YAMAHA A-S701 - tear-down, thoughts about the internals & few measurements

[ViperDom]

I am leaning towards A-S701, however looks like Yamaha limits subwoofer cross over to 90Hz, while KEF LS 50 specs state a 79Hz crossover. Is there any workaround with this limitation?

I dont think these Yamaha's have bass management.
Perhaps a low-pass built into the sub-out?, but no available high-pass for the speakers.

Consider the A-S501 + MiniDSP2x4HD(w/mic) comes in under you budget @$754 and gives you infinite options to integrate the sub & speakers and get them dialed in with your room.

 

[bdvan]

I dont think these Yamaha's have bass management.
Perhaps a low-pass built into the sub-out?, but no available high-pass for the speakers.

Consider the A-S501 + MiniDSP2x4HD(w/mic) comes in under you budget @$754 and gives you infinite options to integrate the sub & speakers and get them dialed in with your room.

thanks, in this case I will be connecting Wiim streamer into the miniDSP. I have only used Audyssey calibration in my Denon AVR, is Umik similar to Audyssey.

 

[TheBatsEar]

I would get the A-S301/501 with a Wiim streamer if the amplifiers are sufficient enough to play without distortion at slightly higher than moderate volume level. I also saw a post you recommend Fosi v3 Class D amp, if Fosi works 60%-70% of a dedicated amp I can live without the rest of performance.

Get the Fosi V3 with the 48v power supply if you can.
I couldn't notice a difference in a mid sized room with Wharfedale Linton 85. However, it has no remote, only one input, no bass or treble. It lacks so much functionality compared to a A-S501. You think you don't need any features, but eventually you do, then you have to buy again.

As for the KEF LS50, i had these as well. They would distort before any of the amps you listed do, i think.

 

[TheBatsEar]

I dont think these Yamaha's have bass management.

The Wiim has PEQ, you can reduce bass by 10dB or so, then just turn up the subwoofers amp to compensate.
It's less complicated and obviously cheaper, as you don't need the MiniDSP 2x4HD right away or possibly at all.
Regardless, you should buy a MiniDSP Umik1 to compensate for nasty room modes.

 

[ZolaIII]

The Wiim has PEQ, you can reduce bass by 10dB or so, then just turn up the subwoofers amp to compensate.
It's less complicated and obviously cheaper, as you don't need the MiniDSP 2x4HD right away or possibly at all.
Regardless, you should buy a MiniDSP Umik1 to compensate for nasty room modes.

±12 dB with WiiM's for PK for now (and 4 slots only).

 

[bdvan]

As for the KEF LS50, i had these as well. They would distort before any of the amps you listed do, i think.

I am thinking about selling the KEF and adding a pair of Revel M116 or 106. I don't have any local stores to hear the speakers playing, but based on the review here they seem to be better than the KEF.

 

[bdvan]

Get the Fosi V3 with the 48v power supply if you can.

I was looking at some "high-end" options reasonably priced (on sale or deeply discounted). Arcam 30 and NAD 3050 looks interesting providing rich features - an ALL IN ONE solution including room correction. I think they use hybrid/Class D amps I am thinking what would be the tradeoff on audio quality compared to A-S701.

 

[nameless13th]

I've been on a search to power a pair of Thiel CS .5 that I got for free (with the exception of having to replace a woofer). Everything I read points to needing a lot of stable power, especially if it occasionally dips below 4 ohms. I've been on hunt for vintage, but the Yamaha as701 looks promising. Any thoughts? Sources are TT and direct digital hires streaming and local files.

 

[trl]

@nameless13th, check audioholics measurements for A-S801 and you'll make up your mind after that. The A-S701 and A-S801 amps are identical in every aspect but the DAC chip which matters not in case you're feeding it with analogue signals.

 

[nameless13th]

@nameless13th, check audioholics measurements for A-S801 and you'll make up your mind after that. The A-S701 and A-S801 amps are identical in every aspect but the DAC chip which matters not in case you're feeding it with analogue signals.

Well, that looks like it would be perfect (maybe even overkill). Will add this to my used market hunt. Thank you.

 

[ZolaIII]

Well, that looks like it would be perfect (maybe even overkill). Will add this to my used market hunt. Thank you.

Regarding same amplifier and better unbalanced analog inputs if that's the way you going to go (and you will sooner or later) hunt for A-S 700.

 

[Barnstormer]

Hi everyone, I'm new to the forum and this is my first post. Probably an overly simple question to do with preamp.
I have just picked up a A-S701 secondhand and am wondering if I'm able to use my tube preamp with it? I'm just not sure how the integrated system works and if I can bypass the the built in pre amp?
I'm only toying with the idea as I already have a Little Dot mkIV se headphone/pre amp. Bit of an experiment with interconnecting devices I currently have to see if there is any noticeable benefits.

 

[TheBatsEar]

I have just picked up a A-S701 secondhand and am wondering if I'm able to use my tube preamp with it? I'm just not sure how the integrated system works and if I can bypass the the built in pre amp?
I'm only toying with the idea as I already have a Little Dot mkIV se headphone/pre amp. Bit of an experiment with interconnecting devices I currently have to see if there is any noticeable benefits.

Welcome to ASR

The A-S 701 has no option to use it in power-amp mode only. You can pretty easily add a pre-amp/main-in loop, if you know how to read schematics and aren't afraid to solder.

But i would simply hook my source to the external preamp and the pre-amp to line-in on the Yamaha and put the volume knob all the way to 100%. Don't overthink it.

 

[Barnstormer]

Welcome to ASR

The A-S 701 has no option to use it in power-amp mode only. You can pretty easily add a pre-amp/main-in loop, if you know how to read schematics and aren't afraid to solder.

But i would simply hook my source to the external preamp and the pre-amp to line-in on the Yamaha and put the volume knob all the way to 100%. Don't overthink it.

Thanks TheBatsEar,
I was just concerned that there may be some issues with 2 preamps inline with each other. I definitely won't be taking to it with a soldering iron at this stage .

Volume knob on the Yamaha or Little Dot to 100%? I'll assume the Yamaha to 100 then use external preamp as volume control.

Do you think there will be any benefit in me trying this? I'm only thinking that I might get a warmer sound that might balance the system if I find it a bit bright without.

 

[trl]

Use a digital multimeter and measure the voltage out coming from your Little Dot while feeding it with a 0dB sinewave (440 Hz, 1 kHz whatever frequency you might like). Play with the volume pot. of the Little Dot until you get a perfect 2 Vrms, then connect the preamp to the A-S701. On A-S701 use the higher volume level you would like to hear in your room, but I would suggest to not pass over 1 o'clock on the A-S701 volume knob.

 

[trl]

[...]

Do you think there will be any benefit in me trying this? I'm only thinking that I might get a warmer sound that might balance the system if I find it a bit bright without.

From a performance point of view I would say NO, but the sound could indeed get change to a warmer signature which some might like it. Not sure how the mkIV se would measure, but the mkIII se is definitely subpar from a measurement perspective.

 

[bboris77]

I have a question for anyone that may have replaced binding posts on one of these amps - how hard is it to do so? I am fairly competent when it comes to soldering - I managed to make my own Bottlehead Crack a couple of years ago. I am also unsure how hard it is to find spare parts for these amps.

The issue with my A-S501 that is out of warranty is that one of the binding posts keeps spinning freely without ever fully getting screwed down. I used some beefy speaker cables and may have torqued them a bit to tightly and perhaps on an angle (by hand only). It seems to me that the thread on the screw of the binding post simply "ate away" at the thin piece of metal that it screws into, making it too wide to get any purchase.

I could use Front B out, but would like to make both sets of binding posts functional, if possible.

Any input will be appreciated.

 

[Doodski]

I have a question for anyone that may have replaced binding posts on one of these amps - how hard is it to do so? I am fairly competent when it comes to soldering - I managed to make my own Bottlehead Crack a couple of years ago. I am also unsure how hard it is to find spare parts for these amps.

The issue with my A-S501 that is out of warranty is that one of the binding posts keeps spinning freely without ever fully getting screwed down. I used some beefy speaker cables and may have torqued them a bit to tightly and perhaps on an angle (by hand only). It seems to me that the thread on the screw of the binding post simply "ate away" at the thin piece of metal that it screws into, making it too wide to get any purchase.

I could use Front B out, but would like to make both sets of binding posts functional, if possible.

Any input will be appreciated.

Howdy @bboris77.

I have replaced binding posts on amps before. It's not a horrible job. It requires a decent soldering iron with enough wattage to melt the solder and heat up the PCB.

For your Yamaha A-S501 it appears the binding post assemblies are available as separate part numbers.

I acquired the service manual although I was advised the website is not accepting new accounts at this time. If you want the service manual then private message me and give me your email and I'll send it to you.

https://www.hifiengine.com/manual_library/yamaha/a-s501.shtml

There are 4 binding post part numbers listed in the service manual. I am not sure which ones you need. The differing part numbers are most likely related to the country the unit is sold in and so you'll need to verify the binding post part number with your country.

I hope this gets you started.

For reference.>

 

[Roland68]

I have a question for anyone that may have replaced binding posts on one of these amps - how hard is it to do so? I am fairly competent when it comes to soldering - I managed to make my own Bottlehead Crack a couple of years ago. I am also unsure how hard it is to find spare parts for these amps.

The issue with my A-S501 that is out of warranty is that one of the binding posts keeps spinning freely without ever fully getting screwed down. I used some beefy speaker cables and may have torqued them a bit to tightly and perhaps on an angle (by hand only). It seems to me that the thread on the screw of the binding post simply "ate away" at the thin piece of metal that it screws into, making it too wide to get any purchase.

I could use Front B out, but would like to make both sets of binding posts functional, if possible.

Any input will be appreciated.

If you have to do this job, then use more solid short binding posts with the connections screwed on the inside.
You then solder short pieces of cable into the board and provide them with crimped ferrules. Easier assembly and disassembly.

 

[AudioSceptic]

If you have to do this job, then use more solid short binding posts with the connections screwed on the inside.
You then solder short pieces of cable into the board and provide them with crimped ferrules. Easier assembly and disassembly.

Michel binding posts/banana sockets used to be popular after-market replacements. I don't know if the connection is any better, but they do look nice (if that matters). <https://www.turntableworld.co.uk/ca...hell-big-mother-binding-posts-pack-of-4-p3523>