GROUP BUY: Universal Audio 176 - a 100% faithful recreation of a legend! CLOSED!

All good Martin,  like a good cheese these things take time to mature, thank you so much for your  massive efforts to the DIY community

JMarcovis said:

No worries Martin, thanks for the heads up.  Can someone post a link to the FB group? I'd like to join. Thanks!

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Here's the link to the FB group:
https://www.facebook.com/groups/1615927638648181/

Hi guys, meters and shields were posted out on 31 May. Please let me know when they arrive so I can stop worrying about the post. So far its cost me over 300 to help you all out, so I hope they all arrive. Cheers

moltenwok said:

Hi guys, meters and shields were posted out on 31 May. Please let me know when they arrive so I can stop worrying about the post. So far its cost me over 300 to help you all out, so I hope they all arrive. Cheers

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Mine arrived, yes. Thank you so much for helping us out on this one molten. Sorry to hear that the process ended up costing you more than anticipated. Super appreciated!

Has anybody made any inquiry regarding the caps? I'm not sure on what specs are needed to ask myself.

Anxiously awaiting to start on this project.

Thanks!

Paul

I have a real 175b....
I was able to find the 40,40,40,40 uf by CE Manufacturing...But As stated before they stopped making the 20/20uf 450V..
And I have been looking and looking with no luck...
Im thinking all the CE Manufacturing where just relabeled  NOS sprague caps. No reason they would stop making them If they
where being sold.
Hopefully a company will make these along with the hard to find 10/10uf 450V circuit board mount can cap. Of course you can use
two single electrolytic caps....
But would be nice to have exact proper caps. I was able to score a couple NOS 10/10uf on eBay..... For recapping my original and
doing one kit.
Anybody have links to can caps that we need? Please post!
Thank,s
John

Good news everyone!!

The chassis are powder coated and on the way here.
Also the front panels are silk screened and and should be here Monday or Tuesday!

I haven't seen neither yet, but I was told they all came out pretty nicely! I can tell you more once I have them here.

Livingnote is about to finish the handmade pcbs and he told me I should have them in the mail later this week.
The turret boards are CNC'd and they should arrive later this week as well.

The only thing left to do now for me is adding the fork turrets to all pcbs & turret boards...
This will take me a couple of days once I have the boards, since it's roughly 50 turrets per kit!!

But we're getting closer now  

Martin

rainton said:

Good news everyone!!

The chassis are powder coated and on the way here.
Also the front panels are silk screened and and should be here Monday or Tuesday!

I haven't seen neither yet, but I was told they all came out pretty nicely! I can tell you more once I have them here.

Livingnote is about to finish the handmade pcbs and he told me I should have them in the mail later this week.
The turret boards are CNC'd and they should arrive later this week as well.

The only thing left to do now for me is adding the fork turrets to all pcbs & turret boards...
This will take me a couple of days once I have the boards, since it's roughly 50 turrets per kit!!

But we're getting closer now  

Martin

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Excellent! Now you see why originals are so much! )) ALOT of work as you know! To make this type of compressor with NO short cuts! Great work Martin! Did you see the one on eBay right now for $11,000 !!!!!!
)))))

John

I did find some CE Manufacturing capacitors that were 20/20/10/10uF and was wondering if this could be used for C8a/b and C9a/b or if they needed to be separate components.

Thanks!

Paul

Another silly question:

I'm looking at the Daven 600/600 attenuators that are listed on the BOM, but the ones I've found do not have threaded shafts to mount to the chassis as shown on the first page of this thread. They have screws that attach to the body of the attenuator. Does the chassis have mounting holes for this or do I just need to find ones with threaded shafts?

Thanks!

Paul

I think Martin said he would have hidden counter sunk?
Under the faceplate......But most real ones have threaded shafts.........
J

All the Langevin ones seem to have the threaded shaft, but the Daven 600/600 ones I've found so far do not seem to be. I'm also bad at the Internet.

Another question I have regarding the Daven stepped attenuators is that I have found some with different dB ratings but are still 600 ohm. What is the gain range for the input and output needed for the UA 176?

Thanks!

Paul

No hidden countersunk holes - sorry.

But it shouldn’t be a problem to drill two little holes into the chassis front-panel to be hidden underneath the black faceplate.

The only thing though:
The faceplate is held in place by all the nuts used to mount the pots & switches on the front.

In the above mentioned case two rather important nuts would be missing.

jslstudio said:

I think Martin said he would have hidden counter sunk?
Under the faceplate......But most real ones have threaded shafts.........
J

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It looks like they have a plate that goes with them that has a threaded part that goes over the shaft.

https://www.ebay.com/itm/173254186435?rmvSB=true

The ones I initially found are missing this part, hence the confusion.

Thanks!

Paul

rainton said:

No hidden countersunk holes - sorry.

But it shouldn’t be a problem to drill two little holes into the chassis front-panel to be hidden underneath the black faceplate.

The only thing though:
The faceplate is held in place by all the nuts used to mount the pots & switches on the front.

In the above mentioned case two rather important nuts would be missing.

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No worries. I can figure something out. I was just trying to make mine as sweet as yours but may have to just go with the Bourns option.

Thanks!

Paul

Potato Cakes said:

All the Langevin ones seem to have the threaded shaft, but the Daven 600/600 ones I've found so far do not seem to be. I'm also bad at the Internet.

Another question I have regarding the Daven stepped attenuators is that I have found some with different dB ratings but are still 600 ohm. What is the gain range for the input and output needed for the UA 176?

Thanks!

Paul

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The original ones are 40db with 2db steps - 20steps

The ones you posted have 5db steps - a little bit difficult to adjust the comp with 5db steps

The original was 2db steps with additional “vernier” pots on input and output for fine tuning

Copy 40dB.

What I think I have decided to do is to make my own stepped attenuator so that the resistor values with more closely matched than vintage ones, especially since I'm building a pair. I'm going to start working on a layout and if I works I'll post it here.

Thanks!

Paul

rainton said:

The original ones are 40db with 2db steps - 20steps

The ones you posted have 5db steps - a little bit difficult to adjust the comp with 5db steps

The original was 2db steps with additional “vernier” pots on input and output for fine tuning

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I went a bit OCD trying to find the exact attenuators for this - Martin you really scored to get the originals for such an amazing price.

Here are some interesting parts, some of which might work. See EDIT note below for exact vintage part numbers for the exact parts.

Daven:
• LA-353-G: Part Rainton used - 600/600 Ladder, 20 steps, detents, 40DB reduction, threaded bushing mount
• T-257-G: 20 steps, 2DB/Step, 600/600, "T", no taper, 40DB total, Detents
• T-320-G: 20 steps, 2DB/Step, 600/600, "T", no taper, 40DB, Detents, last step infinity
• T-520-G: 20 steps, 2DB/Step, 600/600, "T" - 1% precision
• P-350: 2DB/Step, Infinite, Linear
• P-354: 2DB/Step, Infinite, Tapered
Langevin:
• RMX-601: "T" 20 step 2DB/Step, 1-gang, infinity cutoff
• RMX-601-2: "T" 20 step 2DB/Step, 2-gang, infinity cutoff
• RMX-601-3: "T" 20 step 2DB/Step, 3-gang, infinity cutoff
• RAT-631: 20 steps, 40DB, 2DB/Step, linear, no infinity, detented positions, Unbalanced Ladder
• RAT-633: same as above, Balanced Ladder
• RAT-601: same as above, Bridged "T"

After many, many months of hunting the snipe - the elusive LA-353-G, Daven 600R 2db stepped 40db total attenuator complete with bushing threads, or a corresponding Langevin, I gave up and contacted Shallco directly and had them custom made. I'm not going to tell you how much that cost.

Looking forward to (eventually) doing this project. Great job Rainton!!!

Mike

EDIT: in post https://groupdiy.com/index.php?topic=66175.msg882754#msg882754John shares the exact part numbers from a vintage unit.

I am going to be using 2x24 position Elma switches to build ladder and t-pads. I think I will be better served with newer components in this position. And I wanted to learn how to do it. I found some formulas and plugged them into Excel to come up with the resistor values.

I also contacted Hayseed Hamfest and they are willing to produce the same multi section caps that they provided Martin, so I'm just going to order from them and keep it simple. They said that the tabs on their capacitors will need some minor trimming to fit these boards but shouldn't be a problem for anyone experienced enough to take on this project. Pricing is reasonable, especially for a low quantity custom order.

Can't wait to get started on this!

Thanks!

Paul

Phrazemaster said:

I went a bit OCD trying to find the exact attenuators for this - Martin you really scored to get the originals for such an amazing price.

As far as "original" specs this is what I dug up, along with related similar parts:

Daven:
• LA-353-G: Actual Part used as per rainton in previous thread here - 600/600 Ladder, 20 steps, detents, 40DB reduction, threaded bushing mount
• T-257-G: 20 steps, 2DB/Step, 600/600, "T", no taper, 40DB total, Detents
• T-320-G: 20 steps, 2DB/Step, 600/600, "T", no taper, 40DB, Detents, last step infinity
• T-520-G: 20 steps, 2DB/Step, 600/600, "T" - 1% precision
• P-350: 2DB/Step, Infinite, Linear
• P-354: 2DB/Step, Infinite, Tapered
Langevin:
• RMX-601: "T" 20 step 2DB/Step, 1-gang, infinity cutoff
• RMX-601-2: "T" 20 step 2DB/Step, 2-gang, infinity cutoff
• RMX-601-3: "T" 20 step 2DB/Step, 3-gang, infinity cutoff
• RAT-631: 20 steps, 40DB, 2DB/Step, linear, no infinity, detented positions, Unbalanced Ladder
• RAT-633: same as above, Balanced Ladder
• RAT-601: same as above, Bridged "T"

After many, many months of hunting the snipe - the elusive LA-353-G, Daven 600R 2db stepped 40db total attenuator complete with bushing threads, or a corresponding Langevin, I gave up and contacted Shallco directly and had them custom made. I'm not going to tell you how much that cost.

Looking forward to (eventually) doing this project. Great job Rainton!!!

Mike

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Hi Mike,
Not trying to rain on your parade!...But the most Common ACTUAL used where the smaller Langevin and Smaller Daven attenuators!
I have an original and the most common Langevin was the small Model 1923 non balanced and mine also has a very rare output being the Cinema engineering 7250 on the output. These are original with untouched solder joints.......
The Cinema is one of the coolest looking done in Blue anodized with a yellow sticker.........
Anyway there are a few units that you will see with the larger stepped attenuators. But the many I have seen in person and in pictures tend to have the small Davens and the smaller Langevin Attenuators.
This is what was happening in the mid 1960,s. The larger Attenuators are left over from the 1950,s.
Of course most 600/600 2 db step 40db will work in these units.....

Very cool you where able to get Shallco to make these.....Maybe we should have had a group buy.????

Best,
John