Yamaha AX-700 integrated amp in the house

Picked up a Yamaha AX-700 amplifier from a local Goodwill over the weekend. I need another piece of gear like a hole in the head but this Yamaha looked clean, well-built and heavy enough so I decided to give her a try.

This is an amp from 1990 or so, with the black face and body. It does look like BPC; the faceplate is indeed plastic but this plastic is very sturdy and solid so it feels like metal. The sign on the faceplate says “Absolute linear amplification... High dynamic power... Low impedance drive capability”. There is a row of input selector knobs in the middle and another row of knobs underneath with the oversized volume knob at the right. A closer look revealed a MM/MC switch for the phono stage, mono/stereo switch, subsonic filter, tone control bypass, muting and “CD DIRECT” buttons. Perhaps, it’s not really a BPC…

I opened her for a Deoxit bath. There is a metal plate beneath the faceplate; the top cover, sides and bottom are metal too. The speaker switches, the MM/MC switch and the “rec out” switch are located at the back and connect with buttons at the front with long plastic rods. The interior is not cluttered and the heatsink looks big. The transformer doesn’t seem that big for the listed 100 WPC at 8 ohms, but the filtering caps are ELNA audio 18000 microF x 2. I also noticed a pair of Nichicon MUSE caps (green) and … a few Black Gates. A pair of them is in the low voltage regulator, and another two are in the pre or power amp (see pictures). Other caps are mostly ELNA. Not that bad for a BPC-looking amp.

I will report on a sound of this Yamaha later on.

Ya know there is a dedicated Yamaha forum now..

Are you sure it's plastic?

I have an ax-500 that's nearly the same but without the muting button
and only rated at 85wpc, but the faceplate is aluminum.

I thought it's metal until I removed the front panel. It's made from plastic, but quite thick ( 3 mm or so) and sturdy. This plastic looks like metal and feels like metal from the outside.

war2thegrave said:

Are you sure it's plastic?

I have an ax-500 that's nearly the same but without the muting button
and only rated at 85wpc, but the faceplate is aluminum.

Click to expand...

Here is the review, as promised:

I’ve used this Yamaha amp for almost two weeks and I’d say I both like and dislike it.

The amp was connected to my main system instead of the Nakamichi and had no problem driving Vandersteens. The sound is very energetic and dynamic, not laid-back or lush. If the volume is cranked up to 12 o’clock or so with CD as a source, I have a feeling that the amp is just physically throwing sound on me. The highs are well-pronounced and clear but not as crisp or crystal-clear as that of the MOSFET gear. The midrange seems balanced EXCEPT the lower part of it, which IMHO is grossly elevated. In some compositions, kick-drums are just getting right to the bones. None of my previous gear did that. The lower frequencies such as contrabass and big drums (that what I consider “bass”) are well presented; however, they don’t sound as rich and pleasant as in the Nak TA-4A or, say, recently recapped Sansui 5000A.

One area where this amp really excels is imaging or “2-D presentation”. Each instrument is extremely well separated from another; for example, is possible to distinguish the vertical and horizontal position of each drum in the drum set. In one of my favorite CDs, ABBA “The Visitors”, I can clearly hear that one of the girls is to the left of the center and another slightly to the right. I think that the imaging of this Yamaha is as good as that of MOSFET gear and excellent overall.

The Yamaha sounds best with CD as a source; using of the “CD direct” button that bypasses some of the internal amp circuits changes sound but I couldn’t decide for better or for worse. The phono stage is OK but not the greatest one; I think that extreme highs and lows are a bit rolled down at the expense of mids. Using of the “variable loudness” button fixed the problem. I didn’t try it with the LOMC cartridge since lack of one.

So, the verdict is- if you like energetic, forward sound with a powerful lower midrange OR if superb imaging is a must, this amp is for you. It might also be for you if your speakers are not very good in bass and lower midrange. However, if one prefers warm, “velvet”, “tube-like” sound – look elsewhere.

Since I personally prefer warm sound, I took this Yammie off duty. Interestingly, last year I’ve had a Yamaha CR-640 receiver that I recapped and I remember it sounded WAY much warmer than the AX-700. Could it be that Yamaha gear changed their sound characteristics in the end of 1980’s?