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Get the iconic Marshall JCM800 roar in a compact format. The Synergy SYN-MJCM800 module features dual channels and 12AX7 valves for authentic British tube tone.
Get the iconic Marshall JCM800 roar in a compact format. The Synergy SYN-MJCM800 module features dual channels and 12AX7 valves for authentic British tube tone.
Alembic F2B preamp
In the interest of continuity, and saving the planet, here is another re-purpose/recycle project.
It started here and involves a part of this.
Or in pictures it could be summarised as:
I'd already built the circuit so I just needed to build the PSU and house it... One of the problems with mounting transformers in a 1u case is getting the fixing bolt to not protrude too much, I decided brute force was the next option to try. Drill a hole, find a short bolt about the right size, grab a hammer and beat the hell out of it!
It actually worked!
Test fitting stuff:
You can see the test panel on there, well it seemed OK so I went ahead and got that, and a couple of others made up including the Calrec, they came out great:
Cool! With the pot and jack holes drilled the panel can be fixed in place (super glue). All that is left is to permanently install it:
There were a couple of weird things to overcome - the 'net' of LED holes from its previous life and the complete lack of front panel where the RJ45 sockets were.
So without further ado some glamour shots:
The good news is it worked first time, no audible hum (even when plugged into the effects loop return [power amp in] on the 50w H&K!) so that's good news. The additional switched ('Bright' - an HF shunt cap that allows HF to bypass the volume control, and the 'HF select' - which shifts the HF frequency downwards) are both really, really useful and effective.
All in all I'm really happy with how it sounds so far, I need to do some faffing with bass (it IS what it is famous for!) also but I can see it being really useful for a number of things now.
Happy days.
Gyraf G9 in 500 format...
A long while ago I built a GIX preamp, it sounds great still so I thought I'd use up some existing parts/components/projects whilst I'm waiting on the few parts I needed to order to build the Calrec EQ - and finally get around to making it's sibling channel...
It didn't take long to get it together, which I suppose is down to familiarity, and it fired up nicely first try which is always a pleasure. Please note that I have misplaced (NOT LOST) the correct control knob for the new unit. It is somewhere here. I'm just not 100% sure where right now:
Ahhh. Aren't they lovely. They also sound freakin ACE! Unfortunately I do not think Rodney (aka Gemini86) is planning on doing another run of boards. The good news is; last I heard he was thinking up other projects. And that can only be a good thing.
Viva la DIY.
X
Chaos in its tracks. And that's the gospel truth.
Sorry, I've been watching Disney films.
Ooooooo. New look BLOG? Why not...
As difficult as it is building two projects at the same time, it appears its even harder to make an easy to follow blog post about it. For that reason I think I'll post the past few days worth of progress in two separate posts.
This one is about the GIX-51x valve preamp.
The last time I left things we had got to this stage:
I needed to add the transformers, add the valves, connect the heater wiring and not burn the house down switching it on.
Kudos to Canford UK (shop) - reasonable prices, sensible postage costs and really quick service/delivery.
These are not the most expensive, turbo-nut-nut transformers - but Jakob (the originator of the G9 circuit... and, previously a gyroscopic stabilizer for professional film cameras!) highly recommends the OEP as a more 'coloured' version when compared to the Lundahls.
I'm all good for that, especially when 4xOEPs cost the same a 1xLundahl.
The OEPs come without Mu-metal Covers so you need to buy them in addition AND fit them. The covers are a standard size and come labelled as themselves. Dunno if that makes sense? OK, put it another way. Label the transformers as you shield them otherwise you wont be able to tell which one is which.
Then install them.
Add the heater wires.
Then the valves and re-construct.
I plugged it in and... SOUND! Hurrah. No flames, no smoke. BUT there was a clearly audible thumping. I remember reading in the GroupDIY thread that this had been fixed, I think I had got too involved in the other recommendations made by Bruce0 and just forgot to put this in. On the flip side it did give a good opportunity to record the noise and show a comparison.
The extra cap is quite simple to install (bottom right, 100n cap):
Lets have a look at the HV board, this converts +24v to +252v for the valve B+.
A quick game of spot the difference.
What possible difference can such a small component make? A MASSIVE difference:
On the left - waveform from GIX with no signal present - NO CAP
On the right - waveform from GIX with no signal - WITH CAP
THIS is what it sounds like. First half no cap, second half with cap. These samples have been gain adjusted by the same amount, i.e. the noise is not THIS loud, but relative to each other they both correlate.
So there we have it. One totally functional, REALLY nice sounding valve preamp that fits in a 51x rack. This is such a cool step for the 51x system to take...
Here it is in its natural habitat - glowing away.
x
