Geezer's Gulch

[jojokeo]

Geezer - I came across this monument in a local park and couldn't go by it w/out getting a picture of it for you buddy. It's a little recognition & thanks for all the info you've shared & helped us all with. Tubenit & Sluckey, hopefully I'll find one with your names on one some day too? 

[jojokeo]

I am remiss to leave out PRR & HBP as well...

[Geezer]

SUWEEEEET! 

I've been taking a bit of a break lately, but have a SF MV Twin Reverb conversion to Dumblish UltraPhonix type thing in the works.

Thanks for the pic & the shout-out!

G

[moonbird]

SF MV Twin Reverb conversion to Dumblish UltraPhonix type thing ...

Geez - I happen to have a similar chassis that is waiting for re-birth. Hope you will share what you find!! thx.

[Geezer]

I will start a thread with results when it happens.

A friend closed down his guitar oriented music shop after 40 years in business, and he gave me a bunch of stuff he had accumulated in the back room, including 2x Silver Face Twins with MV....one is an older 100w (74 maybe) and a "newer" 135w UL (78 I think).
I stole parts off the 135w to get the 100w up and running. I'm in the process of getting it sounding right in stock form, then will start the modding once I'm sure I have a good foundation to build on.

To start your research, take a look at this thread over a The Amp Garage. (Link below)

http://ampgarage.com/forum/viewtopic.php?t=20345

Smitty has shared a design he uses to mod these into a Dumble type format. That is what I'm using as a guideline.
My normal channel will be stock, and the vibro channel (vibe components removed) will be the dedicated Dumble OD channel....using an A/B box to switch between the two. This is reverse from the way Smitty describes, but I like the idea of having all the OD controls in the same section of the front panel.
Speed and intensity will become OD drive and level controls
Reverb on the normal channel only
Effects loop so I can run my Dumbleator there

G

[jojokeo]

SUWEEEEET! 

I've been taking a bit of a break lately, but have a SF MV Twin Reverb conversion to Dumblish UltraPhonix type thing in the works.

Thanks for the pic & the shout-out!

G

Geezer - I originally built a Little Wing amp back in the day, then changed it to a 5879. Maybe it was a 56T or something? Those changed names seemingly so much it's hard to remember exactly what we were doing? In the years since it mostly sat around getting play here and there but was mostly a one trick pony w/ not a whole lot of headroom or output power. I thought, "well, it is what it is." That is until I worked on it the other day after seeing how the screen resistors had overheated to the point where you couldn't even tell what values they were. The colors were white and the spaghetti tubing had also turned crispy over the leads. This happy accident got me thinking about why, how, & what happened. Turns out I was overly concerned about exceeding the screens' max ratings that I used too high a value and they were choking the amp down w/out realizing it. Replacing these and a few other things besides re-doing the grounding theme has turned this amp into a total versatile little tone machine. The 5879 in pentode mode sounds lush, full, and harmonically rich - as it should - with headroom and in triode mode stays clean w/ punchy headroom at volume like a small BF Twin. It's like I have a whole new amp now. I still have the Smooth Hot Potato and Spanky Blues tunes you had recorded and it actually sounds very damn close if not dead on. I love those two tunes and they sold me on building the amp & giving me the inspiration needed. Did you or Larry record those I forget? Anyways, thanks again for everything!

[tubenit]

Replacing these and a few other things besides re-doing the grounding theme has turned this amp into a total versatile little tone machine. The 5879 in pentode mode sounds lush, full, and harmonically rich - as it should - with headroom and in triode mode stays clean w/ punchy headroom at volume like a small BF Twin. It's like I have a whole new amp now

That is waaayyyyy cool to hear!!  Congrats with that!   

I feel like I've kinda rediscovered Geezer's HoSo56 also with the recent 56T PLUS build I've done.  It's a very very fun amp to play.

I am very much looking forward to hearing Geezer's Twin to UltraPhoenix thing going on. 

with respect, Tubenit

[jojokeo]

Thanks T! Ya know, we never stop learning...or at least I hope!? That's the goal anyway. And with my own one-off builds I don't sell my first ones. I used the Little Wing/56T as guide line but they're close enough in general terms that they are like cousins or brothers & sisters even. Not that I sell them all at some point after building or anything as they're like musical children in a way. And it's not the first time I've gone "back in" to a past design and tweaked and re-worked things. I KNOW you know what I mean! You are a master of tweakage in my book (that's a compliment). It's in going back into the past that really helps at times with a much better understanding of the present which in turn helps provide positive progress into future directions. My later builds have had much less of that need but you never know quite when or what new things learned can help or be validated on as with past projects? Carpe Diem!

[moonbird]

To start your research, take a look at this thread over a The Amp Garage.

Geez -

Thanks much for the link -- lots to absorb. I will be looking for your build report.

[Geezer]

His instructions aren't the most concise, but there's enough there to understand the basic idea. Look at the other available Dumble info for more direction.

I've got mine running using just parts I had on hand....Sounds good enough to go ahead and invest in some "mojo" parts.
I'm even still running the original 40 year old filter caps. That will be a big improvement right there when those get replaced with fresh ones!

here's a test clip (iPhone) of the amp with no tweaks, just a mishMash of assorted parts I had on hand (although I did use the correct RN65 Dale plate resistors)
50w mode (2 tubes pulled) with Dumblator in the loop, into 8Ω 12" closed back, ES339 guitar

http://soundcloud.com/dageezer/twin-ultraphonix-test-1

I'll start a new thread  as soon as I can.

[SILVERGUN]

Great stuff there Geezer!.....thanks for taking the time to put that demo up....very well done 

I have something similar laid out on the breadboard right now, but haven't had the time to get back to it,,,,but, this has me thinking.....again 
I've got the AB763, single chan, reverb, no trem, with 2 added gain stages (Dum topology),,,,,and couldn't get the Master past 2 without it howling and wanting to "take off" 
I sat playing it like that for a while, and was just waiting for some parts and the time to get back to it......so I'm really looking forward to your new thread

It's just sitting there waiting for me to get some help........and Smitty's schematic looks like a good reference

Thanks for getting him talking jojo! 

[Geezer]

Thanks for getting him talking jojo!  

Ha ha!  I've been quite busy lately and was intending to do this as a long term winter project, but got inspired to go for it.
Plus, it was so darn easy to do! If anyone has any experience at all inside an amp, this is do-able.

My intent is to give the details and know-how to do this, hopefully giving folks a chance to build a real pro-quality sounding amp without having to break the bank. They should be able to watch Craigslist or other local sale spots and pick up one of these SF MV amps at a bargain price, then be free to mod away!

Maybe I'll call it the "Geezer's Gulch" project 

BTW, the amp looks totally stock from the front (have the OD trimmer, NFB switch and effects loop on the back panel) so it's a real "stealth" rocker!

G