Sonaro vs. 200s vs. Sorado

[PBman]

I know that the 200s and the Sorado were the same amp. The names were given to them depending on which cab it was sold with. In the case of the Sonaro, it's 60 watts ( like the 200 & sorado) with 6550's. So take away the name plate are they the same?
AND, if the are am I safe to use the 200/Sorado schematic?

Thanks

[AdmiralB]

The Sonaro isn't the same.  It uses much smaller transformers and lower voltages.  It's a 40W amp (and then only maybe), and just popping in 6550s doesn't turn it into a 200S.

[PBman]

The Sonaro will take 6550's. With my bias tester those transformers easily produce 525 to 575 volts needed for the 6550's it came with. Chek out this page below because it shows that the Sonaro came with both EL 34's and 6550's. the list starts 3/4 down the page





http://www.richbriere.com/Sunn_Shack_2.htm

[max headrrom]

this seems to be a recurring theme. Sunn seemd to use 2 different amps (40 watt [dynaco MK IV] and 60 watt [Dynaco MK III]) and label  them the same thing (sonaro). be careful. is the 2nd tube a 6AN8 or a 7199 ? not the definative test but worth considering. http://www.geocities.com/vintageaudio/ this site has Dynaco shcematics for your consideration.
if it is a 60 watt Mk III/ 200s & use the KT-88's  IMHO

[PBman]

6AN8

[max headrrom]

good chance you have a 60 watt (mk III). all the ear marks seem to be there.  
double check the sonic I - 40's schematic to make sure it does NOT match this model. take note of voltage applied to the output trans (in the 400+ range or the 500+range) also note the output of 8 &16 ohms on sonic vs 4&8 ohms on 200s and the output trans part numbers are differnent ALL BIG deals. if is the correct trans tweak away and play.

[AdmiralB]

Easiest way to tell is just size the output transformer.  A 40W OT is about the size of a baseball; a 60W is bigger than a softball.

Plate voltage with a tube rectifier would be about 560V in a 60W, about 515V in a 40W.

[Soundmasterg]

PBman, the plate voltage isn't an indicator of which output tube is correct for an amp as long as it isn't too high for whatever tube you want to use. The output transformer's primary impedance and the tube's transconductance are what really matters, because they affect the tone and the power and how well the tubes match the transfomers. Also the size of the transformer is not always, but often is a good indication of how much power and bandwidth it will put out.

As far as the Sunns are concerned, Admiral B is right about seeing what the plate voltage is and deciding from there as far as what tubes to use. The 40 watt amps used smaller transformers and have lower voltages as a result so the output transformers don't blow from too much power. These amps use EL34's stock. The larger transformers are the same ones as what was used in the 200S and are meant for 6550's or KT88's. You can use either one of those, or the EL34 in the bigger transformer amps, and there will be a different match between the tube and the primary impedance, but either one will work and sound fine. In the smaller amps, the 6550/KT88 types could blow the output transformer from too much power, so you do have to be careful there.

Greg

[bentbolt]

so does that mean I can plug EL34s in my 200s? maybe I didn't understand. (I'm not a Tech)

[AdmiralB]

I've used JJ EL34s in a 200S, as well as Philips 6L6GCs and the current Chinese KT66s.  They all worked, but IMO don't sound all that great because you have to bias them to a really low current.  

The final EL34 spec was 800V plate, 500V screen.  That puts the screens a little over-voltage in a 200S, but adding 1K screen resistors would probably make it workable long-term.