Sunn Clone

[DummyLoad]

Sunn Model-T clone - The early 70's model, not the Fender/Sunn abomination.

Fun amp, but MUCH too loud for me! Built by request and requestor is picking it up tomorrow.    I ended up using a 2A SB fuse for the HV fuse.

Breadboard Pics:

https://www.dropbox.com/sh/jie7hqec4dn134b/AACHdcrNStZx6o7jFvI0G2bYa?dl=0

Assembly Pics:

https://www.dropbox.com/sh/gna2k9iangqb8lz/AADE89EWb7yvjakEO5CM26Jea?dl=0

EDIT: Attached corrected schematic - Line out divider / 16ohm tap connections drawn wrong, but wired correctly.

 

[tubeswell]

Looks awesome

[sluckey]

Very nice! From computer to paper to finished amp. What a beast. I know you enjoyed this project. You should be proud.

[66Strat]

NICE!

[g-man]

Deleted

[glass54]

VERY NICE project Dummyload 
Thank you for sharing the (quality) pix of your BEAST.
Can I nominate you for "Project of the Year, 2022"? If I'm allowed 
Kind regards
Mirek

[DummyLoad]

That looks great! How many hundreds of pounds was it at final weigh in? 

Thank you all for the kind words. It was a challenge but was also a lot of fun watching it all come together. Still though, a bit excessive but a joy nonetheless. 

The chassis with the sockets, PT, OT, and choke I weighed at 59.7 Lbs. Finished it's 64.9 Lbs. In hindsight I should have affixed a handle to each end. The buyer is building the cabinet; I'll post some pics of the finished amp when that happens.


--Pete

[66Strat]

That looks great! How many hundreds of pounds was it at final weigh in? 

Thank you all for the kind words. It was a challenge but was also a lot of fun watching it all come together. Still though, a bit excessive but a joy nonetheless. 

The chassis with the sockets, PT, OT, and choke I weighed at 59.7 Lbs. Finished it's 64.9 Lbs. In hindsight I should have affixed a handle to each end. The buyer is building the cabinet; I'll post some pics of the finished amp when that happens.


--Pete

Excessive? Nay, I say. Too much is not enough. Play it loud and long.

[shooter]

Finished it's 64.9 Lbs.

  lifting help Isle 3


I built ONE 60lb'r, it became the parts cabinet for many 12lb'rs 


Your test bed is an amazing creation!

[dwinstonwood]

Just Wow. Everything from the drafting of the schematic (that's a new standard for me), to the breadboarding, the layout and lead dress, to the final project.
Monumental!

[kagliostro]

Nice amp VERY COOL construction 

 

Franco

[JPK]

Uh.... I don't think I'll be posting any more of my chassis gut pics here. 

[shooter]

Uh....

always stive for 110%, sleep well at 87%

[pullshocks]

Hats off!
From the R&D to the layout and exquisite build details, this is terrific. Not to mention the sheer heft and wattage.


Reminds me of the unique and cool builds on the old STAC web site (which I keep hoping will make a comeback…)

[timel34wun]

Nice, but on the schematic the line out and NFB are wired wrong.  In the schem the line out is wired same as the 16 ohm spk tap, not as a line out. And the line out resistor dividing network is shown as in the NFB path which it should not be.  Just need to move one wire to the other side of the 33K.  Maybe it's just a schematic error and not that you actually wired it like that.

Besides that, a related question is why did you change the stock sunn NFB resistor R20 from 22K to 220K. Was it just a preference for less NFB adjusted to taste by ear, or done to get the same amount of NFB with the output trans you used to behave same as the original, as I assume it is a very different trans than the original sunn dynaco output trans. 

[DummyLoad]

Nice, but on the schematic the line out and NFB are wired wrong.  In the schem the line out is wired same as the 16 ohm spk tap, not as a line out. And the line out resistor dividing network is shown as in the NFB path which it should not be.  Just need to move one wire to the other side of the 33K.  Maybe it's just a schematic error and not that you actually wired it like that.

Besides that, a related question is why did you change the stock sunn NFB resistor R20 from 22K to 220K. Was it just a preference for less NFB adjusted to taste by ear, or done to get the same amount of NFB with the output trans you used to behave same as the original, as I assume it is a very different trans than the original sunn dynaco output trans.

Thanks for pointing out the error in the schematic - I corrected and re-attached to the opening post. It was built correctly, but drawn incorrectly. 

With a 22K value resistor in the NFB loop, the output was so low you couldn't play the amp, almost 50% NFB. Look at the ckt again; with 10K on the tail at the injection point, what would be the optimum value there for 10-20% FB ratio?

--Pete

[Lectroid]

Your test bed is an amazing creation!

What shooter said.  Wow!  Even Leo would be envious.

[SILVERGUN]

Dude.
Sweet.

Can I nominate you for "Project of the Year, 2022"?

I second the nomination  

[DummyLoad]

Dude.
Sweet.

Can I nominate you for "Project of the Year, 2022"?

I second the nomination

Thnx Dr. D!

--Pete

[SILVERGUN]

Hey WAIT!!
This was 2022 also: https://el34world.com/Forum/index.php?topic=28678.0
Except, some people weren't around for it   

[DummyLoad]

Your test bed is an amazing creation!

What shooter said.  Wow!  Even Leo would be envious.

Thanks! If you'd like to build one for yourself, I have several plans of a few sizes that I have built; I can email or provide a private link to them. 

--Pete

[DummyLoad]

Hey WAIT!!
This was 2022 also: https://el34world.com/Forum/index.php?topic=28678.0
Except, some people weren't around for it 

Hangs head in shame, kicks dirt. Awww shucks! I missed that one.   

Very nice construction BTW, did you sell or keep it?


--Pete

[SILVERGUN]

did you sell or keep it?

Kept it.

It was built for me all the way.

When you get a chance let me know what you think about the split signal "fix" that I pulled on the PI. That was my "breakthrough" of 2022.
Anywho, I want a recount! The voting was rigged! 

Mirek, I thought we were friends 

[Platefire]

I've tried to get into your pixs on this for several days but my old computer wouldn't cooperate, but I finally got in tonight. Wow! what a finepiece of work! When you think of all the planning, prep, precision work and down right experience required to pull this off, all I can say is Great Job. Now I'm ready to Jam on it a bit, you tote and I play

[DummyLoad]

Now I'm ready to Jam on it a bit, you tote and I play

Ugh! That's what I basically stated to the new owner - "Love playing it, but damn sure don't wanna haul it around, have fun!" I tried like hell to get him to use the smaller OT, but was refuted repeatedly - I wanted to use the Hammond 1650TA as it's literally about 1/2 the size and weight of that Hammond 1650WA. 

Wow! what a finepiece of work!

Thanks plate! - Hope you and yours are doing well!

BTW how's that Hammond turned Plexi holding up these days?

--Pete

[pdf64]

It look amazing, great job!
I like the power supplies, full wave rectification for the bias, and best option for a single HT fuse.

[Platefire]

 Hi Pete
Sunn amps as I remember were made Heavy Duty but this one is Super Heavy Duty. But what can you say, "The Customers always Right"! especially if he demands it and is paying for it. I only played on a Sunn amp one time, when my band set in on another groups equipment---but that's a story for another time:>)

The Wife and I, the children, Grandchildren and Great-Grandchildren are all doing good and looking forward to getting together for Christmas. I Pray you and yours are doing well and have a Merry Christmas.


On the Hammond/Plexi, it is doing well. Believe it or not, I played on it yesterday. It was a rainy day and I decided to fire up most of my amps to make sure they were doing ok and it was. That was the last build I did back in 2017. Couldn't have ever pulled that one off without your help because what we accomplished in that was slightly over my head:>) It's a sweet amp and capable of shooting fire, rolling thunder, clean as a whistle and quiet as a mouse>>>>>