found a chassis in my storage place :D

[norburybrook]

hmm a few cracking intermittent issues to sort out today....the OT secondaries are crackling when chopsticked.....is that normal?


Edit: its quite bad now, loud enough to maybe damage the speaker pressing on the OT Ht and secondaries (4-8-16) wires is where the noise is coming from. The connections at the switch are fine though and individually they're silent when chop sticked, pressing on the twisted together wires makes the noise come and go. Its not volume dependant so I presume nothing to do with the pre amp stages.

this is a new one on me. It was on all day on fire up day no problem.

Anyone?

M

[martin manning]

:Edit, its definitely working OK , I'm hearing the bottom end drop and level change today. perhaps my ears were tired the other day.

That sounds right, and the net effect will depend on the pot settings. You can do a simple resistance check from the bottom of the treble to the top of the bass, and from the top of the bass to its wiper. You should see zero ohms for both in normal, and something much bigger (depending on settings) in PAB.

Pull V1 and V2 when you measure, and turn preamp volume all the way down.

[norburybrook]

hmm a few cracking intermittent issues to sort out today....the OT secondaries are crackling when chopsticked.....is that normal?


Edit: its quite bad now, loud enough to maybe damage the speaker pressing on the OT Ht and secondaries (4-8-16) wires is where the noise is coming from. The connections at the switch are fine though and individually they're silent when chop sticked, pressing on the twisted together wires makes the noise come and go. Its not volume dependant so I presume nothing to do with the pre amp stages.

this is a new one on me. It was on all day on fire up day no problem.

Anyone?

M

Sorted....

it turned out to be plate wire from the PI that was running underneath the OT wires so prodding them was causing the hidden wire to crackle. Re-flowed the joint at the plate resistor and shortened the wire and its lovely and quiet again.



I threw my NUX verb/delay pedal in the loop today. Works great as it has a +4 setting so will take line level/hot signals if i so wish. Interesting that the NUX is exactly the same size/layout as my Strymon flint.

Also with something in the loop i can hear the effect of the bright cap. I might actually remove the bright cap from the loop and put a separate bright cap on the clean master, that will make sure the OD never gets to bright which it could with the loop.

More tweaking

It's funny, I plugged my second gen amp in to A/B against the hybrid new build and not having used it for a while as I've been using my Princeton and Tweedle dee, I thought it sounded awful!! LOL Bizzare...your ears/mind change depending where you 're at . Ive got 2 demos using that amp that sound fantastic, yet today it sounds horrible! go figure, probably the guitar I'm using it with, these amps are incredibly picky and temperamental with guitar choice i find.

I think I'm going to end up with a one pickup telecaster and or a Les paul Junior and ONE AMPLIFIER......


M



M

[talbany]

Marus
Glad everything fired up ok
Let's do a real test With the loop jumped out with a patch cord only the master all the way up send set at noon and the return set at noon. At those noise levels could you play a show or would everyone be looking over at you?
Also at those settings is it at all buzzy or do you just hear just a little hiss in the background?
Curious as to what you found!

Tony,

Just done this test, it's fine noise wise,I'm testing in a quiet studio and there's some hiss like you'd expect on stage no one would notice.


M

Marcus
AWESOME!.
BTW. Your 2nd gen stack works like mine does along with an original 2nd generation Dumble amplifier.
Mine is wired correctly

Tony

[10thTx]

I think I'm going to end up with a one pickup telecaster and or a Les paul Junior and ONE AMPLIFIER......

That's funny!

[martin manning]

The key to understanding the apparent difference in PAB effect between the Skyliner and 2nd Gen stacks is recognizing that the boost you get depends on the TMB pot settings that you start from. Both stacks have similar EQ characteristics in PAB, regardless of where the TMB pots are set, and the 2nd Gen PAB can be either more or less than the Skyliner, depending on the pot settings. If the PAB effect for the 2nd Gen is generally perceived to be less, that means that the preferred 2nd Gen settings in normal mode are making it so.

[norburybrook]

need to wait until next thursday before I can get my speaker in the Cab and see how that is so perhaps Erwin's board may be here by then and I can see if my 9v experiment to the footswitch works. That 'could' add grounding issues I think. I got the idea From Clifff Brown at 633 engineering here in the UK he does that with his amps.

I'm curious as to how this turns out too.

So there is precident for this system you are trying? Got any links describing the Cliff Brown system?

Spoke to Cliff and he said

) I would suggest you use a ground free floating power supply for your pedals.

He wouldn't expand on that

When I did my last one with the 9v on the amp, the pedal was in front of the amp so it was wired ground free and the ground came from the jack/guitar. This is on a loop so it would ground with the loop jack ground, no?


M

[martin manning]

Spoke to Cliff and he said

) I would suggest you use a ground free floating power supply for your pedals.

He wouldn't expand on that

When I did my last one with the 9v on the amp, the pedal was in front of the amp so it was wired ground free and the ground came from the jack/guitar. This is on a loop so it would ground with the loop jack ground, no?

A floating supply could be done with an isolated DC-DC converter inside the foot switch enclosure. That would require a small board with a converter module and a half-dozen other parts.

Since the pedal signal ground is common with its power supply ground, wherever the power supply is grounded becomes another signal ground in the loop. I would try it as it is, and see what happens. If it's noisy, then you can try the DC-DC converter approach, which is pretty simple and cheap. I would consider replacing the 9V regulator and send 12V to the foot switch for that.

[norburybrook]

Spoke to Cliff and he said

) I would suggest you use a ground free floating power supply for your pedals.

He wouldn't expand on that

When I did my last one with the 9v on the amp, the pedal was in front of the amp so it was wired ground free and the ground came from the jack/guitar. This is on a loop so it would ground with the loop jack ground, no?

A floating supply could be done with an isolated DC-DC converter inside the foot switch enclosure. That would require a small board with a converter module and a half-dozen other parts.

Since the pedal signal ground is common with its power supply ground, wherever the power supply is grounded becomes another signal ground in the loop. I would try it as it is, and see what happens. If it's noisy, then you can try the DC-DC converter approach, which is pretty simple and cheap. I would consider replacing the 9V regulator and send 12V to the foot switch for that.

thanks Martin. Waiting for Erwins board so I can actually get 9v to the pedal Hopefully another week unless I make a quick eyelet board today I'm hoping with just one modern/digital pedal there won't be any ground loop. I'm an optimist though

M

[norburybrook]

well, my girlfriend is away this weekend so after my last post I went to the studio and threw together a voltage doubler while Erwins PCB is being made so I could test this all out.

Got a nice healthy 14v coming out but a terrible hum when I fired up. Unplugged the footswitch..same....So I disconnected the 9v regulator. Totally quiet again. I then reconnected just the input, again quiet with a steady 9v showing on the output, so I connected the output...hum. I had a think and then looked at the routing of the 9v send to the footwitch jack on the amp. It was running around the edge behind the main rectifier board, so I thought ' I wonder if it's the routing?' so I pulled the wire and flew it from the back of the chassis back the regulator. This time success...Silent. So I plugged the footswitch in again...silent.....then the pedal and connecting leads....Silent a success. very pleased

IMG_20191116_155133.jpg

IMG_20191116_155230.jpg

just need to route the wire permanently now away from the recifier board and tidy up



M

[martin manning]

Nice! So what you have now is like this? And, quick work on the doubler board ;^)

[norburybrook]

Nice! So what you have now is like this? And, quick work on the doubler board ;^)

exactly Martin.

Just wired everything i permanently. There's a slight increase in noise now when the pedal is in, you only notice if you unplug it. I wonder if i used a shielded cable and grounded the shield with the regulator if that would be even better? splitting hairs now, but why not. I've also put the Russian military NOS 2000pf cap in the treble..I think it sounds better than the orange drop 6ps it looks cool anyway so its staying.

IMG_20191116_173526.jpg

Voltage doubler board was simple its only a few eyelets and a bit of under board wiring the hard bit was getting it in, it wouldn't fit against the side panels because the capacitors and the captive nuts so i had to use long standoffs and move it out...bit of a head scratching moment

[martin manning]

What happens if you power the pedal from a 9V adapter? Is it quiet then?

[norburybrook]

What happens if you power the pedal from a 9V adapter? Is it quiet then?

Maybe a tiny bit quieter, not much in it really.

that takes care of that then


can you tell me what order the gain controls are?

We have input volume...then a loop send volume and loop return volume and a master volume. there's so many possibilities to add gain in this chain I'm not 100% sure what's driving what.

I don't have a bypass switch so don't have a ball park level setting.


M

[martin manning]

...can you tell me what order the gain controls are?

We have input volume...then a loop send volume and loop return volume and a master volume. there's so many possibilities to add gain in this chain I'm not 100% sure what's driving what.

I don't have a bypass switch so don't have a ball park level setting.

The Clean and OD masters determine the input level to the send buffer, and they are independent. You can set those low or high depending upon how hard you want to drive the CF, and differentially to balance clean and OD. Assuming 10% taper master pots, I'd start with both around noon, and lower one of them to balance the Clean and OD.
Then you have loop send level, which should be set for the desired signal level out to the FX. The CF buffer's gain is always near unity, so the FX send level will also vary with the MV settings.
The FX return level wiper goes straight into the PI, so it is a pre-PI MV, same as the front panel global master on an ODS.