All things LA2a related

[fum]

Ya Wil, put down your twins and pick up that soldering iron :!: :wink:

ju

 

[EmoRiot]

What about Lundahl? Do they require a mod and how do they stack up?

 

[EmoRiot]

Also, I see in google there was a thread on recording.org where a lot of you guys were comparing the A10 with the new reissued HA100X.

Unfortunately, only the first page is cached with Google and it appears to be off of recording.org. Does anyone know the results of this comparative analysis.

Is the reissue worthy of its name?

It just seems to me conceptually that the closest thing to the HA100X would be a new HA100X...

or did UA just label a second-rate unit an HA100X to fool people like me? :wink:

 

[Scenaria]

there were some quirky things with the re-issue that CJ came up with .. IMHO the A10 would be closer to the original thing (it actually IS) than the re-issue...

lundahls are very nice trannys but two things to consider... they seem a bit more transparent (less color) and are a little more tedious to mount...

seriously... go with sowters.. they really are good value for the dollar... (I dont own stock in sowter) :green:

:guinness: :guinness: :guinness: :guinness: :guinness: :guinness:

 

[CJ]

The A-10 and the HA-100X are the exact same transformer. Only the cases have been changed to protect the innocent.

A-10= 1 can
HA-100X = three wanna be mu metal cans and 1 steel can.

As mentioned before, 1:10 ratio is a little hot for the input.
A 10k:10k bridging would be better, which is what Jensen recomends.

Any plate to line output could be used. Triad HS-50/52 would be an upgrade.
Peerless S-217-D would be a real upgrade.

Here is the high end plots of un-terminated transformers:

Here is some other info:

 

[thedug]

I have a question about LA2A gain.

Should the gain affect the gain reduction at all.

Mine appears to be working, however the gain seems to act like makeup gain and not input gain. I had to crank my mic pre to really see the gain reduction meter start moving.

Maybe I just need to adjust my GR meter.

Doug

 

[Scenaria]

use the peak reduction control to set the amount of compression... then use the gain control to set the amount of gain you want coming out of the box..

the gain control does not affect compression

basically the peak reduction sets the amount of compression/threshold


its not like the 1176 where you use the input level..

 

[EmoRiot]

I'm getting ahead of myself, as my Bloo kit hasn't even arrived yet, but I thought I'd pass the time by asking questions that will ultimately come up anyway.

Today's Question: What are the best Tubes to use? Of course, Telefunken is an obvious choice but I've heard about Mullard tubes being as good, if not better? What's the best choice here?

 

[Scenaria]

dont get too carried away with tubes..

I have tried telefunken smooth plates... RCA's, sovteks, raytheon, CEI and JJ's

to be honest I couldnt hear a difference that could justifiy a $80 12AX7 from a $15 one...

just go with a respectable name brand... dont get caught up in the telefunken stuff with this compressor...

the sound is in the iron

 

[Bluzzi]

I am looking at starting to buy the parts for 2 LA2A and will be starting with the transformers.

The UTC seem to be getting rarer and more expensive these days so I am contemplating others.

I've heard the Jensen and Lundhal ones result in a cleaner more transparent sound (oxymoron?) and so I have included the Sowter ones as well as possible subs. I don't mind a "clean" sound. By that I mean I am not stuck on the clone being exactly part for part as the original. Of course I don't want to stray too far either and build an altogther different beast.

I would just like your opinions as to the best ones and what the differences are when it comes to the sound. What think you all?

Thanks

 

[EmoRiot]

If you look at the previous page on this thread, you'll see our discussion about this exact issue.

I raised the same question and the answer basically boiled down to:

Jensen requires a mod and is expensive
Lundahl is very transparent, almost too much so
Sowter is nearly identical to the UTC and very affordable

Sounds like Sowter's the winner to me.

Like I said you can check the previous page for more in depth discussion and diagrams - the works.



I haven't given up on finding some UTC transformers, though. When you mention that they're getting more rare and more expensive, have you found a place that has them and they're just more than you'd like to spend?

I'd still be interested in them if you could point me in the direction. That is, again, if you have found them anywhere.

 

[Bluzzi]

The Sowters it is then! I was just on their site and it comes to just under $400.00 Canadian for 2 sets (4 Xfrs). The Lundhal and Jensens would be more so the Sowters wins in all cases.

As to finding UTCs, no my only source was eBay and I don't see that many these days. When they are there they go for too much in my opinion and you never have a 100 percent guarantee that they are working!

The T4B is easy to find so now I must look for the VU meter. Should I buy new or used? Hmmmmm. Time to hunt on eBay again.

Thanks for your comments, it made me make up my mind.

Jim

 

[CJ]

Sometimes you can get away cheap if you use your noggin and do a little diggin.

Like this auction. Vintage Triad in and out, blows the socks off UTC. Now sitting at 11 dollars for both. Plus, you get a vintage 12AX7a and other parts:

Triad

 

[Bluzzi]

Thanks CJ. But I don't have a noggin for Transformers. I wouldn't know what would be an acceptable substitute for the LA2A.

So are you saying the Triad is good for the input? Without changing any part values?

I'm doing this for fun of building but I am not an electronics technician. I've made kits before and some other projects but from schematics and/or wiring diagrams. So to redesign for me is scary.

Thanks for your tip.

Jim

 

[JerryPbury]

I just picked up an A-10 and an A-24 for less than the Sowters on EBAY just this last week. I also bought a Thordarson 25A58 (A10) from the Black market. For the output try doing a search for a Thordarson 25S12 (A-24).

Jerry

 

[Bluzzi]

[quote author="JerryPbury"]I just picked up an A-10 and an A-24 for less than the Sowters on EBAY just this last week. I also bought a Thordarson 25A58 (A10) from the Black market. For the output try doing a search for a Thordarson 25S12 (A-24).

Jerry[/quote]

I must be looking in the wrong places because I just looked a week ago and found nothing (unless I just missed it). encouraging though.

I'll check for Thordarson part. Thanks.

Jim

 

[CJ]

Jim, the Triad's are line to grid (in) and plate to line (out). Just make sure what you bid on has that description along with about a 15db rating and you will be alright.

 

[Bluzzi]

[quote author="CJ"]Jim, the Triad's are line to grid (in) and plate to line (out). Just make sure what you bid on has that description along with about a 15db rating and you will be alright.[/quote]

OK I'll verify. Let me try and understand what you are saying (don't laugh). Basically the transformers for line input for a tube are almost all the same? The 15 db rating is that the gain?

Jim

 

[CJ]

Yes, the line to grid x-formers usually have impedances that are within the ballpark of each other. One thing you do have to watch out for is if you are going into a push-pull tube stage-then you must have a dual secondary or center tapped secondary. Every UTC I have seen is built with dual secondaries. Most Jensen's I have seen only have one secondary.

The db rating is how much voltagepower the transformer can handle before saturation/distortion.

Line level stuff requires about 15 db, where as if used as a mic input, the db level can be lower, like the UTC ouncers.

 

[Bluzzi]

Ok, thanks I get it. Hence the larger size due to handling higher level.

I'll keep my out for other Trannies but for my first try at teh La2A I am too timid to take a chance and will be sticking with the usual suspects.
If I can't get the UTC ones I will go for the Sowter. After successfully completing at least one La2A I'll feel a lot more confident. Plus I'll have it to experiment with other transformers!

Thanks guys for not making me feel like a total dummy. Its also very encouraging seeing all of you happy with your finished projects.

Oh one more thing. The chassis will be hand made by a friend that has a machine shop. It will be aluminum however and as we all know soldering to chassis is not effective. Do you think there will be a problem with grounding? I'll be making sure that all grounding is done to solid screwed in terminal strips or screws. My experience is that this is OK as long as the screws do not loosen up in any way.

Aluminum is just easily available and easily machined.

Jim