Author Topic: The COOLEST amp EVER....... (Read 13270 times)

TIMBO · « **on:** October 27, 2018, 05:28:21 pm »

Hi guys, I'm amazed by the heart and soul that goes into the design of not only the endless number circuits that tantalize our ears, but the great creation that house then.

This post is just some of your collective thoughts on amps that have crossed your path that have had the WOW effect from cab design, circuit design and layout, and of course just freekin COOL.
http://www.paulsguitarboutique.com/amplifiers/montgomery-wards-airline-gim-9171a
https://reverb.com/nz/item/8356394-airline-montgomery-ward-gim-9171a-silvertone-1485-killer-1970
I think this is just IT.

shooter · « **Reply #1 on:** October 27, 2018, 06:35:12 pm »

Quote

have crossed your path that have had the WOW

There are a few builders here that rate WOW factor, build quality, schematic, layout, Docs!!
Finding that "gem" combination from circuits of old........ the world may have moved on, but it's taking the past with it

tubenit · « **Reply #2 on:** October 28, 2018, 10:52:00 am »

YouTube of the Montgomery Ward amp

TIMBO · « **Reply #3 on:** November 05, 2018, 03:42:11 am »

Thanks guys, Some drilling and filing.............

The circuit is GIM-9151a with one tube reverb and the trem from 9131a circuit.

TIMBO · « **Reply #4 on:** November 22, 2018, 03:54:30 am »

Hi guys, Some slow progress....

TIMBO · « **Reply #5 on:** November 25, 2018, 03:49:21 am »

Stage 1 almost done.

sluckey · « **Reply #6 on:** November 25, 2018, 03:59:04 am »

That's pretty!

DummyLoad · « **Reply #7 on:** November 25, 2018, 06:24:46 pm »

very nice!

--pete

TIMBO · « **Reply #8 on:** November 26, 2018, 12:14:43 am »

Thanks guys, The front control panel is back from the powdercoaters.

This should be fun!

TIMBO · « **Reply #9 on:** November 30, 2018, 04:20:27 pm »

Hi guys, Some progress pics.

TIMBO · « **Reply #10 on:** December 05, 2018, 03:59:07 am »

Thanks guys, Injected life and alls good.

A couple of minor changes.

Voltages are a bit low but I had the transformer on hand.
Sounds cool.
The stock channel is super clean.
The slightly modified channel has a nice bit of SUPRO growl about it.
Reverb is lush and strong.

Just a couple of problems...
Trem doesn't work :scratch.
I did change the speed pot to 1M as I did not have a 2M but I would not think that it would make much difference. Foot switch is "on"
The treble pot is wired in reverse ( I had a 50/50 chance of getting that right)
The stock channel is accessible to change but the other is not, so this will be a builders anomaly.

Sadly my lighting feature is a bit DULL.
The 6.3v bulbs are not bright enough to shed enough light through blue Perspex.
I rewired the supply to the lighting bulbs to DC but I'm only getting 6.7v with the bulbs in.
I have some LED bulbs that fit the bayonet type holder being delivered. These draw a lot less current so the volts may jump up a bit although they are 12v bulbs.
Maybe the DC supply can be wired with a voltage doubler rectifier???

bnwitt · « **Reply #11 on:** December 05, 2018, 09:22:02 am »

Timbo,
Nice project buddy. I can see the .0047uf and the .033uf capacitors in the trem circuit but the blue cap is face down and can't be read. That's a 0.01uf right. Have you checked voltages on the trem tube?

Barry

Ed_Chambley · « **Reply #12 on:** December 05, 2018, 09:29:05 am »

Very nice work Timbo.

dude · « **Reply #13 on:** December 05, 2018, 02:55:54 pm »

And who needs a board

TIMBO · « **Reply #14 on:** December 07, 2018, 04:31:57 am »

Thanks guys.

Barry
I went over the trem circuit and some DOPE put the wrong cap values in.
I now have some trem.
It's a bit weak and I noticed that I have a 270k plate resistor in V1b. The trem circuit was taken from the 9131A schematic that has a 100k plate resistor, so I'll give that a go.
I'll also try using the "A" node supply the increase the volts on the oscillator.

TIMBO · « **Reply #15 on:** December 09, 2018, 03:54:18 am »

Hi guys, Cab is ready for tolex.

Hmmmmmm, I think I'll do it in black.

shooter · « **Reply #16 on:** December 09, 2018, 10:45:24 am »

Nice work!

You could do a "many coat" lacquer alternating translucent black with translucent mahogany, 5 - 6 coats then a hard clear, some ghost flames and you'll blind everyone

TIMBO · « **Reply #17 on:** December 16, 2018, 04:17:24 am »

Thanks mate, Cab complete.

John · « **Reply #18 on:** December 16, 2018, 05:11:44 am »

Prettay, prettay cool!!

Tone Junkie · « **Reply #19 on:** December 17, 2018, 03:14:11 am »

looks sweet my friend. you always seem to find the gems from the past.
Bill

TIMBO · « **Reply #20 on:** December 17, 2018, 04:24:05 am »

Thanks John.

Hey Bill, Great to hear from you.

sluckey · « **Reply #21 on:** December 17, 2018, 08:24:15 am »

Timbo, you continue to entertain me. You always seem to have some unique projects going on and you always do a great job on the electronics and cabs. I'm sure your projects are an inspiration to a lot of folks. Don't ever stop!

TIMBO · « **Reply #22 on:** December 18, 2018, 12:36:14 am »

Thanks sluckey, Still got a few up my sleeve.

TIMBO · « **Reply #23 on:** December 20, 2018, 03:41:25 am »

Hi guys.

Chassis in....

Dashlights on....

In the dark.

Now to find some knobs

cboysen · « **Reply #24 on:** December 20, 2018, 03:51:35 am »

Ohh.. that .. is .. slick! Well done! :)

Ed_Chambley · « **Reply #25 on:** December 20, 2018, 09:26:46 am »

WOW!

I never really liked the cheap builds of theses amps. If they would have you design them I would probably own one. You really do great work Timbo. This ons is fun, can wait to see the completed version, knobs and all.

davidwpack · « **Reply #26 on:** December 20, 2018, 02:52:42 pm »

I bought some clear/translucent knobs for some pedals I've built. Your amp would look awesome with those I think.

tubeswell · « **Reply #27 on:** December 21, 2018, 08:46:12 am »

Dat is super wicked!

Awesome.

TIMBO · « **Reply #28 on:** December 21, 2018, 02:08:15 pm »

Thanks guys, The 1x15" cab is now under construction.

TIMBO · « **Reply #29 on:** January 01, 2019, 03:01:37 am »

1X15" cab almost complete.

TIMBO · « **Reply #30 on:** January 05, 2019, 03:24:50 am »

Cabs just about done.

TIMBO · « **Reply #31 on:** January 05, 2019, 05:55:37 pm »

Almost there......

Glenn · « **Reply #32 on:** January 06, 2019, 08:24:59 am »

Wow that is nice and it�s just
like your title says

DummyLoad · « **Reply #33 on:** January 06, 2019, 09:10:19 am »

beautiful! looking forward to some recordings.

--pete

TIMBO · « **Reply #34 on:** January 13, 2019, 04:03:25 am »

Thanks guys, A mate put it to the test and sadly it fell a little short in the volume department.

At 300v on the 6L6 plates and 200 ohm resistor cathode, I've got bias at approx. 23w/tube.
If I decrease the cathode resistor i'll get the watts up but the plate voltage goes down.

Is there a way to increase the watts output with out a different PT??

bmccowan · « **Reply #35 on:** January 13, 2019, 07:27:56 am »

Wow, that is such a gorgeous job! You need to get it sounding right, eh? With people on the forum much more expert than me, I hesitate to offer anything, but will anyway.
Those voltages are down in 6V6 territory, eh? And at those voltages, it seems the bias is way too cool. Should be more like 50ma at 300?
If it were me, I'd see what I was getting out of the PT unloaded. And I would try disabling the trem and reverb circuits and see where the voltages end up.
Again, what beautiful work. Even if I had the skill, I would not have the patience.

shooter · « **Reply #36 on:** January 13, 2019, 07:35:04 am »

before ya start swappin, bust out the scope and make sure you're getting at least 18Vac rms drive to the PA tube grids.

PA B+ somewhere close to 350-400 should get them earning their pay

John · « **Reply #37 on:** January 13, 2019, 07:57:12 am »

Beautiful work as always!

For more watts without swapping PT, I'd first try lowering value on the screen Rs to the power tubes. And even if lowering the K values lowers your plates, if it increases current that should squeeze a little more out too.

Bmc has a good idea, pull the tubes to the other channels, and see what your B+ is with just one channel "plugged in", so to speak. If it goes up a fair amount, it might be as simple as adding a separate filament tranny to take the load off the main one?

But, with your skillz popping in another PT is a breeze

Except for the money, of course!

Slimtim · « **Reply #38 on:** January 13, 2019, 09:57:28 am »

DAMN that looks nice.Great work.

PRR · « **Reply #39 on:** January 13, 2019, 04:13:31 pm »

> A mate put it to the test and sadly it fell a little short in the volume department.

Get a different mate. Someone who knows how to use a 22 Watt amplifier.

Getting to 350V supply would be near 30 Watts output, about as much as possible on cathode-biased 6L6. 22W to 30W is not a "wow" difference.

That OT is intended for 400V fixed-bias (think 5F6a) and 40+ Watts, which is not only a different PT, it needs a different driver. (Have to change the paraphase to get happy bias on both driver and power tubes.)

TIMBO · « **Reply #40 on:** July 20, 2021, 04:19:13 am »

Hi guys, This one is done...

RadioComm · « **Reply #41 on:** July 23, 2021, 08:57:25 am »

Undeniably the coolest amp ever! Excellent job!

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Author Topic: The COOLEST amp EVER....... (Read 13270 times)