Non parafeed Paramount
- Thread starter xcortes
- Start date
Paramount. Corrected the original post.
I don't have the 025s yet. Mike will build me a very special and unique pair. In any case the difference from the plate choke I don't think will be much more volts and the soft start driver provide for adjustable voltage so dialing up is easy. But do I have to do something with, for example, the ps caps?
Thanks
I don't have the 025s yet. Mike will build me a very special and unique pair. In any case the difference from the plate choke I don't think will be much more volts and the soft start driver provide for adjustable voltage so dialing up is easy. But do I have to do something with, for example, the ps caps?
Thanks
Paul Joppa
Moderator
You do not HAVE to make any other changes.
But for the best sonics, I would do the following:
1) replace the 270-ohm power resistor in the power supply, with a filter choke such as the good old C7-X. For you Xavier, see if you can find one of the made-in-Mexico Triad ones!
2) For the last PSU capacitor, replace the two electrolytics with a 630-v film capacitor of 20uF or greater, and take the negative end to the hum pot center terminal (the effective cathode connection) rather than to ground. This capacitor carries the signal current, and thus has a similar effect to that of the parafeed capacitor.
But for the best sonics, I would do the following:
1) replace the 270-ohm power resistor in the power supply, with a filter choke such as the good old C7-X. For you Xavier, see if you can find one of the made-in-Mexico Triad ones!
2) For the last PSU capacitor, replace the two electrolytics with a 630-v film capacitor of 20uF or greater, and take the negative end to the hum pot center terminal (the effective cathode connection) rather than to ground. This capacitor carries the signal current, and thus has a similar effect to that of the parafeed capacitor.
@ Aaron: the all silver version of the QS 025 doesn't have 4 ohm taps so Mike will build me an all silver pair with 4 ohm secondaries.
@Paul I already have MQ filter chokes BMC8 I think so point A has bee taken care of. As for point B let's see if I uderstood correctly. I take out the two last filter caps (270uF) and install the new one from the + rail to the hum pot. And make it a nice one. Am i right?
Thanks a lot Paul.
Ps I'm at the storage facility leasing some space for the big horns, Karlsons etc. Didn't knew how big and sunny my living room is. Now the three pair of Paramounts will be different: one pair Ni tfa 2004, the second Co pinstripes 2004 jrs and the third series feed silver primaries and secondaries. Each game has different types of fun. Let's see for how long I can survive without the big sound.
@Paul I already have MQ filter chokes BMC8 I think so point A has bee taken care of. As for point B let's see if I uderstood correctly. I take out the two last filter caps (270uF) and install the new one from the + rail to the hum pot. And make it a nice one. Am i right?
Thanks a lot Paul.
Ps I'm at the storage facility leasing some space for the big horns, Karlsons etc. Didn't knew how big and sunny my living room is. Now the three pair of Paramounts will be different: one pair Ni tfa 2004, the second Co pinstripes 2004 jrs and the third series feed silver primaries and secondaries. Each game has different types of fun. Let's see for how long I can survive without the big sound.
Paul Joppa
Moderator
You're right. Should be interesting! :^)xcortes said:
Right now I don't have a system 
But you're welcome any day. We have a guests' room and now that I rented some storage it may even come with a useable shower!
If things go well I hope to start renting a place in Coronado next year. I used to go to SD several times a year when my girlfriend (now wife) lived there. And subsequently for many years until my inlaws moved to Mexico about three years ago. Most of my BH kits and MQ iron went to their Chula Vista house.
But you're welcome any day. We have a guests' room and now that I rented some storage it may even come with a useable shower!
If things go well I hope to start renting a place in Coronado next year. I used to go to SD several times a year when my girlfriend (now wife) lived there. And subsequently for many years until my inlaws moved to Mexico about three years ago. Most of my BH kits and MQ iron went to their Chula Vista house.
Grainger49
New member
Xavier,
I would imagine with that many tubes removed your living room is not only larger but cooler.
I would imagine with that many tubes removed your living room is not only larger but cooler.
Paul, I promise that this will be my last how to modify anything questions for 20013.
If I want to do the said conversion to the 300B version of a Paramount or a Parabee, would the changes be the same.
AND, for what current would you recommend that the transformer be gapped?
Thanks a lot!
Xavier
If I want to do the said conversion to the 300B version of a Paramount or a Parabee, would the changes be the same.
AND, for what current would you recommend that the transformer be gapped?
Thanks a lot!
Xavier
xcortes said:
Are you planning on FS-030's or TFA-204's?
Ds025s all silver. Mike is building me a pair with all silver windings and 4 ohm secondaries which normally don't appear in the silver version.
Originally I was planning to build a Baby Ongaku. Later I decided to try a 300B BO (Ongaku Jr?). But it looks like the SR45 project will leave me with three spare pairs of Paramounts so probably I can just rebuild one. And I also have two pairs of ironless Parabee to rebuild so.....
My last request to Mike was to gap it for 70mA following a PJs post on the MQ forum where he auggested:
"2) You can ask Mike to make some DS-025s that are gapped for more current. You will lose some inductance and hence some deep bass, but otherwise it would retain the Baby-O basic character. Gapped for 70mA and operated at 300v at 60mA, which is a well documented 300B operating point, with very nearly the same cathode resistor - less than 2% different. You might get 7 watts. Full power DC current is 74mA, so DC overload will be similar to the Baby-O"
http://db.audioasylum.com/mhtml/m.html?forum=magnequest&n=10634&highlight=300b+baby&r=&search_url=%2Fcgi%2Fsearch.mpl%3F
Thanks
Originally I was planning to build a Baby Ongaku. Later I decided to try a 300B BO (Ongaku Jr?). But it looks like the SR45 project will leave me with three spare pairs of Paramounts so probably I can just rebuild one. And I also have two pairs of ironless Parabee to rebuild so.....
My last request to Mike was to gap it for 70mA following a PJs post on the MQ forum where he auggested:
"2) You can ask Mike to make some DS-025s that are gapped for more current. You will lose some inductance and hence some deep bass, but otherwise it would retain the Baby-O basic character. Gapped for 70mA and operated at 300v at 60mA, which is a well documented 300B operating point, with very nearly the same cathode resistor - less than 2% different. You might get 7 watts. Full power DC current is 74mA, so DC overload will be similar to the Baby-O"
http://db.audioasylum.com/mhtml/m.html?forum=magnequest&n=10634&highlight=300b+baby&r=&search_url=%2Fcgi%2Fsearch.mpl%3F
Thanks
OK Paul, since you're about to go for vacation I'll make it a single question and no more for the year
I'd like to replace the TFA 2004 and exo 03 in a Parabee with a ds025 gapped for 70mA. I like the idea you mentioned before of doing ultrapath: replacing the last electrolytic in the ps with a nice one and going to the cathode instead of to ground. So the big question is: what size a cap would be correct here?
Thanks !
I'd like to replace the TFA 2004 and exo 03 in a Parabee with a ds025 gapped for 70mA. I like the idea you mentioned before of doing ultrapath: replacing the last electrolytic in the ps with a nice one and going to the cathode instead of to ground. So the big question is: what size a cap would be correct here?
Thanks !
