GUIDANCE NEEDED to mod - MARANTZ SA 7001

[Thomo]

Originally Posted by 6h5c

Hi Lee,

There's just one ferrite bead separating the IC's from the rest indeed, not very impressive. I have to open my player anyway, to fit a new analog output stage, and I have a spare Tentlabs shunt here. I'll have a look at it, thanks for the tip!

Ray

No worries Ray. It made a big difference, which I expected to be honest.

That board looks tasty, I presume it's the improved DOS which I'm going to have to get me. I think I'm going to struggle to remove all the noise coming out of the dac with just the LPF section of the original output stage and a couple of cap tweaks.

Cheers, Lee.

[Thomo]

Originally Posted by arupg

Hi Lee
Super PSU you've got there. I like the biggie caps from Mundorf/FTCaps - one of the best around! You should be getting a night-to-day change in the 7001. Aren't you?

Arup

Hi Arup.

It certainly sounds a lot better than the standard machine, which I found quite flat, and uninvolving.

The Mundorf's are fantastic parts and I love most Mundorf products (I have a pair of their AMT's in my Jamo Concert speakers now), but I have to say that the low noise regs on the dac and splitting the psu's made more difference. The original circuit has the dac sharing the psu with the servo

Cheers, Lee.

[arupg]

You have the Concert 8 or 11 ?
excellent transparency off that mid/bass driver with the gold bullet plug. Pity good things disappear...........

[6h5c]

Originally Posted by Thomo

No worries Ray. It made a big difference, which I expected to be honest.

That board looks tasty, I presume it's the improved DOS which I'm going to have to get me. I think I'm going to struggle to remove all the noise coming out of the dac with just the LPF section of the original output stage and a couple of cap tweaks.

Cheers, Lee.

Yep, it's the new DOS with Complementary Feedback Pair and current sink in the output section. Thanks to Steve!! I was hoping to fit the board this week, but it looks like it's not going to happen... Too many other interfering stuff.

Ray

[dennusch]

Originally Posted by Thomo

I modded my SA7001KI yesterday and discovered a simple, free tweak that really gave a large gain in sound quality.

I took the signal straight after the "Low Pass Differential" stage of the output section, and bypassed the HDAM and Current LPF sections. This really opened the sound up, and the bass is crazy in it's depth and power. It's not perfect as I'm pretty sure the filter is incorrect now, but it's a whole lot better than before.

Lee.

I did this mod, and i hear a big improvement. As i understand correctly the filter has become 2 pole (originally 4 pole). I don't hear any noise, i think that a 2 pole filter is good enough for me.

[Lautar]

Originally Posted by Thomo

I took the signal from the dac side of R622 and R672. Another benefit is that it has only a few mV dc offset and so doesn't need DC blocking caps, which is nice.

Lee.

and your mast remove C609,C859,R623,R673,C610,R660

[SoNic_real_one]

No, he doesn't... That filtering is necessary to properly reconstruct the audio signal, filter the ultrasonic/aliasing components and lower the THD+N to the specifyed one. It doesn't affect the audio band, they have a corner freq at 60kHz (first RC) and 80kHz (second RC).