Hello,
Does anyone remember this nice old amp ? 10 watts with positive forward feedback. How does it sound compared to today's Class A amps ?
thanks.
Does anyone remember this nice old amp ? 10 watts with positive forward feedback. How does it sound compared to today's Class A amps ?
thanks.
Never heard the amp itself, but I wish him and Gary would get back into building amps again. The quality of their product is impeccable. I own some of his other gear.
we really never stopped
RadiantNRG,
Gary and I continued building amps we really never stopped. All the new amps will be listing shortly.
John B
RadiantNRG,
Gary and I continued building amps we really never stopped. All the new amps will be listing shortly.
John B
This is about audio and not energy
Tekko,
What difference would that make? This is about audio and not energy. So I will keep to the subject of amplifiers. If you chose to have that debate this is not the place. I did not want to join here as I knew this would come up. But I was asked to help with some of the amplifier parts. You want me gone just say the words.
John B
.
Tekko,
What difference would that make? This is about audio and not energy. So I will keep to the subject of amplifiers. If you chose to have that debate this is not the place. I did not want to join here as I knew this would come up. But I was asked to help with some of the amplifier parts. You want me gone just say the words.
John B
.
as I'm always eager to learn something , may I ask for 10/10 sch ?
off course , if possible .
btw. Bedini name certainly mean something , so your place here is long ago deserved .
off course , if possible .
btw. Bedini name certainly mean something , so your place here is long ago deserved .
Why, oh why?
Guys,
Did Nelson Pass or Frank Schroeder or others get treated like this? If so, do you think that they'd have stayed?
Guys,
Did Nelson Pass or Frank Schroeder or others get treated like this? If so, do you think that they'd have stayed?
Nanook
feel free to say "Tekko" , instead of "guys" .
Tekko was sole one rude around.
feel free to say "Tekko" , instead of "guys" .
Tekko was sole one rude around.
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John, Thank you for joining us here are DIY, Please forgive any such negative comments you may have, or will experience here as there are FAR more of us that appreciate your time!
Thank You!
Zc
Thank You!
Zc
The 25/25 with Quads was the hot setup back in the day. I heard a few different versions of that setup, consistently nice. Never heard a system with a 10/10, never even seen one in person. What kind of speakers was it intended for?
I understand all this negativity
Look guys, I understand all this negativity but sometimes that is where life takes us.
The diagram was posted from someone that removed company information. The model 10/10 is not much different from the 25/25, so you have the diagram. The difference is the bias.
This was a toss up at the time for an auto bias amplifier, that is why you find the 5.6 k
resistor in the emitter circuit of all the amplifiers. This resistor locks the bias for leakage on the output transistors. Some of my designs come from the days of Acoustic Control working with the model 400 amps which were all auto bias. To make any of the Bedini amps auto bias you need a resistor placed in the VBE multiplier circuit to ground and the 2K pot removed. I would not suggest doing it on these boards, but it can be done. Remember who I worked for Maden Sharma he was a tricky guy with circuits.
I have a question for you guys. A friend brought me a DIY Leach clone that he was having problems with, here is the problem I see right away.
The negative half of the wave clips before the positive half, is this normal on this build? Also the square wave is not flat at 1K it's rounded on the leading edge is this normal? To me these are very bad results and not very stable. The THD of this Amp is over 1%. It also seem to be lacking base response compared to the Mk 100/100. So maybe someone here could help before I get into it.
Thanks for your support.
John B
Look guys, I understand all this negativity but sometimes that is where life takes us.
The diagram was posted from someone that removed company information. The model 10/10 is not much different from the 25/25, so you have the diagram. The difference is the bias.
This was a toss up at the time for an auto bias amplifier, that is why you find the 5.6 k
resistor in the emitter circuit of all the amplifiers. This resistor locks the bias for leakage on the output transistors. Some of my designs come from the days of Acoustic Control working with the model 400 amps which were all auto bias. To make any of the Bedini amps auto bias you need a resistor placed in the VBE multiplier circuit to ground and the 2K pot removed. I would not suggest doing it on these boards, but it can be done. Remember who I worked for Maden Sharma he was a tricky guy with circuits.
I have a question for you guys. A friend brought me a DIY Leach clone that he was having problems with, here is the problem I see right away.
The negative half of the wave clips before the positive half, is this normal on this build? Also the square wave is not flat at 1K it's rounded on the leading edge is this normal? To me these are very bad results and not very stable. The THD of this Amp is over 1%. It also seem to be lacking base response compared to the Mk 100/100. So maybe someone here could help before I get into it.
Thanks for your support.
John B
Mods. please read (sole rude one...)
I was making a general statement and meant to include any that might read the thread. Yes specifically Tekko was rude (it would be a nice olive branch to have Tekko apologize and take any other matters up with Mr. Bendini directly in a more appropriate manner)
Mr. Bendini, please stay, any insight or comments are appreciated (I do not own, nor have ever owned any of the Bendini gear). Your experiences and comments are valued by most here far more than you can imagine and can create a huge resource for many of us that are truly interested in this hobby or ours. I can say any DIY projects I touch are terribly implemented but thankfully well designed (which I don't usually do) and benefit from the inspiration from others.
I suspect that Tekko had no real interest in reading or partaking of any knowledge that would be cleaned here.
for mods and readers: The basic rules of the forum state that no personal attacks are to be tolerated. Let's keep this forum within the realm of it's intention: diy audio.
The Leach clone question:This is exactly what this forum is about! Sometimes even greats amongst us can use a little help🙂. Unfortunately I have no information to help but any others?
I was making a general statement and meant to include any that might read the thread. Yes specifically Tekko was rude (it would be a nice olive branch to have Tekko apologize and take any other matters up with Mr. Bendini directly in a more appropriate manner)
Mr. Bendini, please stay, any insight or comments are appreciated (I do not own, nor have ever owned any of the Bendini gear). Your experiences and comments are valued by most here far more than you can imagine and can create a huge resource for many of us that are truly interested in this hobby or ours. I can say any DIY projects I touch are terribly implemented but thankfully well designed (which I don't usually do) and benefit from the inspiration from others.
I suspect that Tekko had no real interest in reading or partaking of any knowledge that would be cleaned here.
for mods and readers: The basic rules of the forum state that no personal attacks are to be tolerated. Let's keep this forum within the realm of it's intention: diy audio.
The Leach clone question:This is exactly what this forum is about! Sometimes even greats amongst us can use a little help🙂. Unfortunately I have no information to help but any others?
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Model 10/10 Bedini
Nanook,
Thanks for your kind words, I take no offense on this issue. But for those that want to know about the model 10/10, that little Amplifier was given to the Dealers at the time as a sales leader. So what they would do is order a mix of amplifiers then send them all back and keep the model 10/10 ( Number Made 40) so Gary and I stopped making them for that reason. You would find then that they were being sold for $500 or more. Today you can not find one for less then that. The 25/25 and the model 10/10 used the RCA 2N3055 H transistor The normal 2N3055 could not survive the abuse. The main use for them was the Stax headphones and Quads. The Topology was to couple a Dual Diff front end to a Quasi output stage feed forward, why because it sounded better. It would be easy to re-build the model 10/10 today with flat packs and I just might do that and DIY it. The Q series is all flat packs and were sold in England. Gary is working on the Bedini pages where we can post all the amplifiers we have left for sale. I hope this answers most of your questions and if not, Ask.
John B
Nanook,
Thanks for your kind words, I take no offense on this issue. But for those that want to know about the model 10/10, that little Amplifier was given to the Dealers at the time as a sales leader. So what they would do is order a mix of amplifiers then send them all back and keep the model 10/10 ( Number Made 40) so Gary and I stopped making them for that reason. You would find then that they were being sold for $500 or more. Today you can not find one for less then that. The 25/25 and the model 10/10 used the RCA 2N3055 H transistor The normal 2N3055 could not survive the abuse. The main use for them was the Stax headphones and Quads. The Topology was to couple a Dual Diff front end to a Quasi output stage feed forward, why because it sounded better. It would be easy to re-build the model 10/10 today with flat packs and I just might do that and DIY it. The Q series is all flat packs and were sold in England. Gary is working on the Bedini pages where we can post all the amplifiers we have left for sale. I hope this answers most of your questions and if not, Ask.
John B
thermal bias is detected two ways
SY,
The thermal bias is detected two ways, if you notice on any of the pictures The VBE multiplier transistor is the same as the output transistors that is why the odd numbers on the heat sink. I always found that the VBE transistor should have the same gain as the output transistor. Since it was going to be auto bias that 5.6 K resistor is fed back to the base of the VBE Multiplier, it is the quiescent current that must be tracked, so I choose to do it this way. I do not believe in putting diodes on heat sinks, it's not fast enough for me.
You know if you lose the VBE transistor you can kiss the amplifier good by. Another way to look at this is by the time you detect the heat of the output stage it's too late. I have never had a failure this way with the VBE circuit. I found all these things out with work on big 300 watt RCA amplifiers in the 70's. I have seen people beat these amps up at 1.6 to 1 ohms so I do it this way.
I do not believe in protection circuits at all as they spoil the sound. It has been almost 40 years now and the come back is minimum. The tweaks kill the amp not John. This is just the way I do it, you might have other ideas. The Heat Sink is the other problem so I have tested that too.
Bent pieces of metal work better then some of the big expensive extrusions and it keeps the cost down for the consumer. The faster the heat radiates the better the amp runs. Some here say he used cheesy heat sinks with bent pieces of metal, but did they do the experiments, no. I have also seen some mounting heat sinks as heat traps, in other words backwards instead of the correct way. So thermal management what is that? I run the amps at 1/3 power for days to see what happens. The 25/25 is an example of over heat as some have said but it keep going to this day, anybody can break anything given enough time. Hope this helps.
John B
SY,
The thermal bias is detected two ways, if you notice on any of the pictures The VBE multiplier transistor is the same as the output transistors that is why the odd numbers on the heat sink. I always found that the VBE transistor should have the same gain as the output transistor. Since it was going to be auto bias that 5.6 K resistor is fed back to the base of the VBE Multiplier, it is the quiescent current that must be tracked, so I choose to do it this way. I do not believe in putting diodes on heat sinks, it's not fast enough for me.
You know if you lose the VBE transistor you can kiss the amplifier good by. Another way to look at this is by the time you detect the heat of the output stage it's too late. I have never had a failure this way with the VBE circuit. I found all these things out with work on big 300 watt RCA amplifiers in the 70's. I have seen people beat these amps up at 1.6 to 1 ohms so I do it this way.
I do not believe in protection circuits at all as they spoil the sound. It has been almost 40 years now and the come back is minimum. The tweaks kill the amp not John. This is just the way I do it, you might have other ideas. The Heat Sink is the other problem so I have tested that too.
Bent pieces of metal work better then some of the big expensive extrusions and it keeps the cost down for the consumer. The faster the heat radiates the better the amp runs. Some here say he used cheesy heat sinks with bent pieces of metal, but did they do the experiments, no. I have also seen some mounting heat sinks as heat traps, in other words backwards instead of the correct way. So thermal management what is that? I run the amps at 1/3 power for days to see what happens. The 25/25 is an example of over heat as some have said but it keep going to this day, anybody can break anything given enough time. Hope this helps.
John B
As SY says, thanks.
I may get lost sometimes, but thanks to folks like you I can usually get myself back on track. And your shared info is one of the great things about it here.
I guess I should seek out a schematic (or if John chooses to post one) to follow along the conversation. Somewhere I thought I had seen an updated Bendini webpage.
I've always like the idea of good small amplifiers. I have a few Class-D amps, but they cannot compare to the Threshold Nak receiver I have, and things like the Musical Fidelity (or British Fidelity) class A integrated amps. I would love to et hold of one of those litttle BBQs to keep as a low powered and reliable reference. The reason I never bought one of those was that I had small kids at the time they came onto the marcket. They're 25 and 30 now so the likelihood of them getting burnt is pretty much gone.
I may get lost sometimes, but thanks to folks like you I can usually get myself back on track. And your shared info is one of the great things about it here.
I guess I should seek out a schematic (or if John chooses to post one) to follow along the conversation. Somewhere I thought I had seen an updated Bendini webpage.
I've always like the idea of good small amplifiers. I have a few Class-D amps, but they cannot compare to the Threshold Nak receiver I have, and things like the Musical Fidelity (or British Fidelity) class A integrated amps. I would love to et hold of one of those litttle BBQs to keep as a low powered and reliable reference. The reason I never bought one of those was that I had small kids at the time they came onto the marcket. They're 25 and 30 now so the likelihood of them getting burnt is pretty much gone.
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Now that answers a nearly as old question of mine, witnessed more than one 25/25 overhere, but not a single 10/10.
25/25, a Real Class A power amp (not like some of them pretenders, ya hear)
For real Class A, a word from our sponsor : BASIC AMPLIFIERS : Department of Defense : Free Download & Streaming : Internet Archive
(not my catch, stumbled across the link while i was reading at the Spanish audio forum a week ago)
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get the real diagram
Jacco,
Go get the real diagram it's posted in the help with the 100/100 One Meg. You can not really make this drawing out. but the 10/10 is just missing two 2N3055H's , so it has a total of three 2n3055H's on the heat sink.
Jacco,
Go get the real diagram it's posted in the help with the 100/100 One Meg. You can not really make this drawing out. but the 10/10 is just missing two 2N3055H's , so it has a total of three 2n3055H's on the heat sink.
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