Alex, can you post the post number? i am on a 50 post per page...i am now only on page 52....)
Tony, post #1337.
BTW, I have breadboarded the 6v6 preamp, but am short on B+, managed only 230VDC, but it sounds excellent!
So am getting a proper ptx that will give me around 340VDC on B+. 🙂
BTW, I have breadboarded the 6v6 preamp, but am short on B+, managed only 230VDC, but it sounds excellent!
So am getting a proper ptx that will give me around 340VDC on B+. 🙂
thanks Alex, if using chokes as plate loads you will get more output swing, higher than what the B+ implies...
http://2.bp.blogspot.com/-8kZ6ISNG69s/T9Hd3aBnoCI/AAAAAAAABSk/BQpGVUBarAs/s1600/6AH4-line-1.jpg
Hello guys,
Will the output transformer on this 6ah4 preamp work without any modifications to the basic 6v6 circuit? If not what spec will the be good for the 6v6?
Thank you
Hello guys,
Will the output transformer on this 6ah4 preamp work without any modifications to the basic 6v6 circuit? If not what spec will the be good for the 6v6?
Thank you
Should be great. Lundahl speces 21 mA if not special gaped tho so check your current and adjust bias if necessary.
Looking for the Alt Q datasheet application at 95H 3.5:1 2kOhm Zo. That will give about 6dB gain and don't bias more than 21mA.
Hi Salas,
I'll just stick with the cap.coupling then. But if cost is not an issue and a lower output impedance is.needed what output transformer spec is ideal?ty
I'll just stick with the cap.coupling then. But if cost is not an issue and a lower output impedance is.needed what output transformer spec is ideal?ty
Something with 150-200H @ 20mA & 600 Ohm output I guess. As for ratio keep in mind that you start with 20dB max available when choke loaded. 15.5dB for resistive load. THD gets seriously better with inductive load as the signal swing increases.
Slightly less and I would say the inductance is ok given that the input signal is decent line level and current is within spec.
Hi all,
Thank you for always responding to my inquiries. The reason I want an output transformer is because I.will be driving multiple amps and need low outtput impedance, and I need just half the gain of the preamp.
Thank you for always responding to my inquiries. The reason I want an output transformer is because I.will be driving multiple amps and need low outtput impedance, and I need just half the gain of the preamp.
Hi Salas,
Im gonna have heyboer wind a pair of Opts using the specs you gave. What primary impedance should be needed? Im gonna need half the gain, so what ratio.will be ideal?
Ty
Hi Salas,
Thank you. What is full gain is needed should I just spec it as 7.5k primary, ratio 1:1?
Thanks
Yes. But no further benefit in reducing the output impedance. With 1:2.5 its 12dB. When 6-9dB gain with a line source should be covering a very wide range of amps and the step down ratio cuts on microphonics and noise too. For 9dB it would be 1:3.5
Hi Salas,
Thanks again... ill see if heyboer can make those opts. My friend heard my 6v6 pre and loves it. His amps is a 3 stage pp 6l6 design which already has enough gain that a normal 2v source can drive it to full power.
He wants to build a 6v6 too and I told him to build the cathode follower version but since an output transformer can be used to step down the output of the common cathode design, what step down ratio is ideal so the common cathode 6v6 will have a 2v output?
Thanks again... ill see if heyboer can make those opts. My friend heard my 6v6 pre and loves it. His amps is a 3 stage pp 6l6 design which already has enough gain that a normal 2v source can drive it to full power.
He wants to build a 6v6 too and I told him to build the cathode follower version but since an output transformer can be used to step down the output of the common cathode design, what step down ratio is ideal so the common cathode 6v6 will have a 2v output?