The Les Paul Recording Guitar
Users Forum
(Part of Dave Gould's Guitar Pages)

This page is a knowledge base for all users of Gibson's Low Impedance guitars manufactured in the late 1960's and 1970's. If you own a Gibson Guitar equipped with Low Impedance Pickups you are invited to participate with stories, photographs of your guitar(s) and any advice regarding the use of these instruments.

NEW - FAQs - see below

Index

Home
The Story
The Les Paul Personal
The Transformer
The Controls
The Pickups
The Les Paul Professional
The L5s
The Les Paul Jumbo
The Les Paul Recording
The Demo Disc
The Les Paul Recording Headstock
Les Paul Recording Spare Parts
The Les Paul Signature
The Gibson LP 12 Amplifier
LPR FAQs
The Users Page
The Forum
Acknowledgements
Home

The Story:

In 1969 Gibson produced their first Low Impedance Guitars - the Les Paul Personal and Les Paul Professional Guitars. The manufacturing life of these instruments was just 2-3 years. During this time two other guitars, the Les Paul Jumbo and the L5s, were also introduced, both using the same low impedance pickups. In 1973 Gibson discontinued the Personal and Professional models and replaced them with the Les Paul Recording Guitar which lasted, with some minor changes, until around 1978-80. The Jumbo was also discontinued around 1971 and the L5s reconfigured with Humbucking (high impedance) pickups in (about) 1973-74. A semi-acoustic ES335 type instrument named the Les Paul Signature utilising low impedance pickups was introduced in 1974 and lasted until around 1978-80 when it was discontinued along with the Les Paul Recording.

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The shape of the Personal was virtually identical to that of the basic Les Paul guitars but just a little (1/2 inch or 12mm) bigger all round. Features were as follows:

• 2 angled Low Impedance Stacked Humbucking Pickups

• Bound ebony fingerboard with block markers (as Les Paul Custom)

• Body binding front and back (like LP Custom)

• Split Diamond inlay on headstock

• Grover tuners

• Unusually, this instrument was the only one (?) ever produced by Gibson with a built-in Microphone on a "Goose Neck" which was plugged into a socket on the upper bout of the instrument allowing announcements etc to be made by the player through the guitar amplifier. Les can be seen putting this feature to good use in the documentary "The Wizard of Waukesha"

• Controls for Volume, Treble, Bass, Decade, Microphone Volume, Pickup Selector, Tone Switch and Phase Switch

• Black laminated plastic pick guard

• Short travel bridge

• Gold plated hardware

• Special lead with built in impedance matching transformer. The Gibson circuit diagram indicates that Guitar Output Socket was a stereo type jack providing separate cabling for the Pickups and the Microphone. I'd like to hear from anyone with an original lead for a fuller description?

Shipping totals: 1971 - 95; 1972 - 49; 1973 - 2

Les with his personalised Gibson Les Paul Personal showing the "Goose Neck Microphone"

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The elusive Gibson Impedance Transformer for the Les Paul Personal. The appearance and spec are identical to the Shure A95U shown here.

A possible alternative, the Electro-Voice 502CP:

The Controls

The following descriptions are applicable ONLY when using a suitable lead with the impedance transformer at the amplifier end. The effects produced are drastically reduced when the internal transformer in the (Recording model) is used.

A description of what each of the controls does:

• Volume controls the volume of whatever combination of pickups is chosen by the Pickup Selector and Tone Switch. Most Gibsons utilise a seperate Volume control for EACH pickup.

• Treble is a treble cut control and reduces the treble frequencies gradually from 10 down to zero. The effect of the Low Impedance circuitry is such that this control works evenly throughout the whole of the range 0 to 10. (The Gibson circuit diagrams indicate that the treble control capacitor values changed between the Personal and the Recording and back again to the original in the Recording second version).

• Bass reduces the amount of Bass gradually from 10 down to zero.

• The effect of setting both Treble and Bass to zero gives an almost acoustic sound at certain settings of the Decade Control.
  From the Gibson description: Interesting tonal blends can be acheived when using treble and bass controls simultaneously. You can preset the desired amount of treble and increase (decrease) bass without affecting treble frequencies. The same goes for presetting the desired amount of bass. You will not affect the bass frequencies if you add (subtract) treble. (Treble and bass controls may be used with the tone selector, phase and  toggle switch (pickup selector).

• The Decade control, although it's name suggests 10 different tones, shapes the sound in only 3 noticeable steps on all instruments I have tried. Settings 1-3 give an almost acoustic sound when used with the neck pickup and setting and settings 8-10 give a sound more like a Gibson humbucker. Settings 4-7 give a sound somewhere in between.
  From the Gibson description: The 11 position decade control "tunes" or alters the treble harmonics. Position 0 will peak the highest frequency and graduates accordingly down the spectrum in steps through position 10. This control is most effective when the tone selector is in position 2 and the bass response has been reduced. You will experience innumerous tonalities when used with the phase, treble and pickup selector toggle switch.

• The Pickup Selector functions as a normal either/both selector

• The Tone Switch is probably the most baffling to the many people who I have spoken to about these guitars. It is a fairly simple and effective way of getting 3 different preset sounds out of the instrument and works this way:
  
  Setting 2 (Middle) allows full use of all controls - Treble, Bass, Decade and Pickup Selector (and Phase Switch with both pickups selected)
  
  Setting 3 (Up) bypasses Treble and Bass and allows control of just the Decade and Volume Controls
  
  Setting 1 (Down) - When either the Neck or Bridge Pickup are selected this setting gives BOTH pickups with Treble and Bass bypassed and Decade and Volume active. Because of some additional capacitors and resistors in this setting the tone of the both pickups is different to the tone of both pickups selected in the Middle Setting (2)
  ---------------------------------------------------------------------------------------
  
  To simplify all of the above here is an often used scenario:
  
  Set the guitar controls as follows,

  Pickup Selector	Neck Pickup
  Treble	5-7
  Bass	5-7
  Decade	3
  Phase	Out

With the Tone Switch on 1 or 3 set the tone controls of your amplifier to achieve your desired solo sound.

By operating the Tone Switch you now have four distinctly different sounds - a rhythm sound on position 2; neck pickup solo sound on position 1 of the Tone Switch; both pickups together on position 3 of the Tone Switch. If the pickup selector is moved to the "Both" position in Tone Switch Position 1 you have the (fourth) Out of Phase Sound.

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The Pickups

The cleanest (and heaviest) pickups around?

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The Les Paul Professional

Features similar to Les Paul Personal except:

• Bound Rosewood Fingerboard with crown markers

• Schaller tuners?

• Plain headstock

• Special lead with built in impedance matching transformer

Shipping totals: 1971 - 116; 1973 - 2

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The L5s

The Gibson L5s was designed to be a scaled down top-of-the-range solid bodied version of the famous L5 model. This first version of the L5s was fitted with Gold Plated Low Impedance Pickups. The circuit diagram for this model indicates that the Impedance Transformer was installed in the body and was connected between the Volume / Tone controls and the Output Jack Socket. All metal parts were Gold Plated and the ebony fingerboard was inlaid with Abalone. The bridge was identical to that used on the Les Paul Recording and afforded a wider travel and therefore more accurate intonation with a wider variety of string guages. It first appeared in catalogues in 1972 and first shipped in 1973. By the end of 1974 it had been re-equipped with humbucking pickups.

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This model was produced in 1970-71. Features were:
Rosewood Fingerboard
Dot Inlays
Single Lo-Imp Pickup
Four controls:
Volume; Decade; Bass; Treble
Bypass Switch
Required use of special Lo-Hi Impedance Transformer Lead as per Personal for use with normal amplifier.

Shipping totals according to Bacon and Day: 49 (1971-73)
(No shipping totals for 1970)

The Les Paul Recording

The Les Paul Recording Guitar is probably the best known of all of Gibson's Low Impedance models and was produced in the greatest numbers. It was introduced in 1971/72 as a replacement for the ailing Personal and Professional models. The first version (top picture) was produced from 1971 until 1977. The second version with a slightly altered layout was produced from 1977/79. The main difference between the Personal/Professional models and the Recordings is that an Impedance Transformer was built in to the body. However, this did not alter the fact that these guitars still performed at their best when plugged into a mixing desk at Low Impedance setting or, when used with an Amplifier, with a suitable Impedance Matching Transformer at the amplifier end of the connecting lead.
Features:

• 2 angled Low Impedance Stacked Humbucking Pickups

• Bound rosewood fingerboard with small block markers

• Bound carved top Honduras Mahogany body - Brown, Sunburst or White

• Split Diamond inlay on headstock

• Grover tuners

• Controls for Volume, Treble, Bass, Decade, Microphone Volume, Pickup Selector, Tone Switch and Phase Switch on panel

• Black laminated plastic pick guard

• Long travel bridge

• Chrome plated hardware

• Built in impedance matching transformer (switchable Lo / High)
  
  Version two:

• Black added to range of finishes

• Pickup selector switch moved from the control panel to the more usual placement for Les Pauls

• Impedance switch removed and replaced with two socket arrangement on side of body giving separate Low Impedance and High Impedance outputs.

Shipping totals: 1971 - 236; 1972 - 1314; 1973 - 1759; 1974 - 915; 1975 - 204; 1976 - 352; 1977 - 362; 1978 - 180; 1979 - 78.

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The Headstock

The Les Paul Recording Headstock
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The Bridge - available from "Allparts" (www.allparts.com).
These bridges were also used on L5s's and SG Guitars during the 70's and Allparts designates it as an "SG" Bridge.
In the UK try contacting the manager at "Vintage and Rare Guitars" Bath showrooms
(01225 330888)

Pickguards - available from Chandler Guitars (www.chandlerguitars.com)

Knobs and Switches - If anyone has any info on this I would be pleased to hear from them!

Also if anyone has the control plate off I would be grateful for any info which can be read on the 3 position Tone Swith - any numbers etc.

Basically, the Signature was an asymmetric ES 335 without the solid central block on which to mount the pickups and bridge. (There is a solid block beneath the bridge but the area between the pickups is hollow, rather like the ES 330 - my thanks to Joel Dingman for pointing that out). While a few early Signatures were said to have had the Recording type pickups installed, most came fitted with the rectangular low-impedance type seen in this photo of a Sunburst. Most were in a gold finish. Other differences were that the Decade became a 3 position tone switch, the Phase switch was rotary and the normal Volume and Tone completed the lineup. Two 1/4 inch  sockets were provided for separate Low and High Impedance outputs - Low Impedance on the face of the instrument and High Impedance on the rim. This, of course, necessitated the fitting of an Impedance Transformer inside the body.

Descriptions to follow!

My thanks to James Ford for the images.
James wants to sell an LP 12 and I will pass any e-mail queries on to him.

What is the purpose of the Hi/Lo switch and how is it used?

The Hi/Lo switch selects between High Impedance and Low Impedance output from the guitar. This switch is unique to the Les Paul Recording version one. Earlier models were supplied with a special lead complete with a Shure A95U Impedance Transformer and the Les Paul Recording version two had seperate High and Low output jacks. The original concept was always that the guitar output should be Low Impedance allowing long leads with no high frequency losses with the Impedance Transformer being placed next to the amplifier to provide the necessary signal boost. Alternatively the guitar could be plugged into the LP12 Amplifier or a recording desk without the Impedance Transformer. Whether the result of complaints from Les Paul Personal and Professional users who had lost (or were afraid of losing) their original lead/transformer or a cost cutting excercise by Gibson the Hi/Lo switch and transformer were built into the LPR as a compromise. I believe that the built in transformer should only be used in an emergency and the correct way to use this guitar is on Low Impedance Output and with a special lead and Impedance Transformer at the amp end of the lead.

My DECADE switch is not working..........

The Decade Control (actually an 11 position switch) is a very subtle control and its effect will not be obvious under certain conditions. For instance if you are overdriving your amp or are using effects it might be difficult to hear these subtle differences. If you are using the built-in transformer (instead of an external transformer at the amp end of the lead) the results of changing the Decade switch may not be obvious. I can only detect 3/4 really obvious changes on my Recording (Positions 0-3; 4-7 and 8-10). To hear these subtle changes to best advantage plug the guitar into a recording desk or Multi-track "Portastudio" set to LOW-IMPEDANCE output and listen using headphones whilst adjusting the various controls.
Try:
Tone switch position 2
Neck pickup
Treble 10
Bass 5
and then alter the Decade control 0 - 10 trying each position in turn.

How old is my Gibson Recording/Personal/Professional Guitar

There is a link from the Gibson site to a PDF file containing all of the available info on dating your guitar here and here.

My thanks firstly to Mark Case at the Gibson Customer Service Department for his patience in dealing with my queries regarding these instruments.

I must also thank Glenn Arnold for providing the incentive to get this page constructed. It had been on the back burner far too long.

Thanks to Simon Davidmann for the picture of the Gibson Impedance Matching Transformer.

Thanks to Leigh Woolford for all of the Jan Akkerman info.