Sure , where are 150w triode DiY amps trashing solid state ARc CL150 on this forum ? Where are 750 W tube amps taking on VTL MB 750 I owned ? We are serving the OP because I assume there is a reason he considers Big tube amps vs what is typically discussed here.
Used ARC amps are usually a tremendous bargain because they are considered " solid state " by tube purists , butt ugly and " overbuilt" by sophisticated folk and fall victims to ARC proliferation in releasing new models one uglier than another by civilized world standards...
Used ARC amps are usually a tremendous bargain because they are considered " solid state " by tube purists , butt ugly and " overbuilt" by sophisticated folk and fall victims to ARC proliferation in releasing new models one uglier than another by civilized world standards...
I did mean, I hope you have better experiences. I am not against solid state. I honestly think hybrids are the way...
You toss toss those power numbers thinking it's like unachievable. But that's totally normal, and even maybe underwhelming, if you do radio. They think it's normal. Aka, easily done. It does broadcast across the planet.
And I don't think you are reading this forum, people routinely trounce factory stuff, or take it to another level.
Don't forget, if you are on here, it's supposed to be fun. It seems you are upset you spent $$$.
Not sure on the design comment, I actually like the Audio Research design of this time. I bought the book and like the new stuff, so maybe all of it?
You toss toss those power numbers thinking it's like unachievable. But that's totally normal, and even maybe underwhelming, if you do radio. They think it's normal. Aka, easily done. It does broadcast across the planet.
And I don't think you are reading this forum, people routinely trounce factory stuff, or take it to another level.
Don't forget, if you are on here, it's supposed to be fun. It seems you are upset you spent $$$.
Not sure on the design comment, I actually like the Audio Research design of this time. I bought the book and like the new stuff, so maybe all of it?
I have a pair of Classic 150.
Over a year ago I had issues with the 'Tube Saver' circuit on one of them. I took it to a recognized ARC Service provider/dealer and after many months they finally gave up. Some of the semiconductors (color coded) are no longer available from ARC and they don't even have selection criteria any longer, I verified this by speaking with the ARC Service Manager at the time.
Currently they sit in my basement, waiting for me to sell or to become 'boat anchors'.
Note: even if you have schematics these amplifiers are very difficult to troubleshoot.
Over a year ago I had issues with the 'Tube Saver' circuit on one of them. I took it to a recognized ARC Service provider/dealer and after many months they finally gave up. Some of the semiconductors (color coded) are no longer available from ARC and they don't even have selection criteria any longer, I verified this by speaking with the ARC Service Manager at the time.
Currently they sit in my basement, waiting for me to sell or to become 'boat anchors'.
Note: even if you have schematics these amplifiers are very difficult to troubleshoot.
Wow, nice amplifiers - I would definitely focus on those. You've clearly got the skilz. Please share your project with us as you go. 😀
My friend was one of the oldest if not the oldest ARC dealer in US . For last 3 years he gradually withdrew from the business and in last couple months they cleaned the shelves and closed the shop so my experience with ARC service dates 3 years back now. I guess things have changed with service dept there. Hard to believe they don't have a cross reference for usually standard semiconductors used in those circuits.
The service is a revenue generating business. If the tech is unable to find the fault fast they put it on the shelf and after months they push it out. Find competent local tech not related to dealer service. it's true the amps are complicated but not more than a big solid state amp so replacing a screen resistor and pocketing $500 is not going to happen.
As to my comments about the numbers and Watts , well if one is able to build better amps than ARC Classic 150 , equalling them for power and build quality for $3.8k my hats off. I want to see those DIY amps .
Actually an employee bought ARC in 2020, and it is back as a closely held local business.
https://www.whathifi.com/news/audio-research-sold-by-mcintosh-group-to-former-sales-director
Well that is good news. I for one love my old, highly modded Audio Research gear. Let us hope they don't collapse.
In 2021 a German professional reseller CJM Audio sold these amplifiers in perfect state for € 3499,- the pair.
So 3500 for a broken pair is way too much.
For that money buy a Threshold SA/4 much better and troublefree amplifier.
So 3500 for a broken pair is way too much.
For that money buy a Threshold SA/4 much better and troublefree amplifier.
Well , it should be a piece of cake to tackle a couple of transistors for experts like you guys. There is no Treshold amp in universe which could touch those ARC amps. That's a rich people audio- 16 output tubes and gobs of heat. Not for DIY schmucks . This is what I'm telling my friends who are thinking of buying old , big ARC amps on cheap to gain on prestige and grow a couple of inches .... Bottom feeder like myself realised this quite a long time ago even if my friend was one of the oldest Audio Research dealer in US and I could grab some of the bargains from his trading in customers . Having said that I'm tackling Reference 75 SE which needed a minor repair and it is an absolutely lovely amp . SS front end , Russian super tube driver stage and KT150 . I wish I had $5k to buy it ($11k list) but I don't so I try not to form an attachment 🙂
AR has no information on the jfets in the Classic 150 amp they say and have no spare parts - 3500 Euros for 1 good amp and a spares unit is too much money - only if you can find a spare.
i have a friend here in Canada with a Classic 15O thats good and one with a problem. I’m sure he can give you a better price for them.
i have a friend here in Canada with a Classic 15O thats good and one with a problem. I’m sure he can give you a better price for them.
..and include free shipping from Canada to Italy. I havent heard that ARC refused to take any of their amps in for repair . They refuse to repair CD players with obsolete lasers but no amps . It just cost money. Why buy a car you can't afford to repair or get a GF which requires a maintenance out of your league?
What do you mean by DIY schmucks?
In what sense? Like burning tubes and failing components? The late chief editor of Stereophile J. Gordon Holt preferred his Threshold SA/1 mono amps over a ARC D250 or M300’s the latter the pentode version of the Classic 150 triodes.
Back to OP question. For background information, the Classic 150 and M300 are twins. The main difference between the 2 is the Classic 150 output tubes are connected in triode, and if you want to get picky, the RCA model has a more sophisticated input stage phase inversion circuit. The balanced input stage of both amps is identical. I have a pair of M300 amps that I bought about 8 years ago as a winter project. I bought them as untested non-working. I never plugged them in or did any checks; just put them on the shelf. 3 years ago I decided to put them on top of the project list. The local ARC dealership, Audio Dimensions in Royal Oak, MI told me that ARC no longer sells parts directly sells parts to individuals. I called ARC and sure enough, they will only sell to authorized ARC dealers. That put the amps back to the bottom of the project list. Fast forward to new owner, and there was a change of heart towards the DIY owner.......parts were once again available to individuals.
I checked on all of the active devices, and unfortunately many are not available. My goal was to buy all of the active devices just to have them on hand. Once I start troubleshooting, the odds of completing a project is better if I have the parts on hand. Putting a pause in the process waiting for parts is the kiss of death. Per the original OP post, the remaining parts ARC has in stock are around $15.00. I feel that's a fair price. I personally don't have the time to take a good part and test it to determine key characteristics. Or the equipment capable to measure some of the parameters like gate capacitance, or a HV curve tracer.
When I talked to ARC, I was told that they can no longer service the M300. If you look at the ARC website there are a number of amps that are no longer serviceable due to parts obsolesce.
In retrospect it's ironic that ARC created the M300, and Classic and VT series of amps because new US production small signal tubes (well all tubes) was at an end. ARC switched to hybrid designs to continue "tube amp" production. And now we are at a point in time where high quality small signal tubes and power tubes are available but semiconductors suitable for audio are no longer available. In the past I heard that the reason the M300 became the Classic 150 is that the Chinese sourced 6550 tubes failed in the M300, but would last in a triode configuration. Makes sense.
My $0.02 is that any of the ARC hybrid amps are on borrowed time. And I'm saying that while openly sharing that I have a bad pair of M300 amps. Once they fail the only viable option is to buy a working amp for parts, or to match up to get a working pair and a broken pair. Who knows maybe with 2 broken doner amps it's possible to keep a working pair running for another 40 years.
Have fun!
I checked on all of the active devices, and unfortunately many are not available. My goal was to buy all of the active devices just to have them on hand. Once I start troubleshooting, the odds of completing a project is better if I have the parts on hand. Putting a pause in the process waiting for parts is the kiss of death. Per the original OP post, the remaining parts ARC has in stock are around $15.00. I feel that's a fair price. I personally don't have the time to take a good part and test it to determine key characteristics. Or the equipment capable to measure some of the parameters like gate capacitance, or a HV curve tracer.
When I talked to ARC, I was told that they can no longer service the M300. If you look at the ARC website there are a number of amps that are no longer serviceable due to parts obsolesce.
In retrospect it's ironic that ARC created the M300, and Classic and VT series of amps because new US production small signal tubes (well all tubes) was at an end. ARC switched to hybrid designs to continue "tube amp" production. And now we are at a point in time where high quality small signal tubes and power tubes are available but semiconductors suitable for audio are no longer available. In the past I heard that the reason the M300 became the Classic 150 is that the Chinese sourced 6550 tubes failed in the M300, but would last in a triode configuration. Makes sense.
My $0.02 is that any of the ARC hybrid amps are on borrowed time. And I'm saying that while openly sharing that I have a bad pair of M300 amps. Once they fail the only viable option is to buy a working amp for parts, or to match up to get a working pair and a broken pair. Who knows maybe with 2 broken doner amps it's possible to keep a working pair running for another 40 years.
Have fun!