Threshold S300 Manual
Used Threshold Stasis for sale on 300+ second hand hifi sites & shops. Threshold Stasis power amplifiers original service and operating manual Italy eBay logo. Threshold S300 Stasis Amplifier Nelson Pass designed and built US Audio. Moving Threshold(17) This value helps to determine whether the DYNAMIXEL is in motion or not. If Present Velocity(615) is bigger than Moving Threshold(17) value, Moving(610) is set to ‘1’. Transmit REBOOT Instruction (For more details, refer to the Reboot section of e-Manual.) Indirect Address, Indirect Data. H42-20-S300-R -180.
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75.18.202.79 | |
| Posted on February 23, 2016 at 15:01:42 | |
alan.revera@yahoo.com Audiophile Posts: 16 Location: California Joined: February 23, 2016 | Hi I have a budget of about $2000, so I incline to go with a used one like the ones mentioned. I am an EE, so I can do my recap and other adjustment. I am looking at these amps, I tend to like the sound on the sweeter and warmer side. I just want to hear from you guys. Thanks |
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| My 2 cents, posted on February 23, 2016 at 16:26:30 | |
Posts: 28626 Joined: May 12, 2000 Contributor Since: April 5, 2002 | I owned a Stasis 3 for over thirty years and was very pleased with its sound quality and ability to drive the reactive loads of the electrostats I paired it with. The Krells are similarly stable with unusually low impedance loads (1 ohm Apogees), but I always found them too dark for my tastes. A reviewer friend used them to drive the subs on his Nola Grand References where they excelled. |
| Go for the Threshold! nt., posted on February 23, 2016 at 19:37:32 | |
Posts: 3208 Joined: June 25, 2001 | nt. |
| RE: Go for the Threshold! nt., posted on February 23, 2016 at 19:52:39 | |
Posts: 456 Location: Brecksville Joined: June 18, 2013 | Warmer/sweeter: Belles 150 Ref Pr,Innersound ESL,Red Dragon Leviathon. To me,the Krell/Threshold/Bryston and OCM high watts all have a leaner sound than I prfer.But it would depend on the rest of the system. Tom:cat |
| Threshold (nt), posted on February 23, 2016 at 19:54:17 | |
Posts: 7587 Location: Hayden, Idaho Joined: October 22, 2004 | . 'A lie is halfway around the world before the truth gets its boots on'. -Mark Twain |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 06:48:42 | |
Posts: 13190 Location: Alabama Joined: September 11, 2010 | Welcome! alan Threshold |
| +1 on the Belles, posted on February 24, 2016 at 09:05:05 | |
Posts: 933 Location: Orlando, FL Joined: November 20, 2001 | very good amp for the money - I owned the Ref 150a for several years. Was a good match with my Merlins, which generally prefer tubes. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 09:54:51 | |
Posts: 16 Location: California Joined: February 23, 2016 | Thanks everyone for your comments. Sounds like Threshold is the way to go. Then my second question is whether the S/300 or S/500 sounds better than the older ones from the late 70s and early 80s like the 400 etc. According to Nelson Pass, the older ones use stacked transistors in order to work with the higher voltage supplies. In the late 80s models like the S/300, higher voltage transistors became available and Mr. Pass changed the design to non stacked. I want to know whether the newer ones sounds better. Thanks |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 11:12:56 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | What speakers Alan ..? |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 13:14:59 | |
Posts: 16 Location: California Joined: February 23, 2016 | Hi Wayne I have a pair of JM Lab 913 right now with Velodyne sub. I am eyeing on a pair of Martin Logan. I like airy, fuller and big sounding. Thanks |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 13:25:41 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | I have had or have the models in discussion , if you are willing to tweak , get the Krell , in standard fare , the Thresholds . The Thresholds are overbuilt and very solid , simple as necessary they will last you forever, the Krells are more finicky and complex but can deliver. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 20:23:31 | |
Posts: 1105 Location: St. Louis, MO, USA Joined: August 14, 2010 | Hold on, I have a Threshold s300 Stasis, and although I agree it does lean a bit warmer than the KSA but in my opinion it's not in the same league as a Krell KSA. The KSA is pure Class A. Threshold does have some pure Class A, not sure which right off, the s300 is A/B with the first 10 watts being Class A. The sound from the KSA does eminate from a black background, I personally like that. The overall sound quality of the KSA is going to be better than the Threshold. The KSA will be more powerful as well. I wish my s300 did perform like a KSA. Another thing my Threshold is single ended with no XLR inputs where the KSA is a balanced design. I'm not sure if any of the other Threshold amps are balanced. Still not pure Class A but for $2k you could find a Pass Labs X250 which has the power and control of Krell yet smooth and warm, very similar to tubes with the right associated gear. The X250 is a differential Balanced Design. It has both RCA & XLR but I thought I got better results going all balanced connections. Depending on where you live this could be a consideration, the KSA will put out some heat where I've been surprised at how cool the Stasis remains even when pushed hard. I like the Threshold, you just aren't comparing amps that are comparable. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 24, 2016 at 21:46:04 | |
Posts: 16 Location: California Joined: February 23, 2016 | Hi Mr. Peabody Thanks for the detail reply. I guess I am comparing S/300 to KSA150 and S/500 to KSA250 which is more price comparable. for S/300, 10W of class A should be plenty for me as I don't listen loud. You sure Krell KSA250 is class A? At over 200W per channel, the amp would be sitting and burning over 600W or more at idle for two channels if it is really a class A. I am designing my own amp also and I bought a chassis that cost me $300. I did calculation, I can only burn 62W of continuous heat per channel on that chassis. Looking at the KSA250, I doubt it can handle over 150W per channel( that is very generous, it's not double the size of mine). My guess is 100W dissipation per channel with a fan. Thanks |
| Krell KSA 250 power amp is operating on class 'A' until 3 ohms.., posted on February 24, 2016 at 23:16:30 | |
Posts: 7472 Location: Calgary, Alberta Joined: October 16, 2007 Contributor Since: April 6, 2008 | Where it will change to class A/B operation. And it does employ the heat sinks, with no fans needed to help control and dissipate the heat from the amp. Here's the measurement from stereophile.. Looking at the KSA-250's maximum output power into varying impedances (see Sidebar 'Class-A?') with one channel driven with a 1kHz probe signal (fig.5, which plots THD+Noise vs output power), we can see it clips (1% THD) at 325W into 8 ohms (25.1dBW), at 635W into 4 ohms (25dBW), and at over 1000W into 2 ohms (actually 1066W at 0.97% THD, or 24.3dBW). When driving 1 ohm, the KSA clipped at 1548W (22.9dBW). This is approaching perfect voltage-source behavior, and could be expected to be closer to the ideal of a doubling of power with each halving of impedance if the AC line voltage were held constant. The AC line voltage sagged during these tests to 116V (8 ohm testing), 114V (4 ohm testing), 112V (2 ohm testing), and 106V (1 ohm testing), from 117V at idle. All maximum power output measurements exceeded Krell's specifications except the 1 ohm measurement, which is a result of the line voltage dropping so low. With a regulated AC voltage, the KSA-250 could probably be expected to put out 2kW into 1 ohm. Although Krell specifies a 4kW output rating in 0.5 ohms, I didn't have a half-ohm resistor that would handle such power. Also below is the link from stereophile's full review of the Krell KSA 250 power amp.. |
| RE: Krell KSA 250 power amp is operating on class 'A' until 3 ohms.., posted on February 24, 2016 at 23:46:03 | |
alan.revera@yahoo.com Audiophile Posts: 16 Location: California Joined: February 23, 2016 | I took a quick look, it draw 12A from the main. At 117V, that's 1400W burning at idle. That's close to my wild guess of at least 600W/channel. That's way way too much heat. You need air conditioning in the room to run that. the amp must be burning hot like a stove!!! The heat sink is being pushed to the very limit. I guess I have to rule this one out. I think I'll be happy with 10W to 20W of class A power and then change to AB. I once increase the bias of my Acurus to 100mA/transistor pair to get about 1W of class A, the amp already got very hot. |
| For a few hundred more, posted on February 25, 2016 at 03:58:15 | |
Posts: 2215 Location: new jersey Joined: November 15, 2005 | You can find a used PASS X250. It runs the first 20 or 25 watts Class A then 250@ 8ohm in AB. Very good sounding amp. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 05:34:10 | |
Posts: 1105 Location: St. Louis, MO, USA Joined: August 14, 2010 | As I said the s300 is a fine amp but it is not a Krell KSA 150. You can make your decision but you asked. The KSA is a nice step up from the s300. From the Stereophile review of the KSA250 ' KSA-250 utilizes class-A circuitry throughout the audio and power-supply regulation stages, and can actually generate 320Wpc into 8 ohms. It is DC-coupled throughout, without any capacitors in the signal path, and is a fully modular design employing gas-tight pressure connections between all subassemblies, allowing quick and easy servicing in the field. ' ' Something else you might take into consideration before purchasing and installing a KSA-250 is the amount of heat produced. All class-A amps run hot, and this one is no exception. Even with the cool fall weather outside, our listening/family room turns into an inferno within 45 minutes after powering up. ' It's also more than A/B versus A, The KSA is just a better amp, period. You can buy a used s300 for under $1k used and may be happy but the fact remains it's not the same level of gear as a KSA http://www.stereophile.com/solidpoweramps/191krell/#ttYyrJ3j2mUvThTp.97 |
| You think KAS 250 is hot.., posted on February 25, 2016 at 06:51:49 | |
Posts: 7472 Location: Calgary, Alberta Joined: October 16, 2007 Contributor Since: April 6, 2008 | Try to live with one of these. Krell EVO 402 power output 400 watts per channel into eight Ohms, 800 watts per channel into four Ohms, 1,600 watts per channel into two Ohms and 3,200 watts per channel into 1 ohm load. Actually it's not too bad as the heat dissipation is no more than the Audio Research D-250 tube amp that it replaced. For more info on specs.. |
| Unless you're really pushing the 402? The KSA 250 runs much hotter. :), posted on February 25, 2016 at 08:09:12 | |
David S. Audiophile Posts: 3313 Location: Mountains of WNC Joined: August 31, 2000 | The 402 is only burning 370 watts at idle. The KSA-250 is right near 1400. That is a WHOLE lot more heat! |
| RE: For a few hundred more, posted on February 25, 2016 at 09:53:52 | |
Posts: 16 Location: California Joined: February 23, 2016 | thanks I was looking around after I read your post last night, none available at the moment. I'll keep looking. Thanks |
| Agreed.. the EVO 402.., posted on February 25, 2016 at 10:55:07 | |
Posts: 7472 Location: Calgary, Alberta Joined: October 16, 2007 Contributor Since: April 6, 2008 | at idle produces less heat, however, when they're fully operating they can consume up to a maximum of 3800 W. and trust me they can run hotter than the KSA 250 of which I had at that time. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 14:57:12 | |
Mr Peabody Audiophile Posts: 1105 Location: St. Louis, MO, USA Joined: August 14, 2010 | Sorry, I answered from my email and see folks already fround the Stereophile review and suggested the X250. The x250.5 is the next gen and X250.8 is current gen, although really expensive. As a side note others involved in Threshold went on to create Coda which are also good amps more along the lines of the Threshold, although newer versions seem to be evolving more. Did you see in the review where Krell recommends a dedicated power line for the ksa250? Another amp worth considering is the ATI 3k series, they are an excellent bang for the buck but do require a 20 amp outlet or work around. They used to be zero feedback designs similar to my s300 but the ATI are beasts. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 18:45:06 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | The KSA is not a balanced design , it has balanced inputs .. |
| RE: Krell KSA 250 power amp is operating on class 'A' until 3 ohms.., posted on February 25, 2016 at 18:50:26 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | No way , a KSA200 pulls 12A , not a KSA 250, they usually idle at approx 5- 7 amps max.. Anyway this is not about which amp idles more or has more class-a bias , the Threshold is a trouble free design, the Krells not as much and the high bias ones will require some service ever few or so years, to stay on top sonically. Ultimately i find fhe Krells better , but it has to be tip top which will require servicing and adjustments . |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 18:58:12 | |
Posts: 1105 Location: St. Louis, MO, USA Joined: August 14, 2010 | Exqueeze me... where did you hear that misinformation? From the KSA manual ' Krell is committed to balanced operation in all products. Balanced systems have |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 19:21:52 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | Where .? from looking inside and modifying . :) The KSA200/250 is not a true balanced design , its also not, nor is there any such thing as class-a to 3 ohms , regardless of how many times they (Krell) say it , it's Called Marketing , aka, BS .
You would need two KSA 250 bridged to have a fully balanced stereo amplifier .. :) As to class -a to 3 ohm , when i stop laughing i can address that .. |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 19:28:26 | |
Posts: 2521 Location: Front row center Joined: November 30, 2011 | BTW , Feel free to show me a bench test describing the Krell as a fully balanced design , I'm not aware of Dan having designed a fully (stereo) balanced Krell , or that they (Krell) have one even today. Spectral mono blocs ( 1 eg) are a fully balanced design .. The KSA200 was considered full class-a because they stayed in class-a mode until clipping at 8 ohm, not the KSA250. When you half the impedance you have half the class-a power available . So ,class-a power available , 200watts at 8 ohm
misnomer much . :) |
| RE: Threshold S/300 vs Krell KSA150 or S/500 vs KSA250, posted on February 25, 2016 at 21:46:53 | |
Posts: 16 Location: California Joined: February 23, 2016 | I don't have the schematic of KSA150 or KSA250, that's part of the question at the beginning whether anyone has link to their schematics so I can read it. I do have schematic of KSA100 and KSA50, I am an EE but I don't know what exactly you mean by balance input. I can assure you there is nothing balance input output of the KSA100 and KSA50, they are the simple basic power amplifier design that the output drive one input of the speaker, the other input of the speaker just connect to the ground return. There is nothing balance about it. In fact I do DIY and building my own amp. without getting to technical, Krell KSA100 and KSA50 is very basic circuit that is NOT what people consider optimal. They both don't have tripple output stage(3EF OPS) nor high gain intermediate gain stage(darlington VAS or cascode VAS). The design is not much better than the cheap Acurus I have. The main difference is Krell has more output transistor pairs running at higher idle current to get a deeper Class AB. Like someone said here, Class A has to be defined at what load impedance. Most amps that are class A for 8ohm load likely to go to Class AB with 4ohm or lower. It's all about the idle current. The peak class A current usually is twice the idle current. If you drive above that, the amp turns into class B( only one side on). Lets do some simple power calculation on the dissipation of the KSA250 that is 250W into 8ohm class A. W=V^2/R => 250=(1/2) V^2/R. Peak voltage is 63V which implies peak current is 7.9A. You need power supply of +/-70V minimum to support 250W. Idle current is half of 7.9A with is 3.95A. Therefore idle power dissipation is W=IV= 3.95A X 140V=553Watt per side. That is at minimum of 1100W of power dissipation just sitting there burning. Real circuit is not ideal, if it is 80% efficiency, The KSA250 would be burning 1375W sit idling. AND it will go into class AB with 4 ohm with this calculation. It would be a lot worst if you want class A with 4 ohm. |
| See if you can mod the Threshold S/300, posted on February 27, 2016 at 18:14:41 | |
Posts: 3371 Joined: August 1, 2002 | The earlier S150 can have the output transistors rebiased, a voltage jumper change done on the transformer, plus a few other simple things done, voila, a much better sounding SA3. Vintage amp repair can help you on that. There currently are both the big Kell SA250 and Threshold S300 on AGon. |
| RE: See if you can mod the Threshold S/300, posted on February 28, 2016 at 00:46:28 | |
Posts: 16 Location: California Joined: February 23, 2016 | Do you mean half the rail voltage and bias the output stage to class A? I heard about this too. I think that's the difference between S/300(class AB) and SE3( or SA3) that is class A. What is Agon? do you mean Audiogon? I looked, there's no Threshold S/300 or S/500 available within 100 miles where I live. I really want to get the S/300 as I don't listen at super high volume, it has a few watts of Class A power which is plenty for me already. |
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Ended!
For sale is a Threshold S/300 Series II Stasis Linear State Power Amplifier with it's original manual. This amp has been gone through by our techs and is in perfect working condition. It is cosmetically great condition with one small scratch at the front of the top plate (see photos for details). This is a great sounding amplifier that will pair well with most hifi systems.
We do not have the original packaging so this amp is for local pick up only, but we can help facilitate shipment of this item via an LTL freight company. Please contact us for a shipping quote if interested.
Specs:
Power output: 150 watts per channel into 8тДж (stereo)
Frequency response: 7Hz to 100kHz
Total harmonic distortion: 0.1%
Gain: 26.6 dB
Signal to noise ratio: 100dB
Semiconductors: 14 x transistors per channel (output)
Dimensions: 8.72 x 19 x 13.125 inches
Weight: 56lbs
Year: 1983
Product Specs
| Condition | Very Good items may show a few slight marks or scratches but are fully functional and in overall great shape.learn more |
| Brand | Threshold |
| Model | S/300 Series II |
| Categories | Amplifiers |
Solid deck for a fair price.
David O. - February 11, 2020
Dylan V. - January 29, 2020
Great speakers thanks!
Shred E. - December 08, 2019
Very fast shipping and unit was as described. Arrived in great shape and probably the best packing job I have seen. I would definitely buy from seller again.
Joe R. - December 01, 2019
Jefferson H. - November 29, 2019
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Shipping Policy
Available for local pickupfrom Chicago, IL, United States
Ships from Chicago, IL, United States to:
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- $137.85CAD
I will ship with tracking to the continental United States. Alaska, Hawaii, and international shipments may incur additional charges. Aimp skins deviantart.
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Return Policy
Return Window
This product can be returned within 7 days of receipt.General Terms
Items must be returned in original, as-shipped condition with all original packaging and no signs of use. Buyer assumes responsibility for all return shipping costs unless the item was not received as described.
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Buyer receives a full refund in their original payment method less any shipping costs.
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We offer a 14 day return from the initial shipping date. Used items must be returned in like condition. New items, with the exception of defective items, must be returned sealed in the box. Return shipping will be paid for by the purchaser.