DECWARE.....ZTPRE anyone have any expeiriance with one ?

Br3098 8-4-2018
I have heard the new ZTPre "V6" design, paired with decware 6Wpc monoblocks and **decware speakers** [emphasis added], and I can definitively say that it is not rolled off on the bottom end.

To add to my previous response, it appears that none of the speakers shown at the Decware website would provide deep bass extension that is remotely close to what is provided by the OP’s Focal Grande Utopias. According to specs indicated in Stereophile the Focals incorporate a 15 inch woofer and an 11 inch mid-bass/lower midrange driver, and weigh 397 pounds. Completely different animals than the Decware speakers, and speakers that would clearly be far more revealing of bottom octave rolloff.

Regards,
-- Al

viking62 asked..."Taking all of this into consideration (And this goes out to everyone) what are your recommendations for a tube pre for this setup."

Have you thought/looked into the Primaluna Dialogue Premium preamp? It is not as sexy looking as the Decware but it sure is a music making machine of the highest order with superb reviews. Also, built like a tank..to last a lifetime. And a tube rollers dream!!! I own one and can not speak more highly of it...it's that good!!! Lots of great info online with great internal snapshots to look at to see what your money is buying you compared to other manufacturers. Good luck with your search.  

1241...that PDP pre looks pretty nice and he is passionate about his product. Noticed the speakers in the background.

almarg
I see that the output tubes are coupled to the output connectors via capacitors having what to me is a very surprisingly low value of 0.1 uf

I just downloaded the latest I believe circuit.
And what Al has pointed out is quite bad, as if that preamp’s xlr output sees an input load of 20kohm the bass will be rolled of at -3db already at 80hz!!!! In other words you’ll have no low bass.

If it sees a Class-D amp which many have 10kohm input impedance, the bass will be -3db at 160hZ!!!! no upper bass either!!!

It’s rca output "could" be fine as they are isolated by the transformer coupling from outside amp impedance’s.

I suggest you don’t use the XLR output with any amp/s less than 100kohm input impedance.

Cheers George

Thanks, George. But actually it isn’t that bad. Note the presence of the 100K output level control. The cap will only "see" the input impedance of the power amp when the 100K output level control is at or near max. (Actually in that case it would see a heavier load than that input impedance since it would be paralleled with the 100K). And my suspicion is that under typical conditions the control would be set closer to the bottom of its range than to the top of its range.

So the resistance that forms a high pass filter in conjunction with the 0.1 uf would probably be comprised of the majority of the 100K, plus the parallel combination of the rest of the 100K and the input impedance of the amp. And if the control is used near the bottom of its range, that would amount to close to 100K overall.

Nevertheless, assuming the schematic reflects the present design, per some calculations I did prior to my earlier posts there would be upwards of 2 db of rolloff at 20 Hz even with no power amp connected and regardless of the setting of the control. Which already considerably exceeds the +/- 0.7 db tolerance of the 20 Hz to 20 kHz frequency response spec. There would also be phase shifts in the bottom octave that could very well be audibly significant. With the rolloff and the phase shifts especially likely to be problematical in a case like the OP’s, involving large speakers having excellent deep bass extension, and also for others who may be using subwoofers. (Compensating for the rolloff with the level control of a subwoofer would be a crude approximation at best, since both the amount of rolloff and the corresponding phase shift would vary as a function of frequency).

Best regards,
-- Al