If using tubes, then SET is definitely the way to go with such a low Qts driver and preferably with a ~matching impedance.
GM
If I get a good opt for SE, will these tubes deliver a nice bass sound? Or with SE you sacrifice some bass to quality overall? Or is this only a myth?
I run 206e's with single ended amps and I'm very happy with the bass, I tried out a high end solid state amp and wasn't impressed. I think a lot might depend on output transformers though and good ones tend to be very expensive I believe.
Audio Note Conquests and Audio note Kit 1. A friend of mine recently built SET monoblocks using 6c33c's and they are very impressive, I think a valve built by the Soviet military to go in a jet fighter has got to be good, it's definately where I'm going next.
It maybe best to try a simpler OTL high impedance amplifier ( with less neg. feedback applied ) - they may work better with low QTS speakers which helps to extend bottom end by wide margin ( according to Nelson Pass test of full-range speakers with high impedance amplifiers ).
Check the following site: The OTL5998L amplifier - about very simple 5998 OTL amp designed for full-range speakers...
I never heard this amp, but have very positive experience with Glass Audio OTL 6AS7G I build 11 years ago...
Check the following site: The OTL5998L amplifier - about very simple 5998 OTL amp designed for full-range speakers...
I never heard this amp, but have very positive experience with Glass Audio OTL 6AS7G I build 11 years ago...
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This seems like a nice project, but I think this would be my next one, after I finish the one that I started. I bought some stuff and would hate to put it on a shelf. Input tranny, tubes, sockets, passive parts that most I will not use in the next project. So I am trying to work with what I have at the moment. For input stages I have E88CC, 6n1p-ev, 6n2p-ev, 6n6p and for output only EL84. So I am looking to keep the input transformer with 240V on secondary and 2x6.3V, maybe get SE OPTs and try a SE schematic using EL84. Would be a shame and waste of money to put everything aside and get new opts, input tranny, tubes, passives etc...
Hi, in this case I can't think of anything better than Decware SE84C single ended triode connected amp with so many happy customers around globe...
Check following site: http://www.decware.com/newsite/ZKIT1schematicrev2011.pdf
I did build this version with my own parts - a very good sounding amp, or maybe pentode connected like RH-84 for more power from the same tube...
Site: RH 84 - Tube Audio ...... RH DESIGN
And a photo of my version of EL84 PP triode connected some years ago ( before Baby Huey existed )...
Max
Check following site: http://www.decware.com/newsite/ZKIT1schematicrev2011.pdf
I did build this version with my own parts - a very good sounding amp, or maybe pentode connected like RH-84 for more power from the same tube...
Site: RH 84 - Tube Audio ...... RH DESIGN
And a photo of my version of EL84 PP triode connected some years ago ( before Baby Huey existed )...
Max
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Very cool tube clock back there!
I will have a look on this website. Thank you!
My bad, am tired and didn't see that you actually built what you linked here. Thanks for the info. The voltage required is quite high, 346V, I would need a choke in my psu to replace a resistor so I might get to 340V.
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Hi, Decware amp will also work with lower voltage than specified - my EL84 SET was happy with approx. ± 300V DC on EL84 plates - don't feel put-off if you don't have all the parts according to drawings - feel free to explore and modify until it works with what you have at hand...
This is the photo of my prototype EL84/SV83 SET amp based on drawing from Decware but with parts from old Philips radios...
Max
This is the photo of my prototype EL84/SV83 SET amp based on drawing from Decware but with parts from old Philips radios...
Max
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What's the fourth tube for? And what kind of tube is that? Where are the opts as well? Is that a PSU case?
-What's the fourth tube for? And what kind of tube is that? Where are the opts as well? Is that a PSU case?-
Tube in the back is EZ81 tube rectifier and output transformers are hidden inside the chassis ( yes it is power supply case from old power Mac ) because of small size + they are very ugly to look at... sound wise is superb - a very high quality amp for little money - if you have sensitive enough speakers!
Max
Tube in the back is EZ81 tube rectifier and output transformers are hidden inside the chassis ( yes it is power supply case from old power Mac ) because of small size + they are very ugly to look at... sound wise is superb - a very high quality amp for little money - if you have sensitive enough speakers!
Max
Nice setup. I can't spare voltage on a rectifier tube, but the rest seems like I could do. Got a nice collection of parts by now and I guess I could try both setups that you presented here. Thank you
Hi Trileru, I hope you don't mind a n00b poking his head in your conversation. I have FE206E in Dallas II cabinets that I built in 2004. I still have the plans in jpg files. They are in decimal/inch x~y coordinate style. Ron Clarke designed so one 4x8 sheet of 3/4" cabinet grade plywood could produce one cabinet. I posted a picture of one that I took last night in the picture thread of this forum and there is a interior shot I took during construction on Planet10's site. I have more pictures that are no longer hosted. PM me and I could email you what I have.
In your first post you said you have no interest in powering them with a chip amp. Then I read this post by GM
My Dallas have never seen a tube amp and I wonder what I'm missing. I first used a RCA 5.1 receiver while I built a My_Ref chip amp. I had it working and then built a Kookaburra preamp but hooked up the trafo wrong and killed both the pre and My_Ref. Later the RCA died and I got a Nakamichi TA-2A 50Wx2. It took hardly any of the SS amp's power to reach a comfortable listening level but when I wanted to show off to my friends the FE206/Dallas could handle all the Nak could throw at them; the air would just become electric as conversation became impossible. Loud and clean with fast bass (around 45-50hz corner loaded in a room similar sized to yours) . Up-front presentation but not great depth or placement. A bit grainy and ragged response but very good detail. The only thing I have more detailed is Etymotic plugs. Very dynamic compaired to my old speakers, Niles 5.25 2way.
Sorry to be long winded but my Nakamichi was hit by lightning, it's pre is gone. I was reading this thread and ordered the LePai T-amp last night as a stop gap measure. I read your thread in the Tube section this morning, didn't understand much. Someone said you should build a bigger amp like a Dynaco 70. I agree but there is so much I don't understand. Why is the Baby Huey so well suited to the FE206E ?
In your first post you said you have no interest in powering them with a chip amp. Then I read this post by GM
My Dallas have never seen a tube amp and I wonder what I'm missing. I first used a RCA 5.1 receiver while I built a My_Ref chip amp. I had it working and then built a Kookaburra preamp but hooked up the trafo wrong and killed both the pre and My_Ref. Later the RCA died and I got a Nakamichi TA-2A 50Wx2. It took hardly any of the SS amp's power to reach a comfortable listening level but when I wanted to show off to my friends the FE206/Dallas could handle all the Nak could throw at them; the air would just become electric as conversation became impossible. Loud and clean with fast bass (around 45-50hz corner loaded in a room similar sized to yours) . Up-front presentation but not great depth or placement. A bit grainy and ragged response but very good detail. The only thing I have more detailed is Etymotic plugs. Very dynamic compaired to my old speakers, Niles 5.25 2way.
Sorry to be long winded but my Nakamichi was hit by lightning, it's pre is gone. I was reading this thread and ordered the LePai T-amp last night as a stop gap measure. I read your thread in the Tube section this morning, didn't understand much. Someone said you should build a bigger amp like a Dynaco 70. I agree but there is so much I don't understand. Why is the Baby Huey so well suited to the FE206E ?
Squalor:
I think the question of what tube type/power level might be "so well" or "best suited" to your 206s would be very subjective - certainly much bandwidth has been/will continue to be spent discussing the matter.
FWIW it's been my experience that drivers of this class would be very enjoyable in an enclosure that squeezes as much performance from them as would the Dallas, an far less than a ST70.
Several of the EL84 based SE amps named are pretty simple builds, particularly if you have a bin of salvaged parts - indeed my first 3 or 4 scratch builds of Zen and RH84 inspired designs were heavily scavanged from Grundig / Nordmende etc consoles and mantle radios. The RH84 is particularly a giant-killer.
If lacking a fully stocked parts bin, another piece to consider would be the Bottlehead Stereomour - stereo integrated 2A3 .
I think the question of what tube type/power level might be "so well" or "best suited" to your 206s would be very subjective - certainly much bandwidth has been/will continue to be spent discussing the matter.
FWIW it's been my experience that drivers of this class would be very enjoyable in an enclosure that squeezes as much performance from them as would the Dallas, an far less than a ST70.
Several of the EL84 based SE amps named are pretty simple builds, particularly if you have a bin of salvaged parts - indeed my first 3 or 4 scratch builds of Zen and RH84 inspired designs were heavily scavanged from Grundig / Nordmende etc consoles and mantle radios. The RH84 is particularly a giant-killer.
If lacking a fully stocked parts bin, another piece to consider would be the Bottlehead Stereomour - stereo integrated 2A3 .
I'd build to test RH84 but I don't have an ECC81 tube (gain of 60) only 6n1p-ev( gain of 35) and 6n2p-ev (gain of 100). Would it be wise to sub with one of these? With their specific resistors of course. Or is that scheme based on the gain of 60 from ecc81?
Well it was a fair while ago that I built my little RH style amps (after several virtual clones of Decware Zen which uses 6n1P/6922 etc to great effect) and they were actually a "mash up" of several ideas, with some help from a chap named Eddie. The driver in fact was EF86, triode connected, as was the EL84 - I was big on the SE triode sound at the time.
Power and output XMfrs and even tube sockets on this pair of mono blocks were scavanged from old European console radios, hence the EZ81 rectifiers (great within its dissipation limits) and derived center tap. Due to concern over lifespan of power transformer, separate filament transformer was used - a cheap Radio Shack center tapped 12.6V that was easily converted to dual 6.3 secondaries.
Parafeed output connection was used due to the limited bandwidth of small OPTs.
Altogether total cost of new parts, including the Hammond chassis, chokes and film caps for power supply and parafeed connection was less than $150
In theory the latter tube should work. RH-style feedback likes to see a high output impedance from the driver stage.
dave
Like most things, it depends. If you don’t match up the amp to the speaker properly and/or don’t design the speaker for the app properly, then it can sound pretty bad.
It’s really sad how nowadays few tube amp manufacturers publish the output impedance or its damping factor [DF] to derive it and fewer still that recommend a correct range of speaker designs suitable for amp model ‘xyz’, etc., so it’s a real crap-shoot for the uneducated buyer to get a good match-up.
The easiest way to compare performances is to use WinISD Pro or similar that allows you to add series resistance to see how high output impedance impacts a particular speaker alignment. Note that it’s normally best to tune the cab so that the two impedance peaks are at the same amplitude with such match-ups.
Obviously, if you design a cab for the 206E or similar low Qts driver just using its T/S specs, you get a tiny cab tuned well above Fs, so an Fs tuning would make it extremely over-damped. Add some series resistance and at some value it will become maximally flat, then increasingly under-damped with increasing resistance; so at this point the cab’s net Vb must increase to keep it from sounding ‘boomy’/’flabby’, a common problem with mating SETs to the higher Qts drivers common today, i.e. designed to be driven with a very low output impedance typical of SS amps.
If you don’t want a bigger cab, then the only alternatives is to either ‘critically’ damp the vent or in extreme cases, the entire speaker to make it ~aperiodic. Some folks get with acceptable results by trying different tunings to mismatch the amp/speaker impedance, but these aren’t predictable with any speaker design program I’ve used, so AFAIK must be found empirically.
Once all this is dialed in, the system’s bass quality [SQ] will still depend on the room’s impact on it and the amp’s tube, OPT, etc., selection and why I long ago switched to high SQ SS amps and EQ driving low Qt speakers to get the kind of bass response I demand.
GM
I haven't reverse engineered it, any idea what output impedance it was optimized for? I mean, at a glance, its filter chamber looks small enough to only be suitable for a P-P's ~0.8 ohm at most, so even a modest SET of ~2.5 ohms would make for a pretty 'warm' [by my standards] mid/bass performance.
GM
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