5B3 Variant Deluxe

[TIMBO]

Hi guys, So I have a chassis that is a great candidate for a 5E3 type build, but it's all OCTAL
The circuit that is present has a similar layout to the 5B3, so that will be the direction I'll be heading.


The chassis has 5 octal sockets and one old style 6 pin.
I don't know of a 6 pin valve that would fit the circuit, so it will be changed a an eight pin
Haven't had much to do with a grid bias preamp and from what I know there not pedal friendly??
So maybe a more conventional V1 circuit
Again having a a spare hole to fill, reverb will be added.
This circuit pinched from an Ampeg reverbrocket.
The coupling capacitors are an easy direct replacement as the values are close to the originals.
The resistors are a different story, as todays values are higher/lower than the originals.
So I am unsure what the difference to go higher/lower will make to the circuit.

[AmberB]

I would not be surprised if the original 6 pin socket was for a connecting cable to another unit, or a speaker connector originally.  I don't think it was a tube socket.

[TIMBO]

Hi guys, Injecting the reverb has been a little challenging.
The main circuit works great, but seems there is not enough signal to drive the tank.

Even increasing both grid leak resistors
V2B from 47k to 1M and V2a From 22k to 220k just get me the tiniest boing.
Next tweak

This kinda works on one channel and there is a slight increase in boing.

This works great huge amount of boing but only wet signal
I have not added the forth input jack as yet to mix the two channels
So in saying that adding the fourth jack would give me a dry signal.

This circuit popped up in one of our vintage amps here.
I have checked this circuit a few times and this is how it was built
Hmmmmm seems like a good way to get a dry and wet signal.
Could this idea be added to the reverb to get good boing and signal.

[Latole]

This is what I do

You do a very clean job , congrat

[TIMBO]

Hey mate, Thanks for the tip.
That photo was the original circuit, I have since removed that part of the circuit to rebuild it into the 5B3
this is what it looks like ATM.

[Latole]

Filter caps are safe now !

[HotBluePlates]

Hi guys, Injecting the reverb has been a little challenging.
The main circuit works great, but seems there is not enough signal to drive the tank.

6SN7 = 12AU7, near enough

I'd be looking to plug another 6SL7 into your input tube socket which behaves like a 5751, near enough.  The 5B3's 6SC7 also has a Mu of 70, it just had a shared-cathode to the 6SL7's individual cathodes.

[TIMBO]

Thanks HBP, Got a SL7 in V1 and reverb is much better





Cab built

Trying to keep the TV front look

[TIMBO]

Cab completed...

[Latole]

Very nice covering job ! Congrat

[isaac_teller]

Hello. What number reverb tank did you use?

[kagliostro]

OLD Thread but just discovered

Nice Job TIMBO, Very Nice

 

Franco

[Latole]

Hello. What number reverb tank did you use?

No answer !

No pictures all finished and mounted .
Has our friend forgotten us?

[TIMBO]

Hello. What number reverb tank did you use?

Hey mate hope it's not tooooooooo late to answer your question
I'm sure it a 4F tank

[Latole]

Hello. What number reverb tank did you use?

Hey mate hope it's not tooooooooo late to answer your question
I'm sure it a 4F tank

Revisit™ Reverb Tank, 17" long, 2 spring, equivalent to Accutronics 4AB3C1B.   Input impedance 8 ohms, output impedance 2250 ohms, long decay (2.75 - 4.0 seconds), input insulated/output grounded, designed for horizontal mounting, open side down.   Primarily used by all Fender™ amplifiers with tube reverb from 1963-1990.   

[TIMBO]

Hey guys, This one is done








There are a few minor changes to the original schematic.
I couldn't find the 16" tank I was using and it wouldn't fit anyway, so a 4D tank seems to work well

[Latole]

Very nice, congrat !

[ac427v]

Dam, that is gorgeous! What a visionary to see the potential to create that retro-look beauty

[tubenit]

That looks amazingly cool!    What a super project!  Thank you for sharing it with us.


With respect, Tubenit

[Lectroid]

Your cabinet is amazing and your Tolex-ing is immaculate.  It looks commercial-product quality, even up close.  Well done!

[tdvt]

Looks great!

I am about to build a head cab for a similar small tube-up chassis & will use a metal grill above the controls, reverb tank below.

If I haven't asked you already in another thread, what method did you use for the face plate?  It looks very nice.

[TIMBO]

Thanks guys, It was a fun build
Faceplates and made by a local trophy shop.
A mate does the graphics, so it keeps the cost down.