Hammond 125D 10 W Universal Push-Pull Tube Output Transformer
Ships from and sold by A5 IT
Exclusive pricing and Net-30 terms. Sign in or create a free account.
Create Free Business AccountKey Features
- 10 W push-pull output; 1,200 to 25,000 ohm CT primary range
- Solder lugs 1-6 match 1.5 to 15 ohm speakers
- 55 mA max DC bias per side; 4.48 H primary inductance
- Typ. 1.0 dB response from 100 Hz to 15 kHz
- 1500 Vrms dielectric strength; up to 105C temperature range
- Open style, 3.25 x 1.75 x 2.00 in, 1 lb
- RoHS and REACH compliant, made in Canada
The 125D is a 10 watt universal push-pull "classic" tube output transformer for general purpose or replacement use (not Hi-Fi). It is aimed at service technicians and amplifier builders who need a single output transformer able to cover many plate-to-plate loads and speaker impedances in a 10 W push-pull stage.
Its secondary terminates on solder lugs 1 to 6. With voice coils from 1.5 to 15 ohms, the lug pair you choose sets the resulting primary impedance, blue wire to brown wire, anywhere from 1,200 to 25,000 ohms. An 8 ohm speaker across lugs 2&4 reflects 22,500 ohms, and a 4 ohm speaker across lugs 3&5 reflects 8,800 ohms.
The 125D is rated for a maximum of 55 mA DC bias per side and lists a primary inductance of 4.48 H. Typical drawing data gives 285 ohms primary DCR (blue - brown), 7.50 H primary inductance and 48.0 kOhm primary impedance at 1 kHz, 1 V, with 1500 Vrms dielectric strength and a temperature range up to 105C. Typical response is 1.0 dB from 100 Hz to 15 kHz, and the unit label reads 100Hz - 30kHz, 10 WATTS.
Physically it is an open style transformer with minimum 5 inch primary leads (BLU plate, RED B+, BRN plate). Overall dimensions are A 3.25 in (83 mm), B 1.75 in (44 mm), C 2.00 in (51 mm) and D 2.81 in (71 mm) with 0.19 in (5 mm) mounting holes, and it weighs 1 lb (0.45 kg). It is made in Canada and is RoHS and REACH compliant. Single ended designs should use the 125SE Series.
Ideal For
- Replacement output transformer for 10 W push-pull tube amplifiers
- Push-pull guitar and audio tube output stages
- Matching tube outputs to 1.5-15 ohm speakers
Overview
| Series | 125A-125E Series Universal Push-Pull Tube Output |
| Application | General purpose or replacement use (not Hi-Fi) in push-pull tube output circuits |
| Description | Audio transformer, universal push-pull tube output, 10 watts |
| Part Number | 125D |
| Short Description | AUDIO TX OUTPUT SE OR PP |
| Single-Ended Alternative | For single ended use, see the 125SE Series |
Dimensions
| A (Overall) | 3.25 in (83 mm) |
| B (Overall) | 1.75 in (44 mm) |
| C (Overall) | 2.00 in (51 mm) |
| D (Overall) | 2.81 in (71 mm) |
| Weight (Table) | 1 lbs |
| G - Mounting Hole | 0.19 in (5 mm) |
Electrical
| Audio Watts | 10 |
| Label Marking | PRI: BLU - RED - BRN 1200 - 25000 OHM CT; 100Hz - 30kHz; 10 WATTS |
| Secondary DCR 1-2 | 115 mΩ |
| Secondary DCR 1-3 | 248 mΩ |
| Secondary DCR 1-4 | 381 mΩ |
| Secondary DCR 1-5 | 550 mΩ |
| Secondary DCR 1-6 | 728 mΩ |
| Dielectric Strength | 1500 Vrms |
| Primary Connections | BLU (plate), RED (B+ centre tap), BRN (plate) |
| Output Power (Typical) | 10 Watts |
| Max. DC Bias Per Side | 55 mA |
| Primary Impedance Range | 1,200 to 25,000 ohms |
| Secondary Impedance 1-2 | 3.13 Ω @ 1.0 kHz, 1.0 V OC |
| Secondary Impedance 1-3 | 19.5 Ω @ 1.0 kHz, 1.0 V OC |
| Secondary Impedance 1-4 | 53.2 Ω @ 1.0 kHz, 1.0 V OC |
| Secondary Impedance 1-5 | 116.7 Ω @ 1.0 kHz, 1.0 V OC |
| Secondary Impedance 1-6 | 208.8 Ω @ 1.0 kHz, 1.0 V OC |
| Secondary Inductance 1-2 | 0.46 mH @ 1.0 kHz, 1.0 V OC |
| Secondary Inductance 1-3 | 2.62 mH @ 1.0 kHz, 1.0 V OC |
| Secondary Inductance 1-4 | 6.78 mH @ 1.0 kHz, 1.0 V OC |
| Secondary Inductance 1-5 | 14.8 mH @ 1.0 kHz, 1.0 V OC |
| Secondary Inductance 1-6 | 41.4 mH @ 1.0 kHz, 1.0 V OC |
| Input Impedance (Typical) | 1200 - 25000 Ω |
| Primary DCR, Blue - Brown | 285 Ω |
| Secondary Impedance Range | 1.5 to 15 ohms |
| Output Impedance (Typical) | 1.5 - 15 Ω |
| Primary Inductance (Table) | 4.48 H |
| Frequency Response (Series) | 150 Hz - 15 kHz at full rated power (+/- 1 dB max, ref. 1 kHz) |
| Frequency Response (Typical) | Typ. 1.0 dB from 100 Hz to 15 kHz |
| Primary Impedance Blue - Brown | 48.0 kΩ @ 1.0 kHz, 1.0 V OC |
| Primary Inductance Blue - Brown | 7.50 Hy @ 1.0 kHz, 1.0 V OC |
Identifiers
| UPC | 623980188904 |
| UNSPSC | 39121301 |
Hook-Up Data
| Speaker On Secondary Lugs 1&2 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 27000 Ω |
| Speaker On Secondary Lugs 1&3 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 5400 Ω; 2 Ω speaker: 7200 Ω; 3.2 Ω speaker: 11500 Ω; 4 Ω speaker: 15000 Ω; 6 Ω speaker: 21600 Ω |
| Speaker On Secondary Lugs 1&4 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 2150 Ω; 2 Ω speaker: 2900 Ω; 3.2 Ω speaker: 4600 Ω; 4 Ω speaker: 5800 Ω; 6 Ω speaker: 8700 Ω; 8 Ω speaker: 11600 Ω; 12 Ω speaker: 17400 Ω; 15 Ω speaker: 21500 Ω |
| Speaker On Secondary Lugs 1&5 - Resulting Primary Impedance (BLU To BRN) | 2 Ω speaker: 1400 Ω; 3.2 Ω speaker: 2200 Ω; 4 Ω speaker: 2800 Ω; 6 Ω speaker: 4200 Ω; 8 Ω speaker: 5600 Ω; 12 Ω speaker: 8400 Ω; 15 Ω speaker: 10200 Ω |
| Speaker On Secondary Lugs 1&6 - Resulting Primary Impedance (BLU To BRN) | 3.2 Ω speaker: 1200 Ω; 4 Ω speaker: 1500 Ω; 6 Ω speaker: 2300 Ω; 8 Ω speaker: 3000 Ω; 12 Ω speaker: 4500 Ω; 15 Ω speaker: 5600 Ω |
| Speaker On Secondary Lugs 2&3 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 18000 Ω; 2 Ω speaker: 24000 Ω |
| Speaker On Secondary Lugs 2&4 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 4200 Ω; 2 Ω speaker: 5600 Ω; 3.2 Ω speaker: 9000 Ω; 4 Ω speaker: 11200 Ω; 6 Ω speaker: 16800 Ω; 8 Ω speaker: 22500 Ω |
| Speaker On Secondary Lugs 2&5 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 1550 Ω; 2 Ω speaker: 2050 Ω; 3.2 Ω speaker: 3300 Ω; 4 Ω speaker: 4100 Ω; 6 Ω speaker: 6150 Ω; 8 Ω speaker: 8200 Ω; 12 Ω speaker: 12300 Ω; 15 Ω speaker: 15500 Ω |
| Speaker On Secondary Lugs 2&6 - Resulting Primary Impedance (BLU To BRN) | 3.2 Ω speaker: 1700 Ω; 4 Ω speaker: 2100 Ω; 6 Ω speaker: 3150 Ω; 8 Ω speaker: 4200 Ω; 12 Ω speaker: 6300 Ω; 15 Ω speaker: 8000 Ω |
| Speaker On Secondary Lugs 3&4 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 16500 Ω; 2 Ω speaker: 22000 Ω |
| Speaker On Secondary Lugs 3&5 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 3300 Ω; 2 Ω speaker: 4400 Ω; 3.2 Ω speaker: 7000 Ω; 4 Ω speaker: 8800 Ω; 6 Ω speaker: 13200 Ω; 8 Ω speaker: 17600 Ω; 12 Ω speaker: 26400 Ω |
| Speaker On Secondary Lugs 3&6 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 1300 Ω; 2 Ω speaker: 1700 Ω; 3.2 Ω speaker: 2700 Ω; 4 Ω speaker: 3400 Ω; 6 Ω speaker: 5100 Ω; 8 Ω speaker: 6800 Ω; 12 Ω speaker: 10200 Ω; 15 Ω speaker: 12800 Ω |
| Speaker On Secondary Lugs 4&5 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 10000 Ω; 2 Ω speaker: 13500 Ω; 3.2 Ω speaker: 21600 Ω; 4 Ω speaker: 27000 Ω |
| Speaker On Secondary Lugs 4&6 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 2400 Ω; 2 Ω speaker: 3200 Ω; 3.2 Ω speaker: 5100 Ω; 4 Ω speaker: 6400 Ω; 6 Ω speaker: 9600 Ω; 8 Ω speaker: 12800 Ω; 12 Ω speaker: 19200 Ω; 15 Ω speaker: 24000 Ω |
| Speaker On Secondary Lugs 5&6 - Resulting Primary Impedance (BLU To BRN) | 1.5 Ω speaker: 8500 Ω; 2 Ω speaker: 11000 Ω; 3.2 Ω speaker: 18000 Ω; 4 Ω speaker: 22000 Ω |
Packaging & Shipping
| Shipping Weight | 1 lbs (0.45 kg) |
Construction & Finish
| Style | Open style |
| Primary Leads | Minimum 5" long |
| Country Of Origin | Made in Canada |
| Secondary Connections | Solder lugs 1-6 |
Environmental & Protection
| Temperature Range | Up to 105C |
Compliance & Certifications
| RoHS Compliant | Yes |
| REACH Compliant | Yes |
Purchasing this for your business?
Business account holders get access to exclusive pricing, volume discounts, and dedicated support. Create a free account to get started.
Frequently Asked Questions
What is the power rating of the 125D?▾
10 audio watts.
What DC bias current can it carry?▾
Up to 55 mA per side.
Which lugs give 6,800 ohms with an 8 ohm speaker?▾
The hook-up table lists 6,800 ohms for an 8 ohm speaker on lugs 3&6.
Is it for push-pull or single ended?▾
It is designed for push-pull tube output circuits; the 125SE Series is for single ended use.
How big is the 125D?▾
A 3.25 in (83 mm), B 1.75 in (44 mm), C 2.00 in (51 mm), D 2.81 in (71 mm), with 0.19 in (5 mm) mounting holes; it weighs 1 lb.
Related Products
Save 52%125C — Audio transformer, universal push-pull tube output, 8 watts
Hammond Manufacturing · 125C
Save 52%125E — Audio transformer, universal push-pull tube output, 15 watts
Hammond Manufacturing · 125E
Save 52%125B — Audio transformer, universal push-pull tube output, 5 watts
Hammond Manufacturing · 125B
Save 52%125A — Audio transformer, universal push-pull tube output, 3 watts
Hammond Manufacturing · 125A