Valab 23 step attenuator musings
BHC+Speedball+Valab
Instillation
Firstly although this should be a fairly straight forward modification if you are doing this after you have built your Crack + Speedball it requires a bit more work than if you had installed it at the start of your build. Because the valab is quiet tall and the connections are located on its top I had to disconnect and replace all of the connecting wires with longer ones.
This meant un-mounting the small speedball boards (but not disconnecting the wiring) to gain enough access to the octal pins at A7 and A2. Space is restricted, de-soldering and reattaching longer wires is a fiddly and time consuming task. I was very pleased to have an illuminated magnifying glass to check clearances and solder joints with as the speedball boards make it a bit darker and restrict your angle of view.
Fitting of the valab 23 step attenuator is quiet straight forward the standard volume pots hole needs to be enlarged by about 1-2mm. The smaller locating pin hole requires elongating slightly a dremel made quick work of these mods.
I initially thought the Valab would not fit but it did there is only just enough clearance for the Valab and it only fitted because the smaller A/B board can slot between the small gap between the Valabs upper and lower banks of resistors (see pic).
Initial impressions with a few hours listening.
Tubes, Mullard 12au7 and Tung-sol 5998
Most noticeable is an improvement in clarity particularly to the mids and top end. Music seems to have more of a crispness and openness and to it.
Placement within the soundstage seems a little more precise. Instruments have a little more attack and bite to the leading edges of notes.
I can hear some woodiness texture to certain wind instruments I had not noticed before.
Listening as I type to Fleetwood Mac, Lindsey Buckingham’s “I’m so afraid” one of my favourite tracks, is more forceful, darker the bass is tighter and has a touch of presence to it rather than just hearing it.
My low level volume channel imbalance has gone.
I was not sure how I would like the volume steps compared to the Cracks standard smooth action pot which I was familiar with in contrast the Valab seemed notchy when trying it before fitting and not very nice at all from a tactile point of operating (I came close to not fitting because of this and had an Alps Blue pot at the ready). This impression improved once fitted and I was adjusting the Valab with the knob fitted.
I am really pleased with the Valab I have had it in my draw for a while and had been a little daunted as to fitting it because of the amount of de-soldering and rewiring that was required in my case and not wanting to wreck my perfectly working Crack in the process.
IMHO the Valab has taken my BHC+Speedball +Tung-sol 5998 to a level of refinement above which I had been experiencing when running with the 6AS7G GEC brown base without the Valab fitted. My perception of performance of the GEC is likewise improved.
