Good Mac Amp for JBL 4435s?

I have these charge-coupled 4435s in a medium-sized room. They're rated at 96 dB and 400 WPC; 8 ohms; 30Hz - 16 KHz. On my Adcom GFA-5800 amp, at 250 WPC, they can get appallingly loud without setting off the clipping indicator lights.



I have always wanted another Mac amp (MC2300 and 2105 way back in my past) and for this job I have these subjective requirements:

• Blue meters;
• Autoformers;
• At least 200 watts per channel, preferably 250 or more;
• More modern, with lower distortion and high signal-to-noise ratio than some of the older ones; and
• Excellent condition, both cosmetically and operationally.

Level controls would also be nice. And my budget is around $2,000, give or take.

As a preamp, I may go with my custom DCB1 or just run the amp directly off my DAC, using my Squeezebox Touch as the primary level control. My DAC does have both XLR balanced and RCA outputs.

So I'm thinking maybe the MC7300 or MC7270 would fit the bill. (I kind prefer the units like the 7270 where the autoformers have their own separate casings, rather than some of the slightly later (?) ones like the 7300 with a big cover over everything.) I have also looked at the MA6000-series (with and without autoformers), although they're generally a bit more expensive and I'm not positive I want an integrated amp.

Any thoughts? I've been scanning CL, eBay, Audio Classics and McIntoshAudio.com. Thanks.

First, let me just say .... Sorry Julian, I thought you was a samsquanch ....

Those JBLs are awesome. One day I hope to find a pair. IMHO, you could use any number of McIntosh amps with excellent success. I've used a slew of different Mc amps with my Altecs over the last 20+ years. Here are my favorite SS Mc amps with them:

1. MC2600
2. MC500
3. MC2300x2
4. MC2300
5. MC7270

I used a pair or a single MC2300 on them for 15+ years and I really enjoyed those setups. The MC2600 and MC500 have far better S/N and that gives either of them a slight edge over the MC2300.

I think you'd really enjoy either of the amps you're proposing but don't rule out an MC500 or even the MC300. Another great option would be the MC7200.

What he said...+ MC 2205, MC 2255 - they're pretty efficient.

Gorgeous. :thmbsp:

MC-2105's, great Amp, I owned 2 for 40 years, bought new, and they never seen a shop. But, with my 4430's, and a larger room, and high volumes, they start running out of gas (power), start running them on the verge of clipping. If I were to buy another 2105 in this lifetime, I'd at least like having it reworked by Terry Dewick.

Don't think $2K with those gorgeous speakers, think $3K to $6K, stave off future obsolescence, have the power on tap when needed, good clean power, a more modern Amp, and if you wanna stick with Mac, here's my suggestions.

MC-352. OK, 352 WPC, but don't figure that, they probably put out 450wpc before clipping. Good headroom, more modern design, won't need re-furbing if you buy a mint, low hour example. Cost, about $3.2K on average for a minto piece. Probably closer to $4K from Audio Classics, but you have some assurance of a good dealer, a company who will stand behind what you buy. With thiers, it might likely have the LED Lamp upgrade installed.

Go beyond that, and save.... The MC-452, the MC-500, MC-302, there's many.
Want Tube richness, then the MC-275, or better yet, if you can sell one of your kids, the MC-2301's.

What am I running with my smaller 4430's? A brand new pair of Bryston 7BSST2 Monoblocks, at 600wpc each. Bench tests show 676wpc with ridiculous low distortion, at like .0019 THD. Sound fine at low levels, but when the volume goes up to appreciable sound levels, one knows where the money went! Tight, clean, not a bit of hiss, hum, zero. dead quiet and powerful, and dynamic.

FWIW I've tried my MC2300 feeding the LF section of my biamped L300's and while it sounded nice, my ugly-as-sin and cheap as dirt Crown Com-Tech 800 provided much tighter, faster and deeper bass than the beautiful Mac on the big 15" woofers. The crown paired with a tube amp on the HF section through a tube pre is heavenly.

Good tip! I have one of the Urei crossovers with the 4435 cards so may have to score me one of those crown amps... i was considering a Nelson Pass First Watt class A low wattage amp for the horns....?

Crestwood23 said:

FWIW I've tried my MC2300 feeding the LF section of my biamped L300's and while it sounded nice, my ugly-as-sin and cheap as dirt Crown Com-Tech 800 provided much tighter, faster and deeper bass than the beautiful Mac on the big 15" woofers. The crown paired with a tube amp on the HF section through a tube pre is heavenly.

Click to expand...

Headroom, As many say, one can never have too much.

The larger JBL studio monitors are at their best when bi-amplified. I have a DIY 4350 which are bi-amplified and I am using a pair of 2205’s for these, I have a dedicated music room and can play very loud, with about 20W from each amp the 4350’s become uncomfortably loud and I generally stay under that power.

I had my eyes on 4430’s and wanted to have a pair for a second system, finally found a clean pair here in Houston, but I was disappointed by the high frequency performance of that speaker, something was missing, it did not have that crisp highs that I had gotten used to with 4350, these speakers can really benefit from a tweeter.

Hope you enjoy the 4435’s.

Vahe

Crestwood23 said:

FWIW I've tried my MC2300 feeding the LF section of my biamped L300's and while it sounded nice, my ugly-as-sin and cheap as dirt Crown Com-Tech 800 provided much tighter, faster and deeper bass than the beautiful Mac on the big 15" woofers. The crown paired with a tube amp on the HF section through a tube pre is heavenly.

Click to expand...

Been to that show between my MC2300 and Crown MicroTech 2400 on the subs in my office system. This turned out to be an impedance mismatch between the Mc and the woofers and was remedied by using the next tap up. Once I did that, the two were indistinguishable.

Great stuff; thanks! Plenty of ideas to chew on. That MC352 really looks amazing to me; could be a lifetime keeper. Hmmm.

Vahe, the 4430s/4435s are pretty much flat to 16K and I can hear to only 14K, so I'm good there ... I've had speakers with much a higher range yet the 4435s' highs sound plenty good to me; YMMV.

I've run my 4430s with tubes up high and SS down low and I may do it again someday...

damacman said:

Been to that show between my MC2300 and Crown MicroTech 2400 on the subs in my office system. This turned out to be an impedance mismatch between the Mc and the woofers and was remedied by using the next tap up. Once I did that, the two were indistinguishable.

Click to expand...

Aha very interesting! By "up" do you mean going from 8 "up" to 4ohm taps? I probably should have experimented more but the 2300 is a BEAST and I am weak and lazy!

In my case, each of my subs are dual 4 Ohms with the coils paralleled netting 2 Ohms. Using the 2 Ohm taps on the MC2300 resulted in somewhat anemic performance. I used my trusty impedance meter (connected to one of the subs) to determine that the lowest impedance from 20 Hz to 80 Hz was actually over 4 Ohms. I swapped from the 2 Ohm UP to the 4 Ohm taps and wallah. If you don't have access to an impedance meter, you can simply experiment.

Zonker92 said:

Great stuff; thanks! Plenty of ideas to chew on. That MC352 really looks amazing to me; could be a lifetime keeper. Hmmm.

Vahe, the 4430s/4435s are pretty much flat to 16K and I can hear to only 14K, so I'm good there ... I've had speakers with much a higher range yet the 4435s' highs sound plenty good to me; YMMV.

I've run my 4430s with tubes up high and SS down low and I may do it again someday...

Click to expand...

It was highly recommended by Ryan at Audio Classics to pair my 4430's with the MC-352. He said he personally has two of them. I almost bought one about 3 months ago, from a seller about 50 miles away from me, but the deal fell through though. Idiotic seller thought I was going to back out if I saw a smudge on the glass, or fingerprint, how crazy that was and refused to deal.

Was supposedly mint, a low hour NOS model that was bought 4-5 years back from Audio Classics. It didn't have the LED Light upgrade though, and the asking price was $3200.

If I recall, I once read a review in some mag, when the MC-352 first came out. It had gotten a glowing review, and the reviewer said he thought the MC-352 was a better sounding Amp than the Krell FPB-300.

While I never heard the 352, I have heard the Krell I mention, and to me, the Krell was an absolute killer Amplifier.

Ivan Messer (Master Lu) over at Audio Afficionado is/was having runs of gorgeous first rate custom made rack handles that will fit the MC-352. To get an idea what they look like, just take a look at the MC-452, his handles looks exactly the same, and are of the same high quality. They are user installable, but they are not cheap!

There is also a third party cabinet maker on the web who custom makes Wood Cabinets that will fit the MC-352. Many choices of woods, some exotic, and I've seen pics, they are gorgeous too.
http://mcintoshcabinets.com/

Great stuff; thanks, Mark!

I am definitely interested in the MC-352 at this point, but since it's out of my price range, I may wait a bit and squirrel away some shekels before shopping for one. Those handles definitely caught my eye, and I am already thinking of ideas to make a custom case.

I'm a very strong believer, of "what is one of the best things to pair a McIntosh Amp with?" (Besides JBL Speakers) That's a McIntosh Preamp.

I love the fact, that my MX-130 Pre-Tuner at least has a pair of Tone Controls, and a Variable Loudness Compensator Dial.
I know such today seems to be sacrilege, but I don't think I'd ever want a pre, no matter how good without some form of tone controls.

I've one day thought of making some upgrade in this area, a C-46, or C-48-C-50, and something like a Day-Sequerra Tuner, or some other nice Tuner offering, a Magnum Dynalab tube tuner, or? Some of those vintage Revox Tuners were sure pretty, and I probably wouldn't turn down a mint Sansui TU-X1.

Any thoughts on the newer integrated amps like the MA6900? The idea of an all-in-one unit is starting to grow on me. ...

the 400 watt rating is the peak rating as I remember. Therefore, you want an amp where the Power Guard turns on around 300 watts if you are full throttle constant listener or at 400 watts if you listen to music with a wide range of dynamics that would reach max power infrequently. That said JBL is usually pretty stout stuff. I would stay away from 2300's because if you push them to hard you have no protection for your very expensive drivers. for a 300 watt amp I wold choose a MC300, 7300, MC 302, because with Mcintosh dynamic rating around 1.8 to 2 db that would give you peaks of 450 watts. A 352 would push close to 525 watts which is out side the envelope. Now if you are cautious listener and never allowed the Power Guard lights to flash you'd be fine. You could even use MC 501's if you're careful.

How about a MA 8000. 300 watts with 450 watt peak rating, but then a 6900 only puts out 1.8 db less power, and thats very small amount of difference. So a 6900 sounds like an almost perfect choice.

Cool; thanks, twiiii; I've really enjoyed and learned from your many Mac-related and other posts. I appreciate it. The MA6900 looks really nice.

OK, it looks like the 4435s are rated at 375 watts "continuous," per their footnoted definition of that term (40 Hz - 5KHz pink noise with a 6 dB "peak-to-average ratio," which I'm not entirely clear on, but is probably analogous to RMS). It also says they can handle 2,000-watt peaks of less than 10ms duration.

http://www.jblpro.com/pub/obsolete/443035.pdf

(Scroll down to page 3 for the specs.)

Probably still good to keep it within the power range you suggest, twiiii.

Mcintosh peak duration is 40 milliseconds. 1 complete cycle of 40 milliseconds would be a complete 25 hz signal, the rise time of a 25hz signal would be 10 milliseconds. So that means you could put 2000 watts of 100 Hz complete cycle to your speakers. while the rest of the pink noise you be at 500 watts, 6 db lower, If the pink noise was constant but it is not. Most pink noise has 10 db peaks being produced at random intervals, but by feeding the signal to a processor or controlling its generation the standard 6 db configuration can be maintained. So if you take a meter that read the RMS average with an average waiting it will read 500 watts, while the peaks with the meter set in the peak mode would read 2000 watts. Now if the meter had a perfect peak reading capability the meter might read higher,how much higher that depends on the original source. I've seen pink noise generators, that are on the nose at 6 or 10 db peaks and others that are not. What you need to understand the HF driver is attenuated to match the lower sensitivity of the woofers, but as the frequencies continue to get higher above the crossover frequency the heating of the coil increases so the speaker has to be derated above 5000 hz. Fortunately the amount of signal above 5000 naturally rolls off anyway with acoustic instruments. But if you like music with electronic instruments , you have to take care or you will fry the HF diaphragm. Back in the old days of analog, Ampex mastering decks VU meters lied about 18 db, and they added another 6 db to the electronics head room for safety. So music with a lot peaks when the VU meter read 0 the peaks might be 18 to 24 db above 0 if the tape didn't saturate. Today electronic meters and Macs accelerated meters only lie by a few db above 2 khz in Macs case, and by more or less as described by the other manufacturers. So while some of you guy feel you might need 2000 watts for the 4435, you have to remember the speaker begins to be come non linear and compress the signal above -10 db below peak level. 200 watts. So when you feed in 500 watts the speaker will have collapsed the dynamic range by 3.4 to 3.7 db. Not much louder than the level at 250 watts where the compression is less than 1 db. So 200 watts equals 119 db at one meter or appox 112 db at your listening position. That easily exceeds concert level of 104 db with a greater than 6 db margin. There fore making a true to life like music reproducer with ideal characteristics of low distortion and controlled directivity to be classified as being a capable studio Monitor speaker. Bi- amping would improve the bass performance, but care full calibration , and flexibility would be required of the electronic crossover processor to correctly match the HF driver to the horn to the woofers .