with respect... I was thinking the same thing. But I did some experiments. To see how right I was? Music and the way it is recorded have changed. The amplifiers we make today do not have tone controls. The best opt With a bad choice of capacitor, it may not sound good. The capacitor that... delivers electricity to opt is very, very important. Both the capacity, the type and the manufacturer.
I'm using a good output transformer with 50 uF. The bass is deep and the B+ maintains fine. That pretty much disproves the need for extreme capacitance.
High filter capacitance was and still is a fad. People don't really understand how much you need. The old engineers knew exactly what they were doing.
High filter capacitance was and still is a fad. People don't really understand how much you need. The old engineers knew exactly what they were doing.
Why do you think I disagree with the old engineers? We love tubes..and this confirms them. But things have changed. Science must have found solutions for better sound. Why did you increase the capacity from 10 to 47? Didn't the old engineers draw that Williamson circuit?You didn't agree with their skills?
for the price that was a lot of iron.
Great to be up and running.
-3dB Frequency seems rather good.
Like the cloth wire and the board with bias pot.
Great to be up and running.
-3dB Frequency seems rather good.
Like the cloth wire and the board with bias pot.
Hi hooman,
I didn't say you disagreed with old engineers, it is a popular fad to use very high capacitance.
I work on equipment from the 1920's and up. We started with about 4 uF, there are probably sets with less. 8uF was very popular. The design used a C-L-C setup with the field coil of the speaker as the inductor and a hum bucking coil in the voice coil assembly. The output tube was a 45 or lower powered, single ended setup. 6F6 was a popular output tube. Current draw and output power was modest, and the other techniques did fine for dropping the level of hum. Single ended designs as you should know are very susceptible to hum.
As time went on, better engineering allowed improvements. The biggest being push-pull operation, far more efficient and much lower distortion. The phone companies really jumped on this for long distance repeaters. The best audio equipment was always push pull, were are talking mostly about large radios. The cheapest products continued with class A operation (table radios, cheap phonographs). This is all real history you can research.
As power levels increased, larger filter capacitance was needed. No shock there at all. Rectifier tubes also had to improve as they could only take so much hot switching current. This forced an intelligent design. If you needed more current and capacitance, rectifier tubes were doubled up, and finally solid state diodes were used for both reliability and they were a lot more efficient. Your average single pair 6L6GC or EL34 based amplifier remained with 47 uF and there was no need to increase it. With solid state rectifiers we saw a move to voltage doublers with 200 uF capacitance, in series this is 100 uF. The ripple levels remained about the same as a full wave setup using 47 uF.
New designers (maybe mid 1970's, solid state and tube) started with the "more is better" idea, and this has been taken to extremes as we have seen. Not an engineered solution for normal power levels and impedances. More of a market acceptance and easier sales pitch. If you wish to drive a 2R load at high power, sure you need larger filter capacitors using a solid state amp without an output transformer. With tube products it is all about output power levels and the proper tap on the output transformer.
I absolutely do agree with their skills. I was taught common sense by those engineers. But mindless increases in supply capacitance "backed up" by anecdotal "evidence" just doesn't cut it. But do not discount the pressure from the marketing department and public opinion. Public opinion was formed from a few marketing department s trying to create an edge for their product, much like the feature races of today.
I didn't say you disagreed with old engineers, it is a popular fad to use very high capacitance.
I work on equipment from the 1920's and up. We started with about 4 uF, there are probably sets with less. 8uF was very popular. The design used a C-L-C setup with the field coil of the speaker as the inductor and a hum bucking coil in the voice coil assembly. The output tube was a 45 or lower powered, single ended setup. 6F6 was a popular output tube. Current draw and output power was modest, and the other techniques did fine for dropping the level of hum. Single ended designs as you should know are very susceptible to hum.
As time went on, better engineering allowed improvements. The biggest being push-pull operation, far more efficient and much lower distortion. The phone companies really jumped on this for long distance repeaters. The best audio equipment was always push pull, were are talking mostly about large radios. The cheapest products continued with class A operation (table radios, cheap phonographs). This is all real history you can research.
As power levels increased, larger filter capacitance was needed. No shock there at all. Rectifier tubes also had to improve as they could only take so much hot switching current. This forced an intelligent design. If you needed more current and capacitance, rectifier tubes were doubled up, and finally solid state diodes were used for both reliability and they were a lot more efficient. Your average single pair 6L6GC or EL34 based amplifier remained with 47 uF and there was no need to increase it. With solid state rectifiers we saw a move to voltage doublers with 200 uF capacitance, in series this is 100 uF. The ripple levels remained about the same as a full wave setup using 47 uF.
New designers (maybe mid 1970's, solid state and tube) started with the "more is better" idea, and this has been taken to extremes as we have seen. Not an engineered solution for normal power levels and impedances. More of a market acceptance and easier sales pitch. If you wish to drive a 2R load at high power, sure you need larger filter capacitors using a solid state amp without an output transformer. With tube products it is all about output power levels and the proper tap on the output transformer.
I absolutely do agree with their skills. I was taught common sense by those engineers. But mindless increases in supply capacitance "backed up" by anecdotal "evidence" just doesn't cut it. But do not discount the pressure from the marketing department and public opinion. Public opinion was formed from a few marketing department s trying to create an edge for their product, much like the feature races of today.
I look at those kits (dynakit, heathkit,)
As iron mines for my DIY endeavors.
I usually pull the iron and scrap the rest.
A dynaco 70 is not that great of an amp that it needs to be preserved.
They made millions of em and they weren't anything special.
This is of course my opinion.
@hooman if you've got anything to say about this project it's welcome here.
We aren't going to get into a capacitor debate on this thread. If you think my work is lacking in some way, you are free to build your own amplifier however you like. I'll build mine, you build yours.
The reason it uses 47uf capacitors in a octal can is because that's how the original builder had it set up.
I thought I might get lucky and do a simple recap and bring it back to life.
I was not so lucky, so rather than pitch these expensive caps in the trash, I used them and they work very well.
Octal bases may be something I start to incorporate on all of my builds because they're just so convenient.
If you're running 4 or 6 of the same design of amplifier you can keep extra can caps laying around with the extra tubes so that when one fails it only brings you to silence for a matter of seconds. Plug in a new one and keep on rocking.
The whole reason I got into tube based audio systems in the first place was so that I could fix my stereo myself. I would regularly blow up the squalid state units I'd pull from dumpsters and even the electronics repair guy wouldn't fix em.
(not high end enough)
So I took matters into my own hands and started collecting tube amplifiers and now i never have to suffer with a stereo that's broken ever again.
there's always something else to pull down off of the shelf and keep the party rollin!
As iron mines for my DIY endeavors.
I usually pull the iron and scrap the rest.
A dynaco 70 is not that great of an amp that it needs to be preserved.
They made millions of em and they weren't anything special.
This is of course my opinion.
@hooman if you've got anything to say about this project it's welcome here.
We aren't going to get into a capacitor debate on this thread. If you think my work is lacking in some way, you are free to build your own amplifier however you like. I'll build mine, you build yours.
The reason it uses 47uf capacitors in a octal can is because that's how the original builder had it set up.
I thought I might get lucky and do a simple recap and bring it back to life.
I was not so lucky, so rather than pitch these expensive caps in the trash, I used them and they work very well.
Octal bases may be something I start to incorporate on all of my builds because they're just so convenient.
If you're running 4 or 6 of the same design of amplifier you can keep extra can caps laying around with the extra tubes so that when one fails it only brings you to silence for a matter of seconds. Plug in a new one and keep on rocking.
The whole reason I got into tube based audio systems in the first place was so that I could fix my stereo myself. I would regularly blow up the squalid state units I'd pull from dumpsters and even the electronics repair guy wouldn't fix em.
(not high end enough)
So I took matters into my own hands and started collecting tube amplifiers and now i never have to suffer with a stereo that's broken ever again.
there's always something else to pull down off of the shelf and keep the party rollin!
One reason people can "roll" tunes is because they have convenient connectors. Adding this feature to other components allows "roll" of those as well. Wanna try 100u instead of 47? This formula coupling cap instead of that one? A cathode bias resistor versus a current sink? Just unplug / replug. Seems simple enough - no soldering required.
I don't advocate rolling tubes.
If you can tell a difference it's likely because something is wrong.
It's not a topic I want to discuss on this thread either besides to say don't do it.
The beauty of a socketed capacitor is that you can swap it out quickly when it's due for service.
That's why tubes have sockets as well.
Not so audiophile dweebs can pontificate on the differences in sound produced by worn out shorted, mismatched or gassy tubes in an amp with an anemic power supply.
I prefer to measure things and act on what I know and can prove.
If you can tell a difference it's likely because something is wrong.
It's not a topic I want to discuss on this thread either besides to say don't do it.
The beauty of a socketed capacitor is that you can swap it out quickly when it's due for service.
That's why tubes have sockets as well.
Not so audiophile dweebs can pontificate on the differences in sound produced by worn out shorted, mismatched or gassy tubes in an amp with an anemic power supply.
I prefer to measure things and act on what I know and can prove.
My father worked in the army and job in telecommunications, big transmiter tubes .... he repaired tube radios for many years. I had been watching tube radios since I was a child. Almost all of them were single-ended. Most were made in Western Germany. The single-ended output kept the price down, but a real class A tube and a large German full-range speaker in a wooden cabinet... a godsend of harmonics.................... But do not discount the pressure from the marketing department and public opinion. Public opinion was formed from a few marketing department s trying to create an edge for their product, much like the feature races of today.....................................
Thanks for your advice...but I didn't see anything mentioned in the tube amp market about capacitor banks? This is unique to solid state.
I think there are many fans of singles too. One of the great advantages of tube power over solid state is that ....a tube ....can easily drive a speaker in hifi . How can we ignore that?
With respect