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
Just pad down your pre-amp interconnects with an coaxial attenuator. 
Just pad down your pre-amp interconnects with an coaxial attenuator.

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I'll let Ricahrd know of this possibility, Just got word froma  Vox dealer, says his audio showrooms does employ some PP amplification on the Vox derivers with no issues. 
Right now i am running a  94 db 8 wide band, and can hear how a 845 tube has less interference  vs my 12 tube PP amplifer.
The better PP Jadis amp for the job would have been a  JA30 monos with only a  pair of 88's on each block. 

Here is where the EL34 will come in nice. I am almost sure the 12 EL34's will work superior to these KT88's ina high sens speaker.
+ I can get 12 EL34's EH's for like under $300. = beats the $500 for the KT88 price. 
Ok for that Italian made 46 step attenuator, allowing more flexibility for vol gain control.

I think this is the lab Richard Recommends
Acoustic Dimension, made in Italy


http://www.acoustic-dimension.com/

So adding the EL34's, possibly toning down the wattage output 
New 41 step attenuator = possibly giving the DPL linestage a  better control on gain.
Trying to work in the massive Defy's power to the high sens single driver. 
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.
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.

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I'll run these possibilities over with Richard when he opens his shop up either sunday or monday.
I'm thinking the EL34 or your suggestion KT88/6L6 might also be  a  better choice

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Look larryi, now i know you've been with me  these past few days, on the low ssns vs high sens, debate.
I have to be honest here and now....
I just got ina pair of 8 94db FR.
And....
Dang it, I might just go back to,,,the Thors,,,ahhh yeah I know i iknow, look how many insults i've been throwing at  xover old traditional designs.

And now after 4 days of mud slinging at xovers,, its possible I might go back to ,,,Thors MTM. 
While listening to the FR ~~SINGLE~~~ driver,, seems, man I  know others here are going to chime in  ~~I TOLD YOU Single was not be all end all speaker~~~~, Yeah I can hear now what they were getting at. Seems the Thors id have a  superior = wider = deeper soundstage. 
Oh man, how did I go from one exteme to the other,.,,,look, this 8 FR and the 6.5 Diatone, although super more sensitive, perahps,,lacks the wider/deeper soundstage, live feeling. 
...
man I can't go back and edit all my slamings on the xover Thors thing. 

I have to take back all my insults  and humbly admit,, I might have been wrong.

I'm thinking we might have possibilites here, as Richard has been on me to get rid of Jadis' cheap vol control and get the AD 41 step attenuator for afr superior sonics. 
Plus adding EL34's may bring in a  braeth of fresh air to the  Defy;'s voicing.

I may hold off on the Vox FR 8's. For right now, while i reassess all my tweaks  like  the attenuator. 
You know I might add a  compression horn tweet for the high fq's as the Millenium lacks that sparkles in the upper registers. 
The DUAL 6.5's Excel just allow a  superior , wider,deeper soundstage vs a  SINGLE driver.

I realize now this is what the xover gang has been attempting to get me to understand, That each design has its drawbacks/weaknesses. 

With a  superior high tech attenuator the DPL  will gain in fidelity performance thus allowing the Defy to benifit and now the Thors can get the power they need to to respond properly, 
Apologies to Seas and all xover designs, Scanspeak, and Troel's Gravensen for my  churlish  comments. 
Back to the Thors. But with a  added compression tweeter. 

Stop overthinking things. This is about simplicity.  Buy a small el84 based amp and sit back for a couple of months.
mozartfan OP

Great amp, this is what Stereophile said about the DF7, you don’t need any preamp that has even more gain with it.

The high input sensitivity is ideal for passive preamp control, while the input impedance is >100k ohms. Input sensitivity: only 950mV in for maximum output.


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.

And no gain will remain the same


Cheers George