Sunn Solarus tune up

[Reeps]

This is my first time posting here but I've lurked for some time now... I've heard it is THE place to be for sunn info!

Just recently I was able to purchase a Sunn Solarus 2x12 combo amp which I am very excited about and love the tone of it (I play a Greco les paul custom through it).  It is my first tube amp so I'm somewhat new to the upkeep and maintenance aspect of that, but from what I'm hearing out of this amp - I've made a great transition!

Now to the questions... the seller of the amp told me about a few issues with the amp which didn't concern me too terribly much but I thought I'd ask here for your input and expertise:

(one thing to note, I live in somewhat rural minnesota so the nearest amp repair places are 2-3 hours away, so I tend to try things out myself. If there is anything I should definitely leave to an expert, please let me know, I know these amps can be dangerous. But if it's something I can learn, I'd love to find out, I really love the DIY aspect of music)

The seller told me that the amp felt quieter than he thought a sunn should be, though compared to my 60 watt SS amp, it 'feels' much louder, perhaps I'm not used to a 2x12 so I can't tell if it's loud or quiet for a 40 watt tube amp.  He told me about a couple things he thought was messing with it:

- For one, the tremolo?/vibrato? doesn't work at all, and he said he believes the tubes were at fault and he didn't have the proper type to test for that. Which tubes control the effect's function? I run numerous effects pedals so this feature doesn't worry me too much, but if it affects the overall sound, I'd like to fix it up.

-secondly, there is a socketed object that is completely wrapped (albeit nicely) with electrical tape.  It looks like it would be a tube socket but it almost looks like two tubes connected, plugged into one socket.. what's that all about? I can post pictures if need be.  He said for him the electrical tape seemed like a dangerous situation and would be best to have that looked at.

Lastly, I plan at some point to upgrade to a 3 prong adapter, is this something I should get done ASAP or whenever the chance arises?

sorry for such a long post but that's my situation and hopefully I've been as thorough as possible. I greatly appreciate your help and advice! Looking forward to hearing what you have to say, Thanks!

[mckinnon audio]

  Hi there,you have a great amp ! There is no tube for the tremolo,they use transistors for that.Could be a trans.,elect.caps or the LDR,(light dependent resistor) which actually makes the tremolo "sound",which is really a change in volume. I'll take a guess about the tube sockets wrapped in tape and say they're someone's attempt to make a plug-in diode rectifier instead of using the tube.Be careful,there are some hazardous voltages in here!! I've got 3 Solarus heads,two are the 40 wrms ones with EL34's (6CA7's) and one is the 60 wrms one with 6550's and the mid boost sw. Hope this is of some help,good luck,Mel.

[Reeps]

Hey thanks for the reply so quick!

Thanks for pointing out information regarding the tremolo, I will look into that. Here are some photos of the electrical taped section:




Also, as far as the tubes go, is the 40 watt combo any different from the schematic of the solarus on this site? Looks like mine has 2 El34's, 1 12AX7, 1 12AU7, and 1 I'm not so sure about, the printing on it is all worn. Again, thanks for the help

[mckinnon audio]

  Hi there,what that is,someone has replaced the orig. can cap. with 2 other caps and taped them together and tried to mount them where the orig. was.You should check the values to make sure they're correct,and replace/remount them.Hope this helps,good luck,Mel.

[mckinnon audio]

  Hi there,forgot to mention this before.The other tube is a pentode/triode combination,in the older amps it's a 7199,in newer ones it's a 6AN8A,good luck,Mel.

[xsolarusx]

The tremolo circuit is pretty useless.  It's weak.  If it's not already shut off, I'd recommend just turning it off and leaving it.

Otherwise, put some 6550's in there, and I think you'll be very happy with the result.

As far as upgrading to a three-prong plug, do it before you intend on using it on any serious level.  I put it off and got some nasty shocks from pretty much everything. It's not easy to play guitar when your picking hand is completely numb for half the set!

Enjoy the amp!

[mckinnon audio]

Hi there,all I know is that the tremolo on my 70's Solarus,through a 2 x 15" cab. knocks people out ! Anything from a heavy Pink Floyd type to a RnB/bluesy type.I replaced all the caps. in the circuit and cleaned up the wiring,check it out I don't think you'll find it's really that bad after all.Good luck,Mel.

[Reeps]

You guys rock, thanks for this info so far. The tremolo circuit might be a fun project to fix up later on, at least it's not affecting the overall tone. 

xsolarusx mentioned putting in 6550's into it, and this has now got me pretty confused. Again, being brand new to the tube 'world' I'm not exactly sure what I've got in there now.  I searched the googles to find pictures of EL34's and 6550's and the two in there now look like the 6550 images that came up. On them, they say "Tung Sol" and have a serial number I'm guessing of 3227508, but no tube 'type'.  They are curvy like the 6550's pictured online, and not cylinders like the EL34's.  After searching I've found that a 6550 can be inserted into an EL34 socket with no harm, but with a lack of volume, and that the EL34 socket has to be modified to accommodate the 6550s?  Could someone have replaced them with 6550's already? Is there a sure fire way to find out what tube type these are and if they are installed correctly?

[mckinnon audio]

  Hi there,if it's the one piece combo that puts it around 67' to 68' I believe,so it should be a pair of EL34's and a 7199 driver. They didn't use 6550's in the Solarus until the 70's I think,the amps have a mid-boost sw. and bigger transformers and diodes instead of a tube rect. Hope this helps,good luck,Mel.

[EdBass]

You guys rock, thanks for this info so far. The tremolo circuit might be a fun project to fix up later on, at least it's not affecting the overall tone. 

xsolarusx mentioned putting in 6550's into it, and this has now got me pretty confused. Again, being brand new to the tube 'world' I'm not exactly sure what I've got in there now.  I searched the googles to find pictures of EL34's and 6550's and the two in there now look like the 6550 images that came up. On them, they say "Tung Sol" and have a serial number I'm guessing of 3227508, but no tube 'type'.  They are curvy like the 6550's pictured online, and not cylinders like the EL34's.  After searching I've found that a 6550 can be inserted into an EL34 socket with no harm, but with a lack of volume, and that the EL34 socket has to be modified to accommodate the 6550s?  Could someone have replaced them with 6550's already? Is there a sure fire way to find out what tube type these are and if they are installed correctly?

Post a pic of the whole chassis from the back with back protection board off, even better out of the case completely.
It's very hard to tell what the output tubes are in the pics you posted of the "home made" can cap, but the little glimpse in your pics sort of look 6550 or even KT88ish.
Which I agree would be the wrong tubes for your amp, seeing how I concur with Mel;

Hi there,if it's the one piece combo that puts it around 67' to 68' I believe,so it should be a pair of EL34's and a 7199 driver. They didn't use 6550's in the Solarus until the 70's I think,the amps have a mid-boost sw. and bigger transformers and diodes instead of a tube rect. Hope this helps,good luck,Mel.

You know for certain it's been messed with because of the electrical tape cap job, get some clean chassis pics and maybe one of us can figure out what's going on in there.

[mckinnon audio]

  Hi there,yeah some pics. would be good.I'd like to see some of the combo,I've always wanted one of these,and one of the Sonaro combo's as well,thanks,Mel.

[Reeps]

Alright guys, I've taken a bunch of pictures and put them up in a gallery for you:

Sunn Solarus Inside

Each image has a description so I have written some info in those corresponding to what you are looking at exactly.  I hadn't seen the top view of that elec. taped cap, turns out there are 5 joined together. Someone must not have had the correct cap value and decided to combine 5 to get the correct value? I hope it's just a matter of un-soldering them and installing one in it's place, I could handle that. Or does it look to you like they have made more modifications in order to allow the 5?


Also, As far as the tubes in there it has:

1 RCA GZ34
2 Tung Sol (Unknown Type...)
1 (RCA?) 7199
1 (RCA?) 7025?
1 Sylvania (Unknown Type...)

Lastly, the speakers don't have a logo on them, but say "C12N C85793" on them, does this mean anything to anyone? I'm curious how many changes were put into this amp.

I will get more 'glamorous' shots of this amp when I reassemble it and have time to do so! Thanks again you guys, this is a big help for me, soaking up as much info as I can.

[mckinnon audio]

  Hi there Reeps,amp looks really good,outside of that filter cap I don't think there's been any body in there "monkeying around" with it.Looks like they cut the can off the multi-cap and used the isolated mountingspacer and the terminals of the orig. to mount the other caps on.It's taped because the positive leads of all the caps would be exposed on the can base,could be a shock hazard.It'll be an easy amp to work on,good luck,Mel.

[EdBass]

Those are 6550's all right. With the date of manufacture, I suppose it could be a '69 model and in '69 Sunn switched to 6550's from KT88, and those Tung Sols (or GE) would be period correct for a '69 Sunn, BUT...
Everything I have shows '68 as the last year for the Solarus combo amp, it does NOT appear in the '69 catalog. Also, every schematic I have, and every description (including the '68 and '69 catalogs) show/describe the Solarus as an EL34 amp rated at 40 watts, not as a 6550 amp rated at 60 watts.
Of course, anything is possible, it might be some sort of hybrid from the factory, the tubes could have been switched at some point in the last 40 years, who knows?
The true test for which tubes it's supposed to have would be if it has a 40 watt or 60 watt output transformer (the one by the speaker jacks). I can't tell in the pictures, you might be able to get some numbers off of it.
Regardless, here's a recent thread dealing specifically with your taped together cap issue;
http://sunn.ampage.org/sdp/index.php/topic,4001.0.html
What you have now is kind of a jury rigged version of the SDS board discussed in the thread, the original was a can cap which has all of those taped together capacitors in your amp shoved into a single tube and mounted where the taped together ones are in your amp.
I don't know about the speakers, the Sunn guitar gear I have from that era has 12" Alnico drivers, and the ones in your amp look to be ceramic. I know they made both types of magnets under the "Sunn Transducer" label but I don't know many specifics. I'm sure some of the other Sunn mavens that post here will have more info.
It looks like you have a nice clean amp there, good luck with your project!