We can trade transistors if matching is a problem.
I started working on the Paradise Pre-Regulator. I will build double mono so i have ordered 4 Hammond 158T chokes. They have 40 Ohm so 200mA will drop 8V. That requires 2 x 24V from the transformer. I found a 30VA 2 x 24V R-Core. As Electrolytics i chose Panasonic TS-HA 10.000uF-35V.
I started working on the Paradise Pre-Regulator. I will build double mono so i have ordered 4 Hammond 158T chokes. They have 40 Ohm so 200mA will drop 8V. That requires 2 x 24V from the transformer. I found a 30VA 2 x 24V R-Core. As Electrolytics i chose Panasonic TS-HA 10.000uF-35V.
Honest, hfe and matching are not that critical in the R3 version although there is a lower limit for -40 specked versions, just what is promised to be delivered from the vendors. With hfe so low as you say you may have a problem with your measurement setup.
Concerning a group buy for the pre regulator i design at the moment, please wait until it is done and the majority likes that. I asked my son if he will organize a group buy if there is enough interest.
Concerning a group buy for the pre regulator i design at the moment, please wait until it is done and the majority likes that. I asked my son if he will organize a group buy if there is enough interest.
Here are new teflon caps. They are for high voltage and 2000pF is the highest value.
I assume they are expensive.Fixed Capacitors - Non-Magnetic from Polyflon Company - a Crane Co. Company
I assume they are expensive.Fixed Capacitors - Non-Magnetic from Polyflon Company - a Crane Co. Company
Here are alternative transformers to the Selectronic R-Core from Hammond. They are spit bobbin and specked for low capacitive coupling. I can get them more easy from Digikey and they are economical priced. What do you think ?
http://www.hammondmfg.com/pdf/5c0013.pdf
http://www.hammondmfg.com/pdf/5c0013.pdf
Hi Joachim,
do you know this site?
http://www.selectronic-kondensatoren.de/media/kondensatoren_audiocap.pdf
Peter
do you know this site?
http://www.selectronic-kondensatoren.de/media/kondensatoren_audiocap.pdf
Peter
Yes, i know the Gad-Vida. I called up Selectronic and they said that they made this caps for a customer in Hongkong and do not have them in stock. I called the guy in Hongkong and he was out of stock too.
I have my own preference in caps. Between my preamp and power amp i have a cap in line that filters with 6dB octave under 80Hz because i do the bass active. I can bypass that cap when i do not play the system so loud that my midranges bottom. I can simply not hear if the cap is in line or not. With the cap inserted the system just plays louder because it is relieved somewhat from the lowest frequencies. I do not say that caps do not matter at that place but i found a combination that is under my auditory threshold and it is not an expensive boutique cap. It is a combination of MKP´s shunted with a small value low inductance Styroflex. Both from well known, major manufacturers and economic priced.
Thanks Frans, yes, that trafo is a good choice.
I have my own preference in caps. Between my preamp and power amp i have a cap in line that filters with 6dB octave under 80Hz because i do the bass active. I can bypass that cap when i do not play the system so loud that my midranges bottom. I can simply not hear if the cap is in line or not. With the cap inserted the system just plays louder because it is relieved somewhat from the lowest frequencies. I do not say that caps do not matter at that place but i found a combination that is under my auditory threshold and it is not an expensive boutique cap. It is a combination of MKP´s shunted with a small value low inductance Styroflex. Both from well known, major manufacturers and economic priced.
Thanks Frans, yes, that trafo is a good choice.
You have to find out yourself. Sorry, no spoon feeding. You find it on this thread somewhere. It is not a secret, just a lot of listening and measurements. One Tip : the rule to bypass the main cap with a cap that is 1/10nth the value does not work. The bypass cap is much smaller.
Study the spec sheet and look where the main cap has it´s minimum impedance and blend in the bypass where the main cap starts to be inductive.
For speakers it it different because of the high currents that flow and the immense shaking. What matters most here is to suppress mechanical resonances.
A densely wound MKT can sound better then a teflon cap with loose windings.
Dielectric absorption is a minor problem in speakers because the cap can not build up much energy. The low impedance of the speaker short circuits the cap mostly all of the time.
Study the spec sheet and look where the main cap has it´s minimum impedance and blend in the bypass where the main cap starts to be inductive.
For speakers it it different because of the high currents that flow and the immense shaking. What matters most here is to suppress mechanical resonances.
A densely wound MKT can sound better then a teflon cap with loose windings.
Dielectric absorption is a minor problem in speakers because the cap can not build up much energy. The low impedance of the speaker short circuits the cap mostly all of the time.