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Poor man's tube system?

Discussion in 'Tube Audio' started by bbqjoe, Oct 31, 2018.

  1. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    Would there be any benefit realized if one took a headphone tube amp with preamp outs, and fed it to an integrated amp?
    My Onkyo amp has the direct source function, and I assume this only bypasses the tone controls, not the amps preamp.
    Would this then be doubling the preamp?
    Would this be stupid?
    Would it be worth it?

    And if so, does someone here have that perfect headphone amp, with the perfect tubes that might save someone such as myself from excessive experimentation?

    I hope this isn't one of those already beat to death topics.

    If so, I'll gladly settle for some links.

    Thanks.
     

     

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  2. linuxslate

    linuxslate Member

    Messages:
    87
    Location:
    Central Florida, USA
    It is, but that's OK. We like to talk about this stuff, and each new thread brings new insight.

    In another post, I mentioned that using a tube pre-amp with a solid state power amp does make sense, where as the opposite really doesn't (in my opinion).

    I used to work in night clubs and disco's with racks of 1000W plus amps. When I was working during the day, the system was powered, but idle. You could hear the hiss that was being generated by the noise of the thousangs of semiconductors in the pre-amps, mixers, equalizers etc. Most of this noise was not comming from the final sections of the power amps, they were just amplifying the noise of the stages before them.

    I used to call it "Johnson noise" but that is not really the correct term. (and I've learned my lesson about using incorrect terms on these forums:whip:).

    The point is that tubes don't make the noise that semiconductors do. Less noise on the input means less noise that is amplified in the later stages.

    I can't really make a recommendation on specific tube preamps, since I don't have one.
     
  3. primosounds

    primosounds SE KT120 w/ 6J5G drivers. Subscriber

    Messages:
    2,734
    Location:
    Terra, 21st century CE
    I am not sure what you are trying to accomplish with that set up. Are you trying to use the headphone amp output into your Onkyo because there would be a sonic benefit? It would be easy enough to try and if you like the result no harm, no foul. You would not be jeopardizing your equipment by doing that.
     
  4. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    Just the pursuit of the perfect sound on a budget I guess.
     
  5. Binkman

    Binkman AK Subscriber Subscriber

    Messages:
    6,555
    Location:
    Chapel Hill, NC
    Greetings;
    what model number onkyo?
     
  6. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    It's the non-existant A-RV401.
     

     

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  7. triode17

    triode17 Super Member

    Messages:
    1,319
    Yes, you can certainly do it, it would act like a tube buffer. High input impedance, low output impedance. I've done it, sounds good.
     
  8. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    My guess is that when the amp is put into direct source mode, it might not color the tube sound any?
    But then I see people "rolling" tubes all over the place $$$$$$
    And some of these headphone tube amps appear to be fake with the tubes doing nothing more than lighting up for looks.
     
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  9. Binkman

    Binkman AK Subscriber Subscriber

    Messages:
    6,555
    Location:
    Chapel Hill, NC
    Greetings.
    Worth it? have to review the sm. Has amp ever been serviced? i.e. cost of current amp caps vrs questionable tube pre. in good shape.

    for gentle readers..
    User and serv. manuals here.
    https://www.hifiengine.com/manual_library/onkyo/a-rv401.shtml
     
  10. tubeactive

    tubeactive AK Subscriber Subscriber

    Messages:
    206
    Location:
    NJ
    The Asian made, tube/hybrid headphone amp celebration occurred soon after the intro of the Musical Fidelity X-Cans. The Mk I and Mk II X-Can amps were in that cylindrical, aluminum case; they sounded as good or better than they looked. The first similar circuit, Hong Kong sourced, hybrid headphone amp I recall was the Indeed brand, with the familiar looking, tube popping thru the clear plastic top, cute chassis. I bought one as soon as I saw it available, even before they offered RCA output jacks. I knew the headphone amp could be utilized as a preamp...I simply had to wire up a stereo phone plug to RCA plugs adapter for an interconnect...

    Sound-wise, the first Indeed Tube/FET hybrid headphone amp, Indeed Gen 2 and Indeed Gen 3 sound excellent. Numerous family members have followed my lead and enjoy their units. These are not simply tube buffers, they have serious gain and drive. They are true hybrids, with the tube and FET active, not only sitting pretty. Of course, that funky looking, red LED underneath and blue LED glowing around the tube can be hypnotic...

    If an amp can drive 32 Ohm headphones, like Sony, think how easily that device can drive higher impedances with lower distortion ! The Indeed could even drive my ancient 4-8 Ohm Koss and Nakamichi 'phones. My more difficult to drive Sennheiser and AKG cans were easily driven to very listenable and loud levels by these hybrids. Driving a line level input will even be easier and will definitely function to "sweeten the sound" when connected between a CD player or other digital source through your solid state or future tube amps. With your digital sources, these hybrid headphone amps can certainly function (very well) as a tube buffer.

    I have used the Gen 2 as a stand alone preamp, driving tube power amps, and can vouch for its' abilities and sound qualities. Note that the Gen. 2 and Gen. 3 have switchable inputs, RCA jacks or stereo mini-phone jack, PLUS switchable filament voltage, 6 or 12 VDC, for 6DJ8 or 12AU7 tubes ! Did anyone say "tube rolling" might be fun ? Well, it certainly is nice to listen with and fun to decide on the tubes you prefer...

    As Indeed welcomed in the market, within a year, suddenly many brands appeared. Some sound great, but some do not ! Then, some companies decided to copy the Indeed product, like the Little Bear. They can sound nice too, but beware of the switching power supplies. Most of these "can" amps use switching mode power supplies, which emit too much EMI/RFI to nearby, high gain circuits like phono and mic inputs. The Lil Bear caused hum with a nearby record player, while the Indeed did not cause any problems; except having to spend more money for the Indeed products.

    I can heartily recommend this $50. to $100. expenditure, delivered to your door, of a genuine hybrid headphone amp (advertised as tube headphone/preamp so it will have the switchable inputs), can be well worth the trial. At the very least, you will have acquired a sweet sounding, tube/FET headphone amp which can drive low to high impedance headphones (now known as "cans"). However, their worth is probably even greater as an "audio sweetening" buffer with gain...ENJOY...
     
    Last edited: Nov 3, 2018
  11. illinoisteve

    illinoisteve Super Member

    Messages:
    3,073
    My poor man's tube system, if you can call it a system, is a fleawatt Motorola 3-channel (stereo mids & HF, and mono bass) receiver with a stereo RCA socket input, meant for a ceramic phono cartridge input. I pulled it from a Motorola coffee-table console that had already had it's turntable and almost all of its original speakers removed.

    I've just picked up a used "hybrid" tube headphone amp off of the auction site, separate reviews of which said the tubes (described as being part of a "pre-amplification" stage, not the solid-state amplification circuit) do give it a tube-ish sound. I'm not sure what the pre-amplification stage does; it can't be the power supply, since that's a little AC adapter you plug into the amplifier. Still, I am interested in hearing what it sound like when it arrives.
     

     

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  12. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    Thank you for a very in depth report.
    For the halibut, I'll give one of these indeeds a try. Indeed.

    Also, not being an electrical engineer, but yet having enough knowledge just to be dangerous, wouldn't a true stereo amp of any sort require a minimum of two tubes?
     
    Last edited: Nov 1, 2018
  13. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    Just wow. Almost every headphone tube amp including the Indeed is a month wait from China.
    No one appears to stock anything in the US.
    I love sending off for stuff, but the slow boat from China is a bit much for me.
    I'll admit here and now, I'm an instant gratification junkie.
    I see a lot of the Douk stuff on Amazon, but there's a mix of too much of it, and a whole lot of questionable reviews.
    I do see the little dot is readily available, but some of the reviews give me great hesitation.

    Please, someone correct me if I'm wrong here, but I keep coming across statements where folks are saying that tubes are much better for strings, jazz and vocals.
    I've read some that say right in their description that their tube amps aren't for "complicated" music.
    I'm pretty much stuck in the 60's to 80's and like a good amount of rock.

    Is there any truth to any of this?
    I realize a grain or two of salt is necessary when reading anything on the internet, but I feel like I might need a block of it at this point.
     
  14. s-petersen

    s-petersen Scott Subscriber

    Messages:
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    Location:
    Middletown,New York
    Many tubes have 2 internal sections, like a 12AX7, each section takes care of a channel
     
  15. bbqjoe

    bbqjoe New Member

    Messages:
    18
    Location:
    NW Arizona
    Thank you.
     
  16. triode17

    triode17 Super Member

    Messages:
    1,319
    OP said , "Would there be any benefit realized if one took a headphone tube amp..." I would say yes, if it's not a hybrid. It must be a true tube amp, all tube to make a sound difference. I built one that has two controls, Gain and Volume. With this I could increase the (tube) gain but lower the volume to compensate for the extra level added. Or use any combination in between. My first tube purchase was the Dyna ST-70 but I had to drive it from a SS preamp. The sound wasn't as good as when I got the PAS-3x preamp to mate with it. Then it sounded like a tube system. Best not to mix "apples and oranges".
     
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  17. Lavane

    Lavane AK Subscriber Subscriber

    Messages:
    7,398
    Location:
    northern cal.
    I bought a hybrid headphone amp with line out. Tube front end and single ended SS output. With better tubes it sounds good. It works well as a preamp as well. Very quiet too. Mine came in a metal case with wood front plate and knob.
     
  18. ldatlof

    ldatlof We are all steak Subscriber

    Messages:
    2,862
    Location:
    Las Vegas
    What speakers are you using? Why not buy a tube integrated amp? I just bought a completely refurbished plug and play Knight KA-25 for $188 including shipping from Barter Town. Sounds great. :music:
     
  19. mcgjohn

    mcgjohn Active Member

    Messages:
    117
    Location:
    Chicago area
    Poor man's system or not, tube systems can be had for a very reasonable price. So I would not restrict the effort to encompassing using your current solid state integrated amp.

    Lots of 1960s tube amps available for not a lot of cash, and TONs of gear available from China. All depends on how much power you need to drive your speakers.

    I have assembled a few tube systems for friends for under 500 bucks...tube amp, turntable, speakers and phono stage.

    lots of options...
     
    ldatlof likes this.
  20. mhardy6647

    mhardy6647 AK Subscriber Subscriber

    Messages:
    52,786
    I haven't exactly followed this thread,but I am guessing the OP might've asked about the simplest possible vacuum tube amplifier?

    We call 'em spud amps. Spud. A one tuber.
    (many of us suffer from profoundly atrophied senses of humor)

    It is possible to build a mono amplifier using literally only one tube (i.e., one tube functionality), but such an amplifier is meant more to be cheap than hifi.
    Here's an example: a stereo phonograph amplifier for inexpensive table top portables (of the early 1960s). The 60FX5 tube was specially designed to be "driven" directly by a ceramic type phono cartridge (about the same output as a "line level" component like a tuner, tape deck, or CD player). This particular design is of the AC-DC "series string" transformerless school of design. This type of circuit was also known as a "killer chassis" because there was no isolation between the AC mains and the user (except, usually, a plastic knob). It is possible to build an amp like this with an isolation transformer, rendering it safe(r).

    [​IMG]60FX5stereoampresized by Mark Hardy, on Flickr

    A more typical "spud" amp might use a single, two-section tube. Dan "Doc Bottlehead" Schmalle, in the 1990s, sold a very nice little two tube stereo amplifier, the "S*E*X" (for Single-Ended eXperimenter's) Amp. This used a two section twin triode as the voltage and power amplifier sections for each channel, and was a fine sounding little amplifier capable of about 2 watts per channel (fine for high-sensitivity loudspeakers). This amp, with two "physical" tubes (two "bottles", so to speak) has four functional vacuum tube elements (each physical tube contains two dissimilar triodes).

    As it turns out, Bottlehead still offers a version of this little amp! The current morph uses two "Compactron" 6FJ7 tubes.
    https://bottlehead.com/product/single-ended-experimenters-kit-3-for-headphones-sensitive-speakers/

    [​IMG]
     
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