Why amps, pre-amps, integrated amps???

Interviews with audio electronics designers often turn to the importance of power supplies. I've seen this in interviews with James Bongiorno concerning the Ampzilla in the '70s, Paul Gower of PS Audio, and several others.

Transformers vibrate and when you add several to the same chassis you are raising the noise floor or you are compromising performance by requiring amp, pre, phono, and tuner to share the same power supply. If you mount and isolate separate power supplies for each component you have a large unwieldy single component where all power supplies are still sharing a single AC source through a single cord.

I started with a receiver. I graduated to separate tuner, preamp (with phono) and amp. I tried to go back to a receiver (Outlaw RR2150) to my extreme disappointment, went to an integrated with outboard tuner and compact phono, and now have separate tuner, phono, line stage, and power amp, all in full-sized 17"w chassis. The power supplies in the phono and line stages are bigger than what you'd get in a wall wart or PS section mounted in a standard-sized integrated.

It's not for panache or status. I'm interested in one thing: the music coming out of the speakers and how much it emotionally involves me. In that arena, so far in my experience separates win. I'm confident that there are integrateds that could beat my humble stack of separates (e.g., Pass, Krell, AR), but at a price I couldn't afford.

12-07-11: Orpheus10
"Hi end" audio is all about diminishing returns. All separate and mono blocks yield the ultimate audio when this is what your ears require, and you listen to music enough to justify the expense.

It's not necessarily more expensive. The maturity of high end audio plus the rise of Chinese-sourced new components change the high end price/performance ratio.

Consider: My combination of Jolida phono and line stage pre's plus vintage tuner and 180wpc power amp cost me a total of $1007. You will *not* find a new receiver or integrated amp at that price that can touch the power, clarity, and musicality of this stack.

Even going new, you can get an Emotiva USP-1 pre (with phono stage) plus 125 wpc UPA-1 power amp for $658. You'd be hard-pressed to find a new integrated--let alone a receiver--that could approach its performance at that price. Entry-level separates are no longer the big jump in price compared to integrateds and receivers worth listening to. The only disadvantages are rack space requirements and the cost of interconnects.

12-08-11: Orpheus10
I like vintage tuners. In regard to the 180wpc power amp as compared to the very same amp as monoblocks, from a price performance point of view the 180wpc would be the winner; but there's nothing like the 3D soundstage of monoblocks, this is a result of the channel separation. While this is over the top, if you ever get used to monoblocks, you're hooked.

Well, it's interesting to note that the Heathkit's big brother, the AA-1800 (rated 250 wpc but more like 350) is a full dual mono design with two power cords. Single chassis, but true dual mono.

If I had the rack space, I'd love to get a second AA-1600 and bi-amp. Then I'd have a separate amp for each speaker.

12-09-11: Orpheus10
If you're into "kits", you can also get deep into the "high end" by substituting parts. For example you could substitute better capacitors, of the same value of course; and other parts as well. This would give you a true "high end" amp.

Actually, I'm not a modder or a kitter. My amp is a Heathkit because that's the name of the company and they made very high quality kits. But I bought mine used, which means it was already assembled. I agree about how--if you're handy with a soldering iron--you can upgrade the parts in a signal path to great effect. I've never done any modding except for some tube-rolling.

I have a Jolida JD-9A phono stage and there are slews of mods out there including capacitor upgrades, but I never learned solder well. However, there's a lot of buzz about replacing the factory socketed op amps (about $1.19 ea) with $18-22 ones made to greater speed and lower noise specs. I'll probably get a chip puller and pop in the upgrade replacements.

12-10-11: Hifihvn
I'm not 100% sure, but I think the "Heathkit" amps from that time frame may have been made by Harman Kardon.

Not Harman-Kardon, but Zenith, who acquired Heathkit in 1979, two years before the AA-1600 amp was produced.

12-10-11: Orpheus10
There is no better way to buy, than buying good designs that have withstood the tests of time, and that is the reason the price is going up on the best used equipment.

The Heathkit AA-1600 is the best vintage amp I had never heard of. Its big brother, the AA-1800, is better known and often fetches $500-600 on eBay. It's a full dual-mono monster rated at 250wpc but actually built to put out 350 wpc.

12-11-11: Hifihvn
Johnnyb53, who do you think made the amp.

Heathkit itself probably made the amp parts. It was sold in kit form only, so ultimate the purchaser assembled it. Heathkit had been around since 1912, and had started offering electronics kits in 1947, so by the time Zenith bought Heathkit in 1979 heath had a well-evolved design and manufacturing facilities. In fact, Zenith bought Heath to get a leg up on home computer technology as Heathkit had a thriving personal computer product line.

The AA-1600 was one of the first amps to take transient intermodulation distortion (TIM) into account. This type of distortion was so new to amp design that Heath's specs for TIM qualified the numbers as "after Leinomen, Otala, and Curl." This may have something to do with why it is such a departure in sound quality from the "classic" amps of the '70s and an intro the much better sounding amps of the '80s.

12-12-11: Atmasphere
The 'TIM' amps of the late 70s and early 80s proved to be a dead end. What they proved was that you can go overboard chasing specs to the detriment of the final product.

There was a THD (total harmonic distortion) spec war starting in 1976 and continuing into the '80s, but I never heard of a TIM war. Effective Jan. 1, 1976, the FTC set a federal standard in amplifier measurement to put an end to the confusing power ratings claimed by using different measurement standards. There was RMS, EIA peak power, and there was IPP (instantaneous peak power), and often a bandwidth and variation tolerance was not specified. The FTC rules starting in 1976 started requiring a 1-hour warm-up at a steady 1/3 of maximum power, followed by power testing. The resulting power specs had to be for continuous RMS power over a specified bandwidth (e.g., 20-20KHz) into a specified resistance (e.g., 8 ohms), a frequency fluctuation tolerance (e.g., +0, -2 dB), and a THD distortion rating (e.g., 0.5%).

This prompted a THD war among lower quality amps. It was easy enough to lower the THD measurement by adding more negative feedback to the amp circuit. Although it made the amp measure better per FTC requirements, it altered the slew rate and limited the amp's ability to perform wide voltage swings. Also, the FTC rule only required testing into a resistor of a specific value. This resulted in some bad-sounding amps that had excessive negative feedback and low current designs optimized to measure well into a resistive load (an 8-ohm resistor) rather than into a reactive load (a loudspeaker). It got to where some receiver designers stopped listening to their products altogether and shipped their designs as soon as they met the bench test spec--which may have been set by marketing. The result was a generation of mid-fi electronics that sounded sterile, flat, harsh, and uninvolving, like all those bogus department store rack systems of the '80s.

If anything, TIM was first described by Finnish electronics engineer, consultant, and professor Matti Otala as an unpleasantly audible byproduct of too much negative feedback, a dissonance that went undetected by the steady state measuring methods of the '70s.

Designing to reduce TIM helps make an amp sound better and is still an important parameter in high end amp design today. See this recent review of a $12.5K pair of Electrocompaniet monoblocks. Also see this recent interview with Tim de Paravicini, particularly page 3, where Tim discusses the challenges and effects of TIM in amplifiers, particularly solid state ones where the negative feedback loops slow down the slew rate and allow transient overload.

12-13-11: Atmasphere
Yes, excessive loop feedback has been a problem in the past! I concur with the THD wars, but amps built for low TIM back in the early 80s or thereabouts definitely got a bad reputation.

Well, audio is certainly a balancing act and if you pursue one spec at the expense of others the overall sound will suffer. Still, taking TIM into account (a balanced approach) probably had a lot to do with why there were more good-sounding SS amps from the '80s than from the '70s.

Another guy who was very hip to this early on was Bob Carver. It probably helps that he's a physicist and not an electrical engineer. He had few preconceived notions and had his own way of tracking down and solving problems. I was just re-reading Absolute Sound's article about 10 most influential amps, and in its writeup of the Phase Linear 700, it mentions that Carver had noticed that tube amps were capable of far wider voltage swings than typical SS amps, so he designed the Phase 700 to make bigger swings like the tube amps. Excessive negative feedback narrows these voltage swings. That may be why Carver never joined the THD wars; his Phase Linear and Carver amps typically claimed .5% THD while his competition was trying to get below .1%.