• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Help with OPT choice....

analog addict

analog addict

Glory or Death!
Subscriber
Well, now that I have a dead OPT on my new SET 45 amp, I am shopping for a new pair. Jay has kindly offered a suggestion, and here are some more suggestions.

Currently I am thinking about the Edcor XSE 15-8-5K or the Transcendar 5K.

I talked to a former AK member/toob guru who doesn't want to shoot where you are standing, and he told me that even if the current primary is 3K, a 5K primary will sound better with 45's versus the 3K, and that I could roll the 5K unit in without any circuit changes. Anyone have a reason why I wouldn't be able to do this?

Anyone want to suggest which choice is better or suggest another unit?

I would like to keep the cost down to less than $120 for the pair.....:D

TIA as always......:thmbsp:
 
Register to hide this ad
analog addict said:
Currently I am thinking about the Edcor XSE 15-8-5K or the Transcendar 5K.

I talked to a former AK member/toob guru who doesn't want to shoot where you are standing, and he told me that even if the current primary is 3K, a 5K primary will sound better with 45's versus the 3K, and that I could roll the 5K unit in without any circuit changes. Anyone have a reason why I wouldn't be able to do this?

Anyone want to suggest which choice is better or suggest another unit?
Click to expand...
Try the Edcors! :yes: At $20 a pop, you can't go wrong. You'll need to find a way to keep fingers away from the buzzy bits, though... I've used those OPTs in a couple of Dolly amps now, and they sound very nice for the price! Typically they're out a week or two when you order them, though.

My understanding is that the higher output impedance will mean a slight reduction in output power, but with more stability (?). I've been wrong before.
 
I just bought a pair of 5k:8 Transcendars for my 2A3 amp. I am glad I did. The bass response is excellent. Max currrent for the Transcendars is 100ma.
 
The Transcendar 5K:8 are very nice transformers, especially considering the price. They work very well for me on my single ended project. I'd vote for them.

 
Anyone know a source other than the e-pray guy, who is apparently the (former) president/owner of the company. Also the phone number isn't working, suggesting to me they are out of business, and he is just liquidating the remaining stock...:scratch2:
 
analog addict said:
Anyone know a source other than the e-pray guy, who is apparently the (former) president/owner of the company. Also the phone number isn't working, suggesting to me they are out of business, and he is just liquidating the remaining stock...:scratch2:
Click to expand...

As far as I know, Gery is still the guy running the show. He is semi-retired, and makes transformers "when he feels like it". When they're made, they go up on eBay. When he doesn't feel like winding transformers, he goes on vacation and lets the eBay store sit idle.

They do show up from time to time, you just need to be patient. Grab them when you see them. Good luck!
 
analog addict said:
Anyone know a source other than the e-pray guy, who is apparently the (former) president/owner of the company. Also the phone number isn't working, suggesting to me they are out of business, and he is just liquidating the remaining stock...:scratch2:
Click to expand...

I ordered mine just before Christmas. They arrived in about three days.

Edit: There is a pair on eBay that ends in 18+ hours. The current price is $100. I got mine at a "buy it now" price of $121.

Robert
 
I've got a message in to him, as I want to get a few more pairs before he runs out. I'll let ya know what he says about the 5K jobs.:thmbsp:
 
Ok....

Put 40 VAC into the primary of the working OPT, got 1.6 - 1.7 VAC out. By Jay's calculations and using a secondary VAC of 1.65, that gives a primary measurement of 4702. Since the DVM is a cheapy, and I'm using a 200 VAC scale, I would then figger it's a 5K primary.

So, 5K it is. Guess I'll send Gary Gaetani a question about selling me a set of the 5K iron....Wish me luck!

Oops - Just saw Jay's last post. I'm all ears....
 
As I mentioned in that previous thread, not that I'm their spokesperson or anything, but for $200 bucks you can also get those magnequest RH40's. I'd let you know how mine sound but I haven't made the amp yet. They're 5k, 40ma, 8 & 16 ohm secondary. No end bells or leads (just solder tabs) and are $99 each. Anybody here have any experience with magnequest xformers at all?
 
For 45amps, I saw an old article in Glass Audio by Eric Barbour I believe entitled "Single ended Glory for $100." or something like that. He stated that the 45 tube was so easy on the outputs that even non SE outputs wouldnt saturate. He advised ( for this low dollar project) using old outputs off things like Fisher 500C units, which are around 7000 or so. He stated the higher
impedance served to make the sound a little more lush. I have one of these things about 85% built, its been sitting idle for years. Maybe its time to pull it out and finish!:yes: Just dont have any 45 tubes!

russellc
 
Russellc said:
For 45amps, I saw an old article in Glass Audio by Eric Barbour I believe entitled "Single ended Glory for $100." or something like that. He stated that the 45 tube was so easy on the outputs that even non SE outputs wouldnt saturate.
Click to expand...

Huh? I don't understand. Transformer cores saturate depending on how much DC current they can tolerate. Putting a gap in the core (as is done with OT designed for SE use) allows it to handle more DC than a non-gapped transformer.

Typical applications for the 45 tube indicate ~35mA idle current at ~250 volts. What makes the 45 any "easier" on the outputs than any other tube running at 9 watts idle dissipation?
 
analog addict said:
From Transcender. 5k pair is $110 +S&H. Working on purchasing a pair...:thmbsp:
Click to expand...

For a few extra dollars, I believe Gery will put an extra tap on the primary at 50%. Might be useful if you ever want to play with a single ended ultralinear configuration on a pentode or beam tetrode type tube (EL34, 6L6, KT88, etc).
 
Ty_Bower said:
Huh? I don't understand. Transformer cores saturate depending on how much DC current they can tolerate. Putting a gap in the core (as is done with OT designed for SE use) allows it to handle more DC than a non-gapped transformer.

Typical applications for the 45 tube indicate ~35mA idle current at ~250 volts. What makes the 45 any "easier" on the outputs than any other tube running at 9 watts idle dissipation?
Click to expand...

I'll look up the article, otherwise, you would have to ask mr Barbour...who knows what he's talking about in my book. Let me dig it up. I can tell you several built these and liked them, so there is something to it. Aparently that amount does not saturate them I guess. Of course you are only getting a watt or two at most.

russellc
 
You must log in or register to reply here.
Back
Top Bottom