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FREQUENTLY ASKED QUESTIONS

992EG

Do I need extra venting in my rack?


Extra venting isn’t required but it is recommended, especially in warmer environments such as outside venues in the sun.




How hot does the 992EG get?


The 992EG will get warm. Eight vacuum tubes WILL generate heat. For this reason we recommend leaving a single rack space empty above the 992. It’s never a good idea to block or cover ventilation holes that are on top covers of the 992EG.




Will this work with my high output tube mic?


Yes. But we recommend using the -20 db pad or be comfortable with only rotating the input knob to about 9 o’clock max. With high output mics it is a good idea to start with the input knob at 9 o’clock and then use the output control to achieve line level. From there you can play with coloration and harmonics. Be aware that with high output mics, the preamp is already starting with a very large signal. It is not going to require much INPUT gain to generate harmonics and even distortion. But, then again, that might be what you’re after!




What is the warranty?


All LaChapell Audio products feature a 2 year warranty on parts and labor for issues relating to manufacturing. The tubes have a 6 month warranty. Please see the Digital Audio Labs Warranty page for more information.




What kind of tubes are in the 992?


The 992EG features (4) 12AX7’s and (4) NOS 5814’s. The NOS 5814 tube is a ruggedized version of the 12AU7. The 12AX7’s are the tubes that provide the most gain and are driven with the INPUT control.




Can I swap out the tubes?


Yes. The manual will provide guidelines in this regard. The 2-bay 583’s (583E and the original 583S) have square openings that are intentionally designed to allow users access to the 12AX7 and replace with other like tubes for additional flexibility. Generally speaking, it’s the input tubes (the 12AX7s or 12DW7s) that would be replaced if you are looking to alter the sound of the amplifier. The 992’s output tubes require a critical balancing step. Because of this, we don’t recommend replacing these. In any case, if there’s ever a question related to swapping out tubes PLEASE give us a call.




Who is using LaChapell Audio gear?


We’ve had folks like Brad Paisley, Hans Zimmer, Phil Keaggy, Depeche Mode, M83 and loads of others choose our preamps over others for critical productions. Many studios in Nashville, LA and the rest of the world rely on LaChapell Audio to capture the sound they want.




What kind of transformers does the 992EG use?


The 992 currently uses the Jensen 115k microphone input transformer and a Jensen JT-11-BMCF line output transformer. We also use the Cinemag CM-DBX for the Hi-Z input stage.




What does the -20dB pad do?


First, it provides for the basic need to attenuate the input signal for “hot” or loud sources. For example, there are some microphones out there that generate such a large signal that a pad is required in order to prevent unwanted distortion. The second reason is for sonic shaping. All LaChapell Audio preamps place the -20dB pad function in such a way that, when engaged, the gain contribution from the input transformer is effectively eliminated. When that loss of gain is made up by dialing in INPUT gain, the user has essentially traded transformer gain with vacuum tube gain. As a result, the distortion is different, the frequency response is different, etc. Users who use this this technique express hearing more “air” and “depth” to the sound. It’s not always preferred but it demonstrates the preamp’s sonic flexibility. Areas where this technique is routinely used are drum overheads and stereo piano overheads.




Why are there two knobs?


LaChapell Audio preamps are unique in how they provide gain control to the user. Our Dual Drive knobs provide separate INPUT and OUTPUT gain controls for increased sonic flexibility. This is key to LaChapell Audio’s reputation of being so versatile. In short, the INPUT gain control is where you can dial in harmonic color. The OUTPUT control drives the very clean, natural sounding output stage. The contrast isn’t extreme, but discovering the perfect balance between these controls for whatever might be connected to the preamp is what makes LaChapell Audio preamps so much fun to use.





983S MK2

Do I need extra venting in my rack?


Extra venting isn’t required but it is always recommended, especially in warmer environments such as outside venues.




Will the 983S work with my high output tube mic?


Yes. But we recommend using the -20 db pad or being comfortable with only rotating the input knob to about 9 o’clock max. With high output mics, it is a good idea to start with the input knob at 9 o’clock and then to use the output control to achieve line level. From there you can play with coloration and harmonics. Be aware that with high output mics, the preamp is already starting with a very large signal. It is not going to require much input gain to generate harmonics and even distortion.




What tube does the 983 use?


The 983M, 983S, and 583 are the same preamplifier and use one 12AX7 twin triode tube per channel. TIP: When selecting different tubes for different sounds, use the -20 pad technique mentioned earlier. Engaging the pad and using Input gain to compensate will feature the 12AX7’s character and allow you to hear the differences between tubes much more than if the input transformer was part of the signal.




What transformers are used on the 983 series?


The 983 & 583 preamps currently use the Cinemag CMMI-10PCA microphone input transformer and a Jensen JT-11-DM line output transformer. The Hi-Z input on the 983/583 amps is transformer-less.




What does the -20dB pad do?


First, it provides for the basic need to attenuate the input signal for “hot” or loud sources. For example, there are some microphones out there that generate such a large signal that a pad is required in order to prevent unwanted distortion. The second reason for the pad is sonic "shaping." All LaChapell Audio preamps locate this function in the circuit such that, when engaged, the gain contribution from the input transformer is effectively eliminated. When that loss is made up by turning up the input gain, the user has essentially traded transformer gain for vacuum tube gain. As a result, the distortion is different, the frequency response is different, etc. Users describe this technique as adding “air” and “depth” to the sound. It’s not always preferred but it demonstrates the preamp’s sonic flexibility. Situations in which this technique is routinely used are drum overheads and stereo piano overheads.





583S

Do you meet VPR requirements?


Yes! The 583S mk2 and the 583e have been tested and approved by the VPR Alliance.




How many 583's can I install in a single 500 series frame?


How many spaces to you have? Since the LaChapell Audio TrueTube technology current draw is within VPR limits, you can load up your entire frame with Mk2’s without issues. There’s a wide variety of power supply options in the market today. On top of that, there are several non-tube modules on the market that pull much more current than LaChapell Audio products. As such, regardless of the module, it’s a good idea to check the user manual of the power supply you are using to make sure it has enough current capacity.




Do you recommend a particular 500 series frame?


Our modules were designed to meet API’s VPR certification standards. Therefore, the API series of 500 series power supplies are an obvious recommendation. But there are many others we’ve found to be very reliable, including units from Purple, Heritage, and others.




Do I need extra venting in my 500 series frame?


No. There is a glowing vacuum tube in your 500 series module, but it is of the 9A preamp type, similar to those used in the AKG C-12, Telefunken 251, etc tube microphones. While the mics have only one section of the tubes active, they also have less internal volume yet the surface temp of these mics never exceed room temperature. As long as you don’t block the venting on your 500 series power supply, you will be fine.




How hot do LaChapell's 500 series units get?


The 583S mk2, 583E, and 500TDI will get warm but no more than any other 500 series module drawing 110-120ma. That said, it’s never a good idea to block or cover ventilation holes on 500 series power supplies.




I've heard it's impossible to provide the correct tube voltage to a 500 series module. Are LaChapell 500 modules "starved plate" designs?


No. From the beginning, we set out to not only make the first tube preamp for the 500 series, but the world’s first high voltage tube preamp for the 500 series. Think of the 583S, 583E, and 500TDI as having a secondary, high-voltage supply within the unit. All LaChapell Audio 500-series modules with tubes feature both a full 250 volts to the plates and a full 12 volts to the filament. This is the proper way of powering a vacuum tube and more importantly, allows the tube to behave the way it was designed without stress from a lack of power.




What transformers are used on the 583 series?


The 983 & 583 preamps currently use the Cinemag CMMI-10PCA microphone input transformer and a Jensen JT-11-DM line output transformer. The Hi-Z input on the 983/583 amps is transformer-less.





583E

How hot do LaChapell's 500 series units get?


The 583S mk2, 583E, and 500TDI will get warm but no more than any other 500 series module drawing 110-120ma. That said, it’s never a good idea to block or cover ventilation holes on 500 series power supplies.




On the 583E, can I use the EQ section independent from the preamp section?


Yes. Think of the EQ section on the 583E as its own independently usable module separate from the 583 preamp or as a simple pre+EQ channel strip. Running the EQ alone is accomplished by flipping the toggle switch on the lower right to “Pre/EQ”. In this mode, the 583E is now two completely independent units. The EQ path is re-routed to the corresponding XLR input/output jacks on the power supply and can be used however the user wishes. When the same toggle is flipped to “Pre+EQ” the EQ path is patched to serve the preamp. Below are a few ways to apply these functions. Scenario 1: The 583E is being used to record acoustic guitar but, you realize you need an EQ on a different preamp that’s being used for the vocal track. In this case, flip the EQ toggle to “Pre/EQ”. In this mode, you can still use the 583 preamp on acoustic guitar but the EQ section is now available to be routed to the vocal preamp. Scenario 2: You’ve finished recording and are preparing to mix. You’re set with in-the-box EQ’s but need something more natural sounding to shape/sculpt the electric guitar track. With the 583E switched to “Pre/EQ” you can patch into the EQ section’s XLR input/output jacks for this task.
Scenario 3: You’re using the 583E to amplify the microphone used to record a violin. You love the mic/preamp combo but would like to nudge a little more low-mids before recording. Flipping the EQ toggle to “Pre+EQ” auto patches the EQ to serve the preamp in this way. In this mode the 583E is functioning as a channel strip.





500TDI

What kind of tube is in the 500TDI?


The 500TDI uses a 12DW7 vacuum tube. The 12DW7 combines the two tube flavors into one. The first stage, driven by the INPUT knob, is a 12AX7 and the OUTPUT stage is a 12AU7.





503


500DT


500CS


General

Who uses LaChapell Audio?


We’ve had folks like Brad Paisley, Hans Zimmer, Phil Keaggy, Depeche Mode, M83 and loads of others choose our preamps over others for critical productions. Many studios in Nashville, LA and the rest of the world rely on LaChapell Audio to capture the sound they want.




What is the warranty?


All LaChapell Audio products feature a 2 year warranty on parts and labor for issues relating to manufacturing. The tubes have a 6 month warranty. Please see the Digital Audio Labs Warranty page for more information.