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Glensing

Starting the 300B Laurel's again

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Yes, newbie but lurked here many years. So covid-19 helped get me serious with my HIFI hobby again. I just finished restoring my 1983 WO black grill Belle's and can't think of a better reason to get my Welbourne Labs Laurels (factory built) out of storage (15 years). My variac will arrive in a day or two to bring them back up but I am wondering, if it will be ok to just start them? I know nothing about these designs or where to check voltages so I'm thinking I should find a knowledgeable SET person around here to go through them for me. Might be some upgrades needed as these are not the ultimate version.  I would love to hear thoughts and ideas.

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It probably is a good idea to recap it, at least the big power supply ones, before firing it up but bringing the voltage up with the variac is an alternative. What you hope happens with the variac is the old caps reform. Look at the caps to see if there is anything leaking out of them is a good place to start. Chances are it will play just fine as is if there is no cap leaking. 

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Henry is correct, have a look at the caps no leakage and no swelling, bring them up slowly on the variac .  I have a couple amps at least that old with no issues (though they have not sat in storage for 15 years)  I did find a NOS dynaco st70 MK2 some time ago that sat in storage for 30 years it played fine with no issues I also had a TT that was 35 years old NOS that played fine with no issues,

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Thank you gentlemen...that gives me the confidence I needed. I recapped the Belle's CO networks with Crites Sonicaps so this leads me to think I can get the Laurels running myself. Is there any reason to think there may be better main caps than what Ron used? If so is it reason enough to do it and will it make a sonic difference? Gonna go find my head lamp cause the variac is out for delivery. Woohoo Thanks again

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20 hours ago, Glensing said:

Thank you gentlemen...that gives me the confidence I needed. I recapped the Belle's CO networks with Crites Sonicaps so this leads me to think I can get the Laurels running myself. Is there any reason to think there may be better main caps than what Ron used? If so is it reason enough to do it and will it make a sonic difference? Gonna go find my head lamp cause the variac is out for delivery. Woohoo Thanks again

 

If you liked the way the Laurels sounded just use the same caps. Replace all of them to avoid future problems.

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Got ahead of myself there for sure Jeff. Thanks.

So While starting the Laurels, the rectifier started acting up at just above 65 volts. I took it to 50 volts over 10 min left it there for 30 min. As I increased the voltage to maybe 65 the variac buzzed from the rectifier shorting  (a little light show) and I shut it down. Darn it.

So I ordered the Sovtek 5AR4's. Should I give it another go when I get the tubes?

The twins look good under the hood. I'll try to insert.

300B bottom.jpg

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Have the p/s electrolytics replaced first.  Any amp tech can do that for you.  Where are you located?

 

 

Maynard

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Thanks Maynard...I am in Arkansas. My first thought was to find a tech to get them back in my system. After a no luck novice effort looking (driving distant shops) I thought I could handle bringing them up with the variac. Otherwise I have extensive packaging experience and our company can help with freight rates. 

Any recommendations are needed ?  (maybe a tube amp designer). 

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Before you consider shipping search for any ham or antique radio clubs in your area.  Both often have members who are audiophiles, many of whom are very well trained in tube electronics.  This is a very easy repair so it would be a shame to incur significant shipping costs and risk damage to the amp.

 

 

Maynard

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