Hagerman Technology LLC: Trumpet

"Trumpet" Vacuum Tube Phono Preamp (discontinued)

The Trumpet phono preamp is a reference quality unit for the most demanding of audiophiles. It's main features are fully balanced operation and switchable polarity. Housed in a single chassis, the power supply is mounted well below the amplifier (about the same height as separate stacked boxes). Eight hand-matched Russian vacuum tubes complement the nearly dual-mono construction of the amplifiers.

The Trumpet implements a number of unusual circuit topologies and tricks to improve performance (way too many to list here). The highlights are: bipolar high voltage power supplies that are fully choke regulated (continuous current), choke regulated dc heater supply, class A differential long-tailed gain pairs, current source loaded cathode follower outputs, passive shunt power supply regulation, split RC equalization, and no feedback anywhere. Frequency response is tremendous, flat from 5Hz out past 250kHz. Distortion is exceptionally low at 0.03%.

Premium components are used throughout. Gold-plated connectors, sockets, and switches, audiophile-grade polypropylene coupling capacitors, metal-film resistors, soft-recovery diodes, film bypass capacitors, high-grade 0.063" thick aluminum sheet metal, cork/rubber damping, and the option of computer-engraved gold-anodized aluminum faceplates or hard maple wood panels (the original).

The chassis is a marvel of anti-vibration architecture. Circuit boards are freely hung like suspension bridges from solid support towers. Acoustic cork rubber is attached to the inside of the chassis cover. Sorbothane feet provide isolation from the mounting surface. Even the vacuum tubes are dipped in special high-temperature paint to reduce microphonics. And that's just the obvious. Look closer and you will find all transformers and chokes on nylon mounts, modified tube sockets that are actually bolted to the circuit board, and o-rings under large capacitors. In addition, the chassis benefits from an inherent chimney effect for enhanced convection cooling and increased airflow past the tubes. The sheet metal chassis forms a complete electric field shield around the electronics (with the exception of the exposed tube plates) with careful attention paid to internal shielding and grounding.

For more information, read my personal review, Michael Fremer's Stereophile review, Scot Markwell's (TAS) online web review, Dave Clark's Positive Feedback review, George Valley's Positive Feedback review, or these posts on audioasylum #1, #2, #3, #4, and audiocircle #5. Also some actual customer testimonials.

Trumpet (Gold) Phono

Trumpet (Wood) Phono

Features

Fully balanced differential circuitry
Class A operation, no feedback
All tube signal path
Choke regulated power supplies
DC heaters
Passive, split RIAA
Extra-low input capacitance
Polarity/Mute switches
Single box design (no separate power supply)
Handcrafted in USA

Specifications

Gain	+44dB
Input Impedance	47k ohm plus 36pF
Output Impedance	750 ohm
RIAA Response	+/-0.5dB from 20Hz to 20kHz
Bandwidth (-3dB)	5Hz to 250kHz
Distortion	0.03% @1kHz
SNR	74dB ref 5mV A-weighted
Overload	250mV @ 1kHz, 1% distortion
Power Consumption	70W (120Vac only)
Size	7" wide x 12" high x 12" deep
Weight	14 lbs.
Tubes	12AX7 (ECC83) x 4, 12AU7 (ECC82) x 4

Reviewer Exerpts

"The Trumpet proved competitive in direct comparisons with the Lamm Deluxe, with an open, airy, detailed, and thoroughly intoxicating sound ... bass was very well-controlled, texturally coherent, and exceptionally nimble ... pacing and rhythmic flow were stellar ... In short, the Trumpet sounded stunning, and was a total pleasure to listen to - which is what I did for hours." - Michael Fremer

"I was particularly impressed with the overall lack of noise. Given that it is a pure tube unit, I expected more hiss and hum. But Hagerman's balanced circuit design and his meticulous attention to all details of noise isolation and tube heating have paid off in a superbly low noise floor and ravishing low-level detail retrieval ... best dynamic authority I have heard on anything short of my Plinius M-14 ... a really beautiful liquidity and utter lack of grain in the midband ... just correct harmonic integrity, excellent background silence, realistic dynamic contrasts, and a remarkable freedom from coloration ... the Trumpet is exceptionally quiet, and an outright bargain of the finest kind at the asking price." - Scot Markwell

"The Trumpet ... was big and dynamic, with a well controlled and powerful bottom end, along with a speed and clarity across the midband that was truly captivating ... The Trumpet had that 'solid state' sound with respect to soundstaging, dynamics, slam, etc., but none of the tradeoffs. It was a smooth and palpable performer that offered an extended and airy treble without a hint of grain, grit, or transistor hardness." - Dave Clark

Trumpet Measurements

Not only does this amplifier sound good, it measures good too! Careful attention to circuit design and phase linearity resulted in extremely good equalization characteristics. The recovered audio signal (from an LP) boasts a very flat frequency response with excellent time-domain performance. The following oscilloscope photos show the square wave recovery (this is the acid test, folks! - something a loudspeaker manufacturer will never show you) is near perfect. The bandwidth limiting is due to a special 32kHz low pass filter I used on the input signal. The actual -3dB bandwidth of the Trumpet measures out to several hundred kHz.

Square wave response (RIAA accuracy)

Distortion is vanishingly low: 0.03% at 1kHz. Such performance is suprising considering there is no feedback used in this amplifier. The photos show the distortion spectra for 50Hz and 1kHz signals. On the 50Hz test there is just a hint of 2nd order distortion, maybe some 60Hz hum in the skirt, and then a trace of 120Hz hum. But pretty darn clean. At 100Hz the total distortion measured 0.3%, and 0.2% at 10kHz. Note the 1kHz spectrum is perfect, all harmonics are lower than the noise floor of the instrumentation.

50Hz distortion 1kHz distortion

However, these are continuous test tones. How does it fare with real music? For this test I used the output from a CD player (Stereophile's "Intermezzo") into my inverse RIAA filter and through the Trumpet. I compared the raw CD signal with the recovered signal from the Trumpet. They are spaced apart vertically for clarity. There are no discernable differences in phase or amplitude. Second photo shows the two traces on top of each other. Yes, that is two separate traces! Perfect performance, at least with test equipment. But hey, if it doesn't measure good first, it's flawed.

Real music

Downloads

StepUp Transformer (discontinued)

This phono step-up transformer accommodates use of low output moving coil cartidges with the Trumpet. It is based on the superb Stevens & Billington TX103. The chassis design copies the Trumpet in both appearance and anti-microphonic qualities. Output cables are hardwired to chassis not only for convenience, but to optimize reflected capacitive loading seen by the cartridge. Keep in mind here, that at 10:1 gain, every foot of output cable is equivalent to 100 feet of input cable. You wouldn't want 100 feet of cable loading your cartridge! That's why output cables are cut as short as possible. Now if you prefer your own cables, you can send me one and I will personally hardwire it into the unit, or I can build the chassis using female RCA jacks (no cables). Gain can be factory set to 14dB, 20dB, or 26dB.

When used with a Trumpet, I recommend using 26dB gain for cartridges of 0.05mV to 0.25mV, 20dB for 0.25mV to 0.75mV, and 14dB for 0.75mV to 1.5mV. Cartridges with higher outputs do not require a transformer.

StepUp Transformer

Specifications

Gain	+14dB, +20dB, +26dB
Input Impedance	1900, 470, 120 ohms
Bandwidth (-3dB)	5Hz to 150kHz
Size	7" wide x 4.5" high x 5" deep
Weight	5 lbs.

System Measurements

Below is the EQ response of new step-up prototype and Trumpet (system gain 64dB). Top trace is input, bottom trace output. This is near-perfect EQ.

Combination of 20dB step-up and Trumpet, top trace input

But that doesn't show the true wideband story. Below is the unfiltered input. Bandwidth into my trusty HP-333A was an astounding 4Hz up to 150kHz! There is a resonant 4dB peak at 130kHz caused by transformer loading and ringing.

Full bandwidth response

Downloads

StepUp Manual (400k pdf)

Customer Testimonials

The trumpet is absolutely awesome looking.
The bass I hear is powerful, deep and well defined. And this when nothing is broken in [yet]! I'm getting really great sound all around and dismissing any thoughts of NOS tubes ... Jim, your Trumpet produces STATE OF THE ART SOUND when powered by the PS300 (preceeded by the XE-12) in the 120-120-50 waveform ... I'm sure it would compare favorably with the best of the best.
As good as the bass is with the Herron, the Trumpet is more dynamic. And not just a little IMO. The Trumpet seems to retrieve detail better and is more relaxed sournding (hard to do). I would say that the Herron sounds thin when compared to the Trumpet. The bass isn't as rounded either, it has more depth and tone. The unit is dead quiet in my system. Same noise floor or better when compared to the Herron.
I received the Trumpet last night. Naturally, I had to hook it up right away and listen. It needs more breaking in, but I can already hear it open up. My initial impressions are that it is clean, fast, and incredibally detailed. I was listening through headphones late last night and heard background voices and sounds I didn't know existed on some of my favorite recordings. My overall impression is one of completely effortless performance, with no grain in the highs or any feeling of strain or distortion, and clean musical bass. Kind of amazing to think that as it breaks in, it will just get better. Also, it is pretty ruthless at revealing flaws in recordings.
Wow. It still isn't fully broken in, but I can not believe the sound coming out of my speakers. That is one fine phono amp. I was listening this morning to a Columbia half speed mastered record of Rampal and Stern playing Vivaldi. All of the instruments were vividly portrayed, especially the solo violin and flute, which were perfectly placed in the soundstage. There was no grain or hint of distortion anywhere. Then I played the Classic 45rpm release of Harry Belafonte singing the blues. He may have been singing the blues, but I was amazed at the clarity of his voice emerging from thin air in front of me. My Avanti speakers and Berning amp are both known for being quite fast and detailed, ans your phono amp obviously fits right in. I am really pleased. Thanks for building such good hifi gear.
I rolled the tubes using Telefunken 12AX7's and NOS RCA 12AU7 clear tops. Things are pretty well settled in now, including the Quicksilver step-up. The tubes did not make a huge difference, but it is quieter and more detailed. Overall, it sounds amazingly good right now. I can (and do) listen for hours at a time with no fatigue. Low level listening is a real treat, with no loss of detail. I almost prefer it, to be honest, although it is nice at times to crank up the SPL's and let Dire Straights rip out Money for Nothing.
Received the unit yesterday afternoon and I can't begin to tell you how thrilled I am. I listened most of the afternoon and practically all night and it just sounds better and better. Needless to say I'm a very happy camper.
The most astounding thing so far is how drop-dead silent this unit is with a noise floor somewhere down around China.
I absolutely love the Trumpet. I feel it is a best buy in audio. Your Trumpet with my passive is simply the best sound I have had in my system ever.
After two weeks with my Trumpet, I must say that it's so enjoyable to play record after record and discover detail, shading and nuances that were previously buried inbackground noise. Also, the explosive dynamics and smoothness of this unit continue to impress.
First real chane I have had to sit down and listen to the Trumpet since rewiring the step-up transformers, and what started out as a one hour session ended up being most of the day ... It's an excellent phono preamp! Very neutral and detailed. The frequency extremes are the most real of any phono pre I've heard before. If I had any complaint, it would be that it could sound a little warmer. But that would probably spoil the clarity, which is something it does in spades.
The Trumpet is certainly the soul of my systems. I have never thought about replacing it. I'm like you - some of the other vinyl enthusiasts should give it a listen. I'm sure they would feel the same. Thank you for such a superior sounding product. It has made my listening so enjoyable.
Well, the thirty days are up and I just wanted you to know - YOU CAN'T HAVE IT BACK! I was very conflicted (that crappy 'review' in Stereo Times) when I first ordered it. I'm also getting to be more leary of tubes the more I gain experience with them, but with the 30 day trial I figured what the hell? It replaces a Conrad Johnson solid state unit that retailed for $2400 in 1993. The Trumpet is now broken in and invites me into the listenign chair, whereas the CJ unit drove me to the other room. The imaging is first rate and I don't know how anyone could describe the sound as not being detailed. Anyhow, I'm very happy. What's not to like? Balanced outputs, tons of iron and great sound from tubes that won't break the bank.
I have not yet modified it since a couple of my friends wanted to hear the unit, and I thought it would be best to leave it stock. We compared it to a Herron and to a Ref Phono. The Herron was easily bested, the AR was a closer race.
I am enjoying the preamp more than you can imagine. The unit sounds fabulous even with the Sovtek and EH tubes. With NOS Amperex BB and Telefunkens the preamp is divine.
I'm replacing a $6k VAC CPA1 mkII full function preamp with an external power supply that would easily dwarf most amps. Yours is more much smoother but more transparent with deeper and cleaner if not more powerful bass.
A couple of weeks ago I became a proud owner of the beautiful wooden fascia Trumpet and a matching step-up trannie. First and foremost, I would like to thank you from the bottom of my heart for the endless joy this superb phonostage is providing me; when I am at home, a record is playing nearly all the time, as I just can't get enough!
Thanks for a wonderful sounding and great looking machine, and your services are examplary! I wish I could give you a positive feedback somewhere :-))