I put this on hold for several reasons:
1) I didn't have the time.
2) I wasn't happy cloning a currently available product. That makes us no different from all the pirate pcb shops out there.
3) I was advised by a service tech in the know that the schematics available on the web have several major inaccuracies.
1) I didn't have the time.
2) I wasn't happy cloning a currently available product. That makes us no different from all the pirate pcb shops out there.
3) I was advised by a service tech in the know that the schematics available on the web have several major inaccuracies.
Dragiing out the old...
I was cleaning my files (looking of divorce paperwork) and found my old 3 / 4B manuals..
I just happen to have a pair of Toroids SCREAMING to be the heart of a 3B..
I absolutely loved my old 3B and liked the 4B pro. The Rowland that replaced the 3B was better but didn't have the same "soul"..
I bet it would STILL sound great and it might even spawn the purchase of newer Bryston amps.
So with that said, I would be happy for optimised PCB's and parts kits with "upgraded" parts for even an original 3B like we did for the Krell KSA-50.
Any takers?
I was cleaning my files (looking of divorce paperwork) and found my old 3 / 4B manuals..
I just happen to have a pair of Toroids SCREAMING to be the heart of a 3B..
I absolutely loved my old 3B and liked the 4B pro. The Rowland that replaced the 3B was better but didn't have the same "soul"..
I bet it would STILL sound great and it might even spawn the purchase of newer Bryston amps.
So with that said, I would be happy for optimised PCB's and parts kits with "upgraded" parts for even an original 3B like we did for the Krell KSA-50.
Any takers?
I know this is an old post, I am researching to buy a power amp, I looked at Bryston and I came to almost exact conclusion and you said them all.
From the pages I read here, Bryston seems to be more touted in PA, recording studio and even for musical instruments. From my experience, it is a totally different requirements than for home audio. You don't use a Fender to play stereo nor do you use a Threshold/Krell for playing guitar or bass.
This thread just talk me completely out of looking at Bryston.
I always had an impression that Bryston 3B and 4B are one of the highest quality amps at a reasonable price. Also they are very reliable backed by very long transferable company warranty. I am surprised by reading this thread that I might have been wrong, although I wouldn't be easily convinced by one or two opinions.
Anyways, which commercial amps electronics engineers and professional amplifier builders consider high quality, and worth cloning by DIYers? Let us not talk about commercial amplifiers of our supporters, like PASS amps.
Anyways, which commercial amps electronics engineers and professional amplifier builders consider high quality, and worth cloning by DIYers? Let us not talk about commercial amplifiers of our supporters, like PASS amps.
Why not talk about Nelson Pass's amps? I am actually waiting for a Threshold S/300 or even S/500 available. I looked at the schematics, it's sure a lot more logical and the designs are praised by popular books from Self and Cordell. There is just not many S/300 or S/500 on the market and I am tired of waiting. that's the reason I start to look at other brands like Nakamichi ( Pass design), Krell and others like Bryston. Krell are just too too too heavy and burn too too much power, You need a special AC inlet and you need air conditioning for the room!!!
Ha ha, anything that is designed for studio, PA and musical instrument HAS to be rugged and reliable to take the abuse of going on the road, delivering full continuous power. We crank them up, drop on concrete and all!!!
Ha ha, anything that is designed for studio, PA and musical instrument HAS to be rugged and reliable to take the abuse of going on the road, delivering full continuous power. We crank them up, drop on concrete and all!!!
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Hi Doug,
I would have loved a great Canadian product, but those were not very good amplifiers. The warranty was a two pronged instrument. Keep folks out of the amps (or the truth would be out) and it was advertising. If you have to spend money on something, spending it on your customers is a great place to do that. I think they had a fantastic idea there. I just wish the amp was everything they claimed it was.
The parts were the least expensive they could buy. The design wasn't ready for production as it had very poor bias control, a strong +'ve tempco on the bias current. Then there was the under-rated power switch and thin chassis metal. My personal opinion is that they were irresponsible for selling that design. Oh yeah, forgot to mention the total lack of speaker protection. They failed, and so did the flaming speaker. I have seen this first hand. A good 1/2" hole in the PC board caused by a simple component failure. Talk about arrogance! "Our amps don't fail" they said. Yeah, right. Everything has a failure rate.
Anyway, I haven't heard or seen the new ones. They are supposed to be much better now that they have a real engineer on staff.
-Chris
I would have loved a great Canadian product, but those were not very good amplifiers. The warranty was a two pronged instrument. Keep folks out of the amps (or the truth would be out) and it was advertising. If you have to spend money on something, spending it on your customers is a great place to do that. I think they had a fantastic idea there. I just wish the amp was everything they claimed it was.
The parts were the least expensive they could buy. The design wasn't ready for production as it had very poor bias control, a strong +'ve tempco on the bias current. Then there was the under-rated power switch and thin chassis metal. My personal opinion is that they were irresponsible for selling that design. Oh yeah, forgot to mention the total lack of speaker protection. They failed, and so did the flaming speaker. I have seen this first hand. A good 1/2" hole in the PC board caused by a simple component failure. Talk about arrogance! "Our amps don't fail" they said. Yeah, right. Everything has a failure rate.
Anyway, I haven't heard or seen the new ones. They are supposed to be much better now that they have a real engineer on staff.
-Chris
Hi Stephen,
Would you like a great amplifier?
Simple. Build one of ostripper's designs. These are top notch amplifiers. The DIYAudio amplifier (available in the store) was designed by ostripper for the forum. It's a winner, and the boards are available. The ultimate Heathkit amplifier!
I'm serious about this. The biggest problem you will have is deciding what case to build / buy for it. Some guys around here do dynamite metalwork.
-Chris
Would you like a great amplifier?
Simple. Build one of ostripper's designs. These are top notch amplifiers. The DIYAudio amplifier (available in the store) was designed by ostripper for the forum. It's a winner, and the boards are available. The ultimate Heathkit amplifier!
I'm serious about this. The biggest problem you will have is deciding what case to build / buy for it. Some guys around here do dynamite metalwork.
-Chris
I don't like the fact they modulized the OPS section on top of the funny looking OPS circuit. we put so much stress on the speaker cable, the connectors, last thing you want is to add more connectors in the signal path. I remember someone said in this thread that direct wiring or connected by pcb thick trace is better, I agree with that.
Hi Stephen,
That actually wasn't a problem at all. It's the one good thing about that design. Don't forget that contacts were in parallel where needed. These connectors have served reliably in industry for longer than many of us have been alive.
That output stage was interesting (4B only), but it was their holy secret. I had to reverse engineer the amp to repair the first one. They really didn't like that too much.
My hand drawn schematic agreed with the ones they eventually published.
-Chris
That actually wasn't a problem at all. It's the one good thing about that design. Don't forget that contacts were in parallel where needed. These connectors have served reliably in industry for longer than many of us have been alive.
That output stage was interesting (4B only), but it was their holy secret. I had to reverse engineer the amp to repair the first one. They really didn't like that too much.
My hand drawn schematic agreed with the ones they eventually published.
-Chris
Thanks for the suggestion. I am going to build my own in the future.
I read Ostripper's thread. I like the idea of high slew rate and using CFB IPS. I am just too busy on my contracting work. I had to drop my DIY. I want a good amp really really bad for listening and my contract is likely to go for another year. That's why I want to buy a good amp as a stop gap AND as a reference amp for future when I start building. So for the mean time, I am just a hifi nut head until I can get back to the DIY.
I know I should and have gone on the hifi forums, but I trust people here more because you guys go beyond just listening and actually look into different designs and with real life experience in building and testing.
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Hi Stephen,
Fine, then get a Marantz integrated amp like the 1180DC or 1152DC. These can be made to sound outstanding. Well worth the coin because when you have time there are things you can do. Until then they sound really nice. J-Fet inputs like the 170DC and the 300DC (my all time favorite). Mine is "detailed" though. Stock it was really good, but nowhere this good.
-Chris
Fine, then get a Marantz integrated amp like the 1180DC or 1152DC. These can be made to sound outstanding. Well worth the coin because when you have time there are things you can do. Until then they sound really nice. J-Fet inputs like the 170DC and the 300DC (my all time favorite). Mine is "detailed" though. Stock it was really good, but nowhere this good.
-Chris
Thanks Chris
Do you have the schematic?
I am looking at Nakamichi PA-7 also. I remember you gave a pretty high recommendation on that also. Just tired of waiting for the Threshold.
Hi Stephen,
Schematic for which? Probably.
The Nakamichi PA-5 / 7 are good amplifiers. They are very reliable.
The earlier Nakamichi 620 was an excellent amplifier, similar to the Marantz amplifiers I just mentioned. These are my favorite design directions for sound quality.
If you find one, do pick up a Marantz 1152DC, 1180DC, 170DC or 300DC. You will absolutely be happy with that decision. Too bad you weren't close to me. The work I do to them really supercharges their quality of sound. The schematics for all 4 are similar, which is why I am recommending them. The Nak 620 is similar, but the Marantz units end up better sounding. Also, the 1152DC and 1180DC are only two volts different in supply voltage and have the same schematic. Hint, hint!
-Chris
Schematic for which? Probably.
The Nakamichi PA-5 / 7 are good amplifiers. They are very reliable.
The earlier Nakamichi 620 was an excellent amplifier, similar to the Marantz amplifiers I just mentioned. These are my favorite design directions for sound quality.
If you find one, do pick up a Marantz 1152DC, 1180DC, 170DC or 300DC. You will absolutely be happy with that decision. Too bad you weren't close to me. The work I do to them really supercharges their quality of sound. The schematics for all 4 are similar, which is why I am recommending them. The Nak 620 is similar, but the Marantz units end up better sounding. Also, the 1152DC and 1180DC are only two volts different in supply voltage and have the same schematic. Hint, hint!
-Chris
Thanks Chris
I broke down, I just bought the PA-7 for $779 including shipment and everything. It was on ebay for a little while and I took a chance and offered lower than asking price and got it. That's the end of my quest, next is to go the Pass Lab forum here and do all the necessary tune up. I think it will serve good as a reference amp for me in the future to compare my own build.
I have been eyeing the Threshold for a long time as you have notice, the Nakamichi is just the same as S/300 with extra pair of output transistors. It has a lot of things that both books by Self and Cordell been talking about. I can't let it slip by anymore. I am tired of waiting for the S/300 that cost more and one less pair of output transistors. I even willing to pay a lot more for the Krell KSA250 until I found out it is 140lbs!!! On top it burns 1400W just sit idling!!! I am not willing to pay for the electrical bill AND turn on the air conditioning every time I use it!!!
Thanks
I don't think it dissipates more than 500W at idle and normal listening levels. Soundwise it is in a different class from the S300/S500 and variants.
Still, the NAC is a decent amp. Full recapping is mandatory at this age.
Hi Stephen,
Well, now you have tunes and should be able to use it right out of the box. Check for DC offset first, and keep an ear out for any odd noises for the first little while. Once you have the time, you can restore it. I hesitate to use the term "recapping" as it is a gross oversimplification for the work you want to do.
Get the manual for this amp and print off the schematic for one channel. Identify the capacitors in the audio path and use a highlighter to single them out. You can check the main filter capacitors with an oscilloscope. If you feel you must, when you replace the main filter capacitors, don't increase the capacitance more than 20%. There isn't anything wrong with the original value. You can check the condition of those capacitors by looking at the voltage waveform across the capacitor while it is running normally. If the leading edges has "pips" on them, that is a sign of wear. The larger those pips are, the worse their condition is. No pips means they are fine as they are.
Almost time to enjoy some tunes there!
What preamplifier are you going to use with this amplifier?
-Chris
Well, now you have tunes and should be able to use it right out of the box. Check for DC offset first, and keep an ear out for any odd noises for the first little while. Once you have the time, you can restore it. I hesitate to use the term "recapping" as it is a gross oversimplification for the work you want to do.
Get the manual for this amp and print off the schematic for one channel. Identify the capacitors in the audio path and use a highlighter to single them out. You can check the main filter capacitors with an oscilloscope. If you feel you must, when you replace the main filter capacitors, don't increase the capacitance more than 20%. There isn't anything wrong with the original value. You can check the condition of those capacitors by looking at the voltage waveform across the capacitor while it is running normally. If the leading edges has "pips" on them, that is a sign of wear. The larger those pips are, the worse their condition is. No pips means they are fine as they are.
Almost time to enjoy some tunes there!
What preamplifier are you going to use with this amplifier?
-Chris
This is the article I read, it said it draw 12A idle from the AC wall.
Krell KSA-250 power amplifier | Stereophile.com
Also I did the calculation to confirm it. If you calculate 250W into 8ohm, that would be W=(1/2)(V^2/R)=250W. This gives V=63V peak and peak current of 63V/8ohm=8A.
So in order to have classA for 8 ohm load, you have to have 4A of idle current. The rail voltage has to be +/-70V. So power dissipation is 4A X 140V=560W idling per side or 1120W for two channels. It is not 100% efficiency, so 1300W of dissipation is very realistic in order to be pure class A for 8ohm load.
If they specify it's class A at lower load impedance, then the dissipation is going to be higher.
Ha ha, when I read that, I ruled it out even though I want to buy it. It's been on the market for a long time, I think I can bargain it down to $2000 including shipping. But the day to day operating cost is just way too high as I have it on average of 4 hours a day!!!
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