AR 9 Mid and HF Cap suggestions

[Pk Vintage]

Thanks to all of you who contributed on my LF suggestions Topic.

As I have now decided on a Mundorf E Cap bundle for the LF side, my attention has now turned to getting the best tried and tested caps for the Mid and High side. Any of you folks have a suggestion for me. I have seen a parts list which was made up of Solens, Although a very good and popular brand,  I am not 100% convinced they are the best for these speakers.

Thanks for any help.

[Stimpy]

Oh Boy, this should be fun, and very interesting!!!  Recap discussions can get 'passionate', for want of a better term.  Some believe that it's best to stick to the original design, and replace electrolytics with electrolytic.  Others think inexpensive poly caps are fine, and as long as the correct values are used, sound just the same as more expensive parts.  Then, there's idiots like me, that use the best parts 'that they can afford'.  A bit different than the best out there, but still more expensive than entry level.

Also, what I did, to save a little money, was use as good as I could for the series capacitors, and entry level for the parallel, shunt capacitors.  The series capacitors are the 4uF, 6uF, 24uF, and 80uF values.  The 8uF, 30uF, and 40uF are the parallel values.  I used Mundorf for the series caps, and Axon True Caps for the parallel caps, and E-Caps for the 350uF, in my AR90s.  When I had to combine caps for a specific series value, I used Mundorf EVO Oil and Supreme caps.  Otherwise, I tried to find the correct values, using a single cap.  I'm still working on the restore of my 90s, and I haven't been able to perform a finished audition, but quick A/B tests so far, have been very promising.

Finally, there's are a few other members here that have been recapping AR9 and AR90 speakers too.  We've discussed our trials and tribulations about the process, amongst ourselves.  It's been frustrating at times, but a good learning experience.  I hope they'll offer their advise too.

Good luck.

[Stimpy]

Oh yea, I have my AR90s and a spare set of crossover boards for the 90s too.  During the recap, I rebuilt the spare crossovers.  So, once the speaker refurbs are done, I can pull out the original crossovers, and swap the new boards in.  Well, after I did the recap, I set up one of the stock 90s, and then pulled the UMR dome from the other, and hooked that to the new crossover boards.  In the A/B comparison, the single dome sounded far, far better than the original speaker.  I heard more mids and highs from the one dome, than both the tweeter and dome mid in the stock speaker.  Clearer and much more open.  Also, there was none of a static type of distortion, heard in the stock speaker, in the new crossover, either.  From that alone, the recap seemed a success to me.  IMHO.

[DavidR]

I have AR90's and decided to try the Mundorf ECaps and used a Vishay 1837 as a bypass cap on the tweeter and UMR. I'll try and get some pictures posted of the assembled caps.

[AR surround]

Here is what I used on my AR9's and I am extremely happy with the results.   The Dayton F&F Bypass Caps across the high range series caps made a difference especially with the UMR 24uF E-Cap.   I do not know why as I own no sophisticated instruments with which to take measurements.

4uF: 4.0uF Dayton PMPC 250V 1% + Dayton F&F 0.01uF 400V 5% bypass capacitor

6uF: 6.2uF Dayton PMPC + Dayton 0.01uF bypass

24uF: 22uF + 2.2uF Mundorf E-Caps + Dayton 0.01uF bypass

8uF shunt cap: 8.2uF Dayton PMPC + Dayton 0.01uF bypass

40uF shunt cap: 40uF Dayton DMPC 250V 5% + Dayton 0.01uF bypass

80uF: 82uF Jantzen Cross-Cap 400V 5% + Dayton 0.01uF bypass

30uF shunt: Dayton DMPC + Dayton 0.01uF bypass

470uF: 470uF Mundorf E-Cap + Dayton 0.10uF bypass

2500uF: 3x680uF Mundorf E-Cap + 1x470uF Mundorf E-Cap + Dayton F&F 0.10uF bypass

[Pk Vintage]

Thanks for the detailed parts list. I see you paired all Caps with  bypass caps. Do you think it was real really necessary? 

I am not really up on all the advantages of using bypass caps. 

[AR surround]

12 hours ago, Pk Vintage said:

Thanks for the detailed parts list. I see you paired all Caps with  bypass caps. Do you think it was real really necessary? 

I am not really up on all the advantages of using bypass caps. 

Bret (Diamonds & Rust) had recommended using bypass caps across every cap, so I did so.   I added the bypass caps afterwards and I could tell that they made a difference on both the UMR and tweeter.  The improvement to the tweeter was more subtle than on the UMR which sounded significantly better than without the bypass caps.  Member DavidR added bypass caps to his AR91's and said that they made a remarkable improvement.     The Dayton bypass caps that I used cost $0.74 each, so it was a small investment with big returns.   Had the experiment failed, I could have snipped them out yet not spent a lot of money.

[DavidR]

On 8/27/2017 at 8:10 PM, Pk Vintage said:

................................ I see you paired all Caps with  bypass caps. Do you think it was real really necessary? 

...........................................................

Yes. It was in my case, I used Dayton 1% on the 4, 8 and 24uf caps and 5% on the 40 and 100uf caps. The 1% is a different cap than the 5%; not just a tolerance difference. I found the 91s would get 'under my skin' and become un-listenable quickly. I did one speaker and put a 0.01uf Dayton film and foil across the 4uf and a 0.01uF Vishay 1837 across the 25uf (24). I did an AB of the 2 speakers. I wasn't sure what was different at first as the bypassed speaker seemed to be not as loud. I finally got down of the floor and and put my ear to the tweeters and mid of each speaker. It became quite clear then. The NON bypassed speaker had brightness and glare. The bypassed speaker was clearer and more detailed. I can now listen to them all day without getting listener fatigue.

I'll be putting bypass caps across all the caps in my AR90 project.

[Pk Vintage]

Ok. It sounds like I will be going the bypass caps route. 

I don't mind spending  a little more money on the bypass caps if it will help. 

I will do some reading  on  bypass caps and get back in a couple of days so I can at least ask some intelligent questions about the procedure and best ones to use. 

Thanks. 

[Steve F]

Far be it from me to open the Pandora’s Box of capacitor audibility and pluses and minuses of different cap types.

You guys can fight over that. Much has been written and argued about and no doubt, more will be written and argued about.

However….I’ll just toss in one experience that I witnessed and youse guys can make of it what you will. 

I worked at Boston Acoustics for 11 years. As Director of Home Audio Product Development, I drove the strategic planning, design, voicing and marketing of all BA’s home speakers during that time frame. There are lots and lots of great “inside” stories that I can tell you (speaker companies don’t always operate exactly the way “outsiders” think they do, that’s for sure!), but let me tell you this one Capacitor Tale.

In 1992, BA came out with a really high-end family of speakers called the Lynnfield Series. There was a 500L and 300L (floorstanding and bookshelf) and they offered some very creative, off-the-beaten-track thinking. They sold well for expensive speakers, but after a few years, we wanted to come out with a slightly tweaked Series “II”. Just some crossover/voicing mods, nothing too radical.

Our lead engineer did the mods and we all listened and agreed that they were an improvement. Then he said, “Give me a day to try one other thing and then you all can come back and listen again.”

Nothing at BA was approved for production until our president Andy Kotsatos (who also was the main person behind the voicing of the original Large Advent and its successors) approved the final crossover.

We gathered the next day to hear the next iteration and we all agreed that this one was even better than yesterday’s. Andy said, “What’s the difference? The frequency response curves are identical between yesterday and today. You can lay them over each other and hold them up to the light and there’s no difference.”

The engineer said, “Bypass caps.”

Andy went, “D*mn!! I absolutely hate it when these esoteric things that you can’t measure make a difference. I hate it.”

But he approved the crossover and the Lynnfield Series II went into production with bypass caps. The lower-priced VR towers (VR-20, -30 and -40) also used bypass caps (same engineer).

Take from that what you will.

Steve F.

[JKent]

Steve,

It IS a Pandora's box. I'm skeptical but I HAVE used bypass caps. Bought some Vishay Roederstein MKP1837s because they were recommended and cost about a buck apiece. Also bought some cheap Soviet surplus PIO caps when I was buying commie vacuum tubes. My thinking is; "why not?" Couldn't hurt and it "may" help.

YMMV 

Kent

[DavidDru]

I think I have seen it spelled out before, but can someone tell me exactly what bypass caps actually do?  In english, not engineer.

[Stimpy]

I read on another board, about bypass capacitors, and why they work.  This is a direct quote, from Danny Richie of GR Research, on why he feels bypass caps improve the sound of a crossover:

"Think of a capacitor as an energy storage device. The larger it is the more it can store. Also the larger it is the slower the rate of discharge. Think of it as power in... charging up... then discharging. The time involved in that process represents some smearing to the audio signal. Faster discharging caps are cleaner sounding. That's one of the reasons a Sonicap (for instance) sounds so much cleaner than so many others. Also, the fast discharge caps really give you the space between notes and that can be a big improvement in sound quality.

Now the tiny little by-pass caps are so small that they hold nearly no charge at all by comparison. It is basically power in and power out. So they tend to help discharge the stored energy of the larger cap when by-passing them. So you have a big needed cap value but you take on some of the fast discharge rate of the smaller cap."

I don't know if this helps, but it's one possible explanation to consider.

 

 

[Carlspeak]

If you want to hear more of the effect of the bypass cap, use a 0.1uF. If you want to hear less, use a 0.01 uF.

Vishay makes a good one.

[harry398]

On 8/29/2017 at 4:59 PM, Carlspeak said:

If you want to hear more of the effect of the bypass cap, use a 0.1uF. If you want to hear less, use a 0.01 uF.

Vishay makes a good one.

I am not sure what you mean by this........

 

can you elaborate?

[Carlspeak]

With the 0.1 cap the bypass allows signals to pass ~ 1 kHz and above. with the 0.01. not until ~ 4 to 5 kHz. So, with a 2-way speaker there's more benefit with the 0,1 uf and with a 3-way, 0.01 uF.

[harry398]

Aha.    Ok.    

Thank you Carl.

[AR surround]

On 8/29/2017 at 3:02 AM, Pk Vintage said:

Ok. It sounds like I will be going the bypass caps route. 

I don't mind spending  a little more money on the bypass caps if it will help. 

I will do some reading  on  bypass caps and get back in a couple of days so I can at least ask some intelligent questions about the procedure and best ones to use. 

Thanks. 

So PK, how do you like the sound of your AR9's?  (Chatter on the forum has been a bit thin lately on the AR verticals.  So I'd like to hear something about them.) It's been 18+ months since you posted on this topic and I assume you did the recapping and have been listening to the speakers.   Did you ultimately go with the bypass caps?