Solo UL impressions

I was having a brief dig at many of "our" trade and shop outlets who were oh so enthusiastic once.

Never mind. The less they promote our incredible hard work the more you buy direct from our online shop, making last year a bumper direct sales year. Poaching sales definitely not! If we were to rely on the trade alone we'd be one of the great has beens like Woolworth, MFI, ... , etc.

And yes, I am working on improvements all the time - the trade don't like it at all, but seeing they're doing very little in our support (apart from a handful and they/you know who they are) we may as well ride roughshod as they say...

One particular improvement on the Solo Ultra Linear is reducing the hiss: using extremely sensitive phones designed especially for iWotsits -- put it this way, such phones weren't around before the iWotsit -- some people experience a very gentle hissing sound behind the music.

As I have repeatedly said over and over, we are customer led (seeing customers buy what we sell it seems reasonable to be like that ...), and so I will always put in the effort for the customers, even if I have to redesign an entire product's electronics, which I have done with the Solo Ultra-Linear on test here. I will add, the Ultra-Linear module itself is the only item untouched because I could not improve on it according to my hearing and a number of measurement tests.

You will note from what I just said - a total redesign... It's not something the average DIY'er could easily fit in an evening.

So what does it achieve? I wanted to get the noise down a factor of 10 (which is 20dB) but that didn't bode well for the music on all headphones because of other factors which would take me an age to discuss here. The noise level is actually down by a factor of 5 (which is 14dB making it now -92dB). The law of diminishing returns has obviously come into play here.

As for it's valve like qualities, it does have some left. It uses something in the region of 14dB global negative feedback (which the old Ultra-Linear Williamson 15W valve amp did). It still has the increased open-loop frequency response. It has a little less input stage linearity but compared to other products out there it certainly is the equal or in most cases better.

It is more "class A" and at the last measurement I found it doing 15mA idling current per channel. With a 32 Ohm headphone that is 0.48 volts, and if we square that number and divide it by the headphone impedance (0.2304/32) we get 7.2mW. If we then take such a headphone to be any of the latest Grado's which do 98dB SPL for 1mW, then by mathematical manipulation we find that it can do 106.57dB SPL (sound pressure level) in class A.

In ear phones are so sensitive that they'll be in class A full time - I just hope that -92dB hiss will be quiet enough for you in-ear guys. And for higher impedances it looks like you'll be in permanent "class A heaven".

So why is it you existing UL owners don't have this? I imagine some of you are going to be quite angry with me? I guess being customer led is a bit of a double edged sword?

Any questions?

DrHouse wrote: Thinking back, if the Solo UL had a slightly more expansive soundstage, this would be a 'be all end all' amp... all in the pursuit of perfection i guess Is Graham currently working on any new products/improvements?

alanbass1 wrote: My question is that I have just purchased my Solo UL and, through my Grado RS1's, I do not hear/notice any hiss (at least at the volumes I listen with).  How would the sound differ between the two, or is it going to be so negligeable that is it just a case of whether you get hiss which becomes obtrusive then consider the revised model?

Let me answer in a roundabout way.

Miguel wrote " I find the UL to be one of the widest (but not artificial) soundstage amps I have listened for under $1,000 USD."

The Solo Ultra-Linear is around $1,000 USD shipping and customs duties factored in. Do we see a problem here?

There are thousands of headphone amps on the market - the market is so diluted for each manufacturer that people like me stopped doing it for the money years ago - you simply make nothing out of this job anymore unless you're Chinese or Vietnamese or from any one of many similar countries where labour is so cheap. We simply do it to make a living (just). Any design more than a year old and the world loses interest - no matter how good it is - that's human nature, always on a hiding to nothing.

Therefore, if you wish to retain a living out of what you do, you have to better the best. If you don't better the best and SHOUT about it you lose - you're out.

So that's what we have to do, and then run the gauntlet of customers who just bought. But tell me, which other way do we do it?

We've tried to soften the blow by offering upgrades, but even then we are criticised.

The noise has come down 14dB is all I'm saying right now.

Graham,

Edited by alanbass1 - 12 Feb 2012 at 9:35pm