[LugBug1]

Quote:

 I have a chance to buy this amp: 
 
onkyo m-504
 

 
 
And the pre-amp:
 
onkyo p-304
 
Anybody care to comment?

Seem to have been popular units and were manufactured up until 2000. In other words 'tried and tested'. If the price is good I'd say go for it. I'm sure you'll be able to sell them on when the time comes. Plus you can always mix and match with that power amp. 

 

[MattTCG]

It won't fit on any rack that I own even on top. It would have to go on the floor or I'd have to get a new rack.

 

[gikigill]

The floor it is!

 

[MattTCG]

Gentleman, you are incorrigible!! 

 
I can already hear my wife, "baby, what's this thing on the floor that looks like a mini fridge?"

 

[SpeakerBox]

Quote:

Gentleman, you are incorrigible!! 

 
I can already hear my wife, "baby, what's this thing on the floor that looks like a mini fridge?"

 
Can you tell her it is a mini fridge with temperature readout meters?

 

[MattTCG]

^^ This is why Iove this thread!! 

 

[hans030390]

I just received this Sansui 5000A yesterday:













It was in very good condition, and it sounds great with the Mad Dog 3.2! It's very powerful and smooth yet surprisingly clean and detailed up top. It might not come out perfect in measurements (more on that next post), but I'm enjoying it thoroughly.

 

[hans030390]

This is a cross post of mine from another forum. Some of it repeats what I said above:

Wow, I can see why people can really get into vintage receivers. The Sansui 5000A sounds great with the Mad Dog 3.2. I wish I had more orthos to try on it. You can tell it's not quite as clean and flat (FR) as some other amps (dedicated headphone amps or not), but there's still something about it that I really like. It sounds surprisingly clear and detailed, smooth, and powerful. Some people have said it's a warm receiver, but I'm not hearing that so much coming from the Leckerton UHA-6S Mk.II.

Out of curiosity, I took some RightMark measurements of the headphone out. Setup went PC with Auzentech Bravura, line out to the Sansui set at 24/96 with volume set at 4 (I believe the Windows volume controls the output voltage, because music clips after a volume of 50 or so, and 50 was too high for RMAA tests), and the Sansui HPO went to the line-in (set at 24/96, 100 volume) of the Auzentech Bravura using the stock T50RP cable.

More simply: Auzentech Bravura line-out -> Sansui 5000A -> Sansui HPO -> Auzentech Bravura line-in

The receiver is plugged straight into the wall. The PC is plugged into a surge protector that is plugged into the wall just above the receiver.

I know this isn't an ideal measurement setup, but I'm just working with what I have.

The first thing I noticed was that the FR was a bit tilted towards the treble with the tone knobs set at 0 according to RightMark. I had to adjust those to make the FR as flat as I could. The channel balance was also off a little bit, so I had to correct for that (I hope that's not a sign that I need to fix or adjust something in the receiver...it was a 0.2-0.5dB difference). Once I got the settings narrowed down as best as I could, I got the following results:

Overall:



FR:



Noise:



THD:



IMD:



DR:



Crosstalk:



IMD + Noise (Swept):



The FR looks worse that in is. There's some roll off at the top and bottom, but it's still relatively small (see the scale). Some of this is also due to my sound card. You can still hear the small differences in the FR when compared against flatter amps, but on its own is nothing to worry about. I'm guessing some vintage receivers weren't designed to be entirely ruler flat like companies focus on today...? I could be wrong. I messed with the tone knobs for a while and could not get a perfectly flat response. I can, however, get the treble response boosted up a bit from what you see here. My ears just prefer it being toned down a tiny bit.

One thing that I noticed in the measurements was the 60Hz harmonic distortion and noise. I would think I'd hear humming (ground loop?) through the headphones, but they're nearly silent when plugged into the receiver. I get a low amount of hiss if I turn the volume up on the receiver with nothing playing. It could be that the noise and distortion is still too low to really hear, but I'm not sure. Could it be just be a byproduct of how I measured the HPO and not indicative of how a HP would really perform from the receiver? Or perhaps I'd just hear it as less "clarity" in the most heavily affected regions and not necessarily a hum?

Discounting those 60Hz and harmonic spikes, the dynamic range, noise, and THD are at or better than -90dB above 300Hz. I'd say that's pretty good for a 40+ year old receiver! Once you get to the upper mids and treble, it's pretty darn clean. Sounds that way too.

I'd be really curious to see how the Sansui HPO would measure given a proper setup.

All in all, I'm really liking it so far!

 

[MattTCG]

Congrats on the Sansui!! It's something special IMO. And I agree about the pairing with the MD. Plugging the MD in a Sansui is what got me on this crazy train to begin with. 
 
Enjoy...

 

[LugBug1]

Quote:

I just received this Sansui 5000A yesterday:




 

Thats one lovely looking receiver. Classic early Sansui. I like it indeedy! 
 
Wish I knew what all those measurements meant on your second post But that noise that is showing, might become apparent if you were to try some sensitive headphones. The orthos probably aren't picking it up. My Sansui au505 has a low hum thats evident as soon as my sensitive Sennheisers touch the hp out.

 

[PhoenixG]

Well that's really interesting! I haven't had a good look at so many good frequency space graphs since grad school (underwater acoustics/signal processing), but those speak volumes to me. The first I want to look at is the THD test - It looks like there are peaks at your sampling frequencies/harmonics. It would probably be safe to knock at least 20 dB off those peaks due to the harmonic behavior. It might be further aggravated by your sound card. I'm sure a real 90dB peak at 1024 Hz would probably be obvious and audible.
Your noise level plots and IMD show strong - about 20 dB - peaks at 60 Hz and all its harmonics. Unless you're putting a square wave into it at the wall outlet (it's not hooked to a UPS backup power supply, right? Those things shoot square waves like it's their job), I wouldn't expect to see those from a good power source. The 60 Hz and 120 Hz noise levels are strong enough to make me think a recap in the power supply might be needed to filter that out. Despite the noise levels at the other 60Hz harmonics, they have less power [width] to them and might be helped by tamping down the main 60/120 Hz frequencies. You might not even hear a hum, but it's there and the computer can hear it. If you can't hear it, then it's not urgent at all haha.
Looking at the overall Frequency response curve, that's actually VERY flat compared to some of the other pieces out there, especially for something that age. It has a textbook roll-off with a corner frequency around 25kHz, which indicates a warm-ish signature. I like the relatively flat bass response, with a loss of only 1.5 dB at 15 Hz. I would expect some serious presence without sounding bloomy.
That program you're using is impressive. It would probably take me all week(month) to write a program to do all that.
My favorite thing about frequency response graphs is that I can almost get a feel for what the amp sounds like without listening to it, and I can compare it to any amp. Also, it makes it easy to find what you're looking for in terms of sound signature. Personally, the flatness of your amp is very appealing to me. I typically enjoy sound signatures very similar to that, but I prefer slightly lower IMB+noise levels if possible, and corner frequencies as close as possible to 5Hz and 50-100Hz.

 

[hans030390]

Thanks for the helpful information, Phoenix! The program I used is called RightMark. It's pretty easy to use and is completely free!

 

[musicman59]

Quote:

Currently viewing a Nakamichi Amp - PA-7AII for $1,275 on eBay.
 

 
 
Any thoughts/experience from others with these amps?

 
This is basically a 200 watts/ch Threshold from the SA series designed by Nelson Pass. it is very powerful and sweet sounding in the warmer side of solid state designs. 

 

[Meewoo]

Quote:

Well that's really interesting! I haven't had a good look at so many good frequency space graphs since grad school (underwater acoustics/signal processing), but those speak volumes to me. The first I want to look at is the THD test - It looks like there are peaks at your sampling frequencies/harmonics. It would probably be safe to knock at least 20 dB off those peaks due to the harmonic behavior. It might be further aggravated by your sound card. I'm sure a real 90dB peak at 1024 Hz would probably be obvious and audible.
Your noise level plots and IMD show strong - about 20 dB - peaks at 60 Hz and all its harmonics. Unless you're putting a square wave into it at the wall outlet (it's not hooked to a UPS backup power supply, right? Those things shoot square waves like it's their job), I wouldn't expect to see those from a good power source. The 60 Hz and 120 Hz noise levels are strong enough to make me think a recap in the power supply might be needed to filter that out. Despite the noise levels at the other 60Hz harmonics, they have less power [width] to them and might be helped by tamping down the main 60/120 Hz frequencies. You might not even hear a hum, but it's there and the computer can hear it. If you can't hear it, then it's not urgent at all haha.
Looking at the overall Frequency response curve, that's actually VERY flat compared to some of the other pieces out there, especially for something that age. It has a textbook roll-off with a corner frequency around 25kHz, which indicates a warm-ish signature. I like the relatively flat bass response, with a loss of only 1.5 dB at 15 Hz. I would expect some serious presence without sounding bloomy.
That program you're using is impressive. It would probably take me all week(month) to write a program to do all that.
My favorite thing about frequency response graphs is that I can almost get a feel for what the amp sounds like without listening to it, and I can compare it to any amp. Also, it makes it easy to find what you're looking for in terms of sound signature. Personally, the flatness of your amp is very appealing to me. I typically enjoy sound signatures very similar to that, but I prefer slightly lower IMB+noise levels if possible, and corner frequencies as close as possible to 5Hz and 50-100Hz.

Wow, there are really some talented persons here!! I hope PhoenixG can advise us patiently in the future!!!

 
 
Just an off topic question here. Do anyone like Adele?? If you do, could you tell me how you feel about her 18 and 21 CD (not vinyl) mastering? Thanks!

 

[Meewoo]

Quote:

 
This is basically a 200 watts/ch Threshold from the SA series designed by Nelson Pass. it is very powerful and sweet sounding in the warmer side of solid state designs. 

 
Do you happen to know the real difference between MKI and MKII? Some says: MKI is as close as Threshold, but has mechanical issue, MKII has improved the issue but deviated from Stassis topology since Threshold blamed Nakamichi copying. MkII is so different  that even Pass was pissed that he didn't want to Naka labeling Stassis on it
If you choose, which version would you pick?