• Welcome to ADA Depot - A Forum To Support Users of ADA Amplification Gear.
 

News:

Need a Schematic? Check the Vault *MP-1 Classic Schematics Just Added!!

Main Menu

Ampulator

Started by Yazoo55, September 29, 2016, 07:18:50 AM

Previous topic - Next topic

Yazoo55

I know the Ampulator is very rare and expensive to buy second-hand. I came across a post on the GroupDIY site by Curtis who built a modified version a while ago. Unfortunately all the picture links he posted are now dead. I have tried contacting him but I haven't had a reply yet.

I found the Ampulator schematics but they do not include the pcb, unlike the Microcab schematics. Has anybody seen the pcb layouts or do you know of any photos? It would be great to have a go at building the Ampulator.

GuitarBuilder

ADA and Rockman Heads
Marshall amps
Strats and Les Pauls

Yazoo55

Many thanks for posting this!

Yazoo55

I have been working on this, recreating the Ampulator in Kicad. I've still got a bit of work to do but I would appreciate some advice.

There is a section of the power supply which splits off to go to a line labelled "MUTE". This goes to the base of three FET transistors connected to the signal out and XLR out outputs. My main query is the reference to "GND2" in the power section for this line. It isn't used anywhere else in the schematics. Should this GND2 be linked to the main GND line?

If you have the patience, what is the function of the transistors? I'm guessing when voltage is applied to the base of the transistors, the output signal is shunted to ground, muted. I don't understand how this is switched on/off though.

This is the power section:

MarshallJMP

Well it should be grounded since it's a Delon voltage doubler. Maybe they mean the "yel" connection on the transformer.(which is also grounded)
When powered on the output voltage of the mute line is slightly positive and goes in a little more then 2 seconds to around -24V.Since the FET's are N types they have a low resistance when the voltage is near zero (50 ohm for 2SK364)  on the gate and go to higher resistance (cut off) when the gate voltage goes negative.

Which transistors do you mean?

Yazoo55

Thanks for posting this. The transistors are the 2SK364s used to mute the outputs.

I tried reproducing this section of the circuit which sends the power to the transistors using a spare bipolar supply. I connected GND2 to the existing ground, as you said, the yellow centre-tapped wire from the transformer. This all worked fine.

I've gone ahead and built the Ampulator. I used Kicad and got the boards manufactured by a Chinese fabricator to keep the cost down. I made a couple of mistakes on the power board and ended up having to solder on a couple of jumper wires and very carefully enlarging the holes for the power connectors, but it is all up and running now. I've posted a picture of it minus the lid.


MarshallJMP

Very nice !!

May I ask where you got those large push switches?

Yazoo55

Thanks!

I got lucky with the 8PDT switches and found them on eBay. The supplier is called acwsoft and they are listed as "Pushbutton Switch Schalter for Marantz 8PDT switch 8xUM Druckschalter". He has other sizes as well.

MarshallJMP

Ok found him, thanks ! :thumb-up:

Yazoo55

There was just one thing I was never sure about when I built the Ampulator. In the schematics the chassis ground symbol appears twice, the symbol which looks like the bottom of a rake. It appears on the power supply schematic and connects to R316 and C310 which are connected in parallel to the yellow centre-tap transformer wire. The only other time the chassis ground symbol is used is for the large cable which connects the two boards carrying the audio signal from U200 to end up at the balanced and unbalanced outputs. I think this is to shield the signal using the third ground core in the cable, connected at only one end of the cable in K204.

What I could not work out though was whether the chassis ground is actually connected to the metal chassis of the box itself. I went through the documentation several times and couldn't find anything. I did connect the bus wire to the tops of the potentiometers and wired this to the main chassis/box, but the signal ground does not seem to be connected anywhere to the main chassis/box.

Have I missed something here?

MarshallJMP

maybe best to put a 10 ohm resistor between the ground and the chassis.

bcklndt

Is the *ampulator* really worth the high price on the second hand market?
I like the concept and ease for recording .. way over miking or virtual in the box stuff.
I now have a GCS-2 .. I guess the *ampulator* would be way better??

rnolan

Hard to say without comparing the 2.  The GCS-2 is where the ampulator kind of went  :dunno: although I suspect the GCS-6 is more equivalent as it's stereo which would suit your MP1 (or 2 x GCS-2s), you obviously don't need anything for you MB1, just go direct with it.
Studio Rig: Stuff; Live Rig: More Stuff; Guitars: A few

MarshallJMP

The ampulator is a power amp sim and also a speaker sim.

Damn-Danny

Got  an Ada ampulator, which 12 ax 7 can I best use for it.
Also got an ADA GCS-6
and a Mooer Radar.
Maybe i'mselling my ampulator, catching dust at the moment.
Ormsby Hyper GTR 6 string
Ormsby RC One   6 Orange Marbles
SKG    Anubis (halve step down)
Bo-el   MC 6
Robin guitar  Raider USA (D Standard)
ADA 3TM mp1
ADA Ampulator
ADA GCS 6
Ada mp2 
Yerasov Detonator - P
Yamaha SPX 900
Marshall 8008 Valvestate
Peavey  6505MH
Rane mpe 28
EVH 5150II Lbx 
Pro Tone Gary Holt signature boost
Pro Tone Jeff Loomis signature OD
Boss OD2
TC Electronic Sentry noise gate
Bugera 333XL infinium (died on me)
Harley Benton vertical 2x12 V30