Browsing this forum (also did a "flea power amp" search) but could not find a suitable amplifier to build for my bedroom.
I think about 5W output power is more than enough and because I have 4 0A2 stab tubes in stock I am intended to use a 150V supply.
Any ideas to realize this are most welcome.
I think about 5W output power is more than enough and because I have 4 0A2 stab tubes in stock I am intended to use a 150V supply.
Any ideas to realize this are most welcome.
5W at 150V of plate supply will be a hard gig - you're pretty much limited to low-voltage high-current tubes. Those tend to have low amplification factor, so separate negative bias supply is needed (and with a healty voltage - 50 to 100V probably), and a good voltage swing from a driver is required too (which is also hard to do at low plate voltage, at least without interstage transformer).
Or do you mean 150V regulated screen voltage and some "normal" (~300V) unregulated plate voltage?
Or do you mean 150V regulated screen voltage and some "normal" (~300V) unregulated plate voltage?
Hi Joe,
Nothing wrong with running the output stage at 250 VDC (happy spot) and your signal stage can run at 150VDC. You don't need to regulate the the outputs at all. In fact, going P-P with 6BQ5 will give you a little more power, nicer sound and just generally a happy amplifier. With the first stages regulated, expect very low noise / hum.
Sounds like you are on the way to making one heck of a nice little amplifier. The extra headroom will be welcome and a P-P output will draw less power than anything single ended at those power levels (5 watts).
The best part is, there are many really high quality 6BQ5 P-P designs out there. Adding the regulated signal stage will be a big improvement on them.
-Chris
Nothing wrong with running the output stage at 250 VDC (happy spot) and your signal stage can run at 150VDC. You don't need to regulate the the outputs at all. In fact, going P-P with 6BQ5 will give you a little more power, nicer sound and just generally a happy amplifier. With the first stages regulated, expect very low noise / hum.
Sounds like you are on the way to making one heck of a nice little amplifier. The extra headroom will be welcome and a P-P output will draw less power than anything single ended at those power levels (5 watts).
The best part is, there are many really high quality 6BQ5 P-P designs out there. Adding the regulated signal stage will be a big improvement on them.
-Chris
ECL82 is your goto for a flea powered amp. Forget your 5w requirement - you really only need 1-2W and this can be achieved well with the ECL82 and a low B+.
6AS7 can produce 7watts at 150V in PP, but its heavy lifting with lots of Iron so I would advise against it for a small bedroom amp.
Its better to go for flea powered in this scenario and rethink your speakers than to try to up your wattage.
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I used to have a little SE ECL82 amp as my bedroom map and it sounded really well. i also had a E55L SE bedroom amp which sounded even better. However I now have a small gainclone with SMPS in the same roll. The reason I switched is because I can leave the gainclone on all the time for negligible power wastage which allows my Kodi box to act as an alarm clock and a go to sleep radio which switches off after a set amount of time (ie when I fall asleep). This was the painful thing about my Bedroom valve amps - you had to get out of bed to switch them on and off.
Shoog
6AS7 can produce 7watts at 150V in PP, but its heavy lifting with lots of Iron so I would advise against it for a small bedroom amp.
Its better to go for flea powered in this scenario and rethink your speakers than to try to up your wattage.
----
I used to have a little SE ECL82 amp as my bedroom map and it sounded really well. i also had a E55L SE bedroom amp which sounded even better. However I now have a small gainclone with SMPS in the same roll. The reason I switched is because I can leave the gainclone on all the time for negligible power wastage which allows my Kodi box to act as an alarm clock and a go to sleep radio which switches off after a set amount of time (ie when I fall asleep). This was the painful thing about my Bedroom valve amps - you had to get out of bed to switch them on and off.
Shoog
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Browsing this forum (also did a "flea power amp" search) but could not find a suitable amplifier to build for my bedroom.
I think about 5W output power is more than enough and because I have 4 0A2 stab tubes in stock I am intended to use a 150V supply.
Any ideas to realize this are most welcome.
PP 6FE5s. PP KT55s if you can find some Or KT33. 7W on 150V supply no problem.
Attachments
I know for our bedroom a small form factor would be a must, not much dresser or nightstand space. So maybe something built with all 7 pin miniature sockets? 6AQ5 comes to mind, its a 6V6 mini, maybe with a 6N1P input stage and concertina Splitter. A couple of smaller Edcors and an Antek torroid for power they are more compact. For some fun a small 8 inch solid state subwoofer under the bed, then you could cut the amp off at 70 hz to open up some nice midrange headroom for the speakers and smaller OPTs that wont have to deal with bass power levels.
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Since having a sub I would never go back, I even built a small one for the bedroom which sits in a cupboard. Fills out the sound no end and releases the main amp to do more at the top end.
A decent sub can be built with a €10.00 chinese digital sub amp with variable crossover and a 4" bass driver.
Shoog
A decent sub can be built with a €10.00 chinese digital sub amp with variable crossover and a 4" bass driver.
Shoog
Many many thanks guys for all your valuable suggestions!!
Much appreciated. Will carefully look at all of them to see if this will result in a first design attempt.
Up to this moment I was only designing amps for headphone use.
In the meantime when I was browsing this forum for ideas and before starting this one, I have completely overlooked this thread:
Low Voltage (60V) Stereo Tube Amplifier for Dummies (2+2W)
Will carefully read it.
But please, keep coming with your selections.
Much appreciated. Will carefully look at all of them to see if this will result in a first design attempt.
Up to this moment I was only designing amps for headphone use.
In the meantime when I was browsing this forum for ideas and before starting this one, I have completely overlooked this thread:
Low Voltage (60V) Stereo Tube Amplifier for Dummies (2+2W)
Will carefully read it.
But please, keep coming with your selections.
Sorry I do not what you mean with this. Are these boards available you mean?
At low listening levels of a bedroom amp, for me at least, bass notes simply disappear. If no sub then maybe a loudness control would be great for a bedroom amp. With a wife and impending sleep I mean we are talking about very low listening levels, not enough to excite any speaker in the bass range adequately. Human ears are the least linear at low volume levels on top of a speaker not moving any air for bass notes.
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Hi Joe,
A P-P circuit uses smaller output transformers and cancels hum. These are popular and probably less expensive to build while having lower distortion than a single ended.
There is a good reason why they moved to P-P designs in the late 20's and 30's. You don't have to use the power, and low power running will simply provide cleaner sound and lower distortion.
-Chris
A P-P circuit uses smaller output transformers and cancels hum. These are popular and probably less expensive to build while having lower distortion than a single ended.
There is a good reason why they moved to P-P designs in the late 20's and 30's. You don't have to use the power, and low power running will simply provide cleaner sound and lower distortion.
-Chris
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