Laney -pre-Supergroup 100w mods?

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Laney -pre-Supergroup 100w mods?

Postby Z*Z*Z on Mon Feb 06, 2017 9:24 pm

Hi guys, can you tell me a bit about the mods on this old Laney, its a bit rough and rugged but I think Ill restore it with a bit of help from my friends - I suspect it will be a tone machine, since its not in working order right now. I have one or two components burned and it needs brand new set of matched el34. And also cosmetic upgrade ;) Do you think its mostly original and is this PT Hiwatt like? Thanks everyone!

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Z*Z*Z
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Re: Laney -pre-Supergroup 100w mods?

Postby Mr. Foxen on Mon Feb 06, 2017 10:24 pm

This looks familiar, see that bus rail before. did you send me pics of this on FB?
New music: https://warriorpope.bandcamp.com/album/anchorite
Gear tinkering blog: http://ampstack.wordpress.com/
Made a Facebook page for my ampguts stuff. Feel free to come post amp guts and rig shots: https://www.facebook.com/pages/Ampstack/351966881575839
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Re: Laney -pre-Supergroup 100w mods?

Postby LD50 on Mon Feb 06, 2017 10:31 pm

To me it looks mainly original.
As you say early LBO100 (alloy chassis, copper bus rail etc)
One of these passed across my desk recently but not onto the bench!
The burned dropper and the cathode resistor look like casualties, these run scary high plate voltages >600v.
They scorch output valve sockets.
I would obviously replaced the burned parts, the octal sockets with good quality ceramics and probably the filter caps as starters.
Also suggest 1k5 screen resistors too.
There is a bias pot added, pi output mustard replaced but I do not know why those other presets are there.
All bleeding stops.......eventually.
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Re: Laney -pre-Supergroup 100w mods?

Postby Z*Z*Z on Mon Feb 06, 2017 11:03 pm

Mr.Foxen - I didnt send you any pics, maybe previous owner or someone else? Ive purchased this head recently :)

LD50 - Thanks, you suggest replacing all 2k5 with 1k5? I think that cathode resistor is alive but it looks burned. Dropper is dead alright. I would like to try and save/use these filter caps, I kinda like sound of old filter caps, new ones always add brightness... Yeah sockets are a must. And some heavy El34 that can manage that heat :) Im puzzled with those additional trimpots...
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Re: Laney -pre-Supergroup 100w mods?

Postby Gooch on Tue Feb 07, 2017 12:47 pm

Looks like some sort of mod to the bias supply, maybe to balance the two sides? Can't really tell from the picture. You could put it back to stock or, if you're getting the proper bias voltage, just leave it as-is.

Running that amp with only two output tubes is not a good idea, the normally high B+ voltage will go even higher, very tough on the screens. The screen resistors appear to be 470Ω, I'd increase those to 1kΩ or higher.

That's an interesting amp, especially the faceplate. Do you think the faceplate is original.? That's an early piece, maybe around '68. Can you get some date codes off the caps? Transformers look original, that's the type Laney used on the early amps. May be Douglas, not sure?

You should post a few pics up on the Laney Facebook page:
https://www.facebook.com/laneyamplification/
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Re: Laney -pre-Supergroup 100w mods?

Postby Z*Z*Z on Tue Feb 07, 2017 8:11 pm

Gooch wrote:Looks like some sort of mod to the bias supply, maybe to balance the two sides? Can't really tell from the picture. You could put it back to stock or, if you're getting the proper bias voltage, just leave it as-is.

Running that amp with only two output tubes is not a good idea, the normally high B+ voltage will go even higher, very tough on the screens. The screen resistors appear to be 470Ω, I'd increase those to 1kΩ or higher.

That's an interesting amp, especially the faceplate. Do you think the faceplate is original.? That's an early piece, maybe around '68. Can you get some date codes off the caps? Transformers look original, that's the type Laney used on the early amps. May be Douglas, not sure?

You should post a few pics up on the Laney Facebook page:
https://www.facebook.com/laneyamplification/

Ill probably leave as is or with one bias trim since its good modification. Ill check bias voltage as soon as I get some good tubes. I dont plan to use it with two output tubes, I got it like this, voltage would melt it for shure.
And probably good idea for grid resistors.
As for cosmetics, its original faceplate but dont know about the color, printing/font looks stock. Ill check date codes this weekend. Ill post some pics there, good idea.
Thanks!
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Re: Laney -pre-Supergroup 100w mods?

Postby Gooch on Tue Feb 07, 2017 10:42 pm

Z*Z*Z wrote:As for cosmetics, its original faceplate but dont know about the color, printing/font looks stock. Ill check date codes this weekend. Ill post some pics there, good idea.
Thanks!



The font is actually a bit off from the norm. here's a good shot of an early faceplate:

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Re: Laney -pre-Supergroup 100w mods?

Postby LD50 on Wed Feb 08, 2017 9:55 pm

Here are pics of one that came to me. All I did was reform the filter caps. The new owner plans to do all the resto work himself (it needs quite a lot) see my other posts of Laney pics - later early 70s with Partridges and steel chassis). My own LBO60 has steel chassis and Douglas trannies so sort of in between. Note the 1uF cap and large resistor on early amps to compensate for different speaker types:

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More pics added
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Re: Laney -pre-Supergroup 100w mods?

Postby Z*Z*Z on Thu Feb 09, 2017 12:22 pm

LD50 - yeah I see what you mean for he font type...
And thanks for the pics, It wil help. I already read all previous topics on vintage Laneys and Im looking right now on old plexi threads, since my reparing skills are lacking.
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Re: Laney -pre-Supergroup 100w mods?

Postby ValveLust on Wed Mar 15, 2017 10:57 pm

My LA100BL

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Re: Laney -pre-Supergroup 100w mods?

Postby ValveLust on Wed Mar 15, 2017 10:58 pm

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