Ants Beresford TC-7520 mods & guide

[chrism]

Hi Ant,

You appear to be considering either going for a Dale type stepped pot in a little box or replacing the Beresford box to gain more room for mods.

Might give the Alps 20k blue ago just to see if any improvement can be gained through the preamp. I liked the Beresford pre as it appears to better many stand alone preamps out there especially when the power supply issue is well sorted.

Regards

Chris

[StanleyB]

I have been experimenting with an optical encoder to see if it would be possible to get rid of the standard pot in a future design. The software part is however mind blowing for me to get right, so don't expect an imminent solution.

[Covenant]

'I liked the Beresford pre as it appears to better many stand alone preamps out there especially when the power supply issue is well sorted'.

+1. Although I am likely to try a pre in the future I am very happy with the variable out on my Beresford connected to a power amp.

[Ant]

Hi Ant,

You appear to be considering either going for a Dale type stepped pot in a little box or replacing the Beresford box to gain more room for mods.

Might give the Alps 20k blue ago just to see if any improvement can be gained through the preamp. I liked the Beresford pre as it appears to better many stand alone preamps out there especially when the power supply issue is well sorted.

Regards

Chris

That's the one, although finding a quality case within my budget is proving difficult.

I'm not sure if an improvement will be gained from an alps blue, maybe Stanley would know?

I remember reading elsewhere that quite a few folks purchased cheap 'blues' from 'bay later to find out they were fakes, so if 'bay is your preferred, choose wisely.

I think I'll go for one of those cheap dale kit jobbies as I quite fancy a solderthon

Cheers,
Ant

[Ant]

I've been looking for a case to fit my planned mods in for a while now and although there's some fine cases out there, there really wasn't anything that I fancied, so, I'm building my own exactly to how I want it, here's a preview:



The render above shows the size difference between the old case and new, much more room for tinkering.

The case will be constructed from 3mm aluminium with oak cheeks (I like oak ) and a light industrial feel thrown in with 12mm allen head bolts to the front and rear corners with 4mm for the top and bottom.

The aluminium, oak and fixings are with me and ready to be drilled, painted and constructed. Then that leaves the switches/rca's/IEC/knob etc etc to fit when they arrive in a few days.

I'm planning on making a build thread all for the case alone from start to finish so all being well, a week or two and it will be complete.


Ant

[StanleyB]

Nice bit of rendering. Which program did you use? Solidworks?

[sondale]

I have been experimenting with an optical encoder to see if it would be possible to get rid of the standard pot in a future design. The software part is however mind blowing for me to get right, so don't expect an imminent solution.

Stanley,

Have you looked at Paul Hynes' VCCS? This is an LDR based solution and it works very nicely - remote and all.

Alan

[StanleyB]

I got a remote controlled version of the Caiman with motorized volume gathering dust in my office . I also tried the LDR path, but SQ etc were not satisfactory. I could hear a dip in performance with the LDR in circuit. But fear not. I haven't thrown in the towel just yet.

[Ant]

I've just been browsing the 7520 circuit ready for my replacement regulators and I've stumbled upon something:

The headphone/variable opamp is supplied purely by the external PSU with no on-board regulation, so in other words: noisy PSU = noisy variable/h'phone output?

Wouldn't a spot of line regulation here be highly beneficial for the headphone & pre-amp guys?

I'm guessing it was due to current delivery that the regulation was dismissed - am I wrong?

Ta,
Ant

[StanleyB]

The headphone/variable opamp is supplied purely by the external PSU with no on-board regulation, so in other words: noisy PSU = noisy variable/h'phone output?

Wouldn't a spot of line regulation here be highly beneficial for the headphone & pre-amp guys?

I'm guessing it was due to current delivery that the regulation was dismissed - am I wrong?

The stock Caiman power supply is a regulated 15V power supply. It can't however deliver the 12V required for the line output stage and LED control circuit, or the 5V required by the DAC and receiver chip. It can only deliver the 15V for the headphone stage. So separate regulators have been added to drop the 15V to 12V and 5V.