Electro-Voice Sentry III with the 15" 3-way horns (Amplifier Kit)

[JWW]

If I am not allowed to ask questions like this please here please let me know and I will proceed no further. I have quite a bit of vintage stereo equipment at the moment that "others" have restored but I would like to personally build a tube amplifier KIT myself, maybe a pre-amp as well to better understand the inner workings.  I would like to keep the cost around a $1000 or so for the amplifier, probably something around 25 quality watts. Unfortunately I am not electronics savvy and therefore not sure if it wise that I tackle something like this from a safety perspective? I am quite capable of reading and drawing blue prints (working drawings), P&ID's but have not dealt with electronic type diagrams.  I have a strong background in welding, brazing, machining, fabrication and CAD and am mechanically inclined. I also am more than willing to learn even though I am an old fart.  I am in no hurry, very detail oriented and slow because of that fact. My primary speakers that I will be using IF I am capable are a pair of old Electro-Voice Sentry III with the 15" 3-way horns. Since I am concerned from a safety perspective and being a neophyte at best, is there a low voltage low power amplifier kit available that would drive these speakers effectively?

Regards,
-JWW

[Doc B.]

Sure, our Quicksand amp and Quickie preamp would fill the bill for a low voltage amp and preamp kit. But with your background you would probably do fine with our higher voltage tube based kits too. 25W is probably more power than you need. Our amps are lower powered than that but would still work well.

[JWW]

Doc,

IF I don't go the low voltage route, what would you suggest for a tube amp kit?  Currently, tube wise, I am powering the EV's with either a pair of rebuilt Heathkit monoblocks, Radio Craftsmen 500 monoblocks, or a Pilot 232 and a PAS 3 preamp.

-JWW

[Paul Joppa]

The speaker's efficiency is 97dB, which suggests a minimum of 3 watts to be "loud enough for most audiophiles most of the time". This is my rule of thumb, but based on several years of reading Stereophile's speaker reviews and their recommended minimum power. It is not enough to reproduce rock-concert levels of deafness (!) but adequate for large symphonic works in typical listening rooms.

The Stereomour at a nominal 3.5 watts would meet that requirement and fit within the budget. It has three inputs and a volume control, so no preamp is needed. Like most of our amps, this is a single-ended triode amp, a somewhat different animal from the push-pull amps you  mentioned. As you might guess, we think this technology sounds better. It's also a simpler circuit, which can be of value if you want to learn about tubes and amps using them.

[galyons]

The Sentry III's are very, very nice speakers.  They deserve high quality amplification!  They want TUBES!    The Stereomour would be a very good match to the Sentry III's.  I have Sentry IVA's , (same mid and tweeter horns, different bass bins, 102dB/1W/1/M), and have driven them with my Paramours, (older monoblock version of the Stereomour), using both 45's and 2A3's.  The 45's are half the output of 2A3's.  The combination was exceedingly great. (Although the 4dB lower output would make the 45's less a match)

You have quite a bit of flexibility with the Sentry III's, as they can easily be configured for biamping.  (Then you could use 45's for the mid/tweeter and drive the woofer with a more powerful tube, 2A3 or 300B, if you stay with directly heated triodes! Yes, please!)  The Stereomour would give you high quality sound and flexibility for future improvements.  The crossovers can be updated for an overall improvement.

Cheers,
Geary