Sunn 200S amp

[billcreller]

One of my sons brought over a Sunn 200S amp, that one of his friends rescued from a house that was being demolished.   
Outside of needing a good cleaning, the thing is in decent shape.  I couldn't find a schematic for it.  It has two KT88 output tubes in it, and two miniatures which I haven't pulled out yet.  One octal type is missing, which I assume is the rectifier.
  I seem to remember Sunn amps from the old days....
anyone have a clue on where to find a schematic for it ??

[DummyLoad]

right here... ;-)

http://www.el34world.com/charts/Schematics/files/sunn/sunn_200s.pdf

AES sells a replacement for the multi-section PS can cap.

http://www.tubesandmore.com/products/C-EC30-20X3-525

recto is a GZ34/5AR4

--pete

[Ed_Chambley]

Very cool amps, nice value as well.  Triode electronics sells lots of stuff for them as well.  That 525v multi cap can has not held in one I restored.  I ended up leaving it and putting a series cap board inside the chassis as there is plenty of room.

Triode sells this board.  You can simply look at and make one yourself.  I believe if you check the voltage you may find you are underspec on your first filter cap due to increased wall voltage.  They were very close when designed for 117vac.  The schematic shows 500v at the first cap. 

I did a restoration on one of these about 6 months ago.  I believe it is a bass amp.  While the customer was interested in keeping it stock, I did check out some larger pot values on the treble.  Very easy to make it a guitar amp. 

[ernie_jr]

you dont want to replace the cap can with a stock replacement. it is only a 525 volt rating and with todays line voltages you will exceed that. copy doug's cap plan for the first 2 stages (ie 100mfd @ 350 volts in series) this will give you 700 volts for the first 2 stages. you can get a cap can that is 32mfd at 500 volts for stages 3 and 4 to put in place of the stock can.
Also, do for get to replace the 3 50mfd caps in the bias circuit.
I have built and refurbished many SUNNs and this way seems to work great.
good luck,
Ernie

[sluckey]

Also, do for get to replace the 3 50mfd caps in the bias circuit.

Three??? I only see two.

[ernie_jr]

thanks, my opps, fat fingers.  replace the 2 bias caps
thanks
ernie

[billcreller]

Thanks for all the responses guys...!   This is a head unit, which I forgot to mention, but you folks likely knew that.
  I have to find out what the guys want to do with it, before fooling with it.  They have a small recording studio, so I don't know what they would use this for.  It still has the two wire cord on it also. What kind of power does the thing have ?
  One of the amps they are using in there is a National/Valco clone I built a few years ago, and I'm surprised that rock musicians would use it.

[billcreller]

  After looking at the schematic, a polarity switch is in the AC...after replacing the cord with a 3-prong type, should I remove the polarity switch ? 
  And I don't know what the symbol is near the primary of the PT (?) across the AC....

I could use a DPDT switch in place of the existing polarity switch, and really switch polarity at the PT, if that is worth the effort for hum etc..  and replace the aux receptacle with a grounded type...
  Hope this makes sense 

[ernie_jr]

remove (or bypass) the polarity switch, not needed when you and in a 3 prong power cord. these amps produce about 60 watts with the 5ar4 rectifier or 80 watts with a solid state rectifier.
 i usually replace the 2 prong receptacal with a 3 prong one. It is not too hard to cut the hole bigger. these amps have very little hum when they have a good set of caps, afterall, they are a copy of the Dynaco Mrk 3 HiFi amp.
goog luck,
Ernie

[sluckey]

After looking at the schematic, a polarity switch is in the AC...after replacing the cord with a 3-prong type, should I remove the polarity switch ?

No. The switch does not really reverse the line connections to the PT. It simply connects a line filter cap to one side of the line or the other side of the line and is used for line noise reduction. That cap is often called the death cap, but once you install a 3 prong cord it is perfectly safe. You could just snip the cap if you're not comfortable with it. The switch is riveted to the chassis and then covered with the face plate. It's not just a five minute job to remove it. And, you may have a difficult time finding a switch that will fit in the rectangular cutout.

And I don't know what the symbol is near the primary of the PT (?) across the AC....

That's a 120vac neon pilot indicator lamp. It's built into the power switch so don't go looking for a separate lamp.

[TIMBO]

Hi guys, I am assuming that Sunn amps are Bass amps only?? I like these amp builders that stray from the norm as I haven't see many that use the Pentode/triode (6AN8) in this position, any other builders that use the 6an8 or similar in guitar amps. Thanks

[sluckey]

I am assuming that Sunn amps are Bass amps only??

No. That particular model is a bass amp. But Sunn produced plenty of guitar amps too, complete with reverb and tremolo. Browse thru the Sunn schematics right here and you'll quickly see which are Bass amps and which are guitar amps.

The power amps are identical. The preamps and speaker cabs determine if it's a guitar or bass amp.

Here's my Sceptre...    http://home.comcast.net/~seluckey/amps/sunn/sunn.htm

[ernie_jr]

ALso, several ampegs used a 7199 instead of the 6an8. both pentode triode
Ernie

[billcreller]

 OK !! I'll "do the right thing"

[PRR]

> haven't see many that use the Pentode/triode

Late-model Ampeg VT-40 is for-sure a gitar-amp (near-zero response at 60Hz due to open cabinet) and uses the pentode-triode.

And different from Sunn. Sunn (ala Dyna) uses the hi-gain pentode to throw a heap of NFB around the output stage for clean hi-fi result. Ampeg runs no NFB, which means very little signal needed at the power-section input. Instead of signal getting bigger each stage, they run a ton of gain up front, a lot of loss in the middle, and more gain at the final.

[Ed_Chambley]

I am assuming that Sunn amps are Bass amps only??

No. That particular model is a bass amp. But Sunn produced plenty of guitar amps too, complete with reverb and tremolo. Browse thru the Sunn schematics right here and you'll quickly see which are Bass amps and which are guitar amps.

The power amps are identical. The preamps and speaker cabs determine if it's a guitar or bass amp.

Here's my Sceptre...    http://home.comcast.net/~seluckey/amps/sunn/sunn.htm

Sunn guitar amps are cool.  I guess the reason you do don't see much of them anymore is they are LOUD and also very clean too.  To get them to break up, you probably would want to be in a big room or have a recording closet.  Ernie is correct tho, the have very little floor noise.

I'll bet Sluckey can give us a tone rundown of a spectre running on about "8."  Or his neighbors.

[sluckey]

I'll bet Sluckey can give us a tone rundown of a spectre running on about "8."  Or his neighbors.

Good idea. I could do The Star Spangled Banner to kick off the Iron Bowl today. Probably have to watch the game from metro though.   

[smackoj]

I don't know if a Sunn Sceptre is still available for low income tube junkies like me, but after looking at Sluckey's link of his, I would take one of those any day over the Canadian Traynor amps everyone seems to want. I'll be keeping an eye out for a Sunn amp myself.  Loud and clean is my 'thing' these days.

 

[ernie_jr]

http://www.ebay.com/itm/Sunn-200s-vintage-amplifier-/161162462276?pt=LH_DefaultDomain_0&hash=item2586080444

4 SUNNs currently listed on ebay

ernie

[billcreller]

When I looked up the KT88s in the tube manual, it stated that they were a Hi_Fi type tube (?).

[Willabe]

Sure, they were the king of hi-fi power tubes because of their power handling.


           Brad     

[Ritchie200]

They are also known for their "explosive" capabilities...

Jim

[ernie_jr]

kt 88 were used in hifi, that is what made them great for bass amps. they have lots of power, headroom and great in low response.
ernie

[Ed_Chambley]

I tested one with KT120's.  They are a little taller, but will fit.  These definitely have the best bass tone over any of the KT's I have tried.   I also this same amp model with some old Tung-Sol 6550, pulls from a leslie.  Sounded great.

[billcreller]

Today I finished the Sunn.  I mounted the new filter caps on a turret board, replaced the bias caps, removed the polarity switch & made a blank plate for the hole.  Replaced the cord, and scrubbed the cab & used some Armorall on the tolex.  It came out quite nice.

Thanks for all the advice !

[Ed_Chambley]

Did you give it a test run and opener up and Blow out the pipes?

How does she sound.  I love SUNN amps.  Even thought it is a bass amp it will still do a guitar ok.  Raise the pot values and it will hurt when cranked with guitar.

Nice alternative to ampeg bass.

[billcreller]

I didn't crank it very high.  Had a Weber 20 watt 12 inch in one of my amps plugged into it.  Seemed to sound OK.....

[6G6]

I would be careful trying to see what it can do.
The original speaker cabinet used a pair of JBL D 140Fs.
Great, clean bass amp.
If it is going to end up in a studio, I'd leave it that way.

Sunn gave Jimi some amps.
He hated the fact that they just would not break up.
Plenty loud, but too clean for him. 

Then again, his midddle name really was Marshall. 

[sluckey]

removed the polarity switch & made a blank plate for the hole.

Hated to see you do that. Those rocker switches had a lot of cosmetic appeal. I'd love to have that switch if you're not gonna do anything with it.

[billcreller]

  I can do that Steve !  I lost your address....

Bill

[sluckey]

Bill, I sent you a pm. THX.