Mundorf AMT 25CS2.1-R

[hifijim]

From post 16, photo 8:

8) cumulative spectral decay. Hmmmm? is this good?

Actually, I am rather disappointed in that CSD plot... I would expect ribbons and AMTs to be better than that. A decent soft dome is better, and a good metal dome is much better... for less money.

 

[eriksquires]

Unfortunately I don't have the measurements anymore, but I remember doing CSD and having far better results on this tweet.

 

[Lojzek]

If you are good at rigging measurements, you can achieve anything and make people decide to open up their wallets.

 

[Cousin Billy]

I too expected a better CSD.

Since this is the first time I've done them, I have no reference as it pertains to my system.

Yesterday I did another set of measurements. Let me post them. After that I'll test another tweeter I have. Let's see how it's CSD looks. If it too is wonky, than it's my system/setup and not the AMT.

 

[Cousin Billy]

Here are yesterdays capacitor measurements. To reiterate, this set of tests are to determine if orientation makes a difference. I do agree with erik, maybe the caps need to settle and/or break in. I'm on a learning curve, and any advice is appreciated. I'll retest in a couple of months. Hopefully break in is complete.

This set of measurements are of three caps, forward and backwards.

Jantzen Superior Z. Mundorf EVO Silver/Gold/Oil. Duelund VSF. All 4.7uF.

1) Jantzen distortion %. After taking the EVO SGO measurements, I didn't look at this again. The EVO has lower distortion. The Jantzen won't be tested again.
2) EVO SGO, aligned backwards. Hooked the +ve to -ve binding post, opps. FR is a little inverted. Distortion shouldn't change. Nice results, especially considering the volumes involved.
3) EVO SGO distortion, backwards
4)EVO SGO fr. Proper alignment
5) EVO SGO distortion, proper
6) Duelund VSF fr, backwards
7) VSF distortion, backwards
8) VSF fr, proper
9) VSF distortion, proper

The EVO SGO has lower distortion backwards, but not by a lot
The VSF was too close to call. It may be slightly lower backwards, but only listening will settle this.

As to comparing the two caps, I had to scroll back and forth multiple times. After looking at the two, I think all testing will be with the Duelund VSF, backwards.

 

[Cousin Billy]

Lojzek, I took your comment to heart.

All 4 cumulative spectral decays are from the same pulse. I just changed one tiny parameter at a time.

Tomorrow I'll dig out a few other tweeters and double check.

 

[Cousin Billy]

Had an Accuton BD25 tweeter laying around? I remember it testing very well. I am using a pair in my present speaker, and with the exception of power compression (there you go erik) at concert hall levels, it's an incredible tweeter.

I didn't have any fancy hookup wire available, so I used a spare piece of Litz 50/32, already tinned.

I first tested the Accuton, with the Litz (pic. 1).
I than soldered the Litz to the Mundorf (pic. 2).

Wayyyyyyy better CSD. I am now very very happy with the Mundorf AMT. It keeps pace with one of my favorite tweeters.

Please don't turn this into a wire discussion.

 

[eriksquires]

Weird. I am pretty sure something else is going on with your mounting/baffle.... but hey, very very cool if this turns out to be repeatable.

As I recall, the Mundorf has banana jacks, right??

 

[jholtz]

Had an Accuton BD25 tweeter laying around? I remember it testing very well. I am using a pair in my present speaker, and with the exception of power compression (there you go erik) at concert hall levels, it's an incredible tweeter.

I didn't have any fancy hookup wire available, so I used a spare piece of Litz 50/32, already tinned.

I first tested the Accuton, with the Litz (pic. 1).
I than soldered the Litz to the Mundorf (pic. 2).

Wayyyyyyy better CSD. I am now very very happy with the Mundorf AMT. It keeps pace with one of my favorite tweeters.

Please don't turn this into a wire discussion.

Hi Billy,

Do you have distortion measurements and a clean frequency measurement? I'd like to see how low it can be crossed.

Thanks!

Jim

 

[Cousin Billy]

Hello Jim

Unfortunately, I'm not very bright. Please be exact in exacting exactly what you'd like me to measure!. What distance? What volume? Value of safety caps? etc.

Since the Acoustic Elegance drivers are still 7 months away, I can test whatever your heart desires.

Have I mentioned you need to be exact?

 

[jholtz]

Hello Jim

Unfortunately, I'm not very bright. Please be exact in exacting exactly what you'd like me to measure!. What distance? What volume? Value of safety caps? etc.

Since the Acoustic Elegance drivers are still 7 months away, I can test whatever your heart desires.

Have I mentioned you need to be exact?

Hi Billy,

I'm a follower rather than a measure guru. I can't advise how to get there beyond 96 db Is the most used volume and speakers are normally measured at one meter. Software is something I can't give any direction on.

Sorry!

Jim

 

[Lojzek]

Hello Jim

Unfortunately, I'm not very bright.

That's easily fixed, you need some rewiring.

 

[Cousin Billy]

I tried rewiring with red wine last night,......., it didn't work?

 

[Cousin Billy]

Jim, here you go.

1 meter, 96dB, single 68uF safety cap, 1/24th of an octave steps, 1/3 octave smoothing.

A 'buzz?'. In all my testing, there's a slight buzz around 1200Hz. There is also a small jump in distortion, both D2 and D3, around this frequency. There is another thread going right now. The OP talks about a buzzing sound during music play. Conclusion; you must cross this tweeter WELL above 1200Hz.

Before 4000Hz there are two major dips. After 4KHz output is very good. I will be crossing this Mundorf AMT to two Accuton C51 2" midranges, D'Apppolito, between 4K and 5KHz. At least I hope this works?

I'll start a new thread for the Accuton's.

Thank you all for following this thread.

 

[jholtz]

Thanks Billy.

Jim

 

[samoloko]

Guys,

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