I've built my DC adjustable Power Diamond Buffer Follwer announced at diyAudio about 6-month ago.
And last month I had a chance to have an A/B test wih my firend's DIY 300B & his ALTEC-604C high efficiency speaker.
His 300B is driven by 5687 and an interstage transformer.
Many of them were impressed of the Power Follower driven by an old MacIntosh C-20,
especially the very high & low Freq. vs his Full Music 300B.
But the gain is still a little bit not enough, the volume was almost at max..
My 10x s.s. pre-amp with the power followr , of course could not dirve
the 107dB speaker loud enough, because the listening seats were about 20 ft from the speakers!
One of my friend is interested of my design, and he is going to add an optional IPT (Input Tranformer)
about 10dB gain with my Power Fllower.
I think it is a good idea, what do you think about a Power Follower with an IPT ?
Power Follower's schematic PDF is at http://www.diyaudio.com/forums/attachment.php?s=&postid=672517&stamp=1120105130,
but without standby circuit.
An externally hosted image should be here but it was not working when we last tested it.
And last month I had a chance to have an A/B test wih my firend's DIY 300B & his ALTEC-604C high efficiency speaker.
His 300B is driven by 5687 and an interstage transformer.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Many of them were impressed of the Power Follower driven by an old MacIntosh C-20,
especially the very high & low Freq. vs his Full Music 300B.
But the gain is still a little bit not enough, the volume was almost at max..
My 10x s.s. pre-amp with the power followr , of course could not dirve
the 107dB speaker loud enough, because the listening seats were about 20 ft from the speakers!
One of my friend is interested of my design, and he is going to add an optional IPT (Input Tranformer)
about 10dB gain with my Power Fllower.
I think it is a good idea, what do you think about a Power Follower with an IPT ?
Power Follower's schematic PDF is at http://www.diyaudio.com/forums/attachment.php?s=&postid=672517&stamp=1120105130,
but without standby circuit.
Re: Re: How about a Power Follower with an IPT?
Hi Workhorse,
I know nothing about how to design , make or measure an IPT,
so I have to count on my friend's sample maybe at nextweek.
My step attenuator cannot set to the max. of input , its max is about -3dB.
The output impedance of my solid state preamp DB-01 is very low I think below 100 mOHM,
because it use a diamond buffer output with RE only 10 OHM and is NFB design.
Hi Workhorse,
I know nothing about how to design , make or measure an IPT,
so I have to count on my friend's sample maybe at nextweek.
Steve Eddy said:
My step attenuator cannot set to the max. of input , its max is about -3dB.
The output impedance of my solid state preamp DB-01 is very low I think below 100 mOHM,
because it use a diamond buffer output with RE only 10 OHM and is NFB design.
mefistofelez said:
Not sure what you mean here. We're talking about an input transformer, not an output transformer. The output of the input transformer would just feed the input of the follower.
Depends on what you're wanting to achieve.
If you're just wanting to take advantage of a transformer's ground isolation and common-mode noise rejection, and don't need any voltage gain, then pick a nice 1:1 input trannie like a CineMag CMLI-15/15B.
If you need voltage gain, what I've been using have been various microphone input trannies which can be had in 1:2 to 1:10 ratios. Though keep in mind that the microphone trannies have been optimized for a 150 ohm source impedance and when loaded properly present a 1.5k ohm input impedance which can be too low for some source components.
Now, Mike LaFevre at MagneQuest has been working on producing some of the old Peerless line level designs (he owns the Peerless name and all their original engineering) and that's looking promising. SY has been doing some measurements on some prototype 15095 trannies (a 1:10 step-up) and so far they seem to work just fine directly driving drive a grid or gate and subsequently offering a much higher input impedance than 1.5k.
se
Re: Re: Re: Re: How about a Power Follower with an IPT?
The hand-made 24-step ladder type attenuator is quite difficult to be fixed,
but I'll try to short the max. level's input resistors.
Thank you for the information of microphone input trnnie, but it seems to be used in low input level,
how will its THD performance be in high voltage output ?
Steve Eddy said:
An externally hosted image should be here but it was not working when we last tested it.
The hand-made 24-step ladder type attenuator is quite difficult to be fixed,
but I'll try to short the max. level's input resistors.
Thank you for the information of microphone input trnnie, but it seems to be used in low input level,
how will its THD performance be in high voltage output ?
Re: Re: Re: Re: Re: How about a Power Follower with an IPT?
Oops. Sorry. I've been talking about step-up transformers and buffers on two different threads as well as with someone in EMail and got situations mixed up.
In your situation, I'd use a 1:2 output transformer on the output of your preamp which would give you another 6dB of gain.
By the way, is there any way to get any more gain out of your preamp?
se
mtlin12 said:
Oops. Sorry. I've been talking about step-up transformers and buffers on two different threads as well as with someone in EMail and got situations mixed up.
In your situation, I'd use a 1:2 output transformer on the output of your preamp which would give you another 6dB of gain.
By the way, is there any way to get any more gain out of your preamp?
se
Re: Re: Re: Re: Re: Re: How about a Power Follower with an IPT?
My preamp's gain can be easily set to 26dB (20X), but the output
is still limited at about 10Vrms because of the supply voltage only +/-18V.
I think 1:2 will work fine, if the transformer can drive up to 20Vrms that will be just fine!
The 0dB Power Follower needs large swing output preamp, so normally I suggest
my friends to use it with a high gain tube amp!
Steve Eddy said:
My preamp's gain can be easily set to 26dB (20X), but the output
is still limited at about 10Vrms because of the supply voltage only +/-18V.
I think 1:2 will work fine, if the transformer can drive up to 20Vrms that will be just fine!
The 0dB Power Follower needs large swing output preamp, so normally I suggest
my friends to use it with a high gain tube amp!
Re: Re: Re: Re: Re: Re: Re: How about a Power Follower with an IPT?
Ah, ok.
Right. And in that case I'd recommend the Jensen JT-11SS-DLCF which in its 1:2 configuration is rated at +30dBu on its output which corresponds to about 24.5 volts.
Now, if you're going to feed that into the 1M input impedance of your follower, you'll need to add an RC snubber network to address high frequency ringing (these trannies want to see a 600 ohm load). Jensen will be happy to work out the proper values for you.
Hehehe. Well that begs the question, why aren't YOU using a high gain tube amp?
se
mtlin12 said:
Ah, ok.
I think 1:2 will work fine, if the transformer can drive up to 20Vrms that will be just fine!
Right. And in that case I'd recommend the Jensen JT-11SS-DLCF which in its 1:2 configuration is rated at +30dBu on its output which corresponds to about 24.5 volts.
Now, if you're going to feed that into the 1M input impedance of your follower, you'll need to add an RC snubber network to address high frequency ringing (these trannies want to see a 600 ohm load). Jensen will be happy to work out the proper values for you.
Hehehe. Well that begs the question, why aren't YOU using a high gain tube amp?
se
SY said:
Hehehe. I threw out my old bulk tape eraser years ago.
But if we just want to demagnetize the core (assuming it has acquired any magnetization), and not worry about the can, all you need is to be able to feed it a low frequency sinewave of a magnitude sufficient to put the core into saturation and then slowly back down the level.
se
Re: Re: Re: Re: Re: Re: Re: Re: How about a Power Follower with an IPT?
Thank you again, my friend Mr. Liu says to me that he will take this (IPT) challenge, he wants to make it himself.
Surely I want to design a hybrid tube+power follower amp like
Pathos does, but I'm not a good tube designer!
Steve Eddy said:
Thank you again, my friend Mr. Liu says to me that he will take this (IPT) challenge, he wants to make it himself.
Hehehe. Well that begs the question, why aren't YOU using a high gain tube amp?
se
Surely I want to design a hybrid tube+power follower amp like
Pathos does, but I'm not a good tube designer!
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