RichardJones said:
I do. Seriously, what's the point of such a low gain pre-amp? If you love your vinyl, then you'll need a lot more gain than that.... and if you use CD's exclusively, you won't need any of that gain.
What is this going to be used for exactly?
Secondly, 71-A's are not cheap, require dc heaters (pain in the butt), and can be fairly microphonic. I love them, but only in power amp duty, with high signal levels.
Joel
well....
Because I want to drive a SE MOSFET Class A amp that has a voltage gain of 1. SO.... I need the higher voltage gain.
Total voltage gain of 1.
PP will minimize any hum.
With a input tranny will be high level signals... 5 or so volts input.
plus the fact I allready have 2 matched globe 71a's.
Because I want to drive a SE MOSFET Class A amp that has a voltage gain of 1. SO.... I need the higher voltage gain.
Total voltage gain of 1.
PP will minimize any hum.
With a input tranny will be high level signals... 5 or so volts input.
plus the fact I allready have 2 matched globe 71a's.
amp
ok.... also my 6B4G amp has an input stage biased at 4v. (ECC99).
So... I need at least 4v input to my amp.
Still want to do a 71a PP pre-amp. with a 6K:1K output tranny, what input step up phase splitter should I use?
Could get away with total gain of 5 or around there.
power supply is LC stage with a 150v regulator tube and say MV rectifier tubes.
Thanks!!!
p.s. I am going to ignore microphonics for now.
ok.... also my 6B4G amp has an input stage biased at 4v. (ECC99).
So... I need at least 4v input to my amp.
Still want to do a 71a PP pre-amp. with a 6K:1K output tranny, what input step up phase splitter should I use?
Could get away with total gain of 5 or around there.
power supply is LC stage with a 150v regulator tube and say MV rectifier tubes.
Thanks!!!
p.s. I am going to ignore microphonics for now.
Ok, so basically you want to use four 71-A's, two presumably well made transformer phase inverters, and two high bandwidth output transformers in order to get a gain of 8 to your power amp that was poorly designed to begin with, since it has an input sensitivity of a whopping 4V!
sheesh.
Richard, I'm all for lots of iron, DHT's, and experimentation - but this really seems fruitless.
sheesh.
Richard, I'm all for lots of iron, DHT's, and experimentation - but this really seems fruitless.
INPUT SENSITIVITY.
Hi,
So -Vg = 4VDC.
No, not necessarily.
It appears to me that you do not really know the input sensitivity of this amplifier.
While it could be true that it is going to need a 4 Volt input to drive it at full power, concluding that since the bias of the input tube is set at -4V you're going to need at least 4V to drive it is not correct.
Cheers,
Hi,
So -Vg = 4VDC.
No, not necessarily.
It appears to me that you do not really know the input sensitivity of this amplifier.
While it could be true that it is going to need a 4 Volt input to drive it at full power, concluding that since the bias of the input tube is set at -4V you're going to need at least 4V to drive it is not correct.
Cheers,
true...
I have an ECC99 running at 150v, 18mA 4v bias. gain is 22.
Bias on output is around 50v. So.... for I need around 2v input for full output. The ECC99 is IT coupled with a 1/1:1 phase splitter to the grids of the 6B4G.
So you are correct.
I'd still like a total voltage gain of around 5 for my pre-amp.
And i'd like to do PP with the 71a's,
I have an ECC99 running at 150v, 18mA 4v bias. gain is 22.
Bias on output is around 50v. So.... for I need around 2v input for full output. The ECC99 is IT coupled with a 1/1:1 phase splitter to the grids of the 6B4G.
So you are correct.
I'd still like a total voltage gain of around 5 for my pre-amp.
And i'd like to do PP with the 71a's,
Joel said:....... in order to get a gain of 8 to your power amp that was poorly designed to begin with, since it has an input sensitivity of a whopping 4V!
sheesh.
.
So, Joel
please tell me what input sensitivity has to do with whether an amp is
poorly designed or not. I'm really curious.......
Jan,
I should have said "IMO". But it is fairly accepted that power amplifiers should have an input sensitivity of ~1V. This was the standard throughout the 40's-60's.
What's my point? My point is that if you design the power amp to go to full power with 1-2V input, then you can eliminate the preamp altogether if using a digital source. That's a plus. Even the best preamp is less transparent than a wire.
This is of course a moot point if you need phono gain.
Is anything I'm saying controversial? I would think it was self-aparent...
I should have said "IMO". But it is fairly accepted that power amplifiers should have an input sensitivity of ~1V. This was the standard throughout the 40's-60's.
What's my point? My point is that if you design the power amp to go to full power with 1-2V input, then you can eliminate the preamp altogether if using a digital source. That's a plus. Even the best preamp is less transparent than a wire.
This is of course a moot point if you need phono gain.
Is anything I'm saying controversial? I would think it was self-aparent...
Hi, Joel , all
I'm just curious, that's all.
We , as amateurs, have a freedom of choice, we can go in every direction,
we can build anything we want.
We are not bound by comercial interests, we don't have to be "sensible".
Accepted by whom? Who cares?
By all means, we should study the old masters, learn all we can, but I don't see why
we should restrict ourselves to building stuff the same way they did in the ' 60s
Let's go the other way. Let's try new configurations, and new unusual valves,
our journey is filled with endless possibilities
I'm just curious, that's all.
We , as amateurs, have a freedom of choice, we can go in every direction,
we can build anything we want.
We are not bound by comercial interests, we don't have to be "sensible".
Joel said:
Accepted by whom? Who cares?
By all means, we should study the old masters, learn all we can, but I don't see why
we should restrict ourselves to building stuff the same way they did in the ' 60s
Let's go the other way. Let's try new configurations, and new unusual valves,
our journey is filled with endless possibilities
Jan, give me a break, please. I hardly think saying that one should try to shoot for a 1V input sensitivity is stifling anybody's creativity - or living in the "60's".
Plus, you obviously don't read the forum that often, as I have built and posted schematics of amps using very un-sixties ideas, and technology. I don't own a 12AX7, EL34, or a push-pull amp of any kind. So can you spare me the lecture on freeing our minds please? Thanks. 
Plus, you obviously don't read the forum that often, as I have built and posted schematics of amps using very un-sixties ideas, and technology. I don't own a 12AX7, EL34, or a push-pull amp of any kind. So can you spare me the lecture on freeing our minds please? Thanks.
Joel said:Jan, give me a break, please. I hardly think saying that one should try to shoot for a 1V input sensitivity is stifling anybody's creativity - or living in the "60's".
Plus, you obviously don't read the forum that often, as I have built and posted schematics of amps using very un-sixties ideas, and technology. I don't own a 12AX7, EL34, or a push-pull amp of any kind. So can you spare me the lecture on freeing our minds please? Thanks.
Hi Joel
No, I don't read the forums that often , I just reacted to this one post from you,
and was curious as to why you was so negative towards Richards linestage?
Cheers
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.