The Lectrolab R700C looks like a great amp. Early to mid 1960’s. It has:
- A pair of 12AX7’s and a pair of EL84’s
- 15″ speaker (usually a Jensen C15P). Some have a 3″ “tweeter”, some shipped without it. My R700C has the baffle cutout for the tweeter, but no screw holes for it. They either ran out of tweeters or came to their senses.
- One channel, two inputs
- Volume, Treble, Bass controls
- Three stages of amplification into a concertina splitter.
- 7189 (like an EL84) push-pull output stage, probably about 15 watts.
- Negative feedback around the power amp to the cathode of the last preamp stage (similar to a narrow panel tweed Fender Super Amp (FE4-A) and others).
I’ve not seen any other Lectrolab “700”s except the “C” version. Cabinet reputed to be solid pine but is probably plywood.
The Custom Kraft Electra Bass Amp (Model 800) is identical to the Lectrolab R700C except for cosmetics. Custom Kraft was an exclusive house-branded product for the St. Louis Music company (SLM), one of the largest musical instrument distributors in the USA. They did not produce any of thier own amps, but apparently had Sound Projects build at least this one model for them. SLM launched the Crate amp brand in the 1970′s, and bought Ampeg in the 1990′s.
Click on pictures to enlarge:
This is a Custon Kraft Electra, the same amp as a Lectrolab R700C:
8/24/10 – This amp just sold on ebay for $360USD. See photos from the auction in the gallery above. It is the only tweed, or tan colored amp in the gallery. I defy you to find a hand-wired 2-EL84 15 watt to 20 watt amp with a 15″ speaker for a better price, unless it’s another Lectrolab!
This is the sellers video of Ex. 5 above, which I bought 9/23/10 on eBay for $255USD. This amp has some issues. I will refurbish it electronically in the next few weeks, and will post the results when through.
Example 4 (above) was sold in June 2010 for $325.00 on eBay. Seller in Citrus Heights, California. Seller’s description included:
- chassis stamped “May, 16, 1967”
- original 15” Jensen Special Design speaker
- additional 3” speaker, which was standard for this model
- original leather handle
- 23” tall by 19 ½” wide
- The amp powers right up and sounds fantastic, with the volume, bass and treble controls working as they should, and the amp getting pretty darn loud when running a guitar through her. She’ll work as a bass amp too, and she has a cool, 1960’s bass sound, but don’t expect thundering bass tones. The amp really shines with guitar, with beautiful highs and lows, and a nice, mild break up near the top of the volume control
From a thread on http://www.thegearpage.net/board/archive/index.php/t-604982.html:
- http://www.vintaxe.com/index.php has an amp catalog section, buy It looks to be a pay to download. They do have a forum devoted to obscure brands like Custom Kraft: http://www.vintaxe.com/catalogs_american_customkraft_1966.htm
- Works great. Some prior owner has or had the cap can replaced.
- My issue is the volume is quite low for a 15ish watt amp.
- The Jensen C15P is in between a ‘Q’ and ‘N’ meaning it is near the higher power handling C12N. It has a ribbed cone.
- That’s definitely the same as my ol’ 60s Lectrolab 700c (cept mine hadn’t been painted black). I really liked the amp & the speaker. That said, I would nudge it up a bit w/ TS-9 just to kick up the vol. & the treble, w/o adding much drive & seemed to work fine at brightening it up a bit while pushing it, too. While I really liked it, I also had & still have two other old Lectrolabs. One is a 700c, also, but has 2 Jensen c12qs & a 3″ tweeter–that amp is oddly sorta bright (& apparently quite rare). The other is a 600c which definitely has a much dif. circuit but a sim. tube compliment, but has got a lot of gain. Cool amps. I’ve never been able to track down a schematic of either.
- with the EL84s installed, I have taken some measurements
- V1A: plate – pin1 – 44vdc
- V1B: plate – pin6 – 121vdc
- V2A: plate – pin1 – 235vdc
- V2B: plate – pin6 – 224vdc
- V3: plate – pin7 – 513vdc; grid 1 – pin 2 – (-14vdc); grid 2 – pin 9 – 388vdc
- V4: plate – pin7 – 512vdc grid 1 – pin 2 – (-14vdc) grid 2 – pin 9 – 387vdc