Thanks for the reply Eli, I might push up my budget a little for better o/p iron, (this would also allow more tube upgrades down the road correct?}
What is gnfb?
GNFB is global negative feedback. The O/P trafo in the 6BM8 setup is inside a NFB loop.
"Gimpy" calmed my fears about getting a SE84 "knockoff" done, within budget. My hunch is that you will be more content with triode wired 6V6 family tubes.
Each O/P tube type has its own needs in the O/P "iron" dept. Stick to the affordable Edcor model. Save the extra money for your next project or buy some recordings.
"Gimpy" calmed my fears about getting a SE84 "knockoff" done, within budget. My hunch is that you will be more content with triode wired 6V6 family tubes.
Each O/P tube type has its own needs in the O/P "iron" dept. Stick to the affordable Edcor model. Save the extra money for your next project or buy some recordings.
Me too! I settled on LA Scala's which I am very happy with. They sound great with SET amps🙂
Eli-
What would be your 'top' recommendation for a triode-wired 6V6 SE amp?
Thanks
John
The schematic I found shows that the Zen SE84 is pretty simple-looking. Was it the desire to 'not build a copy' or parts expense that led to the knockoff?
I can't design interesting amps 'from scratch' so it seems to me that just copying the Zen would be the easiest if I wanted another EL84 type amp. (The Zen schematic shows SV83s which are even cheaper than EL84s.)
I built this little 6V6 SE amp, Love it, it sounds great and clear and clean at full volume, It's around 6 Watts. I did remove the 110k resister and put the wiper to the grid. I also beefed up the power supply a bit.
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The 6GE5 is very similar to a 2A3 except for the heater supply. It should work well in an SSE but I haven't tried it.
My plesure.
I was piggybacking this thread to get a opinion about my schematic from the more experienced people here (and I thanks Jeff for the answer - still waiting a opinion about the G2 resistor value 🙂.
If you need a physically small and compact amplifier in the 3 - 4 w power range, the schematic I posted works well, it is cheap, easy to build, almost no background noise and will tolerate a wide range of component variation/substitutions. It is a 1965 schematic that has been implemented countless times on 1960's era radios and small consoles, it definitely works. Jeff Yourison posted a sample of the equally good 6BM8/ECL82 variation. Just don't skimp on the output transformer quality.
If your budget is a little higher and a bigger chassis is no issue, I second the idea of the 6L6 / 6V6 amplifier because it is more customizable and powerful. I have one myself and after a bit of tube rolling I ended up fitting it with EL34 tubes.
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Here is a thread on a SE 6L6 amp. The only change I would make would be to replace the second 6SL7 cathode follower with a FET Source follower and just use one tube for both channel common cathode stages, and change the 200 Ohm cathode resistor to 250 Ohm. A 2Watt resistor would be sufficient.
http://www.diyaudio.com/forums/tubes-valves/226200-easy-little-6l6-se.html
http://www.diyaudio.com/forums/tubes-valves/226200-easy-little-6l6-se.html
Yes. There are actually two parts lists and at one point they didn't match. I checked and they now match. The purchasing list was always correct.
Thanks for the reply's everyone. So consensus says for what I am looking to accomplish I should go for the Decware SE84 tube amp?
Thanks!
Thanks!
I'd wait for Jeff and Eli to weigh in on that before deciding which to build - the Decware Zen SE84 or one of the 'knockoff' circuits with different tubes.
Here's the rest of the page that I found with the Decware schematic:
Consensus! We don't need no stinking consensus! in my best Scarface impression.
But seriously, every one has their own favorite it seems, and since no one has stepped up for the RH84 amp i will do that since i have made 5 of them and 7 higher powered versions of the same basic circuit. I have also rebuilt more than 5 other SE el84, and 7868 amps of Magnavox, Zenith, RCA, Airline, EICO, Monarch, etc, brands. and the best sounding of all of these is the RH84. I won't qualify that statement since deciding, i have built at least 12 of them. I am not the only one who feels that way as they are literally hundreds, probably thousands of these little amps. Here is the circuit.
RH Amplifiers: RH84 amplifier - revision 2
In this version the el84 bias is set by a LM317 voltage regulator. This works well but some don't like a SS device handling part of the sonics so you can replace it with a 270 ohm 3 watt resistor bypassed by 1oouf x 25 vdc cap.
If you search thru the blog you will find other schematics with different power tubes. I found that the 4 watts from the el84 is adequate but 6 to7 watts from the same circuit at higher voltages is better. And the better the output transformers the better your sound quality. The better your power supply, the better sound quality. CLC is the minimum, and CLCLC is better, and if you can manage a high voltage power trans then LCLC has better voltage regulation which is the best sounding all things being equal.
In general if you have not made many amps start with a simple el84 type console amp and hone your skills with that then step up to a higher powered version with better parts for an even better sonic experience. You should be able to get a SE console amp for less than 100 and the new parts would only cost a few dollars more. Good luck
But seriously, every one has their own favorite it seems, and since no one has stepped up for the RH84 amp i will do that since i have made 5 of them and 7 higher powered versions of the same basic circuit. I have also rebuilt more than 5 other SE el84, and 7868 amps of Magnavox, Zenith, RCA, Airline, EICO, Monarch, etc, brands. and the best sounding of all of these is the RH84. I won't qualify that statement since deciding, i have built at least 12 of them. I am not the only one who feels that way as they are literally hundreds, probably thousands of these little amps. Here is the circuit.
RH Amplifiers: RH84 amplifier - revision 2
In this version the el84 bias is set by a LM317 voltage regulator. This works well but some don't like a SS device handling part of the sonics so you can replace it with a 270 ohm 3 watt resistor bypassed by 1oouf x 25 vdc cap.
If you search thru the blog you will find other schematics with different power tubes. I found that the 4 watts from the el84 is adequate but 6 to7 watts from the same circuit at higher voltages is better. And the better the output transformers the better your sound quality. The better your power supply, the better sound quality. CLC is the minimum, and CLCLC is better, and if you can manage a high voltage power trans then LCLC has better voltage regulation which is the best sounding all things being equal.
In general if you have not made many amps start with a simple el84 type console amp and hone your skills with that then step up to a higher powered version with better parts for an even better sonic experience. You should be able to get a SE console amp for less than 100 and the new parts would only cost a few dollars more. Good luck
If you want a nice linear triode amp with more power than the Decware SE84 you can try this. To make the build less expensive you can use Edcor Iron and don't split the power supply into two channels; E.G. Disregard where it says "copy for other channel", just tie both channels to the same power supply nodes.
The 6HJ5 is cheap $4 and has extremely linear curves similar to a 300b, you won't get the same power as a 300b for it is a 24 watt tube but you will get +3db over the Decware amp and did I mention the tubes are cheap 😉
A fellow member is building one with a single 5670 to drive the 6HJ5's so I intend to update the schematic for him and post it. Having only one driver tube cuts down on the cost and parts count. You can easily build this amp for $300 and it sounds great.
The 6HJ5 is cheap $4 and has extremely linear curves similar to a 300b, you won't get the same power as a 300b for it is a 24 watt tube but you will get +3db over the Decware amp and did I mention the tubes are cheap 😉
A fellow member is building one with a single 5670 to drive the 6HJ5's so I intend to update the schematic for him and post it. Having only one driver tube cuts down on the cost and parts count. You can easily build this amp for $300 and it sounds great.
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I'm with DAK on this recommendation. I've built a few RH84s and they are great little performers - and very tolerant of parts selection (cheap console scavenged OTs, PTs that don't deliver exactly the right B+, etc).
You realize that the DECware zen outputs less than 2watts from its triode connected sv83 power tube. My Altec 19 speakers are about 100db efficiency, and i can easily hear the difference between 2 and 4 watts, 4 and 8 watts. The higher power manifests as more impact and more definition even at the same sound pressure levels.
Since the DEC uses no feedback they need to use triode mode for the power tubes to achieve adequate speaker damping. cheers.
Dak808 can you give me an example of say Edkors CLC, CLCLC, LCLC , Meaning a model number for each?
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