[anubisgrau]

As said above - I need a super quiet preamp with low imp (100 ohm or less). Output trannies preferred. A kind of SET circuit preferred too. Simplicity. Good PSU. Can be even battery powered - I have a car battery for my DAC.
But first of all it has to be dead quiet.
Kit option welcome - DIY as well.
Any hints? I need it for a highly efficient horns (over 100db) cause I want to fiddle either with First Watt amps or some gainclone.
Thanks!

[schw06]

Transcendent Sound Grounded Grid preamp is a very popular combination with the first watt amp and the hornshoppe horns.

[Big Red Machine]

Let's hope the Dodd fills the bill!

[Gordy]

John Broskie's Aikido preamp's are superb!  Your choice of 24v battery, octal or 9 pin based circuit boards... Glassware Audio  with more info here... Tube Cad Journal

[markC]

How about a Mcalister PL10? 140 ohm output impedance.

[tanchiro58]

As said above - I need a super quiet preamp with low imp (100 ohm or less). Output trannies preferred. A kind of SET circuit preferred too. Simplicity. Good PSU. Can be even battery powered - I have a car battery for my DAC.
But first of all it has to be dead quiet.
Kit option welcome - DIY as well.
Any hints? I need it for a highly efficient horns (over 100db) cause I want to fiddle either with First Watt amps or some gainclone.
Thanks!

Anubisgrau,

I have the same opinion like you in a super quiet preamp (definitely very dead quiet) with low impedance and output trannies/SET circuit (if you mean by point to point without pcb) preferably but not battery powered (the designer was not believed in battery powered).

[anubisgrau]

thanks everyone - tanchiro, what's that beast on your pic?

[anubisgrau]

John Broskie's Aikido preamp's are superb!  Your choice of 24v battery, octal or 9 pin based circuit boards... Glassware Audio  with more info here... Tube Cad Journal

Can Aikido be set to 12V? This would mean a deal, to power it direct from my Exide Maxxima car battery.

[tanchiro58]

thanks everyone - tanchiro, what's that beast on your pic?

That is a SET preamp using 5u4 rectifier tube and 8608/8233 output tubes. It weights 30-40 lbs (do you see chokes and Tango tranny?) and has double C-core output trannies with 46dB output. Good luck in the search.

[Gordy]

Can Aikido be set to 12V? This would mean a deal, to power it direct from my Exide Maxxima car battery.

I built the 12sn7 version so, I'm not the best to ask.  I suppose the filament heater circuit could be wired for 12v instead of 24v (4 - 6v tubes in series) but, I really am not familiar with the tube used.  Zacster has built this version though, you might try contacting him?

[Imperial]

Modwright is pretty quiet... I think.. 110ohms output.
Quicksilver pre's also have about 100 ohms..
Tron pre's are quiet, and have a low output.
Supratek have quiet operation, powerfull output, not sure how low..
Wyetech pre's are in the super quiet club, a bit high yeah on the ohms, but HUGE powersupplies to counter that..
Manley Shrimp: 50 ohms.. Rather quiet too!!!
Then there is the Viva Audio linea xp, 130ohms, and transformers.. but that ain't cheap stuff!
Imperial

[tanchiro58]

Modwright is pretty quiet... I think..

Imperial

I agree. Dan has built a very highly rave preamp that I listened at CES 2008. It is really very nice preamp sonically and physically.

[Danny Richie]

The Dodd Audio battery powered tube pre-amp is the most dead quiet that you'll find. It uses 4 large 12 volt batteries running at a 24 volt level. I think Gary said the batteries could output 100 amps. It also has incredibly low distortion for any pre-amp. I don't think you'll be able to find a better one at any price.

[dado5]

You need a passive switch/volume control or a unity gain (or less) unit.

100dB speakers with a First Watt or Gainclone does not require additional gain.

The circuit I use for my headphone amp would be a good fit:

ECC99 with a 17.7:1 output transformer (that's 2.5K to 8 ohms). This gives a slightly more than unity gain with less than a 10 ohm output impedance.

I use an 'ultra-path' bypass capacitor connection - 50uf film type from the high voltage side of the output transformer primary to the top of the cathode resistor.

Power supply is a 150V CT transformer - 220uf - 15 Henry 75ma - 220uf - 15 Henry 75ma - 220uf.
Choke input could  be done by changing the power transformer to a 225V CT and taking out the first capacitor

I like solid state diodes, but a low drop rectifier like an EZ81 should give similar voltage outputs (175 V for 150V on the plate + 25V for the transformer drop and the cathode resistor [220 ohms @ 18 ma for 4 v bias]).

The ripple with the pi filter would be less than half a micro-volt and with the choke input it would be around  50 micro-volts. Either one would be dead silent at more than 115 db below the output signal. I hear no hum, buzz or hiss with the volume control wide open and no input (remember this with phones right on the ear!).

DC on the filaments or AC with a grounded secondary center tap (tightly twisted and carefully routed wiring).

Power transfomer- Hammond 269 EX or GX $30

Chokes - Hammond 158L $18

PS Caps - $15-$20 (buy extras)

ultrapath caps $15 for motor run oil cans, maybe double that for polyprop films up to several hundred for teflon or other exotics.

Output transformers - custom from ElectraPrint $200 (2.5K to 8 ohms @ 25 ma)

tubes: EC99 $15 EZ81 $10

volume and switching - whatever you want

[Bill Baker]

If you are in to building one yourself, the Audio Note L3 is a transformer coupled output with a 10 ohm output impedance.

 I have build quite a few of our custom versions for my customers and they are dead quiet. They are also available in kit form from Audio Note Kits. I am running both the L2 and L3 in my showroom now. Even the L2 is noise free.
 The L3 has balanced and single ended output.


 Further details on the kit version can be found here:
http://www.audionotekits.com/line.html

[S Clark]

There is a new Dodd battery for sale now over in the For Sale: Amplification circle for $2500.  Great deal, and exactly what you are looking for.

[sts9fan]

100dB speakers with a First Watt or Gainclone does not require additional gain.

Gainclone maybe but the First Watt does need the gain of a pre. 
here is a link where the man himself says it.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114063
the Zv9 is nearly identical to the F3.  Also I am running a F1 currently and with my Zu Druids and I cannot push it very far at all without my pre which has a gain of 13db.  These amps only have ~13db gain.  Obviously a F4 would need a pre or a SET intergrated. 

Kris

[dado5]

100dB speakers with a First Watt or Gainclone does not require additional gain.

Gainclone maybe but the First Watt does need the gain of a pre. 
here is a link where the man himself says it.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=114063
the Zv9 is nearly identical to the F3.  Also I am running a F1 currently and with my Zu Druids and I cannot push it very far at all without my pre which has a gain of 13db.  These amps only have ~13db gain.  Obviously a F4 would need a pre or a SET intergrated. 

Kris

I did not know the Pass amps were that low gain. At 13dB it would take less than 2 volts input to produce 10 watts at 8 ohms, but how loud you listen and how far away you sit from the speakers would still need to be taken into account, even with 100dB sensitivity.

Chip amps gain is on the order of 30dB, so most definitely no gain is needed.