but it is ofcourse possible that you did not use both coils.
An externally hosted image should be here but it was not working when we last tested it.
Does anyone know what determines the size of this cap 15uF here? Is it's function not just a bypass cap...and therefore a 100uF be suitable?
Hi Thorsten,
I read somewhere that you advise newbies not to build such an amp because 300B's can blow up..
I am planning to build this design into my diyHifiSupply's LD+..
But I really don't understand the problems that could arise with DRD's...could I build it first with a capacitor between d3a and 300b grid to do a smoke test...and if it works remove the cap??
Regards,
Bas
I read somewhere that you advise newbies not to build such an amp because 300B's can blow up..
I am planning to build this design into my diyHifiSupply's LD+..
But I really don't understand the problems that could arise with DRD's...could I build it first with a capacitor between d3a and 300b grid to do a smoke test...and if it works remove the cap??
Regards,
Bas
Konnichiwa,
Lower supply voltages imply a reduction in power and a complete readjustement of the circuit.
For D3a choke loaded on an LD+ Chassis, look here:
http://www.jogis-roehrenbude.de/Leserbriefe/TH-Loesch-Amp/Th-Loesch-Amp.htm
This has got all the needed stuff, just adjust the input valve cathode resistor to suit the triode wired D3a.
Sayonara
Bas Horneman said:
Lower supply voltages imply a reduction in power and a complete readjustement of the circuit.
For D3a choke loaded on an LD+ Chassis, look here:
http://www.jogis-roehrenbude.de/Leserbriefe/TH-Loesch-Amp/Th-Loesch-Amp.htm
This has got all the needed stuff, just adjust the input valve cathode resistor to suit the triode wired D3a.
Sayonara
Hi all ,
I have built the DRD style amps, currently as 45s.
You can find bits of it over at "Audio round table, group build"
I used Lundel and James outputs, Jacks DRD chokes and the Lady Day style power transformer from DIY HI FI. If I am not mistaken , Thorsten had a big hand in it’s design.
This is a very flexible transformer. Between it’s multiple HV taps, buck boost taps, full or half wave and cap or choke input filters. There is a very wide range of voltages to play with.
Not to mention the clever filament secondary arrangement. Worth a look.
I first breadboarded these as a 45 amp with plans to run 2a3 and 300b as a series of post to ART.
I first set one up with a 6an4 driver , parts bin "fast rectifiers" and some honking big adjustable cathode resistors that could accommodate all 3 tubes. Dialed up the various voltages and had a listen . good. Build another .
Now one of the stated objectives of this project was to try some alternatives to AC heating But with this lash up. There is almost no hum. With my 96db/w speakers, I think what I hear is the diode switching noise. It has to be a very quiet night in N-town before this level of noise is heard.
I have been very busy at work and have not had a lot of time to play. I did toss a pair of 300’s in as a quick and dirty experiment but my heart was not in it. I did not have the time to do it properly and the 45’s were working well for me. I will get back to it as time permits.
In the mean time this is a very worthily configuration to consider…John
I have built the DRD style amps, currently as 45s.
You can find bits of it over at "Audio round table, group build"
I used Lundel and James outputs, Jacks DRD chokes and the Lady Day style power transformer from DIY HI FI. If I am not mistaken , Thorsten had a big hand in it’s design.
This is a very flexible transformer. Between it’s multiple HV taps, buck boost taps, full or half wave and cap or choke input filters. There is a very wide range of voltages to play with.
Not to mention the clever filament secondary arrangement. Worth a look.
I first breadboarded these as a 45 amp with plans to run 2a3 and 300b as a series of post to ART.
I first set one up with a 6an4 driver , parts bin "fast rectifiers" and some honking big adjustable cathode resistors that could accommodate all 3 tubes. Dialed up the various voltages and had a listen . good. Build another .
Now one of the stated objectives of this project was to try some alternatives to AC heating But with this lash up. There is almost no hum. With my 96db/w speakers, I think what I hear is the diode switching noise. It has to be a very quiet night in N-town before this level of noise is heard.
I have been very busy at work and have not had a lot of time to play. I did toss a pair of 300’s in as a quick and dirty experiment but my heart was not in it. I did not have the time to do it properly and the 45’s were working well for me. I will get back to it as time permits.
In the mean time this is a very worthily configuration to consider…John
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