New build finished. Spring 2018. I haven't been here in a while.

[nandrewjackson]

Hello    I haven't been active on here in a few years. Life gets in the way. First off, an apology to anyone here who is also on Facebook tube amp group. I lost my marbles and mouthed off over there recently, sorry. We just lost my dad, stage 4 cancer, 3 months of mixed blessings. We spent a lot of good time together while that monster chewed him up from the inside.


I just wanted to share this build here. It's a "mutt". Similar to Mesa rectifier and SLO 100 with a few twists. Weber 100 watt PT (discontinued now). Weber twin reverb OT with single 4 ohm output. SS rectifier.


Thanks goes to Lyle from the Facebook group, who led me the right way on the transistor switches, and coincidentally was the recipient of my idiotic ranting and raving, apologies. I ended up using "LCR 0203" LDR'S for the switching. They go from 300 ohms to about 4 Meg ohms. On/off.


I used local NFB in the 2nd stage of the clean channel to make it more clean.
I'm going to add zeners and a high/low power switch for funsies, waiting on parts in the mail.
Most components are cheap Chinese eBay purchases.
It sounds really good. It turned out better than I thought it would.
The FX Return level pot is in there, but it really doesn't help, or hurt the circuit, I haven't needed to turn it down yet, maybe there'll be a reason for it sometime. The FX send pot needs to be at about 1 o clock for stompboxes in the loop.

[nandrewjackson]

Here's the LDR transistor switching network

[nandrewjackson]

Picture links Google drive


https://drive.google.com/file/d/1i7BlV8Lc1ngv1Uzs2BGyvYRKgjMd2QtL/view?usp=drivesdk

[nandrewjackson]

Picture links Google drive


https://drive.google.com/file/d/1wCt2IUy4IXsPcZMSMY5qywdCE5x7o59V/view?usp=drivesdk


https://drive.google.com/file/d/1al9qu42_SCANVmsUCszJeLAV95W3nfbW/view?usp=drivesdk


https://drive.google.com/file/d/1FfWqO1g-7gBna1_W7lVOOs2Ja3JfvTqk/view?usp=drivesdk


https://drive.google.com/file/d/1EoryW7xuf9kp96ju8tXs0i7JRrQnQ-ml/view?usp=drivesdk

[nandrewjackson]

To clarify: when channels are switched, you get a preamp gain and a master volume for each seperate channel. The two different EQs can be switched independent of which channel its set on.

[nandrewjackson]

Chassis is from eBay username "synapticamps". Very good quality, custom size, quick delivery.

[purpletele]

Chassis is from eBay username "synapticamps". Very good quality, custom size, quick delivery.

That is very cool.  I'm seeing that style more and more, it looks like Chinese writing at first glance.

Synaptic Amplification has been building chassis for me lately and does a great job.

[nandrewjackson]

two small changes.


Effects return switching jack is now coming off of a different spot so as to bypass the send pot and send jack entirely when not in use.  As recommended by 2deaf.




V1B grid resistor removed, 600K added above clean channel volume pot.  I really don't like how the clean channel starts to get dirty from 10 O'clock and up on the pot.  I'd rather have a true clean channel.......   I may remove V1B entirely, instead of trying to clean it up.

[TIMBO]

Hey man, That's some awesome switching you've got going there.
I have built this http://el34world.com/Forum/index.php?topic=23179.0 and I have absolutely no idea on how I can do a switching matrix for it.
The only way I have thought of doing it is a bunch of relays and a pedal board with several switches.

[nandrewjackson]

Timbo;


The "LCR 0203" light dependent resistor /LED combo-in-one-package is working real good. When on, the resistor side has ~400 ohms and when off it has >3 Meg ohm.  So it's plain to see it's potential.


The switching matrix I built "works" however there is a voltage leaking that I attempted to correct by lowering the supply from 5VDC to about 4.7 VDC. Like I said, it works with my voltage change band-aid, but for how long.


Lyle from the Facebook tube amp group pointed me towards the transistor switches and that's the circuit I ended up with after research (Google) 


Forum member PRR drew up an improved version for me, using basically the same components. I have yet to build it, but will do so soon.


The LDRs can be put right next to the other components in the build, and the tiny DC supply lines that go to the LED side of the component Havent induced any noise into my circuit, and it looks like a bowl of spaghetti!  I've built the high gain side of the preamp before, several times, and some were noise machines, this one is NOT a noise machine.


On one build I used relays for clean to high gain switching, it was the noisiest of all.


Theres also a little dip chip called H11F1, it's a chip with LED/transistor inside. I have a few of those but haven't worked them up yet. The circuit would basically be the same as with LCR0203s.