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Quick AR-5 questions L-pads.


OOvvHH
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Hi I am finally restoring my AR-5's and in the process of finding the correct way to replace the pots for L-pads found all the repeated numerous answers going back to 2005. Thank you @JKent.

Downloaded the 3A manual looked intensively at page 15 etc.

2 questions remain to make myself at ease, because i found the answer but first time doing this so want to be absolutely sure .

The 25 ohm resistor is placed across 1 and 2 terminals of the l-pad, which are connected to the driver terminals. It is the variable parallel leg of the l-pad (corresponding to 2 and B of the original control).

This goes for all AR models ? Because i finally found that sentence in a 3A post.

I got some nice NOS capacitors from a tube friend to use with the 4uF and 24uF but for the larger 72uF i bought 2 68uF mundorf ecaps that measure 75uf.

Is that ok to just use or should i stick to the label and add 4uF in series to get the label values right ?

Kind regards Oliver.

post-101828-0-37968300-1415991380.jpg

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Welcome to CSP Oliver

Thanks for the shout out but the work on L-pads, as well as the above photo, are the work of RoyC.

I'm surprised the Mundorfs don't measure spot on but yes--it's OK to use them alone. That's within acceptable tolerance. And yes--use resistors with the L-pads in all applications.

Just to confuse matters, here's an alternative to L-pads: 

 

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Hi thanks for the welcome. The answers i meant were also about which capacitors to use. I saw a distinct pattern 😂 .

Is there any sonic difference between the L-pads and your offering ? Your shipping from the states ? How long would that take to europe ?

Already bought the L-pads but luckily i have more AR speakers that also need restoring. I went on a collectors binge 10 years ago, need to get the whole series complete AR1 through AR10.

I read on the forums that the 5 deserves the most love because it is designed the best ?

Of course now i am reluctant to use the Mundorfs. I'll get them tested again by a friend just to be sure.

Thank you.

 

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I sent you a PM regarding the potentiometers.

What is your question about the capacitors? You said a friend gave you 4uF and 24uF caps. For the 4uF you should be using a film cap. For the 24 you can use either film or NON-POLARIZED electrolytic (NPE). For the 72 most go with an NPE because film caps in that value are big and expensive. Some members here recommend Mundorf E-Caps. What exactly did your friend provide?

One other thing: When combining capacitors to make a higher value they must be in parallel (not series as you wrote in your first post).

Kent

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2 hours ago, OOvvHH said:

read on the forums that the 5 deserves the most love because it is designed the best ?

The 5 is a paradox. While there is a solid argument for the above sentiment, properly working 1s, 3s and 3as always get more love from the marketplace. Are you in the US?  

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"Best" is a relative term. The 3/3a was TOTL for the classic era, but if you had a small room and not enough power they would have been a terrible choice for your needs. The 5 was designed and marketed as a sort of "3a kid brother" that would provide the same mid and high performance as the 3a for people with more modest spaces and amplifiers, but most people who A/B'd them against the 2ax didn't think their performance was worth the added cost and opted for the less expensive model.

So looking at from the POV of designing for success in the marketplace, the AR-5 ultimately proved to not be not a very good design choice for AR.

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On 5/10/2021 at 2:47 PM, JKent said:

they must be in parallel (not series as you wrote in your first post).

Noted, thought parallel wrote series.

I dont have any questions about the capacitors , i am a natural worrier so when capacitors are supposed to be 68 and measure 75 i need to double triple check.

I got this new peak ESR70 meter for just capacitors I'm relatively new with this electric stuff.

But i also read in some of your posts that its all ok, i mean the difference is in the 5% noted on the capacitor.

On 5/10/2021 at 2:47 PM, JKent said:

What exactly did your friend provide?

 

906200792_Screenshot2021-05-11at19_00_22.thumb.png.0a6ef163d3f99bbc8bf12aeac3231ad4.png

This is what he made for me.

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