Spring and Fall are the best seasons to enjoy food and drinks on our deck. To complement the beautiful atmosphere, I assembled an e-z to set up and dismantle hifi system!
Music Source
This stack consists of a Raspberry Pi 3B loaded with Volumio music player/streamer tethered to a Signstek USB to SPDiF converter which connects to a Muse TDA1543x4 Non-OverSampling DAC.
Volumio offers a wide choice of radio stations streaming MP3 files up to 320 Kbps. The Radio Paradise channel has even started broadcasting FLAC files. 👍
Amplifier
In the late 80s, I built my first amplifier from scratch using transformers from a cosmetically challenged Dyna SCA35. I used this paraphase circuit from the Dynaco Transformer Catalog with a 6SL7 driving a pair of push-pull 6V6s. Musically, I preferred this amp to my then highly modified Dyna ST70 and pair of MKIVs.
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| with 6F6Gs courtesy of John Piro |
Since I always had reservations about the 1626 triode's musical abilities, I converted the JEL Darling Style amp to use triode connected 6V6s. Wow!👍
!!!WARNING!!!
The voltages in this circuit are potentially lethal! Build at your own risk!
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| Input sensitivity = 0.3V, no need for a preamp This amp also does a good job of driving my collection of orthodynamic headphones via adapter. |
Triode connected 6V6s mimic directly heated triodes much better! 🎻🎸
Speakers
This pair of Electro-Voice Sonocasters came from the flea market. I guesstimate the sensitivity to be in the mid 90s dB @ 1W @ 1M. Driven by 1.4 triode watts per channel from the SE6V6 amp, I sure won't be annoying the neighbors. 🤣
The 8" drivers are unmarked but look very much like MC-8s - not quite an Altec 755C or Pioneer PIM8L in terms of refinement or realism, but not too shabby either + a lot more rugged!
Hello! How much is the load resistance you recommend? Using an ultra linear transformer would be a good idea? Then how much would be the load resistance of primary? Thanks in advance!
ReplyDeleteBest,
Martin
Since the 6V6 in triode has a plate Z = 1960 ohms, rule of thumb is to load it at 2.5 > 3 times the source Z. The surplus Sony RTR OPT I used = 5K primary Z. I have no experience with UL transformers in single ended, sorry.
DeleteGreat! I didn't know this rule of thumb, thanks!
DeleteIt's curious that I can't find much information around about UL on single ended.
It's no different to driving power amps from a lower source impedance preamp.
DeleteBack when I used to modify (hack) Dynakits and Eicos, I realized that PP EL84 and PP EL34 connected in triode sounded much better especially if negative feedback is lessened. Ultra-linear was developed as a compromise to preserve some of the "linearity" of a triode + the efficiency of a pentode, necessary to drive inefficient speakers.
Some Japanese SE OPTs have UL taps but I never used them since I've built mostly DHT SE amps. In this particular project, I wanted to mimic the sound of a DHT, hence, triode 6V6 connection.
Hi JE. Happy Holidays. I would like to build the 6v6 se will a 6sl7 be okay to use without changing anything on the circuit? Thank you
DeleteYes!
DeleteHi JE, Happy New Year. I would like to thank you for sharing the 6v6 set amplifier. I finished the build and it sounds great. I used the 6sl7 and did not change anything. Kindly let me know if my voltages on the 6sl7 are okay. I got 170v at the plate and 1.2v at the cathode. Will increasing it be better? Thank you and you are very much appreciated.
DeleteKeep it as-is and enjoy. Happy 2023!
DeleteHello! I built it and it's sounding just wonderfully (enough to my sister asking one for herself! :D ). I made a few small changes as I wanted an mono amp - power supply and adding a RCA mixer with 6SC7. Anyway this circuit surprized me because the great sound.
ReplyDeleteGlad you like it, happy listening!
DeleteHello! How are you?
ReplyDeleteI liked so much this amp that I would like to build another one, but now stereo and slighty more powerful. So I thought about 6L6GB or 6P3S. Z load 5k, as TungSol manual says. Do you think that the 6F5 circuit will be OK with 6L6, just altering the 470k to 250-270k (as the middle point of maximum rating)?
The 6L6 I would put 320V. Current 60mA, so plate dissipation would be 19W. Cathode resistor would then be 420 ohms.
(Of course the power supply would be quite different but that's easy).
Thanks in advance!
Best,
Martin
As you probably know by now, my formal training is in classical music and not engineering.😊 I'm mainly an avid audio DIY hobbyist. That said, the 6F5>6V6 circuit above is very similar to the Simple 45 circuit I formulated in the mid 90s - http://jelabsarch.blogspot.com/2012/06/je-labs-simple-452a3.html - in this article I basically chose my operating point (and tweaked by ear) based on the resistance-coupled amplifier chart for the 6SL7 as provided by RCA.
DeleteThe last 6L6 type amp I owned was a pair of Heathkit W4 amps with 5881s in the early 90s. Back then, I preferred EL34 and EL84 based amps. But don't let that stop you from building your proposed 6F5>6L6 amplifier. You have to hear and tweak it to satisfy your musical tastes.
Here's a Resistance-Coupled Amplifier Chart in pdf -http://www.tubebooks.org/tubedata/hb-3/Receiving_Tubes_Part_1/Resistance-Coupled_Amplifiers.PDF - I'd consult the 12AX7 chart as the equivalent of a 6F5.
Good luck!
But surely your circuits are far better than most I have heard around... ;) I'm not an engineer either - just have been playing and listening records for a looong time.
ReplyDeletePerhaps it's mere coincidence that we have similar tastes(?). But I appreciate your kind words!
Delete