ampage Tube Amps / Music Electronics	For current discussions, please visit Music Electronics Forum.

ampage archive

Vintage threads from the first ten years

Re: Distorted LA-2A

7/23/2000 2:12 AM
SpeedRacer	Re: Distorted LA-2A So I've been looking at this thing for a week or 2 now, and it looks like it would be very easy to stick one of these in an amp. - you're one sick puppy! That would be pretty interesting! I'm curious how it would sound on the "other side" if you will.. I've only ever heard their effect as outboard (post recording). FWIW I think it would be a fantastic thing to incorporate in an amp for acoustic guitar. Probably not too shabby on electric either... Picture this: power brake with some basic EQ and a built in LA-2a style compressor w/ recording output. I'd buy one. Tone in a box. Somebody build me one! That's my idea of a line out..

7/23/2000 2:12 AM

SpeedRacer

Re: Distorted LA-2A

So I've been looking at this thing for a week or 2 now, and it looks like it would be very easy to stick one of these in an amp.

- you're one sick puppy! ;-)

That would be pretty interesting! I'm curious how it would sound on the "other side" if you will.. I've only ever heard their effect as outboard (post recording). FWIW I think it would be a fantastic thing to incorporate in an amp for acoustic guitar. Probably not too shabby on electric either...

Picture this: power brake with some basic EQ and a built in LA-2a style compressor w/ recording output. I'd buy one. :-)

Tone in a box. Somebody build me one! That's my idea of a line out..

7/23/2000 5:05 PM
Paul C	Well, clean sustain is one of the big tones everybody wants. If a standard, circuit like an AB763 can have the TB4 worked into the volume control circuit it would be just like you had somebody slowly turning up the volume as the note died down. It really wouldn't add any circuits in the audio path to add noise, and coloration. I gotta see if I can dig up a used TB4 to try this. I think that site you listed shows a place that has 'em for $60.

7/23/2000 5:05 PM

Paul C

Well, clean sustain is one of the big tones everybody wants. If a standard, circuit like an AB763 can have the TB4 worked into the volume control circuit it would be just like you had somebody slowly turning up the volume as the note died down. It really wouldn't add any circuits in the audio path to add noise, and coloration. I gotta see if I can dig up a used TB4 to try this. I think that site you listed shows a place that has 'em for $60.

7/24/2000 6:18 PM
Scott Swartz	There are viable alternatives to using the LA-2 opto unit. One viable alternative is the Vactrol VTL5C6, which has an LED light source, attack and decay specs that are about right, and a relatively high resistance range suitable for tube circuits. Available at Newark Electronics for $5. I have built a compressor using this device and it sounds great!! I wrote an article on it that is supposed to be published in Glass Audio, so I can’t divulge the circuit as they are paying me, but I can divulge the rough concept. Take a 1+1 gain plus cathode follower and use the LDR as a feedback resistor. The side chain is a gain stage, full wave rectification, and a cathode follower that varies the current through the LED of the LDR. When the current increases through the LED, the LDR resistance goes down, increasing the feedback and decreasing the audio stage gain. This is a little different than the LA-2, which has the LDR as part of an attenuator. I tried both approached and found the feedback resistor approach to be simpler and have lower distortion. In case anyone thinks this is all BS, heres an email from Glass Audio. They were late publishing the other article I sent them, so it isn’t a complete surprise. I returned the edited copy referenced below in Feb. 2000. Issue 4/00 is out currently. Meybe if they knew there was interest in this type of circuit, they'd hurry up an publish it, so feel free to email them. Yeah OK I'd like to get paid too (no check till it hits the newsstand). Scott Swartz ------------------------------------------- Dear Mr. Swartz, The photos you sent are fine. Your article is tentatively slated for Glass Audio 3/00. Once the article has been edited a copy will be sent to you to look over and make any corrections or changes.; Kind Regards, Marianne At 04:50 PM 11/23/1999 -0600, you wrote: >Marianne, > >I sent jpg format photos of the unit several weeks ago in an email to you. >Has the graphics department checked to see if they are suitable? Has the >article been slated for a particular issue? Please reply. > >Scott Swartz > > --------------------------------------- Marianne M. Conway, Editorial Assistant Audio Amateur, Inc. Phone 603.924.9464 Fax 603.924.9467 marianne@audioXpress.com

7/24/2000 6:18 PM

Scott Swartz

There are viable alternatives to using the LA-2 opto unit. One viable alternative is the Vactrol VTL5C6, which has an LED light source, attack and decay specs that are about right, and a relatively high resistance range suitable for tube circuits. Available at Newark Electronics for $5. I have built a compressor using this device and it sounds great!! I wrote an article on it that is supposed to be published in Glass Audio, so I can’t divulge the circuit as they are paying me, but I can divulge the rough concept. Take a 1+1 gain plus cathode follower and use the LDR as a feedback resistor. The side chain is a gain stage, full wave rectification, and a cathode follower that varies the current through the LED of the LDR. When the current increases through the LED, the LDR resistance goes down, increasing the feedback and decreasing the audio stage gain. This is a little different than the LA-2, which has the LDR as part of an attenuator. I tried both approached and found the feedback resistor approach to be simpler and have lower distortion.

In case anyone thinks this is all BS, heres an email from Glass Audio. They were late publishing the other article I sent them, so it isn’t a complete surprise. I returned the edited copy referenced below in Feb. 2000. Issue 4/00 is out currently. Meybe if they knew there was interest in this type of circuit, they'd hurry up an publish it, so feel free to email them. Yeah OK I'd like to get paid too (no check till it hits the newsstand).

Scott Swartz

-------------------------------------------

Dear Mr. Swartz,

The photos you sent are fine. Your article is tentatively slated for Glass
Audio 3/00. Once the article has been edited a copy will be sent to you to
look over and make any corrections or changes.;

Kind Regards,
Marianne

At 04:50 PM 11/23/1999 -0600, you wrote:
>Marianne,
>
>I sent jpg format photos of the unit several weeks ago in an email to you.
>Has the graphics department checked to see if they are suitable? Has the
>article been slated for a particular issue? Please reply.
>
>Scott Swartz
>
>
---------------------------------------
Marianne M. Conway, Editorial Assistant
Audio Amateur, Inc.
Phone 603.924.9464
Fax 603.924.9467
marianne@audioXpress.com

<<First Page

<Prev

Page 6 of 6