Forums - OA3 replacement?

Hipfan Senior Member Posts: 65	OA3 replacement? 09/04/12 at 01:45:43 I was losing power in my left channel and noticed that the left channel OA3 regulator tube was flickering, so I shut the amp down. Upon re-power up, it seems OK. Not sure if it is bad or not. If so, what is a recommended replacement? The stock tube in the Sylvania OA3.
Back to top	Torii MK3, Icon Audio PS2, Rega P5, azur 640C V2, Klipsch Forte II (Crites), PS Audio Duet, MAC cabling IP Logged

Lon Seasoned Member "Love without guts is worthless!" Philip K. Dick Posts: 26749	Re: OA3 replacement? Reply #1 - 09/04/12 at 04:12:24 I've had good luck with RCA OA3, so I would recommend trying one of those.
Back to top	HR-1,ZBIT,ZROCK3,SEWE300B; Rega RP3 all GrooveTracer mods;PSAudio:PST+DSD, DAC Mk II,NPC,PowerBases,AC-12 pwr cbls, Reference spkrcbls; Mapleshade SamsonV3;VeraFi Audio cpts VooDoo:Cremona+Amati interconnects;Stack EQ; headphones:Sennheiser HD800S,ZMF Ori,Oppo PM1 IP Logged

will

Seasoned Member

Posts: 3136

Re: OA3 replacement?
Reply #2 - 09/04/12 at 04:43:47

I have tried a number of OA3s and like them all for different sound, some brighter and more open, some warmer, some punchier, some more or less balanced, but my fav now is a short straight sided bottle labeled Ameperex. The 50s RCA ST coke bottle shape that came with my amp is a least favorite for me, but a perfectly good sounding tube.

Tubeworld usually has a good selection if you can't find what you want on Ebay or wherever. Some OB3s are really good too, especially Raytheon or Tungsol.

Have you checked the tube pin connections... cleaned the pins and slid the tube in and out of the socket a bit with deoxit on the pins?

Back to top

All Modified: PSA-P5>DIY Strip/Shunyata Defender, Verifi...>RevolutionMacMini/Amarra-KTE Singxer/MP-DX DAC/ZR2/Zstage/CSP3>Torii IV>Omega SAHOM/AudioSmile Tweeters, SVS Micro3000>mostly DIY PCs, ICs, USB, I2S, Speaker>Stack and aluminum w ball bearing feet...

IP Logged

Hipfan Senior Member Posts: 65	Re: OA3 replacement? Reply #3 - 03/11/13 at 22:28:30 Regarding the Sylvania OA3. I noticed there are a few variations of these tubes. I've seen the coke bottle type in 3 different sizes and also a non-bottle tubular version. Do these all sound the similar?
Back to top	Torii MK3, Icon Audio PS2, Rega P5, azur 640C V2, Klipsch Forte II (Crites), PS Audio Duet, MAC cabling IP Logged

will

Seasoned Member

Posts: 3136

Re: OA3 replacement?
Reply #4 - 03/12/13 at 01:58:37

I am not sure. The only Sylvania OA3 I have is early 80s, ST (coke bottle) shape and they have a really good, complete sound that is quite open and transparent. The 50s STs I have are warmish. Also the OB3 ST and OC3Ws I have from the fifties are warmish...the Raytheon/Tungsols are nice tubes and warm, and the Sylvania OB3 ST I have are a little less warm, but still on the warm side.

A Russian tall/straight bottle I have is very open....tending to hard/edgy unless balanced with pretty warm tubes. I have some sylvania short straight OC3s (70s) that are quite open and sound good. Some Raytheon, RCA and Amperex, short/straight, all warmish and probably earlier vintage.

So go figure! I wonder if the early stuff is more warm and the later...more open...no solid information here though.

Back to top

All Modified: PSA-P5>DIY Strip/Shunyata Defender, Verifi...>RevolutionMacMini/Amarra-KTE Singxer/MP-DX DAC/ZR2/Zstage/CSP3>Torii IV>Omega SAHOM/AudioSmile Tweeters, SVS Micro3000>mostly DIY PCs, ICs, USB, I2S, Speaker>Stack and aluminum w ball bearing feet...

IP Logged