I have been learning how to use REW. I finally have some of it down. In the process, i realized some of my patch cords are crap! I sorted out the bad. I then re-tested my stereo, for practice. Finally, I re-opened my Aiwa AI7012, one more time. I ran a slew of tests: listed as follows, for anyone who'd like to know.
Note: I returned my first unit. I wanted to see if another unit would play tapes any better. In so doing, I ran across something unusual. My first Aiwa boombox came up as AI7012 when searching bluetooth. This new Aiwa unit comes up as LT-BT600RUC, which is a Leotec brand. I am aware Leotec markets this unit in other countries, under different brand names. But I am surprised this came up as-is.
Amp Section: Chip: CD7379CZ (seems to be a copy of the TDA7379)
I measured the amp's Power Bandwidth to be 70 Hz to 20 Khz within +/-1 dB. This is a strict high-fidelity rating parameter.
All following amp stats are: (2-channels driven into 4 ohms)
10.4 W + 10.4 W, 1 Khz, 10.8% THD.
10.4 W + 10.4 W, 70 Hz to 20 Khz, <12% THD.
10.4 W + 10.4 W, 20 Hz to 20 Khz, <14% THD.
While Aiwa states a peak power output claim of 40 watts, some of its European sister models claim a much more realistic 10 WRMS x 2. I imagine this refers to 10W per channel at 10% THD.
I believe the following should be considered this unit's actual rating: (refer to the first graph, below)
8 W + 8 W, 70 Hz to 20 Khz, <0.45% THD (<0.5% THD+N)
The top curve is the power bandwidth. It is quite flat above 100 Hz to 20 Khz. Below 100 Hz it begins a gentle roll-off, dropping off more sharply below 40 Hz. The amp's response is within +/-3 dB from 45 Hz to 20 Khz, which is pretty good.
The middle white line is the THD level. It too is pretty flat across the board, at this output.
The bottom curve is the noise floor level.
The amp chip's data sheet claims this chip can push 12+ watts into 4 ohms with a 12 volt power supply. I could not duplicate.
The data sheet also states THD as low as 0.02% THD with typical levels of 0.3%. I could not duplicate those very low THD stats.
I measured at very low output to see if specs improved:
0.6 W + 0.6 W, 70 Hz to 20 Khz, <0.2% THD (<0.3% THD+N)
I saw some dipping slightly below 0.1% THD in the mid-freq range, but nothing below about 0.08% THD)
Amp S/N Ratio:
My Yamaha receiver, RX-V377, claims a S/N of >110 dB from 22 Hz to 22 Khz. I measured 116 dB, so I believe my results somewhat accurate.
Aiwa S/N: >121 dB, from 22 Hz to 22 Khz.
Crosstalk:
My receiver claims 70 dB/50 dB @ 1 Khz/10 Khz, respectively. This is considered the standard of a high fidelity amp.
I only measured 48 dB/38 dB. The only spec where the Yamaha falls short of claimed.
Aiwa Crosstalk: 58 dB/40 dB.
Frequency Response: (Aux-in to front, Aux-shorted, 22 Hz to 22 Khz)
My receiver claims 10 Hz to 100 Khz, -3 dB. I can only measure accurately to 20 Khz. I measured 10 Hz to 20 Khz, -1.5 dB. So I believe this measurement is fairly accurate.
Aiwa Freq Resp: (Aux-in to front): 75 Hz to 20 Khz, +2 dB/-3 dB (20 Hz to 20 Khz, +2 dB/-11 dB)
Damping Factor: (Measured at 50 Hz, the standard for bass/subwoofer measurements)
My receiver claims >120, from 22 Hz to 22 Khz. I measured >121 @ 50 Hz. So, I think my measurement is fairly accurate.
Aiwa DF: 139
Note: 100 to 150 is considered excellent. Above 150 is generally considered to add negligible improvement.
Tone Controls:
I measured my receiver's tone controls. Yamaha claims up to +/-6 dB @ 50 Hz & 20 Khz. I measured exactly +6 dB for both.
Yamaha also claims turnover frequencies of 350 Hz for bass and 3.5 Khz for treble. I measured 1 Khz for both.
Aiwa: +/-12 dB @ 100 Hz, turnover at 1 Khz.
+/-12 dB @ 10 Khz, turnover at 1 Khz
CD Player Section:
I compared the Aiwa CD player to my old LG BP-540 Bluray DVD/CD player (about 10 yrs old). The LG measured 22 Hz to 20 Khz +/-2 dB
Aiwa FR: 22 Hz to 20 Khz, -6 dB (in deep bass end, see screenshot #2)
Cassette Deck Section: I used a new Maxell UR 90. I recorded a 20 Hz to 20 Khz sine sweep from the Aiwa's CD player onto the tape and then played back the tape.
Aiwa Cassette Deck FR: Approx 90 Hz to 8 Khz, +/- 3 dB (0verall FR: 60 Hz to 11 Khz, -10 dB) (Refer to screenshot #3)
Note: It is possible the Maxell tape is no longer a premium product. I don't know if Maxell is even around, or if this tape is just another brand name taken over by some foreign interest. So, the tape might skew the results.
However, I have owned many good quality tape decks and boomboxes back in the day. None of them sounded like this.
The background noise is extremely high.
Fidelity is not good.
Recording seems very low. I never liked ALC (automatic volume control) for tape deck recording. But, this is really piss poor.
I am looking for a pre-recorded test tape, with perhaps some sine wave sweeps and so forth. Just to see if this deck will do better for playing back only. But, I have not found anything useful thus far.
Speakers:
The speakers are of nice quality. The woofers perform like genuine woofers. They have a measured free-air resonance of 62 Hz, which is quite good for this size bass driver. Furthermore, this woofer seems to roll-off beyond about 2.5 Khz, making it an easy woofer to blend-in with a tweeter.
The tweeter is a fabric (textile) soft dome, 0.75 inch diameter. It performs very well. Treble is smooth and clean. This tweeter does not exhibit sibilance. It is crossed over at about 8 Khz and probably reaches down enough to blend with the woofer.
The final two screen shots are of a basic measurement at 1 meter, on-axis with the tweeter, near a corner of the room.
Screen shot #4 is of my large floor speaker with 15-inch woofer.
Screen shot #5 is of the Aiwa in the same position.
The final 6th picture is of my main audio system and the Aiwa boombox, for comparison.
Final thoughts:
I like this boombox overall. The deck is disappointing. But, I did not have high hopes to begin with. I have researched several new component tape decks on the market. You need to spend a lot for a possible decent performing tape deck that comes anywhere near the decks of the past.
The CD Player performs admirably well. Response is close to my LG DVD player. Sounds very good. You could use the headphone jack to connect the boombox to a separate amp and play CDs with some confidence of high-fidelity.
The Aiwa has a decent amp. Not screaming loud. But well balanced and pretty clean for what it is. In my opinion, the Aiwa's amp measures up well to the classic collectible one-piece boomboxes of the 80's.
The Aiwa speakers are definitely better than most of the speakers found in the 80's boomboxes. The bass-reflex cabinets are well tuned. Bass reaches down into the 40-50 Hz range and can hit some pretty low notes. Speakers sound clean. Much less hollowness and coloration as compared to other comparatively priced retro styled boomboxes currently on the market.
This is a retro-thing. I like it because it reminds me of days long gone by. For me, high-fidelity audio was king back in the 80's, before the advent of personal computers, surround sound and miniaturization and music compression. I have very fond memories of all the audio that was available to purchase, or just to sample, for fun. Young people nowadays are missing out on being able to shop literally dozens and dozens of stores, just for audio equipment. To be able to touch, feel, and audition so many big brand high quality components was a joy and a privilege. This Aiwa boombox brings back a little of those feelings and memories.
