make proper alignment because vinyl replay is inaccurate ?
 
I have 147ks so could go even closer. But meh, I like how it sounds now.

It's not about what we 'should' do, for me it's about giving people exactly what they want. I'm not prescribing what they should enjoy. If they said they wanted ruler flat riaa I'd do it, happily.

But seeing what people prefer with cart loading has taught me that neutrality isnt the game that sells best.

In my own set up I tilt the bass with cart loading to compensate for the roll off of my yams under 75hz. I listen quietly.
 
Am I right in saying that the new Arkless phonostage is electrically similar to this one?
 
In short, yes.

As does the Ryan Sound Labs design and the Dynavector P75 (when in Dr T* mode).

* I think Dynavector are calling this PE (for Phono Enhancer) mode now.
 
Lol, he really is drinking that kool aid, oh wait he's best mates with the guy...

That's a big box.
 
Many of us used to think that the Naim K boards were fantastic. Below is the RIAA response curve for one of those boards. As you can see, the bass response is not great below 100Hz. Nowadays even without doing hand-selecting of the RIAA components, it's fairly easy to use 1% resistors and even buy 2.5% capacitors and stay within +/- 0.3db all the way down to 20 Hz. Doing better than that, I agree, is a matter of personal taste.
NaimK.jpg
 
Might that bass cut be deliberate in order to calm the Karma cartridge and its following incarnations? Just a thought.

Cheers,

DV
 
YNWOAN said:
In short, yes.

As does the Ryan Sound Labs design and the Dynavector P75 (when in Dr T* mode).

* I think Dynavector are calling this PE (for Phono Enhancer) mode now.
Click to expand...

I prefer really to use either the correct technical term of transimpedance amplifier or just call it a current input phono stage. I used the term "Dr T" in the title as many will recognise the term and hence it may create further interest but I don't see why DV should get any credit for a bog stock dead simple text book idea that has been used for remote control receivers since the year dot....
 
I've been listening to jez's across a wider variety of stuff today and it really is very good.

I'm hard placed to come up with anything at sensible money that delivers as much. It reminds me very much of the Linn Uphorik, just squeezed into a tiny little box.
 
RyanSoundLab said:
Many of us used to think that the Naim K boards were fantastic. Below is the RIAA response curve for one of those boards. As you can see, the bass response is not great below 100Hz. Nowadays even without doing hand-selecting of the RIAA components, it's fairly easy to use 1% resistors and even buy 2.5% capacitors and stay within +/- 0.3db all the way down to 20 Hz. Doing better than that, I agree, is a matter of personal taste.
NaimK.jpg
Click to expand...

I once started advertising a service to vastly improve RIAA accuracy (and make a few other improvements while I was at it) of Naim phono cards but it then occurred to me that if anyone decided that they didn't like the result then they are stuck with it... or would have to pay me to reverse it... Hence your replacement cards are a good idea for this Kit as then people still have the originals to go back to:)
 
Might that bass cut be deliberate in order to control the sound of the Karma cartridge and its following incarnations? Just a thought.

Cheers,

DV
 
The roll-off on the K boards is due to the input capacitor size - 10uf tantalum. This is a size cap that Naim uses almost everywhere in their designs and they apparently felt it was adequate for this application. This is the cap at the front of the circuit that the cartridge must put its signal through and, to keep noise at an acceptable level, it feeds into a fairly low input impedance on the board, which is what's causing the LF roll-off. The underlying issue is their use of a single-sided power supply which forces the use of a capacitor for MC cartridges (but not necessarily for MM cartridges).

I don't think it has anything to do with the Karma. My LP system is now flat down to below 20Hz and I have no problems whatever with Linn cartridges (used with Troika and Arkiv). I just think it was about the best that Naim could do at the time. Plus, their philosophy has been to keep the amplifier response close to the limits of human hearing.
 
Arkless Electronics said:
I prefer really to use either the correct technical term of transimpedance amplifier or just call it a current input phono stage. I used the term "Dr T" in the title as many will recognise the term and hence it may create further interest but I don't see why DV should get any credit for a bog stock dead simple text book idea that has been used for remote control receivers since the year dot....
Click to expand...
Some of us were playing around with transimpedance MM phono over on Vinylengine many years ago, I was using a small series resistor to pad the coil to enough resistance to get the 75 us time constant with the coil inductance
 
You must log in or register to reply here.


advertisement


Back
Top