2a3 output transformers....

button_fly · 9th October 2007, 04:18 AM

I've got a MIDWEST AUDIO 2a3 valve amp which I love and sounds great. However I've discovered it's using just Hammound ot's !! The 125s's... So I know It will sound better with some real iron. The only real facts I have are it's at least 70ma out. 16 ohm speakers, the km-30 phy-hp's (13.8) with 370 vdc input max. From stuff I've read it may need a 2500 ohm primary ? Are possible choses: Magnaquest, llunduhl (expensive) and the hammound 1627's ? What's your opinion ????? Thanks, Mike

One last thing my speaker are only 97 db so I hope the 2w I have won't be reduced with a different trans. Which has the lowest hum ???????

planet10 · 9th October 2007, 04:28 AM

Contact Bud Purvine (aka BudP here) at O'netics.

dave

arnoldc · 9th October 2007, 05:39 AM

I use MagneQuest DS-025 on my 2A3 amp and love them.

You've got other options, like what Dave mentioned, and others such as James (on my 300B amp).

number9 · 10th October 2007, 02:05 PM

Years ago I built a SE 300B amp and owned at the same time a pair of Electra-Print, Audio Note (English), and MagneQuest OP transformers. In the long run I could only keep one pair. I auditioned each pair on Quad EL57 speakers. The only difference I could hear was in the base. In the midrange it was a draw. I decided to keep the pair that has the best bass with those Quad speakers. I decided that interaction between the speakers and those transformer was the best match. I later learned when you order from a boutique winding shop, the winder can set the air gap to the current of the output tube. If I were you I would upgrade the coupling caps. More result for the buck spent. Other effective use of your dollar, upgrade of the resistors to tantalum (see Parts ConneXion catalog) , higher wattage values sound the best. Upgrade of the power supply caps, if you have the room, to Nichicon KG caps (see Michael Percy catalog). They can make the amp sound faster all through the amp’s frequency response. The best sound will come from an upgrade to very large polypropylene caps (see Michael Percy catalog). If you have the real estate below deck and can mount the terminal strips below deck. Each one of these changes adds a small percentage of improvement. You will notice the most expensive tube amps all have these improvements at delivery. On another point, you will not hear any difference in the hum level between these transformers. You are using very efficient speakers and you should expect some hum unless the amp builder has the knowledge and done the work to eliminate the hum before delivery.

9th October 2007, 04:18 AM	#1
button_fly diyAudio Member Join Date: Oct 2007	2a3 output transformers.... I've got a MIDWEST AUDIO 2a3 valve amp which I love and sounds great. However I've discovered it's using just Hammound ot's !! The 125s's... So I know It will sound better with some real iron. The only real facts I have are it's at least 70ma out. 16 ohm speakers, the km-30 phy-hp's (13.8) with 370 vdc input max. From stuff I've read it may need a 2500 ohm primary ? Are possible choses: Magnaquest, llunduhl (expensive) and the hammound 1627's ? What's your opinion ????? Thanks, Mike One last thing my speaker are only 97 db so I hope the 2w I have won't be reduced with a different trans. Which has the lowest hum ???????

9th October 2007, 04:28 AM	#2
planet10 frugal-phile(tm) diyAudio Moderator Join Date: Oct 2001 Location: Victoria, BC, NA, Sol III Blog Entries: 5	Contact Bud Purvine (aka BudP here) at O'netics. dave __________________ community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi p10-hifi forum here at diyA

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9th October 2007, 05:39 AM	#3
arnoldc diyAudio Member Join Date: Apr 2003 Location: Makati	I use MagneQuest DS-025 on my 2A3 amp and love them. You've got other options, like what Dave mentioned, and others such as James (on my 300B amp).

10th October 2007, 02:05 PM	#4
number9 diyAudio Member Join Date: Jan 2007 Location: Boston Massachusetts	Years ago I built a SE 300B amp and owned at the same time a pair of Electra-Print, Audio Note (English), and MagneQuest OP transformers. In the long run I could only keep one pair. I auditioned each pair on Quad EL57 speakers. The only difference I could hear was in the base. In the midrange it was a draw. I decided to keep the pair that has the best bass with those Quad speakers. I decided that interaction between the speakers and those transformer was the best match. I later learned when you order from a boutique winding shop, the winder can set the air gap to the current of the output tube. If I were you I would upgrade the coupling caps. More result for the buck spent. Other effective use of your dollar, upgrade of the resistors to tantalum (see Parts ConneXion catalog) , higher wattage values sound the best. Upgrade of the power supply caps, if you have the room, to Nichicon KG caps (see Michael Percy catalog). They can make the amp sound faster all through the amp’s frequency response. The best sound will come from an upgrade to very large polypropylene caps (see Michael Percy catalog). If you have the real estate below deck and can mount the terminal strips below deck. Each one of these changes adds a small percentage of improvement. You will notice the most expensive tube amps all have these improvements at delivery. On another point, you will not hear any difference in the hum level between these transformers. You are using very efficient speakers and you should expect some hum unless the amp builder has the knowledge and done the work to eliminate the hum before delivery.