1979 Sansui Au-717 / TU-717

[punchycool]

Good to hear, guys.

I did forget to note that the two presets for bass and two presets for treble do not alter the sound at all so parts of those boards are probably bad as the mad scientist was hinting at above. I leave all four of these buttons not-depressed (or off, if you will).

 

[knifeswitch]

Anyone know the approx cost range to fully repair an AU-717 amp if the future demands it?

And may I assume the glue issue shouldn’t affect the TU-717 tuner?

My 6600 goes in for restoration sometime in December. When I asked for a loose ballpark, he said we’ll start at 5. The glue was used in a lot of boards including my TU-217’s.

 

[punchycool]

I know, maybe wrong subforum, but since many here know my situation, and because I’d like to be all Sansui, I’ve found a local deal on a Sansui P-L35 turntable. Is this a decent unit and would offer reasonable serviceability paired with my AR9s and Sansui AU-717/TU-717? If not, what should I purchase that won’t break the bank but make my Simon and Garfunkel, Bread, Yes, Rush, etc etc etc albums sound nice?

 

[punchycool]

Re: my AU-717 / TU-717 gear…

I’ve noticed when using the tuner, the volume in the right channel is much lower than the volume in the left channel. Would this be due to that channel’s board in the amp or is a board in the tuner to blame?

I also notice the balance control does not offer much range from any audio source. 0.5 increments from zero yields probably a 50% shift to that speaker. Do I need to clean it’s potentiometer with some deoxit? Or do I need a recap?

When using an MP3 player via the aux port on the amp, the volume between the speakers is even unlike when using the tuner as noted above.

Lastly, I’m driving a pair of Acoustic Research AR9 4-ohm speakers. Is it normal to expect to only use the first approximately 7 clicks of the volume control. Much higher would break the windows in the house . Or does this pot need to be cleaned? I know 4-ohm speakers don’t take much to receive power.

Yes, one or both of these Sansui pieces needs to be recapped at some point. I’m just trying to understand what areas are at fault for these matters and if there is anything I could do prior to that work. Other than these issues, this gear is really nice.

 

[JoseHH]

Lastly, I’m driving a pair of Acoustic Research AR9 4-ohm speakers. Is it normal to expect to only use the first approximately 7 clicks of the volume control. Much higher would break the windows in the house .

This could be due to the input sensitivity of the Aux input which in these units expects signals of only 150mV. If you drive the Aux input with an mp3 player, it could be that you are feeding close to 1V to the input, and this may explain what you see. Some others in this forum recommended to use attenuators to prevent this. I adopted this in one of my amplifiers (AU-D907) and it worked for me.

 

[punchycool]

Wow, JoseHH, this is very kind to offer this advice. Looks like I’ve got some homework to read. Thank you!

 

[punchycool]

JoseHH or anyone - two questions I cannot find answers to.

1. My AU-717 amp does not support banana plugs (only speaker wire) so can I put the rothwell attenuator into my speaker and then put the banana plug into the attenuator? I don’t own these yet.

2. Doesn’t a -20dB attenuator do the same thing as using the -20dB muting switch on my amp? Both in theory let me turn up the volume, to improve the range of the dial, by twenty decibels. What’s the difference though?

 

[percivilla]

JoseHH or anyone - two questions I cannot find answers to.

1. My AU-717 amp does not support banana plugs (only speaker wire) so can I put the rothwell attenuator into my speaker and then put the banana plug into the attenuator? I don’t own these yet.

2. Doesn’t a -20dB attenuator do the same thing as using the -20dB muting switch on my amp? Both in theory let me turn up the volume, to improve the range of the dial, by twenty decibels. What’s the difference though?

The attenuators go on the RCA's, not the speaker wires.

Yes, they both do the same thing. The attenuators just move the resistors outside the unit. The switch just runs the signal through some resistors.

 

[punchycool]

Right. Ridiculous question, percivilla. Sorry. I suppose I would want the attenuators on the aux source ports. My tuner and aux sources, though, operate the speakers to a medium listening level with only four notches of the volume knob from zero. I’m driving AR9 speakers that run at 4 ohms. I suppose this is why I have such a short knob range on the master volume.

And, ok. I suppose I just keep the -20dB muting switch ‘on’ and call it a day. Wasn’t sure if I was losing quality by doing so.

Thank you much for the lesson.

 

[Hyperion]

And, ok. I suppose I just keep the -20dB muting switch ‘on’ and call it a day. Wasn’t sure if I was losing quality by doing so.

No, you won't lose quality, the -20dB switch is provided by Sansui for this exact reason, to make the volume steps more usable and to tame sources with a higher than optimum output level. As for me I only have one source, either a CD player or an Internet streamer (never used at the same time) which has higher than optimum output. So for these I use a pair of RCA attenuators, I have found that 10dB is just right. There is an output control on the TU-717 and you can use this to fine tune its output level, and ideally make it the same as the other inputs in terms of volume control position and hence sound level to you.

 

[punchycool]

Hyperion, I didn’t notice the volume control on my tu-717 tuner. Right! It does let me dial in the audio level.

I was going to buy attenuators for both aux and tuner sections but now learned I needn’t do so. Thanks all.

 

[Multimode]

No, you won't lose quality, the -20dB switch is provided by Sansui for this exact reason, to make the volume steps more usable and to tame sources with a higher than optimum output level. [snip]

I'm surprised that source outputs in the days before CDs, streaming etc, could run at levels that might overload amplifier inputs. I'd assumed the intended purpose of the -20dB switch was purely to mute the sound temporarily, to avoid any need to turn the volume control down and then reset it. For instance, I used it when swapping my MC cartridge with/without its dedicated transformer between MM and MC inputs when making sound quality comparisons.

A benefit of attenuators over using the Mute switch in normal listening is, of course, that there's then no risk of accidentally switching out and hence overloading your speakers (and ears!). For that reason alone, the cost of attenuators was worthwhile for me with my sometimes idiotic actions.

I do recommend, however, using the Mute switch - and the Jump switch where provided - as an aid to deciding on the level of attenuation needed. My first choice of -10dB wasn't at all sufficient in my own case (Cambridge Audio CXC CD player and CXN internet streamer into AU-919 amplifier, through to Spendor SP1/2R2 speakers) and -25dB turned out to be exactly right.

 

[percivilla]

Yeah, really the only downside to that switch would be accidentally switching it off, or leaving it off when switching from PHONO to AUX.

I recently looked into this same thing and learned that yes, the switch just engages resistors prior to the pre-amp. Those in line attenuators just have a set of resistors inside a nice packaging.

I run the -20dB pad on AUX as my Schiit DAC has 2V output and the 717 (and most vintage units) have 150mv inputs. I could really only use the first 5 clicks on the volume before things got too loud. With the switch on I'm able to use way more of the dial and the clicks aren't nearly as drastic. I switch it off for PHONO and the levels stay very similar.

 

[punchycool]

I am very careful to clock the master volume on the au-717 all the way to the left when changing sources to avoid massive humming on the phono or static on the tuner should the muting switch be on. But, good point.

 

[Multimode]

I am very careful to clock the master volume on the au-717 all the way to the left when changing sources to avoid massive humming on the phono or static on the tuner should the muting switch be on. But, good point.

In normal circumstances I make sure the volume control is right down (indicated -70dB) when switching on as well as when changing sources. I made an exception when comparing MM and MC sound quality and there was no humming, but I agree it's not best practice.

 

[punchycool]

I am looking to subscribe to a music streaming service like Qobuz, Apple Music, or Tidal. My question is not about which one.

My question is…I intend to run the music stream through its app on a new iPad out via lightning connector and into the aux ports of my au-717 amp via RCA left and right channels to drive my AR9 speakers. All 60s-80s music only. Do I even need a hi-res audio subscription? Without a DAC, does my amp essentially receive low quality mp3 resolution with this setup? Figured I’d ask here since I have an audience doing similar stuff. I’ve never heard music not through a DAC and through a DAC, back to back, to know what I’m missing. Lastly, is the sound quality better in this situation if I made my music available offline on my iPad? Ive got a lot to learn but can’t find any lessons on these areas.

 

[Knucklehead]

JoseHH or anyone - two questions I cannot find answers to.

1. My AU-717 amp does not support banana plugs (only speaker wire) so can I put the rothwell attenuator into my speaker and then put the banana plug into the attenuator? I don’t own these yet.

2. Doesn’t a -20dB attenuator do the same thing as using the -20dB muting switch on my amp? Both in theory let me turn up the volume, to improve the range of the dial, by twenty decibels. What’s the difference though?

There is an easy way to add 5 way binding posts to your 717. I just did mine last weekend and it came out looking great, and now I can use my favorite terminals, spade lugs. They are nice and tight and won't come off accidentally. I soldered the spades to the 12ga wire.

There are some of these for sale on Barter Town. I can't post the for sale thread here since you're not a 'Subscriber' and you wouldn't see the ad. I have a set of these coming for my 317 as well, and will be modifying it when that set gets here.

I like like my vintage gear, I just don't like all the compromising connections that vintage gear comes with. I need to round up something for my Kenwood as well. I dislike spring loaded speaker terminals. I have no idea how I'm going to modify the 1000a, it uses screw terminals. I do have small copper spade connectors for it, for now. At some point I'll fix that up with binding posts too.

Here's a pic of my 717 with the new binding posts. The edges of the panel looks ragged, it isn't, it's just the play of light on the edges. Makes the 717 look like it came with these binding posts.

 

[Knucklehead]

I am looking to subscribe to a music streaming service like Qobuz, Apple Music, or Tidal. My question is not about which one.

My question is…I intend to run the music stream through its app on a new iPad out via lightning connector and into the aux ports of my au-717 amp via RCA left and right channels to drive my AR9 speakers. All 60s-80s music only. Do I even need a hi-res audio subscription? Without a DAC, does my amp essentially receive low quality mp3 resolution with this setup? Figured I’d ask here since I have an audience doing similar stuff. I’ve never heard music not through a DAC and through a DAC, back to back, to know what I’m missing. Lastly, is the sound quality better in this situation if I made my music available offline on my iPad? Ive got a lot to learn but can’t find any lessons on these areas.

There is only one way you can connect to the 717, that will be analog, you can use tape, tuner or aux. You need a DAC, no choice there since your streaming service will be digital. If you're using an ipad you can get a 3.5mm to RCA cable of the appropriate length and use the headphone jack, in which case you're using the internal DAC of the ipad.

I use a DAC for both of my setups, one is an Emotiva Big Ego, it's a USB external sound card that I connect to my laptop's USB port, the other is an Emotiva XDA-2 (no longer made) in the main setup via ARC on my TV then to the XDA-2 via optical.

I know nothing about ipads, but if it has a USB port you might be able to get an external DAC. At any rate, regardless of how you connect, get the high res music, it usually sounds better unless the MP3 is 256/312mbps. I stream (FLAC) music from my HTPC computer to the XDA-2 then to the Aux port on whatever I have in the audio rack, which is the 717 ATM. It sounds very good with my Salk Song Towers. And I don't need or use a sub.

 

[punchycool]

Thanks for the details. knucklehead. I am hoping to avoid a laptop and am hoping an iPhone or an iPad, brand new, has a sufficient DAC built-in to stream music directly to the 717. I’m doing it now and it sounds great, I think, but don’t have a DAC to know what I may be missing, if anything.

 

[percivilla]

I stream using an ipad. If you're going to use a DAC you will also need a lightning to USB adapter. The crappy thing about using an ipad is that since it has one stupid port (lightning), you can't charge it while listening to music. That being said I probably get around... dunno... maybe 8-10 hours of music before it needs charging.

Tell you what, I'll try mine this weekend with a headphone jack to RCA and see how it sounds compared to my Schiit Modi 3.