All things LA2a related

[crisotop]

Hey Dennis,

I'm not that experiences either, but I would suggest to go with drips suggestions as a start. Most parts are not that expensive (besides trannies) and I'd rather solder in some non-fancy components that are brand new and working to get the unit up and running and then start to exchange some important caps in the audio path or install vintage tubes, etc. ohterwise troubleshooting might be a huge pita.

Good luck with this thing
christoph[/i]

 

[Bluzzi]

Dennis - I wouldn't worry too much about using fancy or esoteric high end parts. Original LA2A is not even close to that. Plain parts all along and very forgiving when substituting (except for a few parts that are critical).

I'm building my second one and if I have any advice it is to go with Jensen or other XFR at least for input.

Also look into making the input gain lower by substituting some resistors and/or tube(s).

If its your first project and you have never done any soldering or at least another tube project please be very careful. The voltages inside the LA2A are LETHAL!

I mean no disrespect but the way you word your statements seem to reveal an inexperience and uncertainty. The LA2A is not the best project to start with if that is the case.

Although DRIP's PCB makes it a lot easier to build an LA2A without problems now.

Please don't take my comments the wrong way. I've just read too many posts where people have failed and get discouraged because of wrong expectations or lack of experience with fundamental skills like soldering and component orientation etc..

Why don't you build one stock and then mod it later?

jim

 

[feza]

[quote author="crisotop"]Hey Dennis,

I'm not that experiences either, but I would suggest to go with drips suggestions as a start. Most parts are not that expensive (besides trannies) and I'd rather solder in some non-fancy components that are brand new and working to get the unit up and running and then start to exchange some important caps in the audio path or install vintage tubes, etc. ohterwise troubleshooting might be a huge pita.

Good luck with this thing
christoph[/i][/quote]

Great post! Yes you're right. Sometimes I want to exaggerate, especially with DIY projects. :grin:

Keeping it more basic is a better plan and probably less debugging. So just the Jensen caps and resistors would be enough. But Still I am very curious about the FRED's. Anyone got some input about compatible FRED's?

 

[tv]

http://www.rightsaidfred.com/

 

[feza]

[quote author="Bluzzi"]Dennis - I wouldn't worry too much about using fancy or esoteric high end parts. Original LA2A is not even close to that. Plain parts all along and very forgiving when substituting (except for a few parts that are critical).

I'm building my second one and if I have any advice it is to go with Jensen or other XFR at least for input.

Also look into making the input gain lower by substituting some resistors and/or tube(s).

If its your first project and you have never done any soldering or at least another tube project please be very careful. The voltages inside the LA2A are LETHAL!

I mean no disrespect but the way you word your statements seem to reveal an inexperience and uncertainty. The LA2A is not the best project to start with if that is the case.

Although DRIP's PCB makes it a lot easier to build an LA2A without problems now.

Please don't take my comments the wrong way. I've just read too many posts where people have failed and get discouraged because of wrong expectations or lack of experience with fundamental skills like soldering and component orientation etc..

Why don't you build one stock and then mod it later?

jim[/quote]

Hey man! You're right about my experience, mate. But it isn't my first soldering project. Planning to do the "big-things" months later when experience is enough. Now just doing basic soldering projects. But I hope that it will be enough over 3 or 4 months and won't do it alone by the way. I'm just so excited, man! :wink:

 

[Bluzzi]

Excitement is very good!

You're taking your time and that is also a good sign. Keep going the way you are and you'll do good.

LA2A was my first project here and I really loved making it and love using it.

Have you looked at Cayocosta's point to point layout? Even if you will be using PCB to build LA2A its very interesting.

jim

 

[feza]

[quote author="Bluzzi"]
Have you looked at Cayocosta's point to point layout? Even if you will be using PCB to build LA2A its very interesting.[/quote]

Well I haven't read all of it. But there were quite some problems with it and with the Drip's guide it's like a sum with all the problems solved when you use his design. Very neat of Drip-Electronics if you ask me? :grin:

 

[nielsk]

Is this point to point layout posted? Can you point me to it, please?

thanks

 

[SSLtech]

Well Feza, you sound like you've read a lot but misunderstood quite a bit of what you've read... (or just been reading people who don't understand as much as they claim).

By FREDs you (I assume) mean fast diodes? -If so, don't bother. -My honest recommendation. -I mean... have you SEEN the amount of series resistance in that power supply??? what the HELL is a lightning-fast diode going to do to improve the sound... unless of course LA2a's sound better if you listen to them with a lightened wallet...

Gold plated sockets? -Well in thirty years time it might make a difference, (five if the unit is left out in the rain uncovered) but again, don't bother. Gold doesn't sound any better than the usual contact material.

ESD? -Show me a single piece of the LA2a which is susceptible to ESD.

Stepped attenuator... that might bite you. The LA2a's gain structure is such that you often end up using the 'left-hand' end of the dials quite a bit... exactly where most stepped attenuators are most cumbersome, inaccurate, and just downright annoying/verging on the useless.

I know that I'd NEVER use one, and I've built LOTS of LA2a's... I seriously reckon that it'd be a WORSE LA2a for the inclusion of a stepped attenuator.

Reading between the lines, I'd say that you've 'decided' to build the ultimate one, and been reading a lot of audiophile tomfoolery..

more expensive tube

...and more expensive is automatically better, is it?

Here's the deal; you're getting LOTS of good advice, but it's all leading the way that you don't want to go: From your few posts thus far it's very clear that you don't have any real electronics build experience to speak of, yet you think that you can make a 'better' unit based on what you've READ elsewhere.

I've been doing this for over thirty years, and I'm STILL experimenting with LA2a options. You don't sound like you want to 'build it twice', but trust me, if you want one that you like, that's EXACTLY wyat you have to do. Build a base model as a reference, then rebuild it to see what changes you like, what ones you dislike, and what ones don't realy seem to make much difference... You'll be surprised how much bullshit you've been swallowing on the other forums that tell you to use gold-plated, oxygen-free, linear-crystal sockets with the most precious tubes that you can find.

I just finished up an LA2a last week, and I swapped tubes for a couple of days, measuring and listening. -the two tubes that I liked best of all (and measured very well also) were cast-offs from a Mesa-Boogie amplifier!!!

So stop making up your mind before you know what you're doing... JUST BUILD ONE using what you can get. then either swap components or build a second one.

Keith

 

[feza]

[quote author="SSLtech"]Well Feza, you sound like you've read a lot but misunderstood quite a bit of what you've read... (or just been reading people who don't understand as much as they claim).

By FREDs you (I assume) mean fast diodes? -If so, don't bother. -My honest recommendation. -I mean... have you SEEN the amount of series resistance in that power supply??? what the HELL is a lightning-fast diode going to do to improve the sound... unless of course LA2a's sound better if you listen to them with a lightened wallet...

Gold plated sockets? -Well in thirty years time it might make a difference, (five if the unit is left out in the rain uncovered) but again, don't bother. Gold doesn't sound any better than the usual contact material.

ESD? -Show me a single piece of the LA2a which is susceptible to ESD.

Stepped attenuator... that might bite you. The LA2a's gain structure is such that you often end up using the 'left-hand' end of the dials quite a bit... exactly where most stepped attenuators are most cumbersome, inaccurate, and just downright annoying/verging on the useless.

I know that I'd NEVER use one, and I've built LOTS of LA2a's... I seriously reckon that it'd be a WORSE LA2a for the inclusion of a stepped attenuator.

Reading between the lines, I'd say that you've 'decided' to build the ultimate one, and been reading a lot of audiophile tomfoolery..

more expensive tube

...and more expensive is automatically better, is it?

Here's the deal; you're getting LOTS of good advice, but it's all leading the way that you don't want to go: From your few posts thus far it's very clear that you don't have any real electronics build experience to speak of, yet you think that you can make a 'better' unit based on what you've READ elsewhere.

I've been doing this for over thirty years, and I'm STILL experimenting with LA2a options. You don't sound like you want to 'build it twice', but trust me, if you want one that you like, that's EXACTLY wyat you have to do. Build a base model as a reference, then rebuild it to see what changes you like, what ones you dislike, and what ones don't realy seem to make much difference... You'll be surprised how much bullshit you've been swallowing on the other forums that tell you to use gold-plated, oxygen-free, linear-crystal sockets with the most precious tubes that you can find.

I just finished up an LA2a last week, and I swapped tubes for a couple of days, measuring and listening. -the two tubes that I liked best of all (and measured very well also) were cast-offs from a Mesa-Boogie amplifier!!!

So stop making up your mind before you know what you're doing... JUST BUILD ONE using what you can get. then either swap components or build a second one.

Keith[/quote]

Wow! what a reply man! Well I just made a fool out of myself, period.

It is just I am new to this and that 'smack-in-my-face' reply certainly gave me a reality-check. Being naive isn't fun. :grin:

Thanks for reply and I'm off to buy books, start reading more...

Greets,
Dennis

 

[Bluzzi]

Dennis - Keith is being to the point I'm sure because he doesn't want you to spend a lot of money for nothing and also to be successful at your first LA2A.

If your first DIY project that comes from here is a failure then everyone looses.

Read all the threads about LA2As here and then decide what you want to do. I know you are eager to get going on a project but be realistic about it and you'll get there.

There's nothing worse than building something like an LA2A and not have it work right away. Its a sinking feeling. However when you power it up the first time and it actually does what it is supposed to do, you will feel elated.

In my opinion that is what allows us to go on to another project or like Keith said mod the next one (that is what I am doing).

We're here to help you as best as we can but only if you trust us (not blindly so its good to ask questions and challenge our so called "experience").

So all this "advise" is never to belittle or discourage you but just to make you aware of the "other side" of things.

All that being said check out

http://www.recproaudio.com/diy_pro_audio/index.htm

have fun

jim

 

[feza]

Bluzzi thanks for the kind words. :thumb:

To tell more about myself. I'm a electronic musician for over 13 years now. When my first tube compressor came I was instantly in love man! For years buying gear is what I did to achieve more and more that 'sound' which is so much heard out there. Over the years fascinated by electronica and it's time to do it myself. I'm not planning to ask the whole process. Those questions were the things I thought would improve Drips design.

So thank you again for the replies and there's work/research to do here, lads. :grin:

 

[SSLtech]

And in answer to your earler question...

You can power up and test an LA2a signal path with ONLY two tubes (12AX7 and 12BH7), the two transformers, and NO T4.

Everything else is sidechain. When the 'Peak Reduction' knob is all the way down, they do nothing.

The BEST way to learn, is to start with something working, then find out WHY ot works. -Even start with something that DOESN'T work, then figure out how to MAKE it work, then figure out WHY it works...

Look at my recent Bloo LA2a build...

It has swappable transformers, mounted on sub-plates. So far, I've tried Jensens (some people LOVE 'em) I've tried Sowters, (some people LOVE 'em) I've tried UTCs (the originals, AND some different UTC options) I've tried EDCORs (some people LOVE 'em) and I've tried Lundahls. (some people LOVE 'em).

Guess what... they're all different characters. They're ALL loved by different people.

Here on THIS forum, you'll encounter some people who've built several different versions of the LA-2a. They've used different options, and they've resulted in different sonic characters. Some have tried "night-light-and-Vactrol" home made T4's, others have swapped tubes. Sometimes they've swapped BACK.

You'd think that if everything was so clear-cut, we could ALL just read up and use our experiences in collaboration with what we read of others' experiences... And yet we ALL tweak and twiddle until we settle with what we like.

Elsewhere, you may read a post by someone who bought the original UTCs for about $650 (the cost of an HA-100X and an A-24 on eBay.. recent sale prices) and they've decided that the LA-2a sounds fantastic with them fitted. -I'm not going to argue... I've got TWO LA-2a's with UTCs in them (one with an HA-100 and the other with an A-10 as the respective input transformers) and they DO INDEED sound fantastic!

...However, that other person (on Gearslutz or wherever) won't have the 'baseline reference' of other options... They just know that their home-build LA2a sounds fantastic. -But LOTS of LA-2a's sond fantastic... probably MOST of them do. -They then start to profess that theirs is the best because it makes them feel better to tell people that theirs is wonderful, and you VERY rarely (if EVER!) hear people saying: "Yeah, my gear's not really all that good... there's better stuff out there!" (-If you did, Behringer wouldn't be making any sales!!!)

So I say that you'll learn more by just making something that WORKS first, then making something that works BETTER... -Why? -Beacuse you'll have HEARD the difference, not just read that there (apparently) is one. You'll have HEARD what the difference SOUNDS like... not just some person's (biased) adjectives.

Here's how far Scenaria and I went in terms of comarison...

JUST DO IT. -You can always fiddle later, and there is NO "best" one... I've built countless versions, and they're ALL great. (something which the gearslutz alphas with their one cherished compressor don't have the luxury of reference, in order to appreciate!)

Build it. Test it. Love it. -Adapt it.. LEARN from it.

Then build another. Some times you'll prefer one, some times the other.

Keith

 

[emrr]

Tell it brother Keith! Tell it!

BTW, did ya build one with HA iron on the output, or LS iron anywhere? Or wire it up freestanding, since it probably wouldn't fit?

 

[feza]

SSLtech what you've build is incredible! Good job man! A lot of LA2A's build with major knowledge about them.

I got months to do research. Better make my time as efficient as possible. It looks very difficult to build and to know what to do with problems with all compressors I see here. It won't take to much time to have enough money to buy those boards/cases from different compressors. It will take a lot of time to build them! :grin:

Greetings,
Dennis

 

[SSLtech]

Well, I'm assembling an LA2a "kit" right now... might be a week or five before it's all finished, but it should contain tubes, sockets, T4 socket, main turret board, meter turret board, all resistors, power transformer, etc. -I MIGHT be able to throw in the same case as I used to build my first one...

I'll have to see what I'm missing, but I think I have everything listed, and maybe more.

Keith

 

[feza]

[quote author="SSLtech"]Well, I'm assembling an LA2a "kit" right now... might be a week or five before it's all finished, but it should contain tubes, sockets, T4 socket, main turret board, meter turret board, all resistors, power transformer, etc. -I MIGHT be able to throw in the same case as I used to build my first one...

I'll have to see what I'm missing, but I think I have everything listed, and maybe more.

Keith[/quote]

I don't fully understand what you are saying. Are you trying to distribute some LA2A kits for people's interest? For me I want to build 4 units so far, eventually. But a great idea though. :thumb:

 

[emrr]

Been awhile since I've scanned all 30 billion pages of this thread. Apologies if I've missed this.

I'm planning a stereo build with no regards to original look, and several changes including the Jensen input transformer (which I happen to have surplus already), and probably try CJ's 12AY7/ 6SN7 line amp idea. I do like octal tubes. Clearly, one could use just about any ole' line amp, but I plan to use the Drip boards for simplicity's sake, so minimal changes. I may even go 'nutjob' and wire the 12BH7 socket, with extension plug to chassis mounted 6SN7 socket.

I digress.

Here it is, the old PSU variation question, specific to the LA-2A. Getting into 'religion' territory.

Has anyone done (does anyone recall anyone doing) a build using a tube rectifier? Experience with sonic outcome; anything notable? Obviously require a change in power transformer for filaments, and to account for tube rectifier voltage drop. I have an aversion to 'instant on' tube circuits, for some reason. I've hacked Amperite time delay relays into a few tube pieces with SS rectification.

Conversely, has anyone listened to circuit using an off the shelf regulated SS supply, like the Power One? The 250 VDC cranks up to 265 VDC just fine, and would run 2 channels just fine. I've got enough surplus regulated supplies to put in DC filament also. Seems competitive pricewise, especially for a 2 channel build.

Thoughts?

 

[Bluzzi]

I can't say for the other stuff but I went with a 12AY7 on my first and also my second now. I like it better.

On the second one I also used 100K for R9 and R13 (also a CJ suggestion) but haven't fully tested it yet.

This was to bring down the gain but then I'm using A10 which is 1:10 and I believe your Jensen should be 1:1.

I see no reason why a SS PS shouldn't work.

jim

 

[cannikin]

Hey Jim,

did you replace both 12AX7 with AY7? or just one?