Tubes: 1-6AU6; 1-6AV6 (Tremolo); 1-EL84; 1-6X4;
Speakers: Two 8″
Another rare amp from Lectrolab, are there any that are not? These guys must not have sold very many amps!
The nameplate on the front of this amp is unique to the S400, S500, and S600.
The Lectrolab S400 is in the Fender Vibro-Champ arena, but moving more air with twice as much speaker. It is very cool to have TWO eight-inch speakers on an amp with a single EL84 output tube (probably about 5 watts). As anyone who has plugged a Fender Champ (similar wattage, one 8″ speaker) into a 4×12 cab will tell you, the speaker is the limiting factor in the volume and tone of these types of “student” amps. Which isn’t to say one eight-incher won’t do… Hey, I’m talking about recording here. Go listen to Layla.
Click to enlarge:
Thanks to reader Craig Olson, we have an S400 schematic!
It shows the use of a 6AU6 pentode as the preamp which feeds the 6BQ5 (EL84) power amp. The 6AU6 shares some characteristics of the EF86, which was used by Vox in thier early/mid sixties amps. The Lectrolab S400 is very similar to the Vox AC-4, except in price, of course! Tremolo duties are handled by a 6AV6, which in this circuit would be very similar to half (one triode) of a 12AX7. Power is rectified through a 6CA4 (EZ81), which can handle about 10% more current than the EZ80 used in the Vox AC-4.
Regarding ex. 3 above, Dan adds: ” The Quam speakers are original. This amp seems to have a lot of gain, and I prefer it with single coil pickups. ”
http://www.myrareguitars.com/1966-lectrolab-s400-guitar-amplifier – Article by Rob Roberge on a very cool site. He said this S400 (ex. 2) is from late 1966 and had two CTS 8″ alnico speakers.
Here is the description of an S400 for sale as of 5/29/2011 at Chris’ Guitars in Albany, New York (shown in gallery above as Ex. 4):
ca. 1969 Lectrolab S-400 Combo, If you haven’t heard of Lectrolab, welcome to the club. My research tells me this was a small company out of Chicago who built very few amps back in the 60’s. My buddy Roy, who sold me this amp was raving about it and was eager to get my opinion. I am totally impressed. Judging by the plain look I was thinking, okay, another 60’s amp with a decent clean tone but probably no character, much like Alamo or Univox, for example. When I fired it up I was in for a very pleasant surprise. It indeed does have a quality clean tone, but even then, a nice thick clean. It’s when I cranked it up I really became a fan. This amp gets thicker with a nice saturation starting at around 5, and gets increasingly saturated as you turn it up further. It also has a good sounding tremolo, with speed and intensity controls to dial it to taste. An all-tube circuit with a single EL84 (aka 6BQ5) for output, 6X4 rectifier, a 6EU7 preamp and, 6AU6 for the tremolo. I like this amp for much the same reason I like an old Fender Champ, which is a nice break-up on a low-powered combo. With a single EL84 it probably cranks out around 5-8 watts. Unlike the Champ though, which has a single 8″ speaker, the dual 8’s on this amp make it sound fuller, more lush. It would be an excellent recording or backstage practice amp. There are a few very good sites on the web with pics, reviews, and schematics. “Obscure but cool,” is how these are described on a great site dedicated to all things Lectrolab, lectrolab.worldpress.com. Another good review is at myrareguitars.com. Speakers are Quincy Speaker Mfr Corp. from 21st week of ’69. I know that Lectrolab did use Quincy speakers in some of their amps so I’m guessing they’re original. Overall this amp is in nice shape for a vintage amp. There’s a hole in the back masonite panel but it’s easily replaced if it bothers you and the brand name is missing from the front, which I may just replace with some stick on letters from Staples (click here to see what it’s supposed to look like). It has a cool pop up bar handle that’s tucked away atop the control panel when not in use. It appears to be all original, including 2-prong power cable, and works flawless, not in need of filter caps or any tweaking whatsoever. It sounds absolutely perfect right now. This amp sounds so much better than all the new Chinese lower-powered combo’s that comparison isn’t possible – plus it’s hand-wired and built to last for a very long time, rather than until the warranty is up. At $325 it’s not much of an investment, but the pay off will be huge.