[runeight]

This is happening for two reasons. Minivan's rails are about 320V and the tubes are heating the heatsinks.

I'd like to recommend to all hybrid builders that, if you are going to use the 3x100V zener string in the PS then sub [Edit]KSC5027 for Q13/Q14 on the amp boards. They are higher wattage devices and will withstand the temperature better. I don't know for sure, but I don't think your SQ will be affected.

 

[runeight]

Gents, here is the beta 2 list. I'll wait another day for more sand orders. If we get 10 of each then we'll go with the double order.

If not, and if the fab says they can split the panel, I will get 10 hybrid boards. cetoole has first dibs on the last hybrid. If he says no, then currawong gets the last hybrid.

The rest will have to wait. Sorry. No doubling up on this round.

 

[Beefy]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif I'd like to recommend to all hybrid builders that, if you are going to use the 3x100V zener string in the PS then sub KSC5042 for Q13/Q14 on the amp boards.

Q13/14 are KSC5042 anyway......?

 

[runeight]

Sorry. I meant KSC5027. Long night and too early. I'm going to edit the post.

 

[runeight]

The other condition that minivan has is high heater voltage. So what we've got on these transistors is:

1. Heatinks in close proximity to the tubes
2. Tubes running hotter than normal
3. Transistors buring more power from 20V more rail

Just enough to make the heatsinks hotter than we would like them to be.

 

[wiatrob]

Quote:

Originally Posted by minivan /img/forum/go_quote.gif ...someone mentioned the o2 clipping on the prototype version, i can't hear it on my beta version. the o2 became so loud before i turn the volume to max,but i can't hear clipping on bass neither on treble...

This is the same experience I had, I can get the amp to clip easily. I just have to sit across the room with the cans off to listen for it...

 

[luvdunhill]

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif This is the same experience I had, I can get the amp to clip easily. I just have to sit across the room with the cans off to listen for it...

wiatrob/minivan: what is your source output?

 

[bidoux]

Come on, where are all the solid states snobs ?

 

[Emooze]

I love solid state. Just a fascinating technology.

My lovely amp is currently at my apartment because i couldn't figure out a way to transport it home safely.

 

[Beefy]

Quote:

Originally Posted by bidoux /img/forum/go_quote.gif Come on, where are all the solid states snobs ?

Everybody loves teh toobs!

For me, the lower height requirements, lower heat output, easier wiring etc. etc. more than makes up for any questionable/marginal differences in sound quality.

 

[wiatrob]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif wiatrob/minivan: what is your source output?

Here's the list I've tested with:


PS audio dac, unmoded (balanced) (too hot output = clipping)
PS audio dac, Cullen mods(balanced) (not too hot output = no clipping)

Opus Dac (balanced)
Cambridge Dacmagic (balanced)(SE)

Marantz CD 5001 (SE)
Denon DCD-330 (Balanced)

I believe Tyler has used his Peachtree nova DAC single ended with the proto as well - don't know if he experienced that clipping.

Too hot a voltage output from your source WILL drive the amp to clip sooner. This is a peculiarty of the source, and not the amp, IMO.

I haven't repeated the test with the unmodded PS audio dac - Larry will have to comment when he gets his hybrid next weekend... But there was like 6V across the balanced output, have to look back at my notes from RMAF.

 

[wiatrob]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif Everybody loves teh toobs! For me, the lower height requirements, lower heat output, easier wiring etc. etc. more than makes up for any questionable/marginal differences in sound quality.

Agreed. The amps have a very similar character. I'm keeping my Sand version cause it's cooler, even though "i LOVE tubes..."

 

[luvdunhill]

Quote:

Originally Posted by wiatrob /img/forum/go_quote.gif I haven't repeated the test with the unmodded PS audio dac - Larry will have to comment when he gets his hybrid next weekend... But there was like 6V across the balanced output, have to look back at my notes from RMAF.

interesting. Have you ever listened to an amp while on an oscilliscope to see what various types of clipping sound like? For example, a single-ended output stage, versus a push pull? Some people say they cannot hear clipping at all, but once you see it and correlate this versus what you're hearing, I think it becomes easier.

I'd like to see some measurements of this amp, but that seems to be so far down on people's list for some strange reason, that I'll have to probably do it myself

 

[bidoux]

Quote:

Originally Posted by Beefy /img/forum/go_quote.gif For me, the lower height requirements, lower heat output, easier wiring etc. etc. more than makes up for any questionable/marginal differences in sound quality.

I agree with this too. Keep it simple is the rule !

 

[ChrisX]

Quote:

Originally Posted by runeight /img/forum/go_quote.gif So the order is full.

One day I didn't look into head-fi, now I'm already too late.

So count me in for the third run, if there will be one. In the meantime I will keep on reading all your listening impressions and building experiences.

Chris