Dared SL2000a Preamp Block Distortion?

zingo

I was listening to music last night and the new Dared SL2000a tube preamp it had a fantastic sound stage and warm detail. However, when I was listening to an a cappella song that hit a big transient (they were stomping), the preamp would distort (almost sounded like clipping) during those points. I tried a pop song with similar transients and it did the same thing, but the distortion disappeared when I ran the source direct to the amp; and the sound quality decreased too.

My first thought was clipping or major microphonics? Since the Hafler amp had volume pots, I tried running it full with low volume on the pre, and low with full volume on the pre with the same results. The music was a bit loud but a reasonable volume that I use for dedicated listening.

I swapped the input tubes this morning, but also tried lowering the output on my source (iPhone which I was using last night as well) and the distortion went away. I found a discussion on "block distortion" online and it seems to be the issue I was hearing. I tried running my Squeezebox as the source and also didn't hear the problem, so I might have been overdriving the preamp, but I'll play around with it more as it doesn't seem like there is an issue with unit.

"Blocking occurs when the output tube grids are driven to the point of conduction. Since the previous stage is a relatively high impedance source, and, to make matters worse, is AC-coupled, it cannot maintain enough drive to the output tube grids to maintain the signal once the output tube goes into grid conduction."

Does anyone have experience with something similar?

Clipdat

zingo wrote: »

also tried lowering the output on my source (iPhone which I was using last night as well) and the distortion went away. I found a discussion on "block distortion" online and it seems to be the issue I was hearing. I tried running my Squeezebox as the source and also didn't hear the problem, so I might have been overdriving the preamp

Input signal was too hot for the preamp to handle at that particular musical transient.

heiney9

Really, an iPhone as an input? That's your issue right there. You can't run that kind of device and expect it to be high fidelity. It's not designed for that. That being in a hi-fi rig.

Even if you turn it down, you can't get serious sound from an iPhone. I know we all have different types of rigs for different purposes and the convenience is nice, but don't use a device like that if you expect great sound, IMHO, of course.

H9

heiney9

Clipdat wrote: »

zingo wrote: »

also tried lowering the output on my source (iPhone which I was using last night as well) and the distortion went away. I found a discussion on "block distortion" online and it seems to be the issue I was hearing. I tried running my Squeezebox as the source and also didn't hear the problem, so I might have been overdriving the preamp

Input signal was too hot for the preamp to handle at that particular musical transient.

More than likely the issue was the signal being too hot for the iPhone to process and probably overloading the output signal. I doubt it's the pre's fault. A device like an iPhone is not in any way shape or form designed to be a stellar hi-fi unit.

H9

Clipdat

heiney9 wrote: »

A device like an iPhone is not in any way shape or form designed to be a stellar hi-fi unit.

I agree, Brock. Unless you are somehow bypassing the internal DAC/3.5mm headphone output.

I guess the point of my post was that the issue lies with the source.

zingo

heiney9 wrote: »

Really, an iPhone as an input? That's your issue right there. You can't run that kind of device and expect it to be high fidelity. It's not designed for that. That being in a hi-fi rig.

Even if you turn it down, you can't get serious sound from an iPhone. I know we all have different types of rigs for different purposes and the convenience is nice, but don't use a device like that if you expect great sound, IMHO, of course.

H9

I was mostly using my Squeezebox Touch, but wanting to do some testing with tracks on my phone, but had never had that result on any tube equipment before.

Clipdat

Well at least you know there's nothing wrong with the preamp! I'm glad you were enjoying the "fantastic sound stage and warm detail"! Sounds like a real special unit!

mlistens03

Clipdat wrote: »

heiney9 wrote: »

A device like an iPhone is not in any way shape or form designed to be a stellar hi-fi unit.

I agree, Brock. Unless you are somehow bypassing the internal DAC/3.5mm headphone output.

I guess the point of my post was that the issue lies with the source.

You can bypass it with a DAC that has a USB input and the lightning cable, or you can buy Apple’s lightning to HDMI adapter. Both of these bypass the internal DAC. I’m sure there are more ways to do it as well.

zingo

I agree after some more testing that the issue is the iPhone as a source, but I'm most surprised because I've never had that issue before with tube or SS equipment.

halo

zingo wrote: »

I agree after some more testing that the issue is the iPhone as a source, but I'm most surprised because I've never had that issue before with tube or SS equipment.

I guess the Dared is a little more revealing? Maybe you should try it in your main rig?

zingo

I've tried a few different sources since this last post, and all of them sound great; AKA a phone is not a good source for many reasons.

I like my NAD integrated, and for fun disconnected the power section and connected this Dared and the preamp, and WOW! It bested the NAD preamp section in every way for musical playback. That's not to say a modern NAD integrated is a bad piece of equipment, but I'm frequently impressed by this simple preamp.

Faustin

The Dared SL2000 was my initial jump into the tube world. A lot of bang for the buck.

heiney9

zingo wrote: »

I've tried a few different sources since this last post, and all of them sound great; AKA a phone is not a good source for many reasons.

I like my NAD integrated, and for fun disconnected the power section and connected this Dared and the preamp, and WOW! It bested the NAD preamp section in every way for musical playback. That's not to say a modern NAD integrated is a bad piece of equipment, but I'm frequently impressed by this simple preamp.

When integrated properly into a system it's a real sleeper, even with mediocre tubes. Roll in some classic tubes and the tone, soundstage and timbre is most excellent.

H9

DaveHo

Krenf wrote: »

It's interesting

You forgot your spam link.

Viking64

DaveHo wrote: »

You forgot your spam link.

I wonder if Vikings like SPAM in link form?

zingo

I personally like my SPAM with eggs. Mmmmm...