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    Preamps for the 120.....

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    corndog71

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    Re: Preamps for the 120.....

    Post by corndog71 on Wed Apr 19, 2017 11:34 am

    I still think you could fit a preamp to the right of your amp.  Maybe squeeze things together a little bit and rearrange those smaller items.

    An even better solution would be to mount a heavy duty shelf above with just the turntable and preamp there and the amp stays on the cabinet.  Then again she probably would hate that idea too.

    I'm accommodating to my girlfriend too but when it comes to proper care of my equipment and sound quality, I win.  cheers My gf is pretty awesome like that.

    mcgyver74

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    Re: Preamps for the 120.....

    Post by mcgyver74 on Wed Apr 19, 2017 1:48 pm

    Ah darn Sad

    How does the PAS3 compare to the SP14 for sound quality? (Guess this is a Bob question Smile )
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    Peter W.

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    Location : Melrose Park, PA

    Re: Preamps for the 120.....

    Post by Peter W. on Wed Apr 19, 2017 3:05 pm

    mcgyver74 wrote:Ah darn Sad

    How does the PAS3 compare to the SP14 for sound quality? (Guess this is a Bob question Smile )

    It is, certainly! I have not experienced the SP14, so I will not render an opinion, other than expecting it to be as good as its siblings, or better.

    With that in mind, I run and have run many pre-amps over the decades, tube and solid state. In ranking for audibility and general pleasantness in use, they are (with a car analogy at each one):

    Revox A720: Pluses: More controls than a Boeing 787. Super rich sound, includes excellent FM tuner with a Nixie tube display. Excellent phono-pre-amp, Adjustable inputs for matching output levels when switching components. Two headphone jacks.  Minuses: More controls than a Boeing 787. A Mercedes 600 S-Class with an indefinite warranty and free fuel.

    HK Citation 17: Pluses: Defeatable on-board equalization. Excellent phono pre-amp. Intuitive controls. Minuses: Does not drive headphones. Require amp input through a special plug for this function. Power-supply can be touchy and should be rebuilt. Solid Mercedes 300 TDT with an indefinite warranty.

    Dynaco PAS 3x:  Very mellow sound. X-mod has center-null tone controls. Includes NAB, Phono and High-level phono inputs. The phono section is not half-bad. Includes simulcast input (meaning an extra spare) Puts out up to 13V  - the most of my pre-amps. Minuse: Scarce in the X-mod version. Will not drive headphones at all. Requires a few basic mods to be 'safe and effective' - the first being the selenium stack. If turned up overly, it will overload amps. A Jaguar 4-door XJ - when working, nothing like it. I have modified mine to a state of excellent reliability and addressed a few of the shortcomings - so a smoothly running XJ.

    Dynaco PAT-5 biFet: Very similar to the Citation 17 in advantages and features, without the on-board equalization. But it does have an EPL in/out (defeatable). Additional Minus: Must remain plugged in at all times due to quiescent circuitry to prevent turn-on thumps (massive if modified for cold-starts). A VW Passat in fine condition. Does many things very, very well, but nothing acutely special.

    Scott LC21: Altogether unremarkable. It stayed in the inventory less than six months. A 1968 VW beetle - gets you there, reliably.

    Dynaco PAS-2:  A weaker sister to the PAS-3X. There is, in my opinion, a significant difference. As the cost difference is not huge, hold out for the 3X. A 1967 VW beetle - gets you there, reliably, but still has the solid rear axles. (NOTE: Thanks to another member, correction that the VW Type I/III up to 1967 had solid half-axles.)

    Dynaco PAT-4: A strange little solid-state pre-amp. Advantages: Drives headphones from on-board amp. Accepts NAB, Microphone, High and Low level phono. Separate center-null tone controls for each channel. Plenty of inputs and outputs. Minuses: cheapest controls possible. Marginal power-supply, but easily rebuilt. Best short description: Could do much worse. Sort of like a Jeep Cherokee, but a better ride. Does many things well, few things perfectly. An excellent match to early solid-state amps.

    Hope this helps. These are all items I have experienced directly, and in several iterations, so my impression is not limited to a single example.


    Last edited by Peter W. on Wed Apr 19, 2017 4:52 pm; edited 1 time in total

    mcgyver74

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    Re: Preamps for the 120.....

    Post by mcgyver74 on Wed Apr 19, 2017 4:14 pm

    Cool analogy's!! Smile

    Thanks man!
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    peterh

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    Re: Preamps for the 120.....

    Post by peterh on Wed Apr 19, 2017 4:31 pm

    Good descriptions, written with humour and insight. Thanks!
    A beetle however has no "solid read axle". It's a swingarm with one joint.
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    Peter W.

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    Re: Preamps for the 120.....

    Post by Peter W. on Wed Apr 19, 2017 4:46 pm

    [quote="peterh"]Good descriptions, written with humour and insight. Thanks!

    OK - agreed. But as compared to the double CV jointed stub-axle, it is solid from the inside the transmission to the threads at the castellated lock-nut.

    Been there.... Done that. 66 type III, 68 type III, 72 type III - then to the dark side with water-cooled VWs.
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    Bob Latino
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    Re: Preamps for the 120.....

    Post by Bob Latino on Wed Apr 19, 2017 5:11 pm

    mcgyver74 wrote:Ah darn Sad

    How does the PAS3 compare to the SP14 for sound quality? (Guess this is a Bob question Smile )

    The Dynaco tube AMPS were miles ahead of the Dynaco PAS preamps with respect to sound quality. The PAS-2 and 3 have a weak power supply and the early versions (non X models) had the tone controls directly in the signal path without the option of switching the bass and treble out of the circuit. No matter what you do to an early PAS preamp, no matter how much money you sink into the PAS preamp, the PAS-2 or 3 or 3X version will NEVER sound as good as Roy's SP14 preamp. The only Dynaco PAS preamp that I ever heard that was fairly good was the PAS-4 preamp from the 1990's. Roy now has a PAS-4 clone preamp. You can read about Roy's PAS-4 clone at the link below ..

    PAS-4 clone preamp page on Tubes4hifi

    My nod still goes to the SP14 though .. KIT or WIRED version, it is equal in sound quality to preamps costing 5X what Roy is asking ..

    Bob
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    corndog71

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    Re: Preamps for the 120.....

    Post by corndog71 on Wed Apr 19, 2017 5:36 pm

    SP13 uses smaller tubes which produce less heat and yet still sounds great. It is the best tube preamp I've heard for the money though I haven't heard the SP14.
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    wgallupe

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    Re: Preamps for the 120.....

    Post by wgallupe on Thu Apr 20, 2017 6:42 am

    Like corndog, I too have the SP13 which uses the 6CG7 tube (9 pin version of the 6SN7). I keep it on a shelf in a cabinet. Normally, I leave the cabinet door open when playing music to allow heat to escape. However, on more than one occasion when done playing music I have unintentionally left the preamp on and closed the door. The heat inside the open back cabinet never got excessive (after a day or two!) and no harm to the preamp.

    BTW, the SP13 is the best sounding preamp I have ever owned.
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    Peter W.

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    Re: Preamps for the 120.....

    Post by Peter W. on Thu Apr 20, 2017 11:22 am

    Now that you are running 12AX7s (carefully, of course), the primary reasons for a pre-amp would be additional inputs and a phono section. And I expect/suspect that you would go back to either 12AU7s or 5751s, were you to invest in a pre-amp.

    Just an observation from 50,000 feet.
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    deepee99

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    Re: Preamps for the 120.....

    Post by deepee99 on Thu Apr 20, 2017 1:46 pm

    Peter W. wrote:
    mcgyver74 wrote:Ah darn Sad

    How does the PAS3 compare to the SP14 for sound quality? (Guess this is a Bob question Smile )

    It is, certainly! I have not experienced the SP14, so I will not render an opinion, other than expecting it to be as good as its siblings, or better.

    With that in mind, I run and have run many pre-amps over the decades, tube and solid state. In ranking for audibility and general pleasantness in use, they are (with a car analogy at each one):

    Revox A720: Pluses: More controls than a Boeing 787. Super rich sound, includes excellent FM tuner with a Nixie tube display. Excellent phono-pre-amp, Adjustable inputs for matching output levels when switching components. Two headphone jacks.  Minuses: More controls than a Boeing 787. A Mercedes 600 S-Class with an indefinite warranty and free fuel.

    HK Citation 17: Pluses: Defeatable on-board equalization. Excellent phono pre-amp. Intuitive controls. Minuses: Does not drive headphones. Require amp input through a special plug for this function. Power-supply can be touchy and should be rebuilt. Solid Mercedes 300 TDT with an indefinite warranty.

    Dynaco PAS 3x:  Very mellow sound. X-mod has center-null tone controls. Includes NAB, Phono and High-level phono inputs. The phono section is not half-bad. Includes simulcast input (meaning an extra spare) Puts out up to 13V  - the most of my pre-amps. Minuse: Scarce in the X-mod version. Will not drive headphones at all. Requires a few basic mods to be 'safe and effective' - the first being the selenium stack. If turned up overly, it will overload amps. A Jaguar 4-door XJ - when working, nothing like it. I have modified mine to a state of excellent reliability and addressed a few of the shortcomings - so a smoothly running XJ.

    Dynaco PAT-5 biFet: Very similar to the Citation 17 in advantages and features, without the on-board equalization. But it does have an EPL in/out (defeatable). Additional Minus: Must remain plugged in at all times due to quiescent circuitry to prevent turn-on thumps (massive if modified for cold-starts). A VW Passat in fine condition. Does many things very, very well, but nothing acutely special.

    Scott LC21: Altogether unremarkable. It stayed in the inventory less than six months. A 1968 VW beetle - gets you there, reliably.

    Dynaco PAS-2:  A weaker sister to the PAS-3X. There is, in my opinion, a significant difference. As the cost difference is not huge, hold out for the 3X. A 1967 VW beetle - gets you there, reliably, but still has the solid rear axles. (NOTE: Thanks to another member, correction that the VW Type I/III up to 1967 had solid half-axles.)

    Dynaco PAT-4: A strange little solid-state pre-amp. Advantages: Drives headphones from on-board amp. Accepts NAB, Microphone, High and Low level phono. Separate center-null tone controls for each channel. Plenty of inputs and outputs. Minuses: cheapest controls possible. Marginal power-supply, but easily rebuilt. Best short description: Could do much worse. Sort of like a Jeep Cherokee, but a better ride. Does many things well, few things perfectly. An excellent match to early solid-state amps.

    Hope this helps. These are all items I have experienced directly, and in several iterations, so my impression is not limited to a single example.

    Peter, very handy comparisons with one bad analogy.
    The Boeing 787 and Airbus equivalents basically have an on-off switch, with an FBW yoke or side-stick to wiggle if the pilots get bored playing Solitaire on their laptops.
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    tubes4hifi
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    Re: Preamps for the 120.....

    Post by tubes4hifi on Fri Apr 21, 2017 6:28 pm

    OMG, McGyver, I'm a little late to post this, but how can you even mention the PAS3 and SP14 in the same sentence!??
    That's like comparing a $1 bill to a $100 bill. Both are money (preamps) and plug into the wall, but those are about the only similarities.
    On a scale of 1 to 10, a PAS3 is a ZERO, a SP14 is about a 15 or 20.
    I might allow you to ask that question concerning something like the SP9 preamp.
    On a scale of 1 to 10, the PAS3 is again a ZERO, and the SP9 is about a 7 or 8.
    A comparison similar to a 1961 VW Beetle and a 2010 Toyota Camry.
    On this scale, the SP14 would be a 2015 Porsche Carrera.
    Hope that sets the comparison straight in simple terms . . . .

    audiobill

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    Re: Preamps for the 120.....

    Post by audiobill on Sat Apr 22, 2017 3:44 pm

    Roy, was that PAS or POS?

    mcgyver74

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    Re: Preamps for the 120.....

    Post by mcgyver74 on Sat Apr 22, 2017 6:41 pm

    tubes4hifi wrote:OMG, McGyver, I'm a little late to post this, but how can you even mention the PAS3 and SP14 in the same sentence!??


    Sorry, I'm still new to all of this Sad

    I really want an SP14, but I need to be sure it won't overheat in the cabinet we would keep it in Sad
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    WntrMute2

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    Join date : 2010-11-21

    Re: Preamps for the 120.....

    Post by WntrMute2 on Sun Apr 23, 2017 1:36 pm

    mcgyver74 wrote:Thanks Sad  100 Watt bulb would quickly roast the inside of that cabinet Sad

    I was really hoping I could build an SP14, but looks like I may need to go SS for the pre Sad

    Remember that the SP14 is already built in a closed box (in stock form) so putting it in a larger cabinet won't matter much IMHO. Two options if you want to insure that things won't overheat. 1) Build or have built a SP14 that has its tubes exposed. 2) Add a small computer fan that comes on when you power the system up blowing air into the cabinet. I believe since the unit is designed to work in a closed space (its own chassis) you will be fine as long as the cabinet has reasonable ventilation.
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    deepee99

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    Re: Preamps for the 120.....

    Post by deepee99 on Sun Apr 23, 2017 2:51 pm

    I fear you're over-thinking the cooling issue. You don't need a cave or a 220-volt box fan to cool an SP-14. With four hurky Chinese mil-spec CV-181s (semi-equivalent to stock 6SN7s) and my beloved Bendix rectifier, all passing signal, mine pulls about 0.2 amps out of the wall. I am not a mathematician, but I believe this equates to an EPA-approved 20-watt light bulb. Assuming about 3 per cent of these 20 watts actually convert to sound energy, and a bit more to light energy, you're down to a 15-watt light bulb's worth of heat. Skizo, Peter W., others with brain cells, help me with the math here but I think I'm close.
    Point being is that a tube pre-amp doesn't need much help staying cool. Even the wooden versions all the rage at the moment still have a metal plate to hold things together and serves well as a heat sink.
    No, don't bubble-wrap the sucker, any more than you'd do with a light bulb, but with a couple of rubber feet (supplied with Roy's products) and an inch or two of air above, behind or in front no harm lurks. Height of where you're putting the thing is the larger consideration. The CV-181s are damn near as tall as a KT-88. They don't generate any more heat nor suck any more juice than a squatty-body 6SN7, but they are taller and you might want to mess with them someday, so keep that option open.
    None of the foregoing applies to the monoblocks or power amps. As a wise man once advised me during my construction of the M-125 kit, I think his name was Bob L., said, the only thing the tops of those power tubes should see is the ceiling. M-125s and ST-120s no likey the shrink-wrap when the power switch is in the upright position.
    And for Dog's sake, please don't even consider a solid-state pre-amp. They generate just as much heat, albeit in a smaller form-factor, and will make the best tube amps sound like turds in the punch bowl.

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