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Using a Power Attenuator with a Mic'd Isolated Guitar Speaker in a Home Studio

I encourage guitar players at home to combine power attenuation with speaker isolation, with multiple mics running back to the control room.

 

This home recording rig setup is great for working with power-tube saturation without bothering people.  It's a slightly adapted version of the classic recording studio processing chain and setup.

 

guitar

eq1

Comp/OD/Dist/Fuzz

eq2

tube preamp in guitar amp

tone stack in guitar amp

tube power amp in guitar amp

power attenuator

guitar speaker, isolated outside the control room

multiple mics

mixer in control room

headphones or full-range studio monitor speakers

 

Using this setup, which enables fingertip control of speaker volume, power-tube saturation, and EQ curves, I concluded that pushing the speaker hard isn't very important; I'm not getting better sound by bypassing the power attenuator compared to using it at a high-attenuation setting.  That's with a 15-watt tube amp and a good 15-watt speaker.  Do you think pushing the speaker hard is important for authentic cranked-amp tone?

 

A week ago, I still thought that it was important to push the speaker hard, so I was very interested in using a speaker isolation cabinet, but was reluctant to accept using a power attenuator.  However, if pushing the speaker hard isn't important, priorities change alot, and it turns out to be a great solution, using a power attenuator together with an isolation cabinet or a conventional speaker cabinet (or spare combo amp's speaker) in an improvised isolation booth.

 

The guitarist who thinks in terms of the guitar amp but not the recording studio might try to avoid using a mixer, and attempt to do without a miked speaker.  Those shortcuts may be possible, but are unlikely to provide the control and real ingredients needed.  Instead, for authentic studio Tone, consider multiple mics with a mixer essential -- in conjunction with the other must-have, immensely practical "desert island" components: a good power attenuator and an isolated guitar speaker.

 

A single mic is adequate but it's really nice to have multiple mic signals available at the mixer.

 

The quieter you need to be, the greater is the need to heavily use the power attenuator and use a fully sealed speaker isolation cabinet.  For example, worst case would be an apartment with thin walls at 3 a.m.  In that case, you'd need to seal the speaker and mics thoroughly, with multiple layers, and attenuate heavily at the power attenuator, so that the speaker is quieter than the unplugged guitar. 

 

In contrast, with a basement studio in a house you own, in the middle of the day, you can get by with a moderate improvised isolation booth and only a little power attenuation.  Then, the worst noise leakage problem would be internal to your studio: monitoring accurately while hearing leakage from the improvised isolation booth.

 

http://www.amptone.com/#spkiboxes -- guitar-speaker isolation

http://www.amptone.com/#poweratten -- power attenuators, including the Hot Plate

 

I have been using a deluxe, large, double-layered speaker isolation cabinet. I need to do more testing of the comparatively light and small Demeter isolation cabinet before I can recommend it with certainty.  Use a decent guitar speaker as your remote, mic'd speaker.  If you use an isolation cabinet, purchase a good speaker dedicated to that cabinet.

 

 

A power attenuator enables you to use a single low-wattage speaker with a high-wattage tube power amp.  I haven't heard any sacrifice in Tone produced by using a good power attenuator to absorb most of the wattage.  The equalization of the Hot Plate swings greatly in the lowest, continuously adjustable setting, so that when turned to the milliwatt level, the speaker has too much high-treble and little bass. 

 

So I avoid extreme attenuation not because the speaker must be stressed or must respond back to the power tubes, but rather, because the Hot Plate malperforms at that extreme, and dynamic mics generate too much self-noise to record an extremely quiet guitar speaker. 

 

If I had to attenuate to that extreme, I could still get great authentic cranked-amp tone, but I'd have to change the post-mic equalization or the mic placement to compensate for the Hot Plate's excessive brightness at that level.

 

In practice, I like to play the speaker as loud as comfortable for the time of day, but I have yet to hear any Tone degradation when moving from the moderately loud to the moderately quiet settings of the power attenuator.

 

The above setup works well for classic rock and blues and quasi-clean (just before any explicit power-tube clipping occurs).  For a 3-stage dummy load setup like Van Halen, I'd keep that setup except I'd use the power attenuator at full attenuation, forming a dummy load, and use its output to drive an additional equalizer then a solid-state amp, pushing the remote speaker.

 

guitar

eq1 [optional]

overdrive or distortion

eq2

tube power amp

    power attenuator as dummy load

    eq3

    solid-state power amp

guitar speaker, isolated outside the control room

multiple mics

mixer in control room

headphones or monitor speakers

 

Whether using a power-attenuator or dummy-load setup, it's nice to have the guitar speaker far away in another room, to monitor in headphones, if you are experimenting with distortion character and nuances of pick attack, or are recording and ultimately only want to hear what the recorded sound -- the line signal -- sounds like.

 

 

A friend was over and played a single-single-humbucker solidbody guitar with various pickups selected. I operated the equipment. His good playing ability combined with my experience and setup and handy supply of gear and both hands free, resulted in a huge success that surprised me.

 

It confirmed the soundness of my setup and approach, and confirmed that the power attenuator combined with a speaker isolation cabinet enables getting first-class amp tone with a miked speaker without the neighbors or house guests hearing.

 

 

He acted as the guitarist and I acted as the recording studio recording engineer. We monitored in headphones -- I really wanted two identical decent headphones; one for him and one for me -- or studio monitor speakers.

 

The books tell always how to place time fx within a chain, and their chain doesn't show the guitar or the mics on the speaker. We must place much less emphasis on the time fx and much more emphasis on EQ stages alternating with distortion stages, and must always show the full chain from the guitar to the studio monitor speakers.

 

Though it's taken years for me to obtain the right combination of basic elements, including a mixer, I *still* don't have a "basic" setup; I need to push home-studio guitarists harder to plan to invest in studio monitors considered as a basic part of their "guitar amp rig". The one thing blocking me from uploading amp tone MP3s now is my lack of studio monitors, to help me master the final EQ settings before uploading.

 

 

In my test tour of amp tones with my friend, the pedals listed were used with a variety of amp settings. When using mostly power-tube saturation, the amp's tone stack was usually set to Treble 9, Mid 5, Bass 3, to avoid crumbling bass and enhance ringing clarity. When using mostly preamp distortion (whether in amp or via OD/Dist pedal), the amp's tone stack was set more to a V curve.

 

The first eq in any of these chains was usually set to slight cut of mid-Bass, and slight boost of mid-Treble, for this guitar. When preamp distortion is used, it was often followed by a V curve.

 

Modelling amps and processors fail to tell you which pickup the setting was designed for. They are probably afraid to alienate guitarists who don't have a guitar with that type of pickup setting, but this is crucial information. There are several pickup selections, and several blends of distortion or overdrive with power-tube saturation.

 

        Which pickup selection is used?

        What is the pre-distortion EQ (guitar EQ)?

        Is OD or Dist used?

        What is the post-distortion EQ (EQ before the power tubes)?

        How much preamp distortion and power-tube saturation is there?

        What is the post-power-tube EQ (affected by speaker, cab, mic, and mixer)?

 

It would take some time to summarize how these settings interact.

 

My friend's most interesting comment was about Delay - do I use it? I explained that the more I studied amp tone settings and principles, the narrower the place for Delay seemed to me. Maybe someday I will return to being interested in Delay -- now that I have distortion voicing and basic amp tone principles down.

 

With his concentrating on the playing, and my dialing in settings with both hands and full attention, and my swapping out pedals, we were able to tour the main varieties of amp tone quickly and establish that this rig is able to produce Blues, Metal, Country, Acid Rock, and Psychedelic amp tones that sound as good as passages on records.

 

 

I usually feel frustrated and challenged as I labor to dial in all sorts of amp sounds to manually model amp tone heard on various records. Now that I understand guitar equipment well, and figured out the response and quirks of the equipment I currently have, I was surprised that everything fell together immediately during this session -- it was a Nirvana feeling like we couldn't get a bad sound if we tried.

 

We always tried to get good sounds, and I swear that there wasn't a bad sound that whole time, and we toured through the main combinations of pickups and distortion settings. Had I recorded the session, I'd have no reservations about uploading it. This would be a good project for me to do -- a quick tour through the world of amp tone.

 

I have watched several videos about amp tone but I could do way better and provide a more relevant and useful video by focusing less on effects, and less on combinations of guitars and amps, and showing how to use a single tube amp setup intelligently, to get the fullest potential out of this gear:

 

 

A book and a video about how to use this basic setup would contribute more than any "recording the guitar" book or "amp tone" video that currently exists. The pieces of this information is present at Amptone.com, but isn't summarized and arranged effectively enough. There should be at least a sound sample for each major setting, showing how to "manually model" not an "amp brand" but rather, a type of sound such as exemplified by particular album passages.

 

Today's amp tone books and videos aren't any better than Amptone.com at summarizing the info for my basic concept of what's needed: how to run guitar gear. There are tons of books on "how to play Rock guitar", and books "about guitar equipment", yet there is still no book that clearly and effectively targets the goal of "how to play a guitar amp" -- that is, how to run a guitar rig.

 

The ideal approach would be to assume a foundation of the above chain, regardless of the type and location of the speaker cab. The attenuator+remote mic'd cab approach is an ideal reference setup for dialing in sounds; that is the best starting point, and variations can be discussed in a later chapter, such as jamming without a mic or PA, or using a cab-sim filter instead of a guitar speaker.

 

The power attenuator is key, for practical home studio use and for experimenting with dialing-in sounds, and the isolation of the guitar speaker is key, regardless of how that isolation is accomplished; that isolation includes the technique of monitoring via headphones or monitor speakers, to factor out the monitoring level and to work with the line-level signal that can be recorded or sent to the full-range PA.

 

Guitarists should know how to get a great line-level signal, because that's a more encompassing challenge than getting a good sound at the guitar speaker. This is the best chain as a reference point, because it's the real recording studio chain, with the slightest possible variations -- power attenuator and improvised isolation booth. From there, anyone can then move toward simpler or simulated systems, applying the classic rig knowledge as much as possible.

 


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