Lowest Power Amplifier?
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the skipper
Professional Curmudgeon
can't argue with the power rating but that would be considered an integrated. I sold a few of them when they insisted.
they did look cute with the matching tuner.
they did look cute with the matching tuner.
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mhardy6647
Lunatic Member
Nor is it solid state -- and this thread is in the solid state forum.
I kind of doubt the SA-150 will give 1.8 watts (per channel?) under anything like the old FTC standards, much less broadband -- although if someone has data, it'd be very cool to see!
In terms of "hifi" bandwidth and distortion, and off the top of my head, this venerable little R/S receiver is probably as low-power as you'll find. 3.5 w, 30 to 20kHz at < 0.9% THD (which is pretty hifi actually and better than my SE 2A3 amplifier is capable of)
EDIR: PS Bob Danielak's aforementioned "Darling" SE 1626 amp is a very nice sounding little amplifier when used with very high-sensitivity loudspeakers (well north of 100 dB SPL /watt @ 1 meter, for best results) and/or nearfield.
source; https://www.radioshackcatalogs.com/flipbook/1977_radioshack_catalog.html
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mhardy6647
Lunatic Member
The original morph of Nelson Pass's single-ended (and hyper-simple) "Amp Camp Amplifier" was good for about 5 watts "per channel" (these are usually built as monoblock). These were sold as kits, (still are, but now capable of 7 or 8 watts), though, not built up. The Class A operating point of the power transistor means this little amp runs hot and needs large heatsinks and/or fan cooling.
Pretty nice sounding little amplifer; broadly similar in presentation to a single-ended 2A3 amp, albeit somewhat less lifelike in the midrange (but with somewhat better bass performance).
https://diyaudiostore.com/products/amp-camp-amp-kit?variant=7072933085218
The ACA morph at my house (built by a very nice and very talented fellow on the Polk Audio forums) was a somewhat radical re-imagining with somewhat tarted-up choice of passive parts (capacitors) and built as a stereo amp using the "Bottlehead" (kit) amp form factor and active (fan) cooling rather than "just" a heatsink.
DSC_2871 (2) by Mark Hardy, on Flickr
DSC_6923 (2) by Mark Hardy, on Flickr
Pretty nice sounding little amplifer; broadly similar in presentation to a single-ended 2A3 amp, albeit somewhat less lifelike in the midrange (but with somewhat better bass performance).
https://diyaudiostore.com/products/amp-camp-amp-kit?variant=7072933085218
The ACA morph at my house (built by a very nice and very talented fellow on the Polk Audio forums) was a somewhat radical re-imagining with somewhat tarted-up choice of passive parts (capacitors) and built as a stereo amp using the "Bottlehead" (kit) amp form factor and active (fan) cooling rather than "just" a heatsink.
DSC_2871 (2) by Mark Hardy, on FlickrDSC_6923 (2) by Mark Hardy, on Flickr
mhardy6647
Lunatic Member
Oh, one other thought.
The little (and even less hifi) R/S "SA-10 integrated amp probably (???) had even lower power output at "hifi" levels of THD.
Used to have one that I picked up cheap at a semiannual antique radio/audio fleamarket/swapmeet here in New England and used (for a while) as a bench test amp.
source: https://www.radioshackcatalogs.com/flipbook/1979_radioshack_catalog.html
P2170002 by Mark Hardy, on Flickr
P2170005 by Mark Hardy, on Flickr
EDIT: 1980 brought us the "modern" looking SA-102
(no outpower spec given)
source: https://www.radioshackcatalogs.com/flipbook/1980_radioshack_catalog.html
... and 1985, the SA-150
https://www.radioshackcatalogs.com/flipbook/1985_radioshack_catalog.html
The little (and even less hifi) R/S "SA-10 integrated amp probably (???) had even lower power output at "hifi" levels of THD.
Used to have one that I picked up cheap at a semiannual antique radio/audio fleamarket/swapmeet here in New England and used (for a while) as a bench test amp.
source: https://www.radioshackcatalogs.com/flipbook/1979_radioshack_catalog.html
P2170002 by Mark Hardy, on FlickrP2170005 by Mark Hardy, on FlickrEDIT: 1980 brought us the "modern" looking SA-102
(no outpower spec given)
source: https://www.radioshackcatalogs.com/flipbook/1980_radioshack_catalog.html
... and 1985, the SA-150
https://www.radioshackcatalogs.com/flipbook/1985_radioshack_catalog.html
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Lavane
Lunatic Member
I had one of those amps I used for testing. Several years ago another AK'r had that set and the amplifier died. So I boxed mine up and sent it to him so he would have his matching set again.can't argue with the power rating but that would be considered an integrated. I sold a few of them when they insisted.
they did look cute with the matching tuner.
Lavane
Lunatic Member
Cool! I think that's the lowest powered SET amplifier I've seen. I guess that makes my 7wpc 300B a monster amp.
mhardy6647
Lunatic Member
I've long thought of SE 300B as big power.Cool! I think that's the lowest powered SET amplifier I've seen. I guess that makes my 7wpc 300B a monster amp.
I am pretty much a confirmed fleapower guy myself.
Just listened to War's Why Can't We Be Friends? via SE 2A3 on the big boy Frankenaltecs. Much fun was had.
DSC_0938 (3) by Mark Hardy, on Flickr
Lavane
Lunatic Member
I don't have any speakers that efficient yet. My lowest powered amplifier is a 5.5wpc spud amp I built. It uses a single horizontal sweep tube per channel.I've long thought of SE 300B as big power.
I am pretty much a confirmed fleapower guy myself.
Just listened to War's Why Can't We Be Friends? via SE 2A3 on the big boy Frankenaltecs. Much fun was had.
Driver and output in one bottle. Single ended pentode wired UL. Its the one in my avatar. Low powered amplifiers can sound very good. I'm starting to really like SE amps.
Lavane
Lunatic Member
There is a thread on one of these. The person recapped it along with a few other things. I think it was an earlier version with discrete outputs.
mhardy6647
Lunatic Member
I thought about spiffing up the one that was once here -- thus the topless photo above
I looked at it, listened to it, and said to myself yeah, no.
While it might have been kind of fun, I am pretty darned lazy.
The one I have here has four little output transistors. It's cute.
The thing it really needs in order to be viable today is a headphone jack.
Lavane
Lunatic Member
At only 1.2wpc, it would be easy to do if there is room. Or just get a set of RCA plug to 1/4 jack cables. And use it as a headphone amp. M6 heasphone amp is rated at 1.4wpc into 16 ohms. That does drop a bit when selecting 32, 64, 300 or 600 ohms.
I thought about installing one, but I didn't have one on hand that would work the way I wanted while I had it apart to deoxit the controls.
