Reggaebass Posted August 28, 2021 Share Posted August 28, 2021 6 minutes ago, BassmanPaul said: Omg, that’s sweet 👍 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted August 28, 2021 Share Posted August 28, 2021 (edited) A change I did make to my unit was to remove the "Polarity' switch and it's capacitor. I then relocated the 'Standby' from the rear apron to where the 'Polarity' switch was. I tried a couple of different drivers in the cabinet, JBL Altec, but liked the original square magnet the best. It's what's in there now. Another change was to wire a fast recovery silicon rectifier in series with the plates/anodes of the GZ34/5AR4. This eliminated a flash over problem that reared it's ugly head. I'd recommend anyone with an original B15 to do the same mod. It increases the PIV of the rectifier system. Edited August 28, 2021 by BassmanPaul 1 Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 On 28/08/2021 at 18:49, skychaserhigh said: I've had the V4B for a couple of years now and it's fantastic. Do you use active or passive basses with yours skychaser Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 On 28/08/2021 at 18:49, skychaserhigh said: I've had the V4B for a couple of years now and it's fantastic. Do you use active or passive basses with yours skychaser Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 (edited) On 28/08/2021 at 18:49, skychaserhigh said: Edited September 5, 2021 by Reggaebass Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 Ipad triple posted there 🙄 Quote Link to comment Share on other sites More sharing options...
skychaserhigh Posted September 5, 2021 Share Posted September 5, 2021 Mainly passive Jazz bass , sometimes P bass , and I have a Jazz that's active/passive but I usually use on active. Everything sounds great through it , the Fender/Ampeg combination is a classic sound! 1 Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 7 minutes ago, skychaserhigh said: Mainly passive Jazz bass , sometimes P bass , and I have a Jazz that's active/passive but I usually use on active. Everything sounds great through it , the Fender/Ampeg combination is a classic sound! Thanks, I got one yesterday and im just trying it out with different basses, the jazz and bb1024 sound superb , my Hohner B2A has an active/passive switch and I just wondered if it’s ok to play active through the 0 dB input Quote Link to comment Share on other sites More sharing options...
skychaserhigh Posted September 5, 2021 Share Posted September 5, 2021 I play everything through the 0 db input, in fact I've never used the other one. What cab are you using it with? 1 Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 Just now, skychaserhigh said: I play everything through the 0 db input, in fact I've never used the other one. What cab are you using it with? Markbass NY115, at the moment Quote Link to comment Share on other sites More sharing options...
skychaserhigh Posted September 5, 2021 Share Posted September 5, 2021 I'm glad you got one , hope you enjoy it ! 1 Quote Link to comment Share on other sites More sharing options...
Reggaebass Posted September 5, 2021 Share Posted September 5, 2021 1 minute ago, skychaserhigh said: I'm glad you got one , hope you enjoy it ! It’s a really great amp and the sound is superb, I’m just finding my way around it, I’ll probably have more questions for you 😁, what cab do you use Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted September 5, 2021 Share Posted September 5, 2021 On 28/08/2021 at 20:36, BassmanPaul said: A change I did make to my unit was to remove the "Polarity' switch and it's capacitor. I then relocated the 'Standby' from the rear apron to where the 'Polarity' switch was. I tried a couple of different drivers in the cabinet, JBL Altec, but liked the original square magnet the best. It's what's in there now. Another change was to wire a fast recovery silicon rectifier in series with the plates/anodes of the GZ34/5AR4. This eliminated a flash over problem that reared it's ugly head. I'd recommend anyone with an original B15 to do the same mod. It increases the PIV of the rectifier system. What silicon diodes did you use? On my recent B15-inspired build I had a GZ34 that was arcing. I fitted a new GZ34 and then tried a UF4007 before each anode on the GZ34, but the amp didn't work with the silicon diodes fitted. Quote Link to comment Share on other sites More sharing options...
skychaserhigh Posted September 5, 2021 Share Posted September 5, 2021 16 minutes ago, Reggaebass said: It’s a really great amp and the sound is superb, I’m just finding my way around it, I’ll probably have more questions for you 😁, what cab do you use I have the Ampeg SVT212 av cab which is a perfect match. I tend to keep the ultra low and hi off, mid select at 800 and just a touch of bass and mid boost for fingerstyle. Ultra low on with some mid cut is great for pick playing. I usually have the master high and use the gain to set overall volume , I prefer that to having the gain high and master low. 1 Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted September 5, 2021 Share Posted September 5, 2021 (edited) On 05/09/2021 at 08:46, JapanAxe said: What silicon diodes did you use? On my recent B15-inspired build I had a GZ34 that was arcing. I fitted a new GZ34 and then tried a UF4007 before each anode on the GZ34, but the amp didn't work with the silicon diodes fitted. Did you put them in the right way around? Positive of the diode to each anode of the GZ34. I can't remember which device I used but I'll try to find out for you. Edited September 8, 2021 by BassmanPaul Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted September 5, 2021 Share Posted September 5, 2021 Diodes I used were UF5408. A 4007 should have worked too but maybe not as well. Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted September 5, 2021 Share Posted September 5, 2021 14 minutes ago, BassmanPaul said: Did you pay them in the right way around? Positive of the diode to each anode of the GZ34. I can't remember which device I used but I'll try to find out for you. Ha ha, yes I know how diodes are oriented! I recently rebuilt a modern Princeton Reverb and it had BYD33V diodes fitted to the rectifier valve in exactly this way. 1 minute ago, BassmanPaul said: Diodes I used were UF5408. A 4007 should have worked too but maybe not as well. Thanks, I might get some of those. Quote Link to comment Share on other sites More sharing options...
BassmanPaul Posted September 5, 2021 Share Posted September 5, 2021 You might find this link to be interesting: https://www.talkbass.com/wiki/technical-amplifier/#39-protecting-the-rectifier-tube-from-flashover Paul Quote Link to comment Share on other sites More sharing options...
beans-on-toast Posted September 5, 2021 Share Posted September 5, 2021 (edited) 8 hours ago, JapanAxe said: What silicon diodes did you use? On my recent B15-inspired build I had a GZ34 that was arcing. I fitted a new GZ34 and then tried a UF4007 before each anode on the GZ34, but the amp didn't work with the silicon diodes fitted. The uF4007 is fine. UF5408 will work but are harder to fit because of their size. The diode must be located after the bias tap if there is one. I describe it here: https://www.talkbass.com/wiki/technical-amplifier/#39-protecting-the-rectifier-tube-from-flashover Edited September 5, 2021 by beans-on-toast d 1 Quote Link to comment Share on other sites More sharing options...
JapanAxe Posted September 5, 2021 Share Posted September 5, 2021 Thanks @BassmanPaul and @beans-on-toast that's really useful. I built my amp cathode biased so no issue with the bias tap. 1 Quote Link to comment Share on other sites More sharing options...
beans-on-toast Posted September 5, 2021 Share Posted September 5, 2021 Cathode bias eliminates one possibility. Something odd is going on then. Carefully recheck the wiring. When soldering on the socket, the rectifier tube should be removed. Check the socket tension, the tube should slip in and out with some resistance. It helps to have a scope to examine what is going on. Test the high voltage AC secondary with the tube removed. Check for the presence of the 5VAC heater. Then check the rectified voltage with the other tubes removed. Be patient. It requires logically checking each step along the pathway. 1 Quote Link to comment Share on other sites More sharing options...
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