I don't know I am at the right position to review Cathedral because I didn't own Holy Grail.
But anyway...
Cathedral looks nice, obviously. The size is right, and connection is straightforward: stereo in, and stereo out. The 9V power socket is boss standard, but the in-box manual said 'WARNING: Use only the XXXX adapter the Cathedral Stereo Reverb comes supplied with. Do not user any other AC adapters. xxxxxxblah blah blah'
Scary
But I still plug in my 1SPOT patch and it works fine.
Maybe just me, but on the adapter, it prints 'replacement for BOSS and Ibanez'. That's why I tried anyway.
Now I have a problem because my amp is just a Roland micro bass RX. I am afraid that I can't distinguish different modes in Cathedral. But of course Reverse, Grail Flerb and Echo are quite different from all the other reverb mode, in a EHX style - wet, weird, and, well, sounds good.
I am not quite sure it is a true pass. but the two footswitches feels different. The lefty tap for tempo input and infinite is soft, but the one on the right for effect on/off is hard and has a clear 'click' switch. I guess they are designed on purpose.
Many people asked about the infinite button. It is easy (in Echo mode it work as a looper switch in real time instead of reverb): When a note is still sustaining, press and hold this button so the reverb wash will not decay. Now you can play some notes, without the reverb added. Release the buttonto allow the reverb to decay.
Unfortunately I didn't find this that useful... Please put your thoughts if you can think anything about this.
The memory function is good, but for each mode, you can only save 1 preset. Bear in mind that some modes are different because the knobs play different roles in some modes.
The Pre-Delay and feedback is okay, but 2000ms is somehow short. So I will not get rid of my DD7 for now.
Blend knob is useful to adjust the mix. and Reverb time and Damping/tone knob do what they should do. If you are familiar with a Reverb effect, you are very good to go.
I haven't tried the Stereo because I don't have twin bass amp. Maybe I can use my guitar amp next time... I do have a stereo chorus so it is possible to test it.
That's my super brief review. Any question and good idea and correction is welcome!
Leon
