Beresford Passive Mod.

For the three and more legged things
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Ali Tait
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#1 Beresford Passive Mod.

Post by Ali Tait »

Thought this would be of interest to any Beresford dac owners here,a passive output mod from the designer,dead easy to do-

http://theartofsound.net/forum/showthread.php?t=6910

I've just done my 7510.First impressions are good.Huge bass!
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The Stratmangler
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#2

Post by The Stratmangler »

I pulled out the daughterboard near the headphone socket on my Caiman and put a couple of 10uF NP electrolytics from Maplin - cost 28p the pair - and I've been amazed at the improvement in sound quality it has brought.

http://theartofsound.net/forum/showpost ... tcount=381

Recommended !
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#3

Post by Mike H »

Erm this "huge bass", are you sure it's not a fluke?

On the other forum one guy said his neighbour keeps coming round to complain about the bass beat. :!:


 
 
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#4

Post by Ali Tait »

Well I've tried it with two different caps now and I still get deeper bass than before.
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#5

Post by Cressy Snr »

Right said Fred!

Fine tipped iron and fine solder poised over the DAC chip; trying desperately
to keep the hands steady, X3 reading glasses perched on the end of my nose, I completed the first hair raising part of the 7510
wire mod and successfully attached a wire to pin 15 of said chip.

Attaching the other end to the positive terminal of EC14 was child's play compared
to what I had just gone through, and linking EC14 to EC 13 completed the wire mod.

The passive mod was carried out with far less bother. Using a pair of 22uF 25V electrolytics, bypassed with 33nF film caps.

The resulting sound is excellent. A definite improvement over the standard
op-amp output.

The passive output mod is well worth doing. The wire mod needed along with it is scary. Steady hands are a must.
One slip of the iron around the DAC chip and it's goodnight Vienna.
I'm going to have a lie down in a darkened room to recover :roll:

Steve
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Ali Tait
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#6

Post by Ali Tait »

I haven't done the wire mod yet Steve,need to get a better soldering iron.Do you find you have deeper bass?
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#7

Post by Cressy Snr »

Ali Tait wrote:I haven't done the wire mod yet Steve,need to get a better soldering iron. Do you find you have deeper bass?
Yes, the bass is more extended and certainly more authoritative. Listening to the modified DAC, there seems to have been a removal of a slight hump in the bass response. Perhaps the op-amp output stage had been tuned for "excitement" at the bottom rather than strict accuracy.

There have been a number of other changes to the sound too, particularly in the areas of pace, rhythm and timing. Pitch relationships between different instruments are more clearly delineated and instrumental textures are brought out better than the standard DAC. Voices convey more of their subtleties and emotional inflections. Bluesy stuff like Keb Mo and Eric Bibb is particularly well served by these mods, sounding more forward of the speakers, but paradoxically, less "in your face" Well recorded drum kits are a joy to hear, sounding solid and deep with cymbal textures nicely portrayed. Piano is another instrument that benefits from the mods, sounding substantial, but at the same time being free of clanginess.

I was up until three this morning listening to all sorts of stuff, before realising the time and turning in, so that says a lot to me about the effect of the modifications.

To sum up, I think the DAC now sounds much closer to a decent turntable.

Stan reckons the wire mod needs to be carried out before the full benefit is realised as without it, the analogue output is no longer loaded correctly after the op amp is strapped out.

However there surely has to be an easier way to carry it out than risking damage to the DAC chip trying to solder a wire to pin 15.
Pin 15 must come out somewhere on the board that is easier to solder a wire to. But without a schematic, you're stuffed.

Stan says in the AOS thread that you don't have to solder to the leg of the DAC chip like he did, but then does not go on to tell anyone where to go on the board to make the mod safer to carry out. Then again there are about six variations to the board in the TC7510 DAC.


Steve
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#8

Post by The Stratmangler »

I've put the daughterboard back into the Caiman.
I put a DVD movie on last night to watch with my son, and I was not impressed with the high frequency noise I heard while the DVD player was sorting itself out .

The board is part of the muting control, as well as having the opamps.

I'm currently waiting to see if Stan picks up on the post I've made over on AoS.
I'd like to return to the passive mod, but not at the expense of the muting circuit.
I can live with the Caiman in its standard form, as it does sound very, very good - better than the modded TC7510 IMO.
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Nick
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#9

Post by Nick »

I can only guess the mute is driven by the ZERO pin on the chip. It should be simple to take that output via a transistor and drive a DPDT relay across the output to add a hopefully blameless mute.
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#10

Post by The Stratmangler »

I may have been a bit too quick to post about the muting - I ran the same DVD as was viewed last night, and the same high frequency noises were heard with the daughterboard in place.

So I've whipped the board out again and popped the caps back in circuit.

I did dig around in the passive output thread on AoS and Stan had commented that taking out the daughterboard and inserting the caps there had no effect on the muting circuit - ie it still works.

Possibly the sounds I've heard are the result of the muting circuit switching on and off.
So far I've only heard it on 1 DVD, and I'm not going to waste any time running through the beginning of DVD discs to see if any more do it.
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#11

Post by Mike H »

SteveTheShadow wrote:Pin 15 must come out somewhere on the board that is easier to solder a wire to. But without a schematic, you're stuffed.
I would have thought so too, well can the track be traced with an ohmmeter?


 
 
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#12

Post by Mike H »

The Stratmangler wrote:Possibly the sounds I've heard are the result of the muting circuit switching on and off.
So far I've only heard it on 1 DVD, and I'm not going to waste any time running through the beginning of DVD discs to see if any more do it.
Could just be sound on the DVD :!: :?:


 
 
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#13

Post by Ali Tait »

SteveTheShadow wrote:
Ali Tait wrote:I haven't done the wire mod yet Steve,need to get a better soldering iron. Do you find you have deeper bass?
Yes, the bass is more extended and certainly more authoritative. Listening to the modified DAC, there seems to have been a removal of a slight hump in the bass response. Perhaps the op-amp output stage had been tuned for "excitement" at the bottom rather than strict accuracy.

There have been a number of other changes to the sound too, particularly in the areas of pace, rhythm and timing. Pitch relationships between different instruments are more clearly delineated and instrumental textures are brought out better than the standard DAC. Voices convey more of their subtleties and emotional inflections. Bluesy stuff like Keb Mo and Eric Bibb is particularly well served by these mods, sounding more forward of the speakers, but paradoxically, less "in your face" Well recorded drum kits are a joy to hear, sounding solid and deep with cymbal textures nicely portrayed. Piano is another instrument that benefits from the mods, sounding substantial, but at the same time being free of clanginess.

I was up until three this morning listening to all sorts of stuff, before realising the time and turning in, so that says a lot to me about the effect of the modifications.

To sum up, I think the DAC now sounds much closer to a decent turntable.

Stan reckons the wire mod needs to be carried out before the full benefit is realised as without it, the analogue output is no longer loaded correctly after the op amp is strapped out.

However there surely has to be an easier way to carry it out than risking damage to the DAC chip trying to solder a wire to pin 15.
Pin 15 must come out somewhere on the board that is easier to solder a wire to. But without a schematic, you're stuffed.

Stan says in the AOS thread that you don't have to solder to the leg of the DAC chip like he did, but then does not go on to tell anyone where to go on the board to make the mod safer to carry out. Then again there are about six variations to the board in the TC7510 DAC.


Steve
Interesting Steve,what you describe is exactly what I hear.I've been using mine for music for the last couple of weeks,though it's usually used just on the sky box.One thing I found was just as great an improvement was the addition of a linear supply.I managed to liberate a few Lambda regulated linear supplies from work,and feeding the 7510 with one made a big improvement.I've got one feeding the Touch too.
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