Hartke LH1000 Bass Amplifier Head User Manual

Hartke LH1000 Bass Amplifier Head

Introduction

Congratulations on purchasing the Hartke LH Series Bass Amplifier! Although these amplifiers have been designed for easy operation, we suggest you first take some time to go through these pages so you can fully understand how we’ve implemented a number of unique features. This manual covers both LH Series models, the LH500 and LH1000. The model LH500 produces 350 watts when connected to a speaker system with an 8-ohm load, and 500 watts when connected to a speaker system with a 4-ohm load.

The Model LH1000 features a dual 500-watt power core for a total of 1000 watts of power. With that kind of power, the Models LH500 and LH1000 are EXTREMELY loud and punchy. The LH Series vintage style tube preamp is pure tone, just plug in. The front panel controls are simple and logically laid out starting with inputs for PASSIVE and ACTIVE basses, VOLUME control, BRIGHT switch, a musical equalizer section featuring BASS, MID and TREBLE controls, plus LIMITER switch and XLR DIRECT OUT.

In addition, the Model LH1000 offers a BALANCE control, which allows you to adjust the level balance between two different cabinets like when powering a rig with one 4 x 10 and one 1 x 15. Speaking of bass cabinets, the LH Series are a perfect compliment for any of the Hartke XL and Hartke VX series bass enclosures. And, for the latest in world-changing (really) bass speaker technology, check out the new Hartke Hy drive HX Series bass enclosures. The Hy drive feature Hartke’s hybrid cone, neodymium magnet, high power handling Hy drive bass speakers (Patent Pending).

Check them out at hartke.com. The LH Series rear panels have 1/4-inch EFFECTS SEND and RETURN for connecting external effects processors, plus 1/4-inch and Speak on connectors for connecting your bass cabinet or cabinets. The LH Series all metal chassis with convenient handles are rack-mountable taking just two spaces in a standard 19- inch equipment rack. The Model LH500 and LH1000 are optimized for use with electric bass instruments, and the front panel controls in both models are virtually identical.

You’ll find either to be an excellent bass amplifier for live performance use in small and medium-size venues; in addition, the classic tube pre-amp make the Model LH500 and LH1000’s ideal for use in recording environments. In these pages, you’ll find a detailed description of the many features of the Model LH500 and LH1000 bass amplifiers, as well as a guided tour through their front and rear panels, step-by-step instructions for setting up and using each product, detailed discussions about equalization and compression, and full specifications.

You’ll also find a warranty card enclosed—please don’t forget to fill it out and mail it so that you can receive online technical support and so we can send you updated information about these and other Hartke products in the future. Also, be sure to check out our website (hartke.com) for complete information about our full product line. With proper care and adequate air circulation, your LH Series head will operate trouble free for many years. We recommend you record your serial number in the space provided below for future reference.

Serial number
Date of purchase

The Hartke Model LH500 and LH1000 bass amplifiers offer classic tone with all the newest concepts in bass amplification design. Here are some of their main features:

• Power to spare — The Model LH1000, a full 1000 watts delivered to a 4 ohm speaker system or 500 watts to an 8 ohm speaker system. The model LH500 delivers 500 watts to a 4 ohm speaker or 350 watts to a 8 ohm speaker.
• Classic 12AX7 tube high-voltage preamp circuit provides great tone.
• Bass and Treble Shelving, plus Mid Peak EQ Controls, allows you to create a broad range of tonal colors for your bass instrument.
• A built-in Limiter which not only adds real “loudness” to your bass sound, but also allows you to smooth out volume differences between notes.
• Two independent inputs to accommodate both passive and active bass guitars.
• 1/4-inch plus Speak on Output connectors for connecting speaker cabinets.
• Protection relay circuitry that protects connected speakers from dangerous overloading and also prevents “thumps” when powering on or off.
• Effect loop send and return jacks that allow you to connect to professional outboard effects processors.
• Electronically balanced direct output that provides a means of routing signal to professional mixing consoles in both live performance and recording environments.
• The amplifier is constructed within a 2 rack space steel chassis with metal faceplate and handles.
• Rugged construction makes the Model LH500 and LH1000 eminently road-worthy.
• Easy to use, great tone and loud!
• Three year extended warranty.

Guided Tour – Model LH500 and LH1000 Front Panel

1. Handle – Two convenient metal handles make the amplifier easy to transport and easy to position while mounting in an equipment rack.
2. PASSIVE Input jack – If your bass guitar has passive circuitry, connect it to the Model LH500 and LH1000 here. This standard, 1/4” unbalanced jack provides a high impedance (100 k Ohms) input sensitivity of 20 millivolts.
3. ACTIVE Input jack – If your bass guitar has active circuitry,* connect it to the Model LH500 and LH1000 here. This standard, 1/4” unbalanced jack provides a high impedance (100 k Ohms) input sensitivity of 60 millivolts.
   * Bass guitars that have active circuitry normally require a battery for the circuitry to be functional.
4. VOLUME control knob – This is the overall volume control. For best signal-to-noise ratio, keep the output of your bass at or near maximum and adjust the amp’s VOLUME control to the desired level.
5. BRITE LED – The indicator light will illuminate when the BRITE switch is engaged.
6. BASS control knob – As part of the tone stack equalizer, the control is used to adjust the low frequency response, providing bass boost from 1 to 10.
7. MID control knob – As part of the tone stack equalizer, the control is used to adjust the mid-range frequency response, providing mid boost from 1 to 10.
8. TREBLE control knob – As part of the tone stack equalizer, the control is used to adjust the high frequency response, providing treble boost from 1 to 10.
9. LIMITER LED – The indicator light will illuminate when the LIMITER switch is engaged.
10. BALANCE control knob (LH1000 only) – This control knob adjusts the level difference between the Channel 1 and Channel 2 amplifiers. If you are using two different cabinets (for example a 115 and 410), you may want to drive one a little harder than the other to balance your sound. In the center (12:00 o’clock) position, both amplifier channels are at equal power. The BALANCE control has no effect when the LH1000 is running in bridge mode.
11. DIRECT OUT – Use this electronically balanced XLR jack to route signal from the Model LH500 and LH1000 to a professional mixing console or as a tap to a main PA system via a mic input on the console. The signal output from this jack is low impedance (100 ohm) with an output level of approximately -30 to -20 DB. You can also use the Direct Out jack to route signal to an external amplifier with a -10 dB input sensitivity.
12. Fan Filter – Removable sponge filter covering the amplifier’s cooling tunnel vent. The Fan Filter can easy be
    removed and cleaned.
13. BRITE switch – Use this switch to turn on the LH Series’ BRITE circuit, which when engaged, adds a pre-set eq curve to enhance the bass instrument’s high-end response.
14. Limiter switch – This switch is used to engage the LH Series Limiter circuit. The LH Series Limiter is an automatic dynamics processors used to control the level from reaching clipping. Use the Limiter to even out the loud transients that can cause distortion. Using the Limiter will also help protect your speaker system
15. Power switch – Use this to power the Model LH500 and LH1000 on or off. The internal power LED lights whenever the Model LH500 and LH1000 is powered on.

Guided Tour – Model LH1000 Rear Panel

1. AC Voltage selection switch – This switch is used to set the LH Series operation voltage. Be sure to check that the switch is set correctly for your country.
2. EFFECTS SEND jack – Use this 1/4” unbalanced jack to send low impedance (100 ohm) signal from the Model LH1000 to a professional outboard effects processor such as a reverb, echo, chorus, flinger, or harmonizer device. Output level is approximately 0 dB to +4 dB and is post-EQ and post-Limiter but unaffected by the setting of the VOLUME control. You can also use the Effect Send jack to route signal to an external mixing console or amplifier with an input sensitivity of +4 DB.
3. EFFECTS RETURN jack – Use this 1/4” unbalanced jack to return low impedance (600 ohm) signals to the Model LH1000 from a professional outboard effects processor.
4. Fan – The fan provides vital cooling to your Model LH500 and LH1000. Make sure that it is kept free of all obstructions and that cool, fresh air is accessible at all times. Also, try to ensure that the Model LH1000 is used in a dust-free environment.
5. SPEAKER OUTPUT A – Connect any 4, 8, or 16 ohm bass cabinet(s) to these standard unbalanced 1/4” jacks. WARNING: Because of the high power levels and low frequency content of the signal generated by the Model LH1000, use only appropriately rated speaker cabinets (at least 600 watts at 4 ohms) that are specifically designed for bass instruments. We recommend that Hartke amplifiers be used with Hartke bass cabinets, although other brands of speakers can be used.
6. BRIDGE output connector – Connect a Speak on connector cable here when operating in Bridge mode.
7. SPEAKER OUTPUT B – Connect any 4, 8, or 16 ohm bass cabinet(s) to these standard unbalanced 1/4” jacks. WARNING: Because of the high power levels and low frequency content of the signal generated by the Model LH1000, use only appropriately rated speaker cabinets (at least 600 watts at 4 ohms) that are specifically designed for bass instruments. We recommend that Hartke amplifiers be used with Hartke bass cabinets, although other brands of speakers can be used.
8. BRIDGE switch – Used to set the LH1000 to operate in Dual Parallel or Bridge modes.
9. AC input – Connect the supplied standard 3-pin “IEC” plug here.
10. Fuse sled – This contains a fuse holder for your Model LH1000. Make sure the voltage rating is correctly set before powering up the amplifier! Fuse ratings are 15 amp for115 vac and 7.5 amp for 230 vac.

1. AC Voltage selection switch – This switch is used to set the LH Series operation voltage. Be sure to check that the switch is set correctly for your country.
2. EFFECTS SEND jack – Use this 1/4” unbalanced jack to send low impedance (100 ohm) signals from the Model LH500 to a professional outboard effects processor such as a reverb, echo, chorus, flinger, or harmonizer device. Output level is approximately 0 dB to +4 dB and is post-EQ and post-Limiter but unaffected by the setting of the VOLUME control. You can also use the Effect Send jack to route signal to an external mixing console or amplifier with an input sensitivity of +4 DB.
3. EFFECTS RETURN jack – Use this 1/4” unbalanced jack to return low impedance (600 ohm) signals to the Model LH500 and LH1000 from a professional outboard effects processor.
4. Fan – The fan provides vital cooling to your Model LH500. Make sure that it is kept free of all obstructions and that cool, fresh air is accessible at all times. Also, try to ensure that the Model LH500 and LH1000 is used in a dust-free environment.
5. SPEAKER OUTPUT – Connect any 4, 8, or 16 ohm bass cabinet(s) to these standard unbalanced 1/4” jacks. WARNING: Because of the high power levels and low frequency content of the signal generated by the Model LH500, use only appropriately rated speaker cabinets (at least 600 watts at 4 ohms) that are specifically designed for bass instruments. We recommend that Hartke amplifiers be used with Hartke bass cabinets, although other brands of speakers can be used.
6. AC input – Connect the supplied standard 3-pin “IEC” plug here.
7. Fuse sled – This contains a fuse holder for your Model LH500. Make sure the voltage rating is correctly set before powering up the amplifier! Fuse ratings are 10 amp for115 vac and 5 amp for 230 vac.

Setting Up and Using the Model LH500 and LH1000

Setting up your Hartke Systems LH Series Bass Amplifier is a simple procedure which takes only a few minutes:

1. Remove all packing materials (save them in case of need for future service) and decide where the amplifier is to be physically placed. To avoid potential overheating problems, be sure that the rear panel is unobstructed and that there is good ventilation around the entire unit, particularly behind the rear panel fan.
2. Begin by hooking up your bass cabinet or cabinets, using the 1/4” unbalanced Speaker output connectors on the rear panel; it is never a good idea to power up any amplifier that is not connected to loudspeakers. We  recommend the use of a single 4 ohm cabinet or two 8 ohm cabinets. Hartke amps are optimized for use with Hartke bass cabinets, although other brands of speakers can be substituted.Any appropriately rated bass cabinet with a minimum impedance of 4 ohms (that is, 4 ohms or greater) can be used. In order to ensure correct phase correlation, the tip of the Model LH500 and LH1000 speaker jack should be connected to the “+” (hot) input of your loudspeaker, and the sleeve of the Model LH500 and LH1000 speaker jack should be connected to the “-” (ground) input of your loudspeaker. If you are using the LH1000 with a single cabinet of 4 ohms or 8 ohms, set the BRIDGE mode switch to BRIDGE mode and use a Speak on cable to connect your cabinet. If you are using the LH1000 with two 8 ohm cabinets, you can use the LH Series in Bridge mono or Dual Parallel. In Dual Parallel (Bridge mode switch off ), use two 1/4-inch speaker cables to connect to the Channel A and B SPEAKER OUTPUTS. For more information on Bridge and Dual Parallel mode see the section, “Using The LH1000 in BRIDGE and Dual Parallel Modes” later in this manual.
3. Next, connect the 3-pin AC plug into any grounded AC socket. Don’t turn the amplifier on just yet, though.
4. Use a standard music instrument cable to connect your bass to the appropriate Input jack on the front panel (if your bass has active circuitry,* connect it to the “Active” input; if not, connect it to the “Passive” input). On the front panel of the Model LH500 and LH1000, set the VOLUME control to “0” (fully counterclockwise) and set BASS, MID and TREBLE to their center “0” position. Finally, set BRITE and LIMITER switch to their “Out” position.
   * Bass guitars that have active circuitry normally require a battery for the circuitry to be functional.
5. Press the front panel Power switch in order to turn on the amplifier. After approximately 20 seconds, you’ll hear a click, indicating that the relay protection circuitry has completed cycling and that power to the system has been provided.
6. Set the output of your bass to maximum and then, while playing, slowly turn the VOLUME control up until the desired level is achieved. If you hear distortion even at low amplifier VOLUME control, back off the output of your bass (or check for a faulty cable).
7. If you are using the LH1000 with two different speaker enclosures, for example a 115 and a 410 you can use the BALANCE control to adjust the proper level of each. Since the two cabinets will likely have different frequency responses, adjusting the BALANCE will function like another tone control. Since the BALANCE control only works when the LH1000 is operating in Dual Parallel mode, be sure the BRIDGE mode switch is off or NOT set to BRIDIGE.
8. When you have settled a good level, the next step is to adjust the three (BASS, MID and TREBLE equalizer) tone controls to taste. For more information, see the “About Equalization” section on page 10 of this manual. When you get a great setting that will complement your instrument and playing style, it’s a good idea to write it down for future use.
9. Next, experiment with the BRITE circuit by setting the switch down to the “on” position. You’ll notice a lift in the high frequency response, which you can use to enhance your tone if you’re snapping strings or just trying to cut through the back line.
10. Now try out the Model LH500 and LH1000 Limiter circuitry. Activate it by pressing the Limiter switch in to the “on” position. The LIMITER LED will illuminate when the Limiter circuit is active. When you engage the Limiter, you’ll hear peak signals (such as string slaps and pulls) begin to sound increasingly “squashed,”
    relative to the lower-level signals produced by standard playing. The result will be a decreased dynamic range but an overall leveling of signal throughout the full pitch range of your instrument.
11. If you’re using an external signal processor, turn your Hartke amplifier off momentarily and then connect a standard audio cable between the Effect Send jack and your effects processor input and another standard audio cable between the Effect Return jack and your effects processor output (if required, multiple effects processors can be daisy-chained together, output to input).Then turn the amp back on and play your bass while adjusting the controls of your outboard effects processor(s). For best results, set both the input and output gain of all connected effects processor(s) to 0 dB (unity gain), so that there is no increase or decrease in level whether the effects are switched in or out. If you have followed all the steps above and are still experiencing difficulties, call Samson Technical Support (516-932-1062) between 9 AM and 5 PM EST.

About Equalization

The Hartke LH Series Bass Amplifier gives you enormous control over shaping the sound of your bass, using a process called equalization. To understand how this works, it’s important to know that every naturally occurring sound consists of a broad range of pitches, or frequencies, combined together in a unique way. This blend is what gives every sound its distinctive tonal color. The LH Series EQ controls allow you to alter a sound by boosting or attenuating specific frequency areas— they operate much like the bass and treble controls on your hi-fi amp, but with much greater precision.

The LH Series tone stack equalizer offers three bands of “boost only” equalization. Each EQ knob (labeled BASS, MID, and TREBLE, respectively) affects a different area of the frequency spectrum. Since the LH series equalizer is comprised of boost only filters, when you turn all the EQ knobs down, the sound will go completely off (unlike an typical PEAK EQ circuit).

When all three EQ knobs are in their center positions (“5”), the response is actually set to a preset equalization curve, with a low and high-end boost and a mid-range cut, producing an EQ contour (at Hartke, we like to say, SHAPE) that sounds great for bass. In general, when an EQ control is moved right of center, the particular frequency area is being boosted; when it is moved left of center, the frequency area is being attenuated (or less boosted).

However, the LH series EQ controls are somewhat interactive, since electronically, the BASS feeds the MID, which feeds the Treble. So, experiment with the LH Series EQ and your particular bass to dial up the best sound. The most important thing to know about the LH equalizer is that it’s extremely musical and sounds great with all EQ knobs set to “5”.

Actually, it’s hard to make LH series EQ sound bad. Turning all EQ controls up the same amount will have virtually the same effect as simply turning up the VOLUME; conversely, turning them all down the same amount will have virtually the same effect as turning down the Volume. Both approaches are pointless (after all,
that’s why we gave you a Volume control!)

In addition to the three EQ controls, the LH Series also includes a BRITE switch, which will add an overall boost to the high-end frequency response. Use the BRITE switch in conjunction with the EQ to control your tone.  In many instances, the best way to deal with equalization is to think in terms of which frequency areas you need to attenuate, as opposed to which ones you need to boost. Be aware that boosting a frequency area also has the effect of boosting the overall signal; specifically, too much Low EQ boost can actually cause overload distortion or even harm the connected speaker.

The specific EQ you will apply to your bass signal is very much dependent upon your particular instrument and personal taste and playing style. However, here are a few general suggestions:

• For that super-deep reggae or Motown sound, boost the Bass EQ slightly while attenuating the MID and Treble EQ.
• To remove boxiness and make your instrument sound more “hi-fi,” try attenuating the Mid EQ control.
• For a twangy, cutting sound, try boosting the Treble EQ. (Putting new round wound strings on your bass will help a lot also!)
• Whenever you get a really good EQ setting for a particular instrument or song, write it down (you’d be amazed how easy it is to forget these things!).
• As you experiment with the EQ controls of the LH Series, don’t forget that your bass also provides significant EQ control in the form of its pickup and tonal settings—this can be particularly effective in instruments that have active circuitry.

Using LH1000’s BRIDGE and Dual Parallel Modes

The LH1000 amplifier is constructed using two 500 watt power cores. Depending in the position of the BRIDGE mode switch, the amplifier can run in Dual Parallel mode, or Bridge mode. In Dual Parallel (BRIDGE mode switch to the left), the two amplifier channels are receiving the same input signal from the pre amp, but are operating separately, so each channel sees its own speaker load.

In BRIDGE mode (Bridge mode switch to the right), the two amplifier channels work as one and therefore, a single impedance load from the connected speakers is presented to the amplifier. Always be sure to check the manufacturers recommended power handling of your speaker cabinets to match the best impedance load and power output ratings.

If you are using the LH1000 with a single cabinet of 4 ohms or 8 ohms, set the BRIDGE mode switch to BRIDGE and use a standard Speak on cable to connect your cabinet. If you are using the LH1000 with two 8 ohm cabinets you can use the LH Series in Bridge mono or Dual Parallel. If you are using two 8 ohm cabinets as a 4-ohm single load, switch the BRIDGE mode to BRIDGE and use a Speak on cable to connect your first cabinet, then use the cabinet’s extension output to connect the second cabinet.

If you are using two 8 ohm cabinets in Dual Parallel mode, be sure the BRIDGE mode switch is in the off (left) position and make your connections using both channel A and B 1/4-inch output jacks. If you are using two 4 ohm cabinets, you MUST use the LH1000 in Dual Parallel mode (BRIDGE switch off to the left) and connect one to each channel of the LH1000 using the 1/4-inch phone jacks.

Using the Direct Output

The LH500 and LH1000 both feature a front panel DIRECT OUTPUT connector used for interfacing to external recording and PA gear. This standard, balanced XLR connector provides a Line-level pre-EQ and pre-VOLUME output signal from the LH Series amplifier. You’ll usually use this to connect the LH Series signal to a Mic-level input when interfacing with PA systems or recording mixing consoles. If you need to connect the LH Series to a PA system or a recording mixing console, connect a cable between the front-panel DIRECT OUTPUT and a Mic-level input on the mixer.

Cleaning the Fan Filters

From time to time, it may become necessary to clean the fan filter. It’s a good idea to keep the fan filter clean to ensure maximum airflow, and cooling, through your LH Series amplifier. To clean the fan filters, follow these simple steps:

1. Remove the fan filter by placing your finger in the depressed area under the fan filter frame.
2. Clean the filter with warm water and let the filter dry thoroughly before replacing.
3. Replace the fan filter by aligning the frame to the top of the panel knock-out, and then, snap the frame back in place.

Specifications

Input Sensitivity

Passive Input: 100 k Ohms, 20 mv.
Active Input: 100 k Ohms, 60 mv.

Rated Output Power

LH500 : 500 watts @ 4 ohms, 350 watts @ 8 ohms

LH1000

Dual Parallel mode : 2 x 225 watts @ 8 ohms , 2 x 320 watts @ 4 ohms, 2 x 545 watts @ 2 ohms
Bridge mode : 1 x 750 watts @ 8 ohms , 1 x 1100 watts @ 4 ohm less than .5%

Total Harmonic Distortion 

Signal To Noise Ratio : approx. 78 dB

Equalizer

Type : Tone stack BASS, MID and TREBLE

Controls : BASS, MID and TREBLE

Send Output Level : 0 dBm

Return Input Level : 0 dBm
Dimensions (Both Models) : 19″ x 14.5″ x 3.25″ 483mm x 369mm x 83mm

Weight

LH500: 23.10 lb. / 10.50 kg
LH1000: 31.90 lb. / 14.50 kg

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Hartke LH1000 Bass Amplifier Head-FAQs