Suitable SE power amp

[Jamesuk1]

Hi ,im thinking of a new project for this coming Autum.I have built a lovely pair of Chilli chang, back loaded horns/bvr's.I have fostex 168e sigma's as the drivers.They sound super but i think i can do even better than 75 watts off push pull 6ca7's.Im thinking of SET amplification.Im wondering if 8 or ten watts will be enough to drive these,i listen at realistic leavels in a smalish room.Does anyone know how sensitive my speakers are .I know the drivers are 95 db.The audio note mono block kits look nice...Thanks ...James

[chrisb]

Originally posted by Jamesuk1
Hi ,im thinking of a new project for this coming Autum.I have built a lovely pair of Chilli chang, back loaded horns/bvr's.I have fostex 168e sigma's as the drivers.They sound super but i think i can do even better than 75 watts off push pull 6ca7's.Im thinking of SET amplification.Im wondering if 8 or ten watts will be enough to drive these,i listen at realistic leavels in a smalish room.Does anyone know how sensitive my speakers are .I know the drivers are 95 db.The audio note mono block kits look nice...Thanks ...James

It's no big secret that no matter how many interesting SS / class T / Digital etc or higher powered P/P tube amps we get an opportunity to play with , a lot of us fullrangers keep migrating back to some sort of SET amp with our favorite speaker.

"Realistic" listening levels? - it could be interesting trying to find a consensus on what those "should" be

But let me take a gamble and suggest that with the speaker you describe, the actual in-room sensitivity rating is sufficient that a "decent 5 watt (or more) amp" would be adequate for most music lovers - a number that's certainly attainable with any number of SET designs.

As simple as their basic circuitry may be, not all SET amps have the same signature or degree of synergy with your type of speaker.

In my collection of SET and P/P tube amps, my personal favorites are the George Wright Mono7 300B (rated at 7.5wpc), Bottlehead Paramour II (2A3 version) and a DIY EL84 P/P loosely based on the topology of the Eli Duttman / Jim McShane "El Cheapo" design.

One that is not in my personal collection, but that I do get a frequent opportunity to hear is the Alex Kitic design RH84. This particular DIY pair was built from vintage reclaimed parts, and due to the questionable quality of the OPT (in terms of adequate inductance for decent bass response), was configured as parafeed, and a triode connected EF86 input/driver. If you can salvage / find enough of the right parts from your junk box, these can be assembled for only a couple of hundred bucks.

During the past 4yrs or so, these have consistently raised eyebrows and cracked some smiles at DaveD's get togethers.



My speaker projects during the past couple of years being virtually exclusively based on Fostex full-range series drivers. Depending on the driver's sensitivity, I've found certain combinations of the above amps more synergistic than others, even though the highest power rating of any of them is less than 10wpc, and certainly the SPL attainable might not be "realistic" enough for some folks.

For example even though my Jolida 302 EL34 has at least 5x the power (and is not my first choice), the EL84 P/P is far more musically satisfying with the Fostex F120A - indeed even more so than the 300B . OTOH, with the FE167 or FE127, I'll trade the far more spacious soundstage and low level detail /texture of the 300B for the tighter bass control of the P/P.


as always YMMV

[Lsharptec1]

James & Chris,

I recently ordered an 8 WPC SRPP SE EL34 amplifier from Tec On in LA.

I plan to design and construct a pair of OB 3 ways with 95 db drivers.

My guess is that this will make for a very SWEET system.

Larry

[Scottmoose]

Originally posted by Jamesuk1
Does anyone know how sensitive my speakers are .I know the drivers are 94.5 db.

Well, placing the drivers in this cabinet doesn't magically change their overall sensitivity. It just increases gain in the LF region. So they're still 94.5db 1w/1m