Distortion at higher level [resolved]

[DrElektrik]

Hello,
i bought an assembled used Smash DHT yesterday. Very good sound, no hum, no buzz. But : When it comes to higher volumes, distortion becomes audible above half volume. I tried 3 Amps all between 10 + 20 k input impedance. I even lowered the Output of the source, the distortion stays the same ...

Any ideas where to start ?


Thanks,

Michael

[DrElektrik]

I received the Manual a few minutes ago, thanks. I will do the measurements the next days.
Is your Preamp totally clean with the volume full up ?

Thanks,
Michael

[Paul Birkeland]

How high are you going with the output?  The Smash can create a ton of output voltage, though it will begin to distort without the Smash-up.  This is either an issue with the limit of incoming voltage (created by the HLMP-6000 providing bias), or the plate load and bias point.  I can't quite remember which, but both are altered with the Smash-up to increase the headroom.

Having said that, you would need amplifiers of unusually low sensitivity to run into this issue; tell us more about your system and we might be able to help.

-PB

[DrElektrik]

Hello Paul,
good to hear that this issue is known, thanks for the reply.  Actually I´m using Quad ESL 63 speaker, driven by Abletec O300 Class D Amps , L15 D Class D Amps or 300 B Tubes ( Transformer Coupled Inputs ). I also tried an old PA Amp and a DNM Reson Amp. 
What makes me wonder : When i use other Preamps or even my SPL Volume 2 ( no gain at all) i can push the amps loud enoug without any audible distortion.
In cause oft he fact, that the Smash sounds sooooo wonderful  in my system, will go the upgrade way soon. 
I also think about the BeePree as an Option, but maybe it´s better to upgrade the smash first ….

Michael

[DrElektrik]

Between the Speakers.

But this is not the issue. When i turn down the volume of an amp, the distortion will be the same.

Michael

[DrElektrik]

I´m located in Germany. No off Voltages so far. The distortion starts around 1 o clock . I really do think that there isn´t enough power without the Smash upgrade, as Paul mentioned before.

Michael

[Doc B.]

Grainger,

PB is the designer of the circuit. He explained to Michael what is happening and I concur with PB's explanation 100%. It is a situation we have heard of once or twice before and reproduced in the lab. The Smashup upgrade is the solution in this case. There are times when we need some space to work with our customers and I would appreciate it if you would respect that.

[DrElektrik]

  .

I will order the Smash Upgrade soon. Although it will be a little bit expensive until it´s here in Germany. I have to pay 19% taxes on the Price incl. shipping. It will be around 200 USD instead of 129,00  ....   There is no way to buy it somewhere in Europe ?

Michael

[denti alligator]

   There is no way to buy it somewhere in Europe ?

You could find a friendly Bottlehead who travels to Europe to bring it for you... I visit Germany somewhat frequently, but unfortunately have no travel plans right now.

[DrElektrik]

Thanks for the idea - if that would be possible i would buy a BeePre  .

Michael

[DrElektrik]

Finally i ordered the Smash-up Upgrade. I will report when it´s finished.

Michael

[DrElektrik]

Hey Bottlehead Crew,
finally i listen to a fresch upgraded Smash.
All trouble is gone and i never thought that it would be such a big step forward !

Better definition, staging, transients, it sounds just "right" and very natural.  At the Moment i listen to My Quad ESL 63´s driven by a Crown XLS 1500 ( you should here it before you judge ;-) ) - tomorrow i will try it on a Uchida 300B.

WOW !

-> What Difference makes a BeePree ? I got some Cetron 300B´s lying around here .... 



Thanks,

Michael

[Paul Birkeland]

The BeePre is a more refined circuit and uses higher quality tubes.  The BeePre can accept more incoming voltage and deliver more outgoing voltage, is very quiet, and offers the flexibility of balanced inputs and outputs.