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I need help selecting a tube amp

OK Tube-heads. You win.

Can anyone recommend a suitable tube amp to drive some old JBL horns? (for 4435 Studio monitors, compression driver model 2425H). Nominal efficiency of 25% (500Hz to 2.5kHz)

With the advice from a friend I recently hooked up an old tube amp to my JBL studio monitor horns and was totally blown away. Those old large format studio monitors finally reached out and touched me. I felt like I was wrapped by a warm blanket after years of being in the cold. Norah Jones, Allison Krauss, Fleetwood Mac, Dire Straits and other vocal-and string oriented SACDS were amazing. I couldn't stop listening.

So into by the sound I've decided to begin educating myself about tubes with the hopes that in the end I'll be able to narrow my search, and ultimately purchase five amplifiers for my surround system (highs).

My system consists in part of five two-way JBL 4430-series studio monitors (vintage the 80's). I've been driving them with Crown's wonderful solid state Reference amps. I've always loved the lows, but the highs always seemed edgy and sterile - that is, until the other night when I tried tubes on them for the first time. What a wonderful surprise! I use active crossovers set at 1k for the bi-amping.

My head end is all Emm Labs: CDSD transport, DAC6e and 6-ch. pre.

My friend (who recommended I try the tube amp) says my horns are a good candidate for tube amplification due to the their efficiency. So I looked up the driver model 2425H online under JBLs vintage page and found that they are "25% nominal efficiency (500Hz to 2.5kHz)"

Help. What does this mean to someone who is looking for a suitable tube amp to drive them?

There are also sensitivity specs like: 117dB SPL, 1W @1m. The specs also say the recommended wattage is 100W. How do I make sense of these specs when choosing a tube amp, correct wattage or trying to get a good match? I need a starting point!

I look forward to being enlightened by all of you tube-masters interested based on your knowledge and experience, and who really know your stuff.

Signed truly tube-happy,

Dean
quantumavman
entrope
482 posts
 
Decware makes a nice product at a great price point for low power tubes. This makes them a good starting point.
the_kid's avatar
the_kid
465 posts
 
Welcome to the Darkside! You will never go back. Take your pick of amps as most anything should power your speakers. I would suggest giving Cary and VAC a serious look.

KiD
trappist
35 posts
 
Cary V12 will do the trick (CAD280). 50 WPC in Triode. Lovely sound. You can drive KT88s if you really want to, but that may be too tight for your speakers. Good luck.
quantumavman OP
20 posts
 
It's great to learn and get help from those in the know...

I sent most of you individual emails, but I've listed below the most detailed reply figuring you'd have more info to work with.

Here are some A's for your Q's. Please note I'm looking for tube amps for the HIGHS ONLY. I will bi-amp and keep the Crown Refs on the lows/15's. I'm also very picky about (self) noise – great suggestion as you mention.

Q: You've got five of the 4435's in one room?
A: Yes. Actually I have:

(2) 4435's for L/R (dual 15, 2-way)
(2) 4430's in the RL/RR (single 15, 2-way) and
(1) 4425 center (single 12, two-way
(2) 4645C 18" Subs
All JBL. I have a dedicated room painted all black and acoustically treated..w/a small 5k video projector in a hush box. Can you believe it? My wife's very cool about it! I consider myself very lucky. [laughs].

Q:Good Lord! Aren't two enough?
A: They were until I discovered hi-res surround music done right! HUGE soundstage. A ton of dynamics.

Q1: how big your room is.
A1: 20'W x 40'L x 9' Tall

Q2: what type of music you listen to(and/or movies)
A2: Everything. Mostly quality vocals, folky, older acoustic jazz, acoustic music. Movies: Not too into action. mostly drama, and good adventure/documentary stuff.

Q3: how loud you like to listen to things
A3: Not very loud, which is prob a surprise considering these monster speakers and amps. But not quiet either. middle range. Comfortable.

Q4: how much you'd like to spend
A4: under $1500 per monoblock, a grand per/(x5) would be perfect

Q5: what the rest of your system is made up of
A5: OK here I go:

EmmLabs CDSD SACD Transport (3 x fiber ST conn)
Modified Denon AV-3910 (w/custom 3xAES outputs for DVD-A)
EmmLabs DAC/6e 6-ch DAC
EmmLabs Switchman-3 6-ch preamp (4x1)
All balanced .5M interconnect (custom Monster M1000i)
Ashly XR1000 active crossovers
(3) CrownRef 1's (for L/R abd Sub)
(3) Crown Ref 2's (for LR/RR and center)

Side note. I have 5 active Genelec 10" two-way monitors on top of each JBL for a much more accurate sound. Combining and mixing both systems is magical actually. Sound weird, but works. Heaven is in the middle of this setup. I have set up the system to the SACD recommended standard for surround geometry. 30-deg in front, 20-deg off to the sides. Center is center and all other speakers are equidistant to the main listening position.

I hope this helps. Have you heard of / about Manley Labs Tube amps? Do you have any experience with them? Also, can you recommend a tube amp that's SUPER quiet? Also, I will place each amp at each speaker, so a monoblock config would be best.

Thanks in advance,

Dean
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