Scott 299 (late) OPT's

Mike K2 · 26th June 2007, 09:59 PM

I recently posted the following on the HH Scott forum. Unfortunately I only received one response. Any thoughts from the diy Audio crowd would sure be appreciated!

With the help of several kind folks on this and other forums (Thank you!), I recently finished rebuilding a 299A (later type). It has a non stock output transformer on one channel that is noticeably smaller than the original, and not surprisingly that channel doesn't sound as good.

I also have 2 other amps that I haven't touched. One is a Heathkit AA-151, the other is a Dynaco SCA-35. Should I cannibalize one of these to improve the 299? Would the other transformers even work in the 299?

Or- is there a source for 299 output transformers?

Mike

Eli Duttman · 26th June 2007, 11:35 PM

Assuming they will fit, I'd use the trafos in the AA-151 to fix the 299A up. That selection is based on the presence of 16, 8, and 4 Ohm speaker taps. You have the choice of tieing the UL taps off or experimenting with them.

Sell the Scott OEM trafo on Flea Pay.

The AA-151 power trafo is a candidate for use in an "El Cheapo" variant. You'd SS rectify the B+ and voltage multiply the 5 VAC winding to get the B- rail.

I haven't the foggiest notion where a single Scott OEM trafo can be sourced.

kevinkr · 27th June 2007, 03:58 PM

Actually the A is the earliest incarnation of the 299 which ran from A to D. The A and B version transformers might interchange, but I cannot attest to that. (They both use 7189A unlike the later C & D which use 7591 output tubes)

You might have some luck looking for another A on fleabay. I had one unfortunately with a blown power transformer and traded it for some parts a few years ago, you might get lucky and find one if you are persistent enough.

planet10 · 27th June 2007, 06:40 PM

Quote:

Originally posted by kevinkr
I had one unfortunately with a blown power transformer and traded it for some parts a few years ago, you might get lucky and find one if you are persistent enough.

I still have one (LK48 -- kit version?)... the stench of the burned guts of the power trafo took days to clear out of the house...

dave

Mike K2 · 27th June 2007, 07:45 PM

According to the HH Scott site, the LK-48 uses an 8-5 series OPT and the late 299A's used an 8-4.

Is there a significant difference?

planet10 · 27th June 2007, 07:55 PM

I don't know... the amp came with 7189s ...

dave

Mike K2 · 28th June 2007, 01:00 AM

Planet 10,

Do you have any interest in selling your OPT's?

planet10 · 28th June 2007, 01:49 AM

I don't know... they are awefully good OPTs, and the other amp we have using them is soooo good, but probably for the right price. I'll have to consult Chris.

dave

(how's that for waffling?)

Mike K2 · 28th June 2007, 02:01 AM

The waffling is understandable.If you don't want to part with them, I can always try the AA-151 OPT's.

planet10 · 28th June 2007, 05:03 AM

OK, we'll let them go... mail me and we can negotiate a price...

dave

26th June 2007, 09:59 PM	#1
Mike K2 diyAudio Member Join Date: Aug 2004 Location: Indiana	Scott 299 (late) OPT's I recently posted the following on the HH Scott forum. Unfortunately I only received one response. Any thoughts from the diy Audio crowd would sure be appreciated! With the help of several kind folks on this and other forums (Thank you!), I recently finished rebuilding a 299A (later type). It has a non stock output transformer on one channel that is noticeably smaller than the original, and not surprisingly that channel doesn't sound as good. I also have 2 other amps that I haven't touched. One is a Heathkit AA-151, the other is a Dynaco SCA-35. Should I cannibalize one of these to improve the 299? Would the other transformers even work in the 299? Or- is there a source for 299 output transformers? Mike

26th June 2007, 11:35 PM	#2
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Assuming they will fit, I'd use the trafos in the AA-151 to fix the 299A up. That selection is based on the presence of 16, 8, and 4 Ohm speaker taps. You have the choice of tieing the UL taps off or experimenting with them. Sell the Scott OEM trafo on Flea Pay. The AA-151 power trafo is a candidate for use in an "El Cheapo" variant. You'd SS rectify the B+ and voltage multiply the 5 VAC winding to get the B- rail. I haven't the foggiest notion where a single Scott OEM trafo can be sourced. __________________ Eli D.

27th June 2007, 03:58 PM	#3
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	Actually the A is the earliest incarnation of the 299 which ran from A to D. The A and B version transformers might interchange, but I cannot attest to that. (They both use 7189A unlike the later C & D which use 7591 output tubes) You might have some luck looking for another A on fleabay. I had one unfortunately with a blown power transformer and traded it for some parts a few years ago, you might get lucky and find one if you are persistent enough. __________________ www.kta-hifi.net

27th June 2007, 07:55 PM	#6
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	I don't know... the amp came with 7189s ... dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

28th June 2007, 01:49 AM	#8
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	I don't know... they are awefully good OPTs, and the other amp we have using them is soooo good, but probably for the right price. I'll have to consult Chris. dave (how's that for waffling?) __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

27th June 2007, 07:45 PM	#5
Mike K2 diyAudio Member Join Date: Aug 2004 Location: Indiana	According to the HH Scott site, the LK-48 uses an 8-5 series OPT and the late 299A's used an 8-4. Is there a significant difference?

28th June 2007, 01:00 AM	#7
Mike K2 diyAudio Member Join Date: Aug 2004 Location: Indiana	Planet 10, Do you have any interest in selling your OPT's?

28th June 2007, 02:01 AM	#9
Mike K2 diyAudio Member Join Date: Aug 2004 Location: Indiana	The waffling is understandable.If you don't want to part with them, I can always try the AA-151 OPT's.

28th June 2007, 05:03 AM	#10
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 4	OK, we'll let them go... mail me and we can negotiate a price... dave __________________ community sites t-linespeakers.org, frugal-horn.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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