Help with a Sunn Sentura II - Question about transformers and tubes.

[slavestate]

Hello there,

I went and took a look at a Sunn Sentura II today locally and I had a few questions. The seller was a nice guy and allowed me to take the chassis out of the cabinet and I had a few basic questions about it.

First thing I saw was that the power tubes were RCA 6550's and the one pre-amp tube I pulled out of the socket was a GE, so I am assuming they are probably the originals to the amp, is this safe to assume?

Second I looked at the transformers and saw there was a Western Transformers Inc input transformer (that had a sticker on it labeled as 200S) and the output transformer had a bit of corrosion and I didn't see any indicators on it however I wasn't able to get a real close look at it.

I looked at the circuitry and didn't notice anything burned up or blatantly replaced and all of the amplifiers functions worked quite well. The tremolo was nice and the reverb sounded good too.

Before I make the final purchase I just wanted to ask about the transformers in specifics. What did these usually come with, and is there any identifications I could try and spot?

Also, the chassis was marked as being from '69.

Thanks!

[loudthud]

Western Transformer was used by Sunn as a lower cost alternative to the Dynaco transformers. They were located in Portland just South of the Ross Island bridge between I-5 and the river. The end bells are usually painted gold. I have a Model T with an output transformer made by Western Transformer.

[Ryan Phelps]

+1 to Loudthud's transformer info. The tubes could well be original, but the important thing is if they sound good and test strong. They could have been replacements from several years ago. No matter, good quality tubes are still available.

Send some gut shots. If the electrolytic capacitors are original, you'll want to recap the amp in the near future. It's also a good idea to install a 3-prong AC cord and disable the death cap on the polarity switch if this has not been done previously.

[slavestate]

I have to say the amplifier sounded healthy with only scratchy pots that after just a few rotations seemed to clear up. The electrolytic capacitors looked to be original and it has it original two prong power chord. I feel like for the price the seller has asked I will take the plunge and pick it up. I'm quite excited to get this thing home and all cleaned up. The reverb was really shrill, however the tremolo was nice and I can see using that. I'll still probably run a separate Fender reverb tank instead of the stock reverb, it was seriously way to shrill.

Now with the transformers, if the OT is a Dynaco that is most likely the original and since the PT is a Western Transformer Inc. it's most likely original as well? I just found it strange there was a strip of tape on the outside that said "200S" and I assumed it came off of one.

Also anyone have a schematic I could acquire?

As always, thank you for all of your responses!

[Isaac]

The shrill reverb seems to be the way they're voiced. My Sentura II is quite shrill as well, but I have found that if I use just a little bit, it still fills out the sound without being overbearing.

[Soundmasterg]

You can get a schematic from the following location.

Greg

http://el34world.com/charts/Schematics1.php

[slavestate]

Thank you endlessly Soundmasterg. I found a few photos, but nothing of the detail that link provides. Seriously, thank you.

[Soundmasterg]

Thank you endlessly Soundmasterg. I found a few photos, but nothing of the detail that link provides. Seriously, thank you.

You're welcome. As you can see, there are many schematics there for other amps too. It is updated on a regular basis and it is a site that will be up for a long time instead of going down all the time like Schematic Heaven.

Greg

[slavestate]

Okay. I got it home today and the first thing I did was wipe it down real good and clean the contact points. After that I took it for a long drive. I am so happy I ended up picking this head up. It has so much accessibility and I am loving the sound it is producing. At this point in time I am pleased with its performance if I were to do anything it would be to swap the 2 prong out. When plugged into the 16Ω jack and I am using an 8Ω cabinet I can just plug a dummy plug into the second spot right?

[Isaac]

No need. The output jacks are switched. Just plug into the 8Ω jack, and you will be connected to the 8Ω tap on the transformer. But yes, you can use a dummy plug, if you want to.