[shigzeo]

I think one major problem is the connector: it isn't standard with any iem, and in direct contrast with what other manufacturers are trying to accomplish. This is Windows VS OSX with the customer getting it in the nose.

There aren't any great options yet, but... there is work on it and it would be great if boutique manufacturers like RSA followed with where the other manufacturers are going. That, however, will not be the case and the customer will have to shell out for a cable which will only work on that amp and if s/he wants to use it on another, there will need to be an expensive interconnect purchase to facilitate it.

 

[Kon-Masti]

As long as the SQ delivers, which it most likely will, and people are willing to go that extra mile to achieve that SQ then some compromises will need to be made and overcome. I'm all for a manufacturer exploring non-standard equipment if it means advancing the technology. Convenience is no excuse for stagnation IMO.

 

[n_maher]

I think it's a good idea to have a thread outside of Ray's paid thread.

For starters it allows to have an open discussion about the design chosen, without interrupting the paid thread. With that in mind I find it curious that Ray chose to have output resistors on the amp. You can see them in this picture.

And also more clearly in this picture (R21, 22, 23 and 24).

I freely admit that my techincal chops are lacking with regard to amplifier design but what I do know leads me to think that having any series resistance on the output of the amplifier, specifically an amplifier design to drive loads which could be as low as 18 ohms in the case of the UE11 Pro, is potentially troubling. It's also curious why Ray did it at all since it's not something I can recall seeing on any of his prior portables. Any resistance on the output will directly contribute to the output resistance of the amp and lower the damping factor. If it's just a couple ohms maybe that's a negligible effect, if it's much more than that it'll become a contributing factor. In other amplifiers that I have worked with this approach was only taken (as a last resort) to reduce noise/hiss. To explain it somewhat differently this essentially (to an unknown degree since the resistance is an unknown) is like having an Ety P to S converter built into the amp that you can't bypass.

 

[Salt Peanuts]

One man's opinions -

1. The amp looks spectacularly mediocre, especially the knob and the square connector.
2. I'm still confused by the choice for the balanced connector. The connector/connection that doesn't rotate on a portable amp is breakage waiting to happen, never mind that it's not a standard connector that isn't used in other audio applications, AFAIK.
3. With the proximity of the square connector and the volume knob, I suspect it will be rather difficult for those with fat fingers to easily adjust the volume when the square connector is used.

 

[TzeYang]

Quote:

Originally Posted by n_maher /img/forum/go_quote.gif For starters it allows to have an open discussion about the design chosen

OH NOES!

I personally think it's not a big deal if the resistor values are small. It provides some current limiting and at the same time, a simple hack for reducing hiss.

Works better if the feedback loop controls it at the other end.

Also, is there a specially designed battery charger for the LI-ION?

I thought it was quite necessary seeing how sensitive they usually are.

 

[Ray Samuels]

Quote:

Originally Posted by TzeYang /img/forum/go_quote.gif OH NOES! I personally think it's not a big deal if the resistor values are small. It provides some current limiting and at the same time, a simple hack for reducing hiss. Works better if the feedback loop controls it at the other end. Also, is there a specially designed battery charger for the LI-ION? I thought it was quite necessary seeing how sensitive they usually are.

You are correct regarding the resistors, my friend, they are very low in value.
They do help protect the drivers, buffers.
As to the charging circuitry, the charger & the batteiers were designed by the same company. The charger has a RED LED when charging the battery, once fully charged the LED turns GREEN.
Ray Samuels

 

[jamato8]

Quote:

Originally Posted by Kon-Masti /img/forum/go_quote.gif As long as the SQ delivers, which it most likely will, and people are willing to go that extra mile to achieve that SQ then some compromises will need to be made and overcome. I'm all for a manufacturer exploring non-standard equipment if it means advancing the technology. Convenience is no excuse for stagnation IMO.

Good point.

 

[The Monkey]

I'm not a big fan of the proprietary balanced connector here, either. But I am a big fan of a balanced portable amp. This is the only "small" connector solution that I've seen (in my very limited experience with such things).

 

[Hopstretch]

Quote:

Originally Posted by Kon-Masti /img/forum/go_quote.gif Convenience is no excuse for stagnation IMO.

Nor is expedience any excuse for poor design.

 

[luvdunhill]

Quote:

Originally Posted by The Monkey /img/forum/go_quote.gif I'm not a big fan of the proprietary balanced connector here, either. But I am a big fan of a balanced portable amp. This is the only "small" connector solution that I've seen (in my very limited experience with such things).

Monkey, Perhaps you've seen the connector that Apple uses (the center one)?

 

[jamato8]

It is a possible option, the TRRS but there aren't many options I have seen for higher quality mini's of that type.

 

[Ray Samuels]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif Monkey, Perhaps you've seen the connector that Apple uses (the center one)?

As Jamato8 has indicated that there is no high quality connector like the one pictured above. Even if it was available it will still have many problems that the 3.5mm connector has as contacts will get loose & the signal start cutting as you move the wire back & forth.

I have done a long search for a reliable connector that could be used with out the pain of loose contacts & hefty price & with smallest possible size.
The Kobiconn Used in the Protector is very reliable. It can withstand the abuse & the shake with out any problems associated with the 3.5mm connectors. It is small, sturdy, priced very low, $2.00, made in Japan for expensive Cameras.
This connector delivers while others will suffer from all kind of problems.
Ray Samuels

 

[Dreadhead]

Quote:

Originally Posted by Ray Samuels /img/forum/go_quote.gif You are correct regarding the resistors, my friend, they are very low in value. They do help protect the drivers, buffers. As to the charging circuitry, the charger & the batteiers were designed by the same company. The charger has a RED LED when charging the battery, once fully charged the LED turns GREEN. Ray Samuels

What do you mean by low? 20 ohm is low compared to 20kohm but doesn't mean that 20ohm isn't large compared to a 18ohm pair of TF10.

 

[luvdunhill]

Why would Apple use a part that is guaranteed to fail, or comes loose? That would seriously impact their bottom line. That connector has seen an infinite more "real world" use *as a headphone cable* than the connector you using. Realistically, how many hours has the connector that you propose standardizing the entire headphone community on seen in real world use *as a headphone cable*? Is this number sufficient to uphold your claim of durability?

As for the TRRS connectors being hard to find, that's just not true. There are even right angle connectors that would address the durability concerns you have outlined. Here is one such connector:

4 conductor 3.5mm right angle cable mount male Plug - TRRS

Need a chassis mount as well that's low profile? Here's one

 

[n_maher]

Let's try to keep this non-confrontatoinal. Ray is sharing his motivation behind design choices that he made and I appreciate that even while I'm free to disagree.

I do share Dread's concern about the "low value" output resistors though. I have direct experience with amps that provide a low damping factor (output impedance close to driver impedance) and while it works with some headphones in my experience it also did not work with others.

Ray, since it's just a matter of reading the value off the resistor on the PCB would you be willing to say what the output resistance is to end that bit of speculation?