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SDS-PAGE · KT88 Joined: 22 Feb 2007 Posts: 733 Location: Davis, CA

Anybody has any experience with these SE OPTs? There are two on sale always on eBay, one being more expensive than the other one. Don't know what the difference is between the two besides their difference in size and DC resistance.

EWBrown · Posted: Wed Nov 07, 2007 11:39 am Post subject:

I've used the 300B SET OPTs, they are the same mounting footprint as the A-470 OPTs used in the ST70 (and they do fit very nicely on the ST70 chassis) and IIRC, the DCR is around 280 ohms, at least I get around 20VDC drop across the primary winding, with 71 mA plate current.

The amp is still in a semi-unfinished condition, so I can't comment on the sound.

/ed b in NH
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Slartibartfast · Posted: Fri Nov 09, 2007 11:10 am Post subject: Re: TRANSCENDAR TRANSFORMERS

EWBrown · Posted: Fri Nov 09, 2007 11:15 am Post subject:

Look here:

http://cgi.ebay.com/Pair-3K-Audio-Output-Transformer-for-300B-SE-amplifier_W0QQitemZ280170946998QQihZ018QQcategoryZ50593QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

These are the larger15 watt version, there is also a smalled 10 W version available.

/ed B in NH
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Real Radios Glow in the Dark

SDS-PAGE · KT88 Joined: 22 Feb 2007 Posts: 733 Location: Davis, CA

I bought the other pair for $90. I did find a major difference between the two, besides power. The ones that I bought has only 8 ohms secondary windings. I look forward to using these for GSG-300B hybrid. Also bargained for a brand new pair of matched EH 300bs for $105 on eBay. Got a 89 cents discount. Speaking of cheap (or being cheap)! :o

Bob Lee · Joined: 04 Jul 2007 Posts: 8

I am listening to a pair (bigger brother ) of Transcendar transformer now.
I don't have a lot of SET transformer to compare with, it sounds great, smooth high, good bass from a
45 tube running at around 270v plate with 35ma current.
I like it so much, I am thinking about buying a pair of the smaller model, replacing the bigger transformer and saving it for another project.
By any chance that you have the mounting holes dimension for the smaller version.

BTW, I am also in the SF bayarea, only 45 min from Davis.

Bob

EWBrown · Posted: Tue Nov 13, 2007 12:42 pm Post subject:

THere's a pair of Edcor 2.5K 25W OPTs on e-bay presently:

http://cgi.ebay.com/NEW-Pair-2-5K-Audio-Output-Transformers-300B-2A3-SE-Amp_W0QQitemZ120182769405QQihZ002QQcategoryZ50593QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

These have a UL SG tap and 8 ohm secondary.

$100 bucks plus another 30 or so for UPS shipping.

THese are "monsters"

/ed B in NH
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Real Radios Glow in the Dark