G22000 enough for AR9s?

[Sgt Shultz]

I’ve been looking through the site searching for “G22000 protection issue“ and it does seem to be a common problem. The AR9s are biampable maybe I’ll try that just to see If it makes a difference. I may just have to come to terms with the fact that it’s only 8 ohm speakers going forward. It does really make me wonder why the G9000 seems unfazed though. I can’t imagine the protection circuits are that different. That soundcraftsmen amp seems like a beast! Im sure it sounds great with those AR58s. I’ll play with it all this week and let you guys know what I find. My main problem to troubleshooting is moving these things around. My main speakers / system are in the house with the ARs in the garage until I get the pairing right. So every time I want to test an amp I need to lug them out to the garage!!

Here's the thing, even if an amp drives them it may not like it and later issues rear their ugly head as I mentioned with the Belles I amps with the power switch. The Belles is no slouch, only 185W into 4ohms but enough current to pull a freight train.

Pics of the Belles






I really thought the Belles wouldn't have any issues, never got hot, but the power switch stopped working. It did malfunction in the closed position so the amp still worked but no way other than unplugging it to shut it off.

Thought it was just a bad switch so installed another of my Belles amps while the first was being repaired. The switch in the second failed, hmmm, something's amiss here. So now one amp the switch keeps failing even with other speakers so there's other damage from the AR's.

So I went shopping and found the Soundcraftsmen and no issues since.

I have the Belles driving fairly power hungry Infinitys without issue so figured the AR's wouldn't be an issue.

Mentioning this only as food for thought about running those AR9's with other amps not 2ohm stable you care about

 

[Sansuiman]

Based upon past posts here on the subject, the 22000 and 33000 have an output stage whose design is more reminiscent of the AU-X1, although not with the same high performance power transistors installed. So, it already differs somewhat from the G-9000 in that regard. I've not studied the circuits of the 22/33K, but apparently the protect circuit differs from that of the 9000 as well. @kevzep is probably the resident authority on these receivers. He has owned one, and is a professional tech as I understand it, so his feedback can be considered beyond reproach.

It is unknown to me if this hyper-sensitivity was an intentional design decision, or a result of age causing component drift that places the circuit outside original spec. Whatever the case, the tendency of the two biggest G's to have a hair trigger protect circuit has been posted about enough here to have established it as a pattern of behavior. While I can understand the mentality that a 220WPC amp should easily power demanding speakers, it isn't just that simple, other factors are pertinent to how the amp gets along with the speaker load.

Some amps, as most in this hobby are well aware, are more temperamental than others. The AU-X1 was well known for its tendency to self destruct due to self oscillation, and Sansui had a handful of other designs over time that were notable for their lack of stability. While the big G's aren't inherently unstable, the protect sensitivity issue is known and spoken of at some length.

Given the complexity and cost of rebuilding an output stage on one of these beasts, I'd not be trifling around with the risk of blowing channels, with speakers that have already shown they will easily put the unit into protection. It'll be an expensive and truly regrettable mistake, should it end up letting the magic smoke out. By all means, have the unit tested to verify there isn't something amiss, but based on the accumulated prior knowledge of these units on here, I'm inclined to say this is a problem that won't be easily overcome, and that different speakers that are not as taxing on the unit should be used.

I guess that suggestion is sort of easy for me to advocate for, as I have lots of different amps and speakers to choose from. I realize most here have not made their homes into shrines to Sansui (or to vintage audio more generally). Which is to say that if you are sensible enough to limit yourself to one or two systems - rather than a museums worth - swapping something else in for better synergy may not be a readily available option. Just want to emphasize that I'd be very careful here, to do serious damage to a G-22000 is not only a serious hit in the wallet, it'd be a gut punch to me if it were mine, and it got needlessly damaged because I chose to go on pushing it too hard.

 

[Sgt Shultz]

Based upon past posts here on the subject, the 22000 and 33000 have an output stage whose design is more reminiscent of the AU-X1, although not with the same high performance power transistors installed. So, it already differs somewhat from the G-9000 in that regard. I've not studied the circuits of the 22/33K, but apparently the protect circuit differs from that of the 9000 as well. @kevzep is probably the resident authority on these receivers. He has owned one, and is a professional tech as I understand it, so his feedback can be considered beyond reproach.

It is unknown to me if this hyper-sensitivity was an intentional design decision, or a result of age causing component drift that places the circuit outside original spec. Whatever the case, the tendency of the two biggest G's to have a hair trigger protect circuit has been posted about enough here to have established it as a pattern of behavior. While I can understand the mentality that a 220WPC amp should easily power demanding speakers, it isn't just that simple, other factors are pertinent to how the amp gets along with the speaker load.

Some amps, as most in this hobby are well aware, are more temperamental than others. The AU-X1 was well known for its tendency to self destruct due to self oscillation, and Sansui had a handful of other designs over time that were notable for their lack of stability. While the big G's aren't inherently unstable, the protect sensitivity issue is known and spoken of at some length.

Given the complexity and cost of rebuilding an output stage on one of these beasts, I'd not be trifling around with the risk of blowing channels, with speakers that have already shown they will easily put the unit into protection. It'll be an expensive and truly regrettable mistake, should it end up letting the magic smoke out. By all means, have the unit tested to verify there isn't something amiss, but based on the accumulated prior knowledge of these units on here, I'm inclined to say this is a problem that won't be easily overcome, and that different speakers that are not as taxing on the unit should be used.

I guess that suggestion is sort of easy for me to advocate for, as I have lots of different amps and speakers to choose from. I realize most here have not made their homes into shrines to Sansui (or to vintage audio more generally). Which is to say that if you are sensible enough to limit yourself to one or two systems - rather than a museums worth - swapping something else in for better synergy may not be a readily available option. Just want to emphasize that I'd be very careful here, to do serious damage to a G-22000 is not only a serious hit in the wallet, it'd be a gut punch to me if it were mine, and it got needlessly damaged because I chose to go on pushing it too hard.

I have three of the Belles I amps and it still bothers me one is in distress. I now have the AR's with the bedroom system of stacked silver faced Kenwood 70's gear with a KA-7300 at its heart. The Soundcraftsmen is doing the heavy lifting to preserve the Kenny.

 

[Hyperion]

The G-22000 & '33000 have the most complicated protection circuits I have seen in a Sansui, more complex than the G-9000. And as I commented in post #2 the above receivers (or the G-22000 at least) are known for having sensitive protection circuits, and thus will not tolerate difficult loads, especially not at high power.

The advice to find an Amplifier rather than a Receiver, be it a Sansui or something else to drive those speakers, was good advice in my opinion.

@kevzep is probably the resident authority on these receivers. He has owned one, and is a professional tech as I understand it, so his feedback can be considered beyond reproach.

+1

 

[CrSens]

It probably has some sort of short circuit protection which does not need to rack up amps to activate. I had the similar issue with AU-717, it would not run Martin Logan electrostatics even at low/medium levels without going into protection. ML Summit dips into 1 Ohm or lower at 20 kHz, and amp detects it although there is almost no musical signal at that frequency. There were simply very few, if any such speakers when the amp was designed.

 

[Overundr1]

If I could play in the G-22000/33000 arena and wanted to drive a set of AR-9's the obvious solution is a Sansui BA-5000, and that would be incredible indeed. Of course one could drive them with any combination of Crown Macrotech amps for a fraction of the price, using the pre-amp stage of the big G. Even the AR-3's are power hungry, have seen them soak up most of what a SX-1980 can dish out and still ask for more. As mentioned above, our vintage gear does many things well but driving 86db 4 ohm loads is not one of them.

 

[Bright_Star]

The BA-5000 is Sansui's most powerful amp, so if the 5K is not enough, I dont know what else would be. You can select
from the three speaker taps, 8, 4, and 2 ohms. The B-2301 is also 300W, whether that unit would perform better with your
AR speakers, I cant predict, atleast with the BA-5K, 2 ohm loads are possible within its design philosophy. If you had two BA-5000's,
you could bridge them to mono for 600 Watt plus operation. (ditto with a pair of smaller BA-3000's, for 170x2).

But despite the 300 Watts, keep in mind the preamp that will be used with it, if its a CA-3000, or your AU-20K (switched into preamp mode)
you will need to turn the volume knob up high, very high I imagine with those inefficient AR's. Even at 300W, the left/right volume knobs dont
make a dramatic difference on the BA-5K, even if you turn it up to max.

You mentioned using the big G as a preamp to your Crown amps- this can be done with a G-9000, but can anyone clarify if this is possible
with a G-22K/33K? I thought the unique umbilical cord meant that both sections mate together, thus an external pre or power amp was not
possible. If so, then I dont think a G22K pre can be used with a Crown power amp.

As for the 4 ohm situation: I am still interested in the so called overly sensitive protection circuit, and the technical details of that design from anyone
who has serviced these units. Lets keep in mind though, 4 ohms is just an AVERAGE. There are speakers that are small woofer-tweeter bookshelf size and those that are large floorstanders with an array of drivers & dual woofers etc and both can be rated 4 ohms. Its still important to know what each speaker's impedance curve is over the 20-20K range- thats alot more useful than just saying its 4 ohms.

The other spec that was overlooked is the Efficiency, in this case 86db, so now I can see that Yes, it could be quite challenging for amps, and would usually
require turning up the volume knob high.. especially on an AU-20000 (with its -3db increments, "linear vs logarithmic" pot taper), thus I'm surprised the AU-20K seemed to "outperform" the G22K in terms of not shutting off into protect. As I asked previously, I am curious to know what song as a test track was being listened to when this happened?

Efficiency plays a big role too, not just impedance itself, as an analogy, thats like comparing two separate pairs of speakers and saying each pair is 4 ohms, in the same way that two men are both 6'0 tall, but the efficiency has to be taken into account as well, such that in the analogy, one guy weighs 160 pounds, but the other guy, who is the same height, but at 250 lb is a much "heavier load". Thus, the point: A G-22K might happen to struggle with these particular 4 ohm AR speakers, but lets not innaccurately proclaim that a G-22K cant handle "ALL 4 ohm loads".

As for the G22K protection circuit: I was wondering if an analogy could be made to how circuit breakers work in our homes, for the purpose of understanding the concept better without getting lost/confused with heavy math and technical details, to better grasp the 22K's behavior.

Whether its a G22K playing music thru the AR speakers, or running multiple 1800watt hairdryers simultaneously, both of these situations tend to have the same result by activating a protection circuit to shut off and prevent damage from happening, either to the amp, or to stop a fire hazard in the house when too many appliances are plugged into a wall outlet or power strip.

In the home, typically the limit is a 15 amp breaker, If that amount is exceeded, the breaker will trip (open) and shut off the flow of electricity. It happened because a certain current level was exceeded (15 amperes) as well as temperature- more current= more heat= higher risk of melted-burning wires (conductors)= fire hazard.

Just like certain speakers might make an amp work harder, or using both the A and B terminals simultaneously will make it work harder (similar to running a 2nd home appliance, instead of just one), a Clamp-on could be used to actually measure the current level. I have done this before when I wanted to see how much current was being drawn by my toaster and coffeemaker. Would using both devices simultaneously put me near the 15 amp trip limit? A clamp on meter could take a measurement to let me know.

In order to do this I had to use an extension cord so that I could strip the insulation to be able to put the clamp on around the hot wire itself, it wont read both hot and neutral wires together, and connect the toaster and coffeemaker to this ext cord, rather than open up the power cords on the appliances which would be foolish.

The reason why I mention all of this- so.. going back to the G22K- obviously it tends to go into protect mode.. so can we try to measure it as well" what if we took an extension cord, opened it up, connected the G22K's power cord to it, plugged it in, powered it up, played some music on the AR speaker, at different volume levels, and see what the clamp on current reading is?

I am just trying to think-out the process and seeing how an audio system compares to a home appliance electrical system. In both cases, whether an appliance or the amp, current is being drawn, and there is a limit to how much current Can be drawn.

However, maybe its more complicated with the audio setup and music signals, speaker crossover circuits have caps and inductors that make up the impedance which changes over the freq range, so it might not be so simple as to ascertain a pattern of how the G22K responds... I am curious as to the specs of the 22K's power output transistors... is there a spec to show some type of max current rating that it can handle before it would shut off into protect? (similar to how in our homes, we know that on any given circuit in a service panel ckt breaker, you are ok running multiple things just as long as you dont approach/exceed the 15 ampere limit.

 

[kevzep]

Using static values for triggering diodes as overcurrent protection is futile in an amplifier.
When these amps were designed, there was never as much dynamic range in recordings as there are now, not as much bass, and other scenarios which cause overcurrent states that happen now, and also the bean counters may not have liked the cost of a proper limiting circuit.

The DC, over-temp, and so forth is all valid, but the overcurrent is a heinously under-designed-over-simplified circuit, there is no over-shoot, or allowance for such dynamics as we have in music, it will literally get to its max power output and then shut down. Most overcurrent protection in proper professional amplifiers involves some kind of limiter.
So, I remove the over-current trigger diodes and call it a day.
My G22000 could do a bees dork over 400 watts into 4Ω with the overcurrent removed.
The output devices can handle it, you just need to watch the temps, you might even see the fan come on!! You will know when its too much for the amp because it will trip the thermal protection.

Monitoring the current of the amp isn't going to tell you much, it will be an RMS or Peak RMS reading, it wont be a true peak reading, and it is the true peak reading which is what we are interested in.

 

[Bright_Star]

Using static values for triggering diodes as overcurrent protection is futile in an amplifier.
When these amps were designed, there was never as much dynamic range in recordings as there are now, not as much bass, and other scenarios which cause overcurrent states that happen now, and also the bean counters may not have liked the cost of a proper limiting circuit.

The DC, over-temp, and so forth is all valid, but the overcurrent is a heinously under-designed-over-simplified circuit, there is no over-shoot, or allowance for such dynamics as we have in music, it will literally get to its max power output and then shut down. Most overcurrent protection in proper professional amplifiers involves some kind of limiter.
So, I remove the over-current trigger diodes and call it a day.
My G22000 could do a bees dork over 400 watts into 4Ω with the overcurrent removed.
The output devices can handle it, you just need to watch the temps, you might even see the fan come on!! You will know when its too much for the amp because it will trip the thermal protection.

Monitoring the current of the amp isn't going to tell you much, it will be an RMS or Peak RMS reading, it wont be a true peak reading, and it is the true peak reading which is what we are interested in.

Yes, that whats I was referring to previously when I mentioned that Sansui did not explain much about low impedance loads in their catalogs until cd players and wide range digital music came out in the 80's.

Thus, when it comes to the G-22K and the above sentence: I would be interested to know how the amp would behave through those AR speakers when playing vinyl and using the phono preamp (instead of playing cd's) and observing if the protection shut off's happen less frequently. In this case, the speakers are still the same impedance, whether the music is vinyl or cd. Either format may require more or less volume level on the G22K, which might play a role as well in causing it to go into protect.

I thought knowing the current level would help, even if its an rms value, just multiply it by 1.41 to get the true peak. I suppose the G22K power meters dont help much in conveying an idea of how well the amp is staying within or exceeding its limits, or does it? I dont know because I asked several questions earlier in the discussion that still await an answer, such as asking the person with the AR's how the high the meters were swinging when he was playing music and it shut off (as well as: what song caused it, and how long was the amp on, and how warm/hot did it get... To me, making note of all these thing would be useful to better understand/predict when such an incident could happen again)

Ps: Would an inexpensive AU-G77X amp really be able to handle the AR speakers better vs the G-22K? If so, due to what? Its power out transistors, the 8-4 ohm impedance selector switch, or a less sensitive protection circuit?

 

[Bright_Star]

Yes, that whats I was referring to previously when I mentioned that Sansui did not explain much about low impedance loads in their catalogs until cd players and wide range digital music came out in the 80's.

Thus, when it comes to the G-22K and the above sentence: I would be interested to know how the amp would behave through those AR speakers when playing vinyl and using the phono preamp (instead of playing cd's) and observing if the protection shut off's happen less frequently. In this case, the speakers are still the same impedance, whether the music is vinyl or cd. Either format may require more or less volume level on the G22K, which might play a role as well in causing it to go into protect.

I thought knowing the current level would help, even if its an rms value, just multiply it by 1.41 to get the true peak. I suppose the G22K power meters dont help much in conveying an idea of how well the amp is staying within or exceeding its limits, or does it? I dont know because I asked several questions earlier in the discussion that still await an answer, such as asking the person with the AR's how the high the meters were swinging when he was playing music and it shut off (as well as: what song caused it, and how long was the amp on, and how warm/hot did it get... To me, making note of all these thing would be useful to better understand/predict when such an incident could happen again)

Ps: Would an inexpensive AU-G77X amp really be able to handle the AR speakers better vs the G-22K? If so, due to what? Its power out transistors, the 8-4 ohm impedance selector switch, or a less sensitive protection circuit?

Pss: If the G22k is apparently so sensitive, then why not have its A+B speaker terminals wired in series instead of parallel- this was done only on the 9090db & 8080db, which is a Sansui mystery to me- why only those two models?

 

[Audiophan1]

Thanks again everyone I appreciate all the insight / discussion. Unfortunately I’m back to work for the next 7 and won’t have a chance to experiment / get it set up again until then. Based on the info above I will endeavour to:

1)Try bi amping with the g 9000 and G22000 together and see if it makes a difference
2) Cycle receivers to both upper and lower portions of the AR9s to see if lower or higher frequencies make a difference.
3) Note the exact volume level the protection kicks in at. Also note power lever meters when it kicks in
4) Note type of music and source. I’ll try similar songs between LP source and Dac / streaming.
5) Note run times, temps and if fan kicks on or not. ( so far it never did)
6) I’ll take static resistance measurements of AR9s as is.I’ll also take measurements of upper and lower sections separated before I Bi amp.
7) Start looking for straight up amp with higher power ratings. Ba 5000 ( high end) , Hafler DH 500, Adcom 555 Lower end ? They seem to be good at lower impedances as well.
8) Start researching Kevzeps overcurrent diode mod just in case I decide to go that route.
9) Ponder my speaker choices / best pairings for the G22000. The AR9s are rare beasts, sound amazing and have that cool factor. But doing some more reading ppl have put upwards of 800 watts to them and they still eat it up. They might need more amp than I am willing to invest in to really make them sing. Does anyone who owns the G22000 have a favourite pairing that they felt got the best out of the amp?

I have other speakers but most of them are some real odd balls with varying impedances and efficiencies. None with low impedances like the AR9. A fun set I would like to try are the Sansui Sp x11000 ( earth shakers) . A ridiculous set of overkill sansui speakers that I found at a swap meet. They have 4 15 inch drivers rated for 350 watts at 8 ohms. But at 102 bd efficiency I think it would not blink an eye at them!

Please let me know if you have any other suggestions. Setting up / testing again should be fun I’ll try to add some pics this time.

Thanks

 

[Bright_Star]

1) If your speakers have two sets of terminals, you can bi-amp them, I do that with my Infinity RSIIA's which are very power hungry, I have a G-901 switched into power amp mode and a Sansui B-2101. The preamp is a Sony and has two outputs, thus one output goes to the G-901 and the other to the B-2101. Perhaps it would be best to use two identical amps, but in my case, I dont think its much of a problem in terms of balancing the sound between both amps when one is driving the mid/highs, and the other is handling the woofers. The G-901 volume control is disabled when its in power amp mode whereas the B-2101 being a dedicated power amp, has left & right channel volume knobs. The Sony preamp is the main volume control for both amps. In your situation, as I asked earlier: can it be used as a standalone pre or power amp, being that it uses a unique "umbilical cord" to attach both sections? If you tried to biamp, could an external preamp be connected to the G-22K's power amp section?

2) Which frequencies: the Impedance chart for your AR speakers would show at which frequencies the impedance dips low. If your AR speakers were at 4 ohms and above, perhaps it would be ok, its when it dips under 4 toward 2 ohms give/take that causes issues.

3) BA-5000 is a great amp, but to buy one might take some looking around, as I said, its HEAVY, like- hernia risk heavy. Finding one locally or within driving distance takes a little bit of good luck, and of course if you're agreeable to the seller's price. As I said, the B-2301 is also a 300 Watt choice. And perhaps a B-2101 would be feasible, if Sansui's claims are true regarding its 1980's era amps being able to handle lower impedance loads.

4) Sansui speakers are typically easy to drive, see for yourself- try the G-22K's with them, I am sure you wont have to crank the 22K up much to hear the music loud, and should not have any protect-shutoff issues. The thing is, Sansui speakers are not really the company's best product with a reputation for excellent sound quality, some folks like them, only your own ears can decide that. I am more of an Infinity guy, and even Infinity made some speakers that were not up to the highest standard, similar to Sansui, their Infinity SM models- 15" woofers, but just because they are large woofers does not necessarily mean the flabby bass is of good quality. For a budget price, I highly recommend the Infinity Qb, Qa or Qe speakers in case youre interested and see any available.

 

[Audiophan1]

The G 22000 does have a pre amp in and out on the tuner section that I believe bypasses pre amp on the tuner ( but still runs through it and the umbilical cord to the power amp)

 

[LBPete]

Does the G22k use the same power output transistors as the G-9000, and have more of them?

Just curious, what song were you playing when the protection activated? Did it happen shortly after the amp was turned on, or was it playing music for a while? Did you place your hand on it to see how warm or hot it was?

The G-22000 and the G-9000 were equipped with the same output transistors. The G-9000 has 4 pairs, the G-22000 has 6 pairs and the G-33000 has 8 pairs. They are extremely fast transistors and nothing comparable is currently being manufactured in a TO-3 case.

- Pete

 

[kevzep]

The G-22000 and the G-9000 were equipped with the same output transistors. The G-9000 has 4 pairs, the G-22000 has 6 pairs and the G-33000 has 8 pairs. They are extremely fast transistors and nothing comparable is currently being manufactured in a TO-3 case.

- Pete

And different rail voltages, 22/33K is the same, the the 9000 is a bit lower.

 

[Sansuiman]

@kevzep: The big G output devices are different from those used in the AU-919, BA-F1 and AU-X1, though, correct? It has been my understanding the latter three used an even higher spec transistor.

 

[Bright_Star]

AU-919/BA-F1 use these.

I would be interested to know if the rare B-1, 250 watt version of the BA-F1 used them as well (350 watts into 34 ohms, was reviewed in the April 1980 issue of 'Modern Recording' magazine.

 

[Bright_Star]

AU-919/BA-F1 use these.

I would be interested to know if the rare B-1, 250 watt version of the BA-F1 used them as well (350 watts into 4 ohms, was reviewed in the April 1980 issue of 'Modern Recording' magazine by well known writer, Len Feldman.

 

[kevzep]

@kevzep: The big G output devices are different from those used in the AU-919, BA-F1 and AU-X1, though, correct? It has been my understanding the latter three used an even higher spec transistor.

Yes that is correct, Sansui really pushed stability limits with the F1/X1, I don't care much for the F1 but love the X1.....

 

[Bright_Star]

I was not aware of the BA-F1 having an stability (oscillation) issues as the X1 does. I view the F1 as essentially an AU-919 in power amp form, so their
performance (DD/DC) should be similar, but the F1 has the space on its front panel for power meters, and the back has room for the speaker terminals
to be spaced further apart, rather than crowded together as they typically are on the other models.

It just seems a bit odd or funny in that timeframe, where receivers ( G-9000, 9700 etc..) are larger and more powerful than dedicated power amps (the F1 at "only" 110 watts). Might not be a concern for most folks, but if someone was looking for a 300 watt unit in '79-'80, the BA-5000 was discontinued by then, so 300 to 110w seems like a big dropoff, so I'm surprised Sansui did not consider making the F1 with more wattage- though... they kinda did with the B-1, but its a Sansui mystery to me why the B-1 was marketed as a rare sound-reinforcement model only....

Well, here's a little treat: a review of the B-1 from the once great mag, 'Modern Recording', you just have to keep scrolling down thru the pages until you reach the review, but its a nice magazine- time -travel- journey:

https://www.worldradiohistory.com/Archive-All-Audio/Archive-Modern-Recording/80s/Modern-Recording-1980-04.pdf