Hello from Sweden

I have been around for some weeks on this board, and it seems to be a very good one. Lots of experienced audio guys, and sometimes the odd guy polluting the threads here and there, effectively killing every attempt for a good discussion. Still, this is a great place to read and learn from.

Now a few words about myself.

Bread and butter comes from working as EE in the automotive business. You learn a lot about EMC stuff and such. Automotive req´s reach far beyond EC-regulations.

In my DIY projects I pay much attention to the active devices - a transistor is easily 100 times more non-linear than a resistor or capacitor. PCB design and tailoring the distortion spectrum is also very important, but is seldom adressed in DIY gear.

My setup consists of a SAA7220/TDA1541A based CD-player with an improved digital section and a DIY analog Class A output stage. Then follows a DIY line stage set at full volume (15 Volts P-P) which feeds 6 meters of interconnect. The receiver end is a passive Creek IR-remote volume control modified for 1,2k input impedance. The output of the Creek feeds two DIY poweramps in a passive biamp configuration. The bass poweramp also feeds the speaker level signal to the sub (better coherence this way, you try it). Speakers are Unity Audio Signature One and Velodyne HGS-12.

I listen to everything from Classical to Club/Trance so I really need both silky mids/highs and rock solid killer bass. Tubes can´t give me both, and solid state is not giving me the best of tubes. So the DIY work goes on....

welcome, although not a SS person myself, i already started to look for new posts from you :)

... and sometimes the odd guy polluting the threads here and there, effectively killing every attempt for a good discussion. ...

(hoping you are not meaning me :) ) Quite bold to write this in an introduction, yet i fully agree. Observed this elsewhere, observed the results. As i wrote in other threads,no need to repeat it here.

So, you too are member of the "full swing/ lowZ GC at the output" club. Me too.
But it is on the paper, not yet built. Curious how it comes out. But i know from my buddies' systems that a 600R gain control and a linestage handling full swing all the time literally boils the conventional linestage (with 50k GC at the input) in oil sonically..
Provided the linestage has enough headroom. Air gets thin with an output transformer here. i wanted to forge nails with heads, settled on a pair of 12B4A and a Lundahl LL1660.

Rock-solid killer bass: heard it once with Allen Wright's tube amp which is a fully differential PP design. Provided the speaker is efficient, best bass i ever heard. So i use this topology for my DHT PP amp. Although the thing is not meant to reproduce much LF most of the time (open baffle subwoofer below 150Hz with a different amp, a SS amp), it must be able to do it for the case i use the amp fullrange with the popen baffle FR speaker. And i badly want good bass.

The bass poweramp also feeds the speaker level signal to the sub (better coherence this way, you try it).

Got lost. Can you elaborate?
Hello Bernard,

I am sorry if those few first lines appeared as being bold, that was certainly not my intention. If the moderator let me, I could edit the text. I was not thinking of insulting any individual when writing "the odd guy". I meant what often happens in discussion threads - a person deviates from the subject and suddenly something else is discussed (sometimes not even audio). The result is that the thread dies prematurely. I think that´s a pity because there is really a lot of knowledge out there. I felt it relevant to the introduction but I think you are right, it really doesn´t add anything valuable. Sorry once again.

"The bass poweramp also feeds the speaker level signal to the sub (better coherence this way, you try it)."

The English sub-woofer champions REL are advocating the concept of feeding speaker level signals to the sub, i.e. the output of the main speaker´s powerstage shall feed the sub, not the low-level output from the preamp. By doing this the sonic character of the main speaker´s bass is copied by the sub, giving better musical coherence in the bass range. I can confirm REL´s opinion. Since I use passive biamping, the bass poweramp quoted above is the one driving the main speaker´s woofer.
REL has a built-in voltage divider but Velodyne doesn´t. So I use an external -22 dB voltage divider, combined with a first order LP-filter (need steper roll-off than the HGS-12 has). 20k in series, then 1.8k in parallel with 5.6 uF shunted to ground. Works perfect.

On killer bass from tubes, I might post a question in the tubes forum. I am interested to hear more about this.

Kind regards


no need to apologize :) , i was not intending to say in roundabout that your statement was too bold. I was saying straight: you are right with your remark, if you intended to hint at a certain guy or not. No need to edit, IMO. Look at the other thread where i referred to your remark, you will see i badly meant what i said.

The forum still is wonderful but IMO it is not in the healthy condition it used to be when i entered it.

interesting concept. But will not work in my case; my poweramps have to act as speaker XO. I have managed to eliminate any coupling cap from my amps except the two speaker XO caps. But these are located withing the tube poweramp and are having >100V across them. Which should be the case with any cap in th signal path.
The subwoofer amp would not get any signal to amplify, considering that it has a built-in low pass. It is worse, it has one 25Hz/6db lowpass overlaid with anoother one of 120Hz/18dB as this is an open baffle subwoofer needing baffle EQ. However, i will be curious if Hugh Dean's AKSA 100W will match with my diff.PP AD1 amp sonically.