X-Can v3 gain adjustment

[kevinb]

Dear all,

Does anyone happen to know how to alter the gain of the v3 (along the lines of the v2 one posted elsewhere). I am currently only using about 10% of the range and it can't be the fault of source mismatching as it is fed directly from an MF A5 cd player!

Yours in music,

Kevin.

[Deleted]

Kevin

Do you have a schematic of the V3 ?

SandyK

[kevinb]

I'm afraid not. Can't seem to find anything on net either...

[kevinb]

Are any of these any help?

www.rock-grotto.co.uk/v3.htm

[Deleted]

Sept 17, 2009 13:12:45 GMT kevinb said:

Are any of these any help?

www.rock-grotto.co.uk/v3.htm

Not really.

[kevinb]

Hopefully!!

[Deleted]

Edit.

[Deleted]

Doing that could raise the noise floor.

Personally, for a thing like the Sana, I wouldn't do it.

First, make sure the Sansa is set on 'Rest of the World' so that there are no daft European volume restrictions and the, for mp3, I'd just feed it into a portable amp like a Neco.

I know this sounds a bit silly, but you could then use the output from the portable into the V3.

I know it adds to colouration/distortion etc, but I personally wouldn't 'taylor' a v3 to a Sansa. It hasn't even got a line out. Or [erhaps use a more sensitive headphone on the V3?

[mrarroyo]

I agree with Ian and would not alter the V3, heck it puts out 1.5 watts!

[Deleted]

Jul 6, 2012 9:27:53 GMT @navermyr said:

I run my X-Can V3 mostly from mp3-players (Sansa Clip & D2) and want to raise the gain. Probably a resistor that needs to be changed, Can anyone help?

R107, R207

Increase in value and the gain lowers.
Decrease in value and the gain becomes higher.
The lower frequency cut-off point will also become higher when the gain is increased so recommend placing caps in parallel to C106/206 as well.
Go for 2.2uF or 3.3uF (depending on the needed increase of gain)

As rabbit mentioned, the noisefloor will also increase.
max. output power (voltage) remains the same.

I do not recommend lowering the gain below a certain value because of the vastly sprinkled miller caps here and there which suggests instability problems.
Increasing the gain is less problematic and is what you want to achieve.

The output voltage of the Sansa's is very low indeed.

[Deleted]

If you adjust the gain to suit the Sansa, the noise floor will be raised and anything else (other than Ipods etc) will just be too loud.

I'd keep the V3 for a decent output from a CD player and buy a CMoy for around £35 from this guy. They are seriously good and give enough to drive a K601 headphone!!!

www.ebay.co.uk/itm/DC-CMoy-Portable-Headphone-Amplifier-with-5-5-2-1mm-DC-input-socket-amp-Headamp-/260951034368?pt=US_Headphones&hash=item3cc1e4ca00#ht_3207wt_813

This amp can be plugged in to a large supply if you want or used on a battery. It sounds really good and is a bargain imo.

That way, you won't risk damaging the V3 which is such a good amp.

[Deleted]

Edit.

[Deleted]

This made me wonder what impedances the V3 is constructed for. The K601 is 120 ohms, the HP50 is 150 ohms, but the latter is pure resistance and demands more current like the DK830.

The v3 has 33 Ohm output resistance and can easily reach 10V.
It can be used with HP's ranging from 16 Ohm to 600 Ohm.

Headphones with a range of close to 120 Ohm can be driven very easily by most amplifiers (even C'Moys) but are less suited to be driven directly from portable gear.
They require very little current but like to see voltage.

The K601 is by far the most sensitive (97mV for 90dB) and can easily be driven to 130dB on this amp.
Both ortho's are 12dB less sensitive and require around 0.4V to reach 90dB and can be driven to around 115dB on the v3

a practical volpot range is between 9 o'clock and 3 o'clock and not related to proper use of energy.
There really isn't much energy required for driving headphones with the exception of a few exotics.

[Deleted]

However Frans, don't modern CD players put out nearer to 2V? The Sansa is way down on that so the input to the V3 is really quite low.

For the V3 to get a Sansa to play loud into a decent headphone is going to need quite a lot of amplification.

Although the V3 gives out a lot, raising the sensitivity will surely raise the the noise levels quite a bit.

My own feeling is a CMoy would probably do a better job in this case!!

[Deleted]

DAC's and CDP are generally delivering 1V to 2V (2V being kind of a 'standard')
The Sansa is max 0.2V, an ipod max 0.3V.

This basically means the Sansa is 20dB 'softer' in output signal than a standard CD player.

Most C'moys only have a gain of 2 to 4 times (so 6dB to 12dB gain)
ofcoarse when using a C'Moy not only the noise of the chip itself is added but also the noise of the player itself is amplified 6 to 12dB.
So the S/N ratio will also increase.

For the v3 to reach maximum output level of say 10V and a gain of 8x (+18dB), I figure the v1 and v3 have a similar gain, you would need to have 1.25V input voltage.
This means a gain of 6x would be needed to fully drive the v3 from the Sansa.

[Deleted]

I used to 'preamp' the DAP before going to the amp!! In reality - double amp, which is a really daft thing to do but it gave me volume from a naff little MP3 player at the time.

Lovely eh .... Amp up the DAP so the disortion/artifacts are amplified, add the colouration of the first amp into the noise and colouration of the second amp ......

More like a cook book!!

[pagan]

Jul 13, 2012 7:07:01 GMT @iancraig10 said:

More like a cook book!!

And add Tube for flavor..

[Deleted]

- double amp, which is a really daft thing to do but it gave me volume from a naff little MP3 player at the time.

It's not daft really and what happens 'normally' as well.
A lot of pre-amplifier designs actually are made up from 2 or even more sections all adding some amplification.

I used to be amazed about how my low output MC cartridge, with 0.5mV output voltage, was sounding on my electrostats which has voltages of 1500V on it and how extremely well/lovely this sounded.

that's 3 MILLION times amplification, in dB's a staggering 130dB, while still having a S/N ratio of 50 to 60dB (which is quite high really).

It consisted of 10x amplification (transistor) into 200x (hybrid RIAA with opmaps) into 5x preamp (OPAMP) into 20x power amp (transistor) into 20x transformer amplification (roughly).
That's a lot of 'amps' behind each other.

[Deleted]

3 MILLION times amplification,

That's a large amount for sure!!

I used to adjust the first amp as high as it could go with out distortion and back off which often meant that the end amp could be used lower down in volume in an attempt to get a low s/n ratio.

I even drove two NAD amps in 'bridged' mode from a stereo amp so that each NAD was used as a power amp and there was a Rotel being used as a pre-amp.

I did all kinds of weird things!!