Pioneer A656 Reference

[Gaz37]

I just had an offer accepted on Ebay for one & pick it up on Friday.

Anybody ever had one, heard one, or know much about them?

I got it quite cheap so should be able to sell it on if I'm not happy with it.

 

[Gaz37]

So for the benefit of anybody googling I'll give my opinion.

Compared to my A300R it is obviously a lot more powerful and more controlled, remaining clear at silly volume, giving much more weight and presence to the music.
It is also more detailed and lifelike than the 300R but saying that it sounds a bit clinical and soul less in comparison.
So far I've only listened with the source direct active so haven't played with the tone controls or loudness.
Also it's damned heavy (13kg iirc)

 

[Vladimir]

From that Pio series, aim at the ones with dual mono design. Example Pioneer A-717 MkII.

If you feel the sound is too dry, you can up the biasing a tad (from 20mV to 50mV) and get that Pio A400 mod roar going on.

 

[Gaz37]

From that Pio series, aim at the ones with dual mono design. Example Pioneer A-717 MkII.

If you feel the sound is too dry, you can up the biasing a tad (from 20mV to 50mV) and get that Pio A400 mod roar going on. 

How do you adjust the bias?

If it can't be done with a screwdriver, spanner, or better still a hammer, it's beyond me 🙂

 

[drummerman]

From that Pio series, aim at the ones with dual mono design. Example Pioneer A-717 MkII.

If you feel the sound is too dry, you can up the biasing a tad (from 20mV to 50mV) and get that Pio A400 mod roar going on. 

How do you adjust the bias?

If it can't be done with a screwdriver, spanner, or better still a hammer, it's beyond me 🙂

No. It's done with a meter, ideally over several timed periods to give the circuit time to settle.

Get it wrong and you increase distortion. Worst case you cause damage due to over heating.

 

[Gaz37]

That is now added to my very lengthy too difficult list.

Thanks for the suggestion though

 

[Vladimir]

You need a multimeter with aligator clips and a small philips screwdriver. If you haven't done anything with a multimeter before or soldered something on a PCB best not to mess with a working amp. You'll get bigger difference by moving your chair few inches than with amplifier tuning. Not worth the risk.

 

[Gaz37]

Moving a chair I can do.

I can solder after a fashion but wouldn't be confident doing so on a crowded circuit board.

Are you absolutely certain it can't be adjusted with a hammer?

 

[Vladimir]

Moving a chair I can do.

I can solder after a fashion but wouldn't be confident doing so on a crowded circuit board.

Are you absolutely certain it can't be adjusted with a hammer?

You can have big sound quality gain from cleaning pots, switches, relays and tarnished RCA connectors. They don't have to be scratchy to be in need of good cleaning.

Sadly this is also hammerless.

 

[MajorFubar]

You can have big sound quality gain from cleaning pots, switches, relays and tarnished RCA connectors. They don't have to be scratchy to be in need of good cleaning.

Sadly this is also hammerless.

+1, this is solid advice supported by basic electrical principles, just in case OP was wondering if it was straying down the rocky road of voodoo pseudo-science.

 

[Gaz37]

I do have a can of switch cleaner, is it just a case of spraying it on everything?

 

[Vladimir]

- Switches

- Potentiometers

- Speaker Relays*

- Tarnished RCA connectors

*To clean a relay you need to take the relay plastic cover off (most older types are removable). You don't just squirt on the relay, you need to clean the contact tips that get oxidized from sparking.

Needless to say, you do this with no power cord plugged in the mains. No squirting anything in transformer, mains switch or especially the big electrolytic capacitors (they keep charged up for days). Ease of doing this shouldn't be an issue for you since the 656 is beautifully layed out and sensitive circuitry is away from PSU in its own Faraday cage enclosure. Lots of instructional videos on Youtube to checkout.

The biggest sound improvement I got when modding my ex Pio A400 by Tom Evans mods was actually cleaning the damn volume pot and selector switch.

 

[Gaz37]

- Switches

- Potentiometers

- Speaker Relays*

- Tarnished RCA connectors

*To clean a relay you need to take the relay plastic cover off (most older types are removable). You don't just squirt on the relay, you need to clean the contact tips that get oxidized from sparking. 

Needless to say, you do this with no power cord plugged in the mains. No squirting anything in transformer, mains switch or especially the big electrolytic capacitors (they keep charged up for days). Ease of doing this shouldn't be an issue for you since the 656 is beautifully layed out and sensitive circuitry is away from PSU in its own Faraday cage enclosure. Lots of instructional videos on Youtube to checkout.

The biggest sound improvement I got when modding my ex Pio A400 by Tom Evans mods was actually cleaning the damn volume pot and selector switch. 

Thanks that's a great help.

I'll give that a try

 

[Gaz37]

Where are the speaker relays and what do they look like?

Actually that's two questions

Thanks

 

[Vladimir]

Where are the speaker relays and what do they look like?

Actually that's two questions

Thanks

Use google and youtube.

Video 1

Video 2

 

[Gaz37]

That's very helpful

 

[Gaz37]

I've managed to clean the volume pot, some switches and the rca connectors and it does seem to have improved SQ.

I wasn't able to get to the speaker relays as they are hidden behind a casing that was way beyond me to remove, this amp is built like a bloody tank.

 

[Vladimir]

Feels good keeping kit in shape and running well after years.

 

[Gaz37]

Feels good keeping kit in shape and running well after years. 

Yup, thanks for the advice