Spinspin69 Posted March 19 Posted March 19 (edited) Looking for recommendations in Sydney (not going to ship a 27kg amp) for a tech that has experience with tube amps. Just want someone to bay an eye over it and adjust bias on a parallel push-pull pull amp with Genelex GL KT77 power tubes. Ignore the missing resistors in the image, they've been replaced. The resistance from ground to the bias point is ~12.2 ohms (24 + 24.9 in parallel). Current voltage drop across the 4 points ranges from 0.25-0.35V... Edited March 19 by Spinspin69
xlr8or Posted March 20 Posted March 20 (edited) Try Chris Kim from Kimil Electronics in Croydon. I would also recommend purchasing a tube bias adapter and measuring the bias with a DMM and adjusting the bias accordingly across each tube. I'm assuming you have a fixed/manual bias circuit. Edited March 20 by xlr8or 3
vinyl-62 Posted March 20 Posted March 20 5 minutes ago, xlr8or said: Try Chris Kim from Kimil Electronics on Croydon. I would also recommend purchasing a tube bias adapter and measuring the bias with a DMM and adjusting the bias accordingly across each tube. I'm assuming you have a fixed/manual bias circuit. Chris Kim from Kimil has retired so the question remains! He is missed. 4
Spinspin69 Posted March 20 Author Posted March 20 1 hour ago, xlr8or said: Try Chris Kim from Kimil Electronics in Croydon. I would also recommend purchasing a tube bias adapter and measuring the bias with a DMM and adjusting the bias accordingly across each tube. I'm assuming you have a fixed/manual bias circuit. Yeah I i did a search before posting and Chris kept coming up. Unfortunately Google says he's permanently closed.
Vinylear Posted March 20 Posted March 20 Phone a pro audio retailer there are plenty of valve guitar amps out there that need work occasionally they should know some one. Good luck.
BRS Posted March 20 Posted March 20 I have used speaker hospital for driver refoaming before and they had some pro gear there being worked on. Doesn't hurt to ask them and see if they sound like they know what they are doing. https://www.speakerhospital.com.au/
Spinspin69 Posted March 20 Author Posted March 20 31 minutes ago, BRS said: I have used speaker hospital for driver refoaming before and they had some pro gear there being worked on. Doesn't hurt to ask them and see if they sound like they know what they are doing. https://www.speakerhospital.com.au/ I've used them before. Let's just say I'm not in hurry to go back.
vinyl-62 Posted March 20 Posted March 20 2 hours ago, Spinspin69 said: Yeah I i did a search before posting and Chris kept coming up. Unfortunately Google says he's permanently closed. It seems to be a real problem in Sydney or maybe it's just endemic of a problem that will only get worse in Australia as people slowly start to retire. 2
Spinspin69 Posted March 20 Author Posted March 20 9 minutes ago, vinyl-62 said: It seems to be a real problem in Sydney or maybe it's just endemic of a problem that will only get worse in Australia as people slowly start to retire. That's the impression I'm getting... 1
xlr8or Posted March 20 Posted March 20 (edited) There are few members here who are dabbling further into tube circuit design. With time their understanding in fault finding is greatly improving. It's a great path to follow. I've got some way to still go, but am learning more and more everyday. You can review the DIY thread and reach out to a few members to see if they can help out. Regarding your post above, could you please confirm the plate voltage on the KT77's? Bias for class AB fixed should be circa 35-40mA for say 350-375v plate voltage. I've assumed fixed bias with pots - is that correct? What's the cathode resistor value? Edited March 20 by xlr8or 1
Spinspin69 Posted March 20 Author Posted March 20 12 minutes ago, xlr8or said: There are few members here who are dabbling further into tube circuit design. With time their understanding in fault finding is greatly improving. It's a great path to follow. I've got some way to still go, but am learning more and more everyday. You can review the DIY thread and reach out to a few members to see if they can help out. Regarding your post above, could you please confirm the plate voltage on the KT77's? Bias for class AB fixed should be circa 35-40mA for say 350-375v plate voltage. I've assumed fixed bias with pots - is that correct? What's the cathode resistor value? Currently travelling. Let me get back to you with those numbers this weekend. 1
Honreekea Posted March 21 Posted March 21 Surely Audio Connection have found a replacement Chris Kimil.....you could ask them.
Spinspin69 Posted March 21 Author Posted March 21 2 hours ago, Honreekea said: Surely Audio Connection have found a replacement Chris Kimil.....you could ask them. I'll pop in and ask next time I drive past...
Glass_and_Tubes Posted March 25 Posted March 25 (edited) I've had a lot of success with Tim - he's honest, reliable and fair. He is often the guy behind Audio Connection or Lens Wallice etc. Tell him Clinton sent you. https://tunedinaudio.com.au/ Edited March 25 by Glass_and_Tubes 1
Spinspin69 Posted March 25 Author Posted March 25 2 minutes ago, Glass_and_Tubes said: I've had a lot of success with Tim - he's honest, reliable and fair. He is often the guy behind Audio Connection or Lens Wallice etc. Tell him Clinton sent you. https://tunedinaudio.com.au/ Thank you. I've already been in touch with Tim and will get my gear to him when I'm back in Sydney...
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