2. amps-preamps
  3. 166357-136265

PP amp + High sensivity speakers dilemma

So here's the situation.
Recent experience with high sens (91 and 94) single driver speaker has  won me over from the low (87db) speaker design. 
Seems the SET is  the ideal match for high sensitivity ~~FR~~ driver.

I recently made upgrades to the Defy7 and am not willing to part with the amp and take a loss. At least not yet, until i recover from my $1800 loss upgrading the 87db speakers which are sitting in a  corner right now.
Was thinking just now, 
what if we swap out the 12 KT88's for a  dozen EL34's, 
The 34's come in at a  much lower watt output 25, vs the 88's 40 watts.
This  might allow a  bit more flexibility on using more gain on the linestage vol knob. 
Also what if we bias the EL34's a  bit lower than specs. This might also lower watt output thus giving a  tad more ability to use more gain on the linestage volume knob.
Right now i only use 9oclock vol on the DLP linestage, both with the Seas Thors 87 db and also with the 91 6.5 FR which I am using now, 
Tonight i will pick upa  pair of Sony cabinets off CL and install the 94db FR 8 inch.

Its definetly more sens vs the 91db, speaker, so maybe even at the low 9 oclock gain it may come a  bit too forward for my preference.
I listen to low/mid volume, as I use music more as a backdrop while reading. 
In some years after i recover from all the mods/tweaks i;'ve made in my system past year, i will purchase a  LM 845 amplifer.
I have intentions adding a  new high sens driver which will  be  rated 98db. 
Now here is where there may be issues with the 100 watt PP amplifier. 
Perhaps Richard Gray may install a  Italian 47 step attenuator which will provide more volume control on the Jadis DPL linestage. = Can use a  high vol gain.
My 88's have about 1500 hrs, so its getting close to buy new power tubes.
Bottom Q is
EL34/biased a  bit low + 97 db sens speaker,, maybe i can just squeeze by  with this lopsided matching,  for some years, til i can get cash for a  845 SET. 
Doable?
All ideas welcomed. 


mozartfan

Showing 1 response by larryi

larryi
4,225 posts
 
I would just use the amp as is, and just operate the volume control over  the lower end of its range; the only possible problem is poor left-right channel balance tracking over the lower range of the attenuator.  Otherwise, the idea given above, for using an in-line attenuator is also a simple fix (downside is adding another thing in the signal path).  

As to using lower output or lower gain tubes, I would only do this if I also liked the particular sound of the alternative tube.  I happen to prefer the sound of some lower output tubes than the KT88, but, that is a personal preference.  If your amp can accept alternative tubes, or your tech can modify the amp to accept such tubes, you could try the EL34's you mentioned or my preferred tubes which are KT66's or 6L6's.  

In my own system, I run a pushpull amp that has Western Electric 349 output tubes.  My amp runs four 349's and outputs 5.5 watts.  It is an amp that I actually prefer over my parallel SET amp (Audio Note Kageki) which outputs a little more power.  Both are excellent amps for high efficiency speakers and I do not necessarily think one type is better than another.  You might also consider output transformerless tube amps that can also deliver fantastic sound.
More to discover