X-CANS impedance matching with AKG-K501 more bass?

[v40jlt4]

Hi all,

First post, but a read hundreds on this forum already  This is a great place to be.

Long time ago I bought the X-CANS (so the V1), that time it was the only MF HA available.
I also bought an AKG-K501. Although I love most of what it does, it has always been lacking in bass.

Few months after buying the X-CANS I put a big thoroid in an aluminum case and had my own X-PSU.
I use Philips miniwatt E88CC SQ goldpins.

Still lacking bass so searching for mods I found this place.
Immediately ordered the CAP upgrade kit and installed it. Also put in some OPA2604's (the same that I put in a CD player years back and liked a lot).
Also have a pair of (untested) OPA2134's. Also on order AD825AR (two per side, on a small print).

www.ebay.com/itm/1x-Dual-to-Mono-Op-amp-module-AD825AR-replace-NE5532-/120771740600?ssPageName=ADME:L:OC:NL:3160

By now mids, highs and soundstage are near perfect. The CAPS-kit is really great. But I still feel that bass is missing (amount of bass and its punch).

It could very well be that the X-CANS doesn't have enough power, but could it also be impedance?
X-CANS are 47 Ohm IIRC and AKG is 120 Ohms.

Could I change the X-CANS in a similar fashion as described here:

www.rock-grotto.co.uk/X-canv2-gain-adjustment.html

If so, what resistors would it take to change the X-CANS?

Or, any other ideas to improve the bass?

Many thanks

[Deleted]

v40jlt4
If you have a more than adequate level of volume before the maximum volume control setting,
try increasing the output resistors R115 and it's mate, from 47 ohms to 68 ohms or even up to 120 ohms.
However, you will then appear to lose a small amount of HF at 100 or 120 ohms.
68 ohms should give you a very modest improvement.
The other modification only reduced overall gain, without altering tonal balance.
Alex

[v40jlt4]

Hi Alex,

Sounds simpel enough to try.
With the volume at 12 o'clock the levels are fine, so there seems to be room.

Thanks,

Janis

[wadiaman]

I have found best improvements overall,including bass performance,from a combination of using OPA2111KP opamps with Telefunken ECC88 valves,and also similar Mullards.Also I am currently evaluating the results of fitting 10 x 1800uf Panasonic FK series cap's to the PSU board,I'll let you know if this is worthwhile !
For me the V1 is versatile and very responsive to valve/opamp rolling making it a very enjoyable amp,I'm sure you'll get your desired results given a little more time and effort !
Cheers !

[v40jlt4]

Thx wadiaman,

I've got many more tubes I can use. Never tried the opa2111. There are too many opamps that fit :-)
Please let me know the results of the cap upgrade.

Janis

[v40jlt4]

Increased R115 and R215 to 82 ohms, and have some more bass. Going to put in some 100 ohm resistors and see what happens.
I used IC sockets (the ones you buy as a strip and you can cut small pieces of) so I don't need to solder to swap resistors.

edit: hmm, some more bass, but the sound is dull, less involving than it used to be.
tried wit opa2604 and opa2134 but sound stays dull, back to the 82ohm.

2nd edit. Yes 82 ohms sounds better. Bit more bass than with standard 47 ohm resistors and no loss of musicallity.