Parts
At this time our shopping cart is unable to process part orders from outside the US and Canada. E-mail us at the link below for assistance in ordering:
Orders outside the US and Canada
or call us at 360-697-1936 M-F 9-5 PT
Bottlehead Filament Choke FC-1
Here
is the balanced, split winding filament choke we use in our own Paramount
300B/2A3 amplifier kit. DC heaters sometimes get a bum rap. By implementing this
purpose built filament choke in your DC filament supply you can get the
sonic advantages attributed to AC filaments, but without the hum and with good
common mode noise rejection. Made in the USA with channel frame construction,
2-7/8"
mounting centers and solder terminals so you can use your favorite wire to hook
it up. Intended to be mounted on the underside of the chassis. This
is a filament choke for 2A3s and 300Bs, wound on a two-bay bobbin. It is
designed for balanced use, with one bay in each leg of the heater supply. It can
be used with no capacitor (as we do in the Paramount), or with one capacitor
either at the power supply end or at the tube end, or in a pi filter
arrangement.
The relatively large leakage inductance which is due to the two separate bays
acts as a common-mode choke to reduce common-mode noise on the filament winding.
Each bay is bifilar wound and can be connected in series or parallel. In series
it has 30mH inductance, 0.5 ohms DC resistance, and a rating of 1.25 amps as a
choke-input filter producing 5vDC. In parallel it has 7.5mH inductance, 0.125
ohms DC resistance, and a rating of 2.5 amps as a choke-input filter producing
2.5vDC.
With these specs one can use PSU Designer II from the Duncan Amps web site to determine the required power transformer filament secondary voltage and current for your application. Be sure to allow for rectifier voltage drops, etc. It will usually be best to err on the high side in terms of the filament secondary current rating. For example, a 6.3V secondary rated for around 5A might help hit the target of 5VDC with a 300B. But please model your circuit rather than assuming these values are universal.
Wiring the FC-1
Connections common to both tubes:
Connect FC-1 terminal 1 to one filament pin terminal on the tube socket. Connect FC-1 terminal 6 to the other filament pin terminal.
Connect the positive filament supply voltage to FC-1 terminal 10. Connect the negative filament supply voltage to FC-1 terminal 5.
Additional connections for 300B:
Jumper FC-1 terminals 7 and 9. Also jumper FC-1 terminals 2 and 4.
Additional connections for 2A3, 45:
Jumper FC-1 terminals 10 and 7. Jumper FC-1 terminals 9 and 6. Jumper FC-1 terminals 5 and 2. Jumper FC-1 terminals 4 and 1.
FC-1 Filament Choke, $45 each (you need one per tube for 300B, 2A3 or 45) plus shipping to US address
FC-1 Filament Choke, $45 each (you need one per tube for 300B, 2A3 or 45) plus shipping to Canadian address
Bottlehead PT-1 preamplifier power transformer
Our search for a cost effective, quiet power transformer for our Seduction phono preamp led us to having our own custom model made. With a large core and both electrostatic and magnetic shielding this transformer radiates less than 2/3 of the electromagnetic field of off the shelf models, making it a great choice where space is limited and the power supply sits close to the amp circuit. It turned out so good that we decided to offer it by itself. Super for line stages, phono preamps, mic preamps, active crossovers, any low level application.
Specs are
120V primary
250V CT @ 20mADC secondary
6.3VAC @ 1.2 A rms secondary
Made in the USA with channel frame construction, 2-1/2" mounting centers and solder terminals so you can use your favorite wire to hook it up. This transformer now ships with our current Seduction phono preamp kits and is essentially a drop-in replacement for the original Seduction power transformer, requiring only a little additional wire for installation. Intended for mounting on the underside of a chassis. The installation of this trans and the recommended Hammond die cast box over the Seduction preamp circuitry will yield a dead quiet tube phono preamp. This super quiet transformer can be useful in Foreplay mod projects too, by drilling new mounting holes and converting to a full wave rectifier. Price is $40 plus shipping.
PT-1 preamplifier power transformer, plus UPS to US address
PT-1 preamplifier power transformer, plus Air Parcel to Canadian address
Bottlehead Cap
We did a tiny run of these caps back in 2001 and they sold out in a day. Well, they're back! It's a black, washed brushed cotton twill unconstructed "gap cap", with a self fabric closure with a ring buckle for adjustability and a 4 stitch sweatband. They hold up so well that Doc still wears his five year old hat daily. These new caps have velvety finish to them that really sets off the gold thread Bottlehead logo. (hat rack not included)
Bottlehead cap, $15.99 plus UPS to US Address
Bottlehead cap, $15.99 plus postage to Canadian Address
Bottlehead cap, $15.99 plus postage worldwide
Bottlehead Badge
Show your authority with the new Bottlehead badge. We looked around for a good looking badge for a long time, and recently bottlehead Wardsweb found us these beauties. The 1" square deeply etched gold tinted badge will add a touch of class to your project and let folks know you're a hardcore Bottlehead DIYer the minute they scope out your system. Comes with a peel and stick adhesive back. Put 'em on wooden bases, transformer bells, speaker cabinets, chassis plates, the fridge, your lunchbox, and darned near anything else that's flat and smooth. Below you see a Bottlehead badge on the front of Doc's personal Seduction, with a custom quilted maple base by Harmonic Design Works
Bottlehead badge, $6 plus priority mail to US address
Bottlehead badge, $6 plus airmail to Canadian address
pair Bottlehead badges, $12 plus priority mail to US address
pair Bottlehead badges, $12 plus priority mail to Canadian address
Hole Shrinkers
We made some of these up many years ago to adapt nine pin miniature sockets to octal socket holes in some of our older kits. Word got out and soon we were selling more to other manufacturers and DIYers than we used ourselves, so we keep on making them. Set of two adapters with ceramic nine pin miniature sockets and the mounting hardware pictured, $12 the pair plus shipping
Hole Shrinkers, pair, plus USPS to US address
Hole Shrinkers, pair, plus Air Parcel to Canadian address
C4S Kit
Camille Cascode Constant Current Source
C4S is a high impedance current limit circuit for preamp and driver tubes, designed by John Camille as an improvement in effective impedance, power supply rejection and stability over previous designs using FETs or tubes. It includes two PNP transistors and two LEDs per tiny PC board (2 boards are provided in the kit for a stereo pair) and an extensive 28 page manual written by "Buddha" Camille himself. This current source may be used as a plate or collector load for voltage differentials up to 300 volts. Use of NPN transistors will allow use if the board as a current sink for cathode loads in cathode follower and differential circuit applications. The circuit current and bias are easily adjusted with just two resistors. The C4S circuit boards are designed for easy series and parallel resistor configurations, for precise matching. What does all this mean? The 5 megohm effective impedance characteristic of these active loads permit near theoretical gain performance from voltage amplifier stages, and can reduce distortion in vacuum tube audio circuits by several hundred percent. Noise generated in this circuit is up to 40 times less than several commonly used circuits. The result is clarity, bass speed and drive that beats resistive loads, choke loads, and other tube and solid state loading schemes like mu followers/stages and SRPP’s. For applications, check out John Tucker’s "Single Ended Direct Coupled Active Loaded Parallel Feed 45" in the October 1997 VALVE, as well as Doc’s Blues Master VV32 amp and Soul Sister preamp in 1998’s VALVE issues. A pair of C4S boards is also used in our Afterglow and Paraglow 2A3 SE amplifier kits, and four C4S boards are used in our Anticipation upgrade to the Foreplay preamp. The detailed manual shows you how to easily adapt the kit to most conventional preamp and driver stages. C4S Kit PC boards for two channels, transistors, LEDs and 28 page manual - $35
C4S Kit plus USPS to US address
C4S Kit plus Air Parcel to Canadian address
Sweetest Whispers stepped attenuator kit
The Sweet Whispers stepped attenuator has been a tremendously popular upgrade to the original Foreplay kit over the past 5 years. The original design offered major bang for the buck and versatility in attenuation ranges. The body of experience we have acquired from the Bottlehead Community has inspired us to take the Sweet Whispers kit to an even higher level of and versatility sonic quality in the form of Sweetest Whispers. It's so much better that it is now standard in the latest Foreplay III kit.
The new dual mono attenuators are built on eleven step rotary switches with a positive stop, something that was missing in the original design. The total range of the steps has been increased from the original 30 dB to a total of 39 dB plus a mute setting, in response to requests for a very low level setting for late night listening sessions.
Perhaps the most innovative feature of this new attenuator is the ability to use it as a 15K ohm series attenuator, allowing operation as a standalone passive control. You can build the Sweetest Whispers as 15K attenuators, add some RCA jacks, a selector switch and a cabinet, and you have a very cost effective "passive preamp", like our Bare Bones passive Foreplay III.
For use in active circuits the basic 15K series design is re-implemented as a shunt attenuator, often regarded as the most transparent sounding attenuator configuration, putting only one "padding" resistor in the signal path. This additional padding resistor may be chosen from among four values included with the kit, to give the nominal 19dB gain of the original Foreplay preamp circuit (with Anticipation upgrade) a more flexible range of gain. You can choose from 9 db (close to being an industry standard), 3dB, -3dB or -12dB maximum overall gain with the change of one resistor. This allows custom tailoring of the gain chain for a broad range of unique system requirements like high sensitivity horn speakers or sensitive solid state amplifier inputs, or low input sensitivity single stage DHT amps and low output DACs.
Like the original Sweet Whispers kit the new Sweetest Whispers attenuators only take about 20 minutes to build. You get a photo and detailed instructions that explain exactly where each resistor goes, and the finished attenuators install in a manner very similar to the stock pots. For installation in an original Foreplay you will just need to drill a couple of 1/8" holes in the chassis (we include an easy to use drilling template) and do a bit of rewiring of the ground buss once you remove the stock pots.
Before ordering, please read: About Ordering
Sweetest Whispers shunt/series 11 step attenuator kit
dual mono attenuators (fits original Foreplay) $40 plus shipping
Sweetest Whispers kit, dual mono, plus USPS shipping to US address
Sweetest Whispers kit, dual mono, plus Air Parcel shipping to Canadian address
Notes for Our Customers Outside the U.S.
At this time our shopping cart is unable to process orders from outside the US and Canada. E-mail us at the link below for assistance in ordering:
Orders outside the US and Canada
or call us at 360-697-1936 M-F 9-5 PT