UP dumble for sale

[Aaron]

Looks like green and orange... 2k2?

Doh! 2&7 not 3&8.

[Bombacaototal]

Looks like green and orange... 2k2?

Doh! 2&7 not 3&8.

Is this still the Hotel Hog?

So there is both a 2.2k between 3&8 and a 15k between 2&7 at V3?
Thiis along with the 3.3M with .1uF between 1&2?

[dorrisant]

Yes... HH.

Nothing between 3 & 8... No 2k2 at all. That was a mis-identification.

3 & 8 are tied together... Wired to the board from pin 8.

15k at the socket, from the board to pin 7 with 7 & 2 tied together.

[Bombacaototal]

Yes... HH.

Nothing between 3 & 8... No 2k2 at all. That was a mis-identification.

3 & 8 are tied together... Wired to the board from pin 8.

15k at the socket, from the board to pin 7 with 7 & 2 tied together.

Awesome! Thanks a lot

[Bombacaototal]

[deleted]

[Bombacaototal]

I think the reverb tends to be somewhat insensitive to the biasing.

The Hotel Hog uses (V3) 2.2K with 22uF; (V4A) 2.7k with 22uF; (V4B) 1.5K with 22uF

I am wondering if anyone has ever tried biasing the reverb more like a Overdrive Reverb Special with: (V3) 2.2K with 10uF; (V4A) 1.5K with 4.7uF; (V4B) 1.5K with 4.7uF? And what impact would that do to the overal sound?

EDIT: For future reference answers here:
http://www.diystompboxes.com/pedals/tubedummy.html

Interesting discussion here:
http://ampgarage.com/forum/viewtopic.ph ... light=lnfb

[Bombacaototal]

Just one doubt: the 470k after the reverb pot acts as an attenuator resistor for the reverb (wet signal) and the 2.2M does the same for the dry signal. Does the 47k to ground affects only the dry signal or both dry wet?

Edit: For future reference answers here https://robrobinette.com/How_The_AB763_ ... _Works.htm

http://ampgarage.com/forum/viewtopic.ph ... le+cabinet

[Bombacaototal]

As I work my Dry/Wet mix values I found this info very interesting and thought about sharing

https://www.harpamps.com/micKfender/Fen ... b-mix.html

In most (if not all) Fender amps w/ reverb there is a multiple
stage voltage divider which controls the dry gain of the reverb
channel and the amount of reverb in the mix. This VD
consists of the 3.3M/10pF pair and the 470k/220k pair
connected to the center tap of the reverb mix control and
the grid of the reverb recovery triode.


Lets look at the reverb level first. The ratio


220k/(220k + 470k)


controls the max amount of reverb available. Changing the
ratio of these two resistors will control the max amount of
reverb in the mix.


George mentioned wanting to mod his reverb circuit
such that on “10” it equalled the stock control on “3”.
Since the reverb mix control is linear, “3” corresponds
to 30% of “10” which indicates that his resistor ratio
above (220k/690k) = .32 should be reduced to .32*.3 = .095.


Second is the gain of the reverb channel. Here the 3.3M/10pF
pair and the *parallel* combination of the 220k/470k pair
form a voltage divider which controls the gain of the
dry reverb channel signal. The parallel combination of
the 220k/470k pair is approx 150k ( the pot resistance
is neg.) Ignoring the effect of the 10pF cap yields:


150k/(3.3M + 150k) = .043 = 1/23.


So the reverb dry signal is being attenuated by a factor
of 23. That is why the reverb channel has only slightly
more gain than the Normal.


Bottom line:


* Decrease the ratio of the reverb signal VD from
.32 to .095


* Maintain the parallel resistance of 150k from
these two resistors.


Bottom bottom line:


* Replace the 470k resistor connected to the
center tap of the reverb control with 1.5M.


* Replace the 220k resistor with 180k.


Then:
Reverb divider ratio = 180k/(180 + 1500)k = .11


Parallel combination = 1/( 1/180k + 1/1500k) = 160k


Which is plently close for what we are doing here.


John Mastrangelo
Osprey Amplification

[Bombacaototal]

I was calculating the high pass frequency cut off point for the high pass filter used by dumble in many of his builts including the HH (220k with 500pF) = 1'275 Hz

Reference:
http://www.electronics-tutorials.ws/fil ... ter_3.html

It seems to impact a large part of the guitar frequency range which I found interesting.

Most of you may already know but I didn't, so ai leave it here as future reference

[Bombacaototal]

There are two ways to tamme the reverb (i) the LNFB on V3; (ii) the reverb attenuator resistor after the reverb knob

I like my reverb between a 1 and 3 of a stock Blackface

I am thinking it is better to tamme it at source (ie V3). Are there any downsides in going down on the LNFB all the way to 1M and then reducing the attenuator resistor from 470k to 220k for example.

The 68 custom fender does the other way around with 1.5M for the attenuator

[Bombacaototal]

Another consideration I was thinking of. Are you using the same voltage dropping resistor for both tonestacks? I was thinking that it might be good to slit them given they are so different and them adjusting each stack viltage individually? Has anyone tried anything similar?