I Want to build 2a3 amp for an old am radio and maybe mp3 player. Fidelity goal is minimal due to sources. Speaker will be mid sized full range in a box. COST is the key. Thinking pp 2a3 with 3 or more watts. Looking for suggestions on simple existing designs that will not break the bank.
Start with the data sheet. A self biased set up is provided. 😉
"Full wave" double the O/P of a triode N-68X isolation transformer to get the B+.
Edcor's GXPP15-8-5K O/P trafo should give you plenty of bandwidth, while being kind to your finances.
"Full wave" double the O/P of a triode N-68X isolation transformer to get the B+.
Edcor's GXPP15-8-5K O/P trafo should give you plenty of bandwidth, while being kind to your finances.
If cost is central to your considerations why on earth choose a 2A3 output tube? These are pricey, And even if you have one of these or particularly a pair...sell them on flea-bay as they are garnering pretty good $$$ and use the profits to finance a modest amp build based on an output stage that's a little less expensive. Think 6V6 based El Cheapo as found on this forum....JMTCW....
Yes,
i agree 100% with devilsindetails.
There are a lot of fantastic tubes with nice prices.
Look at:http://www.diyaudio.com/forums/tubes-valves/254613-me-clone-proto-el-pl-504-a.html.
Maybe this is what you are looking for.
Regards,
Hilmar
i agree 100% with devilsindetails.
There are a lot of fantastic tubes with nice prices.
Look at:http://www.diyaudio.com/forums/tubes-valves/254613-me-clone-proto-el-pl-504-a.html.
Maybe this is what you are looking for.
Regards,
Hilmar
And for an AM radio isn't the frequency responce limited to about 6k?
So a cheap tube like the 6as7 with it's two triode sections and a small
toriod power transformer used as an output transformer might be a good
cheap way to go.
So a cheap tube like the 6as7 with it's two triode sections and a small
toriod power transformer used as an output transformer might be a good
cheap way to go.
Thus the question.
Honestly I was thinking of sticking with period tubes for the amp too. But yes price is a big motivator here. Thanks
Honestly I was thinking of sticking with period tubes for the amp too. But yes price is a big motivator here. Thanks
The 2A3 was not used in many early radios, as it was introduced rather late... (1933) a year after the 41 and 42 power pentodes, two years after the 47. It's main usage was in PA amps, 15W in AB2 P-P. Single-ended was almost never used - some high-end radios used P-P 2A3. For some circuits, see the 1934 Thordarson Sound Amplifier Manual on my website: http://www.audiophool.com/Misc/1934SoundAmp.pdf
A triode connected 2A5, 42 or 46 will cost less and give similar performance to a 2A3. A 56 or 76 as driver may not give enough gain - a 2A6 or 75 certainly could, though those require grid caps..
A triode connected 2A5, 42 or 46 will cost less and give similar performance to a 2A3. A 56 or 76 as driver may not give enough gain - a 2A6 or 75 certainly could, though those require grid caps..
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