Search found 88 matches

by BungleSim
Tue Jun 27, 2023 11:30 pm
Forum: Technical Discussion
Topic: Ampeg V5 to Hiwatt DR103 Conversion Project
Replies: 11
Views: 805

Re: Ampeg V5 to Hiwatt DR103 Conversion Project

Swapping the OT primaries solved it! Thank you to Stevem and xtian for your help! There's another issue somewhere in the preamp because the audio signal isn't making it all the way through, but I think that's just either a bad tube or the conductor in my shielded wire is getting shorted to ground. I...
by BungleSim
Tue Jun 27, 2023 10:57 pm
Forum: Technical Discussion
Topic: Ampeg V5 to Hiwatt DR103 Conversion Project
Replies: 11
Views: 805

Re: Ampeg V5 to Hiwatt DR103 Conversion Project

Well Its time to start removing tubes to deactivate circuits and then replace them one by one. Yank them all out but for the output tubes, do you still then have the issue? I pulled all the preamp tubes and started putting them back in, going backwards from the PI (V4), and the noise returned when ...
by BungleSim
Tue Jun 27, 2023 12:05 pm
Forum: Technical Discussion
Topic: Ampeg V5 to Hiwatt DR103 Conversion Project
Replies: 11
Views: 805

Re: Ampeg V5 to Hiwatt DR103 Conversion Project

After looking at some wiring layouts, last night I moved the grid stoppers right onto the power tubes. I did the same for V1. Now the noise at the output is a steady 86.27Hz at 75Vp-p. So... progress? :lol: First thing I tried was removing the NFB but the noise persisted. I have yet to start popping...
by BungleSim
Mon Jun 26, 2023 3:23 pm
Forum: Technical Discussion
Topic: Ampeg V5 to Hiwatt DR103 Conversion Project
Replies: 11
Views: 805

Re: Ampeg V5 to Hiwatt DR103 Conversion Project

93 volts P to P is over 1000 watts into a 8 ohm load, so your 300 watt load resistor should be burning up! Is that the case? I try not to let oscillations, especially of this magnitude, run for too long while I'm testing so I haven't really noticed the load getting very hot. I only run it for maybe...
by BungleSim
Fri Jun 23, 2023 5:03 pm
Forum: Technical Discussion
Topic: Ampeg V5 to Hiwatt DR103 Conversion Project
Replies: 11
Views: 805

Ampeg V5 to Hiwatt DR103 Conversion Project

A few months ago I posted about converting an Ampeg V5 to a Hiwatt DR103. You can read the post here if you'd like. Quick background: My friend/guitar player in my band bought an Ampeg V5 in hopes of having a cool variation on a 2203 circuit but we found out after purchasing (Reverb) that the previo...
by BungleSim
Mon Jan 30, 2023 6:49 pm
Forum: Technical Discussion
Topic: Please Review: Ampeg V5 to Hiwatt DR103 Conversion
Replies: 2
Views: 674

Re: Please Review: Ampeg V5 to Hiwatt DR103 Conversion

mhuss wrote: Mon Jan 30, 2023 6:20 pm Sounds like a good project. I don't have any objection to any of your bullet points.

Best of luck with it.
Thanks and thank you for the schematics on your website that I referenced!
by BungleSim
Mon Jan 30, 2023 3:30 pm
Forum: Technical Discussion
Topic: Please Review: Ampeg V5 to Hiwatt DR103 Conversion
Replies: 2
Views: 674

Please Review: Ampeg V5 to Hiwatt DR103 Conversion

Quick background: My friend/guitar player in my band bought an Ampeg V5 in hopes of having a cool variation on a 2203 circuit but we found out after purchasing (Reverb) that the previous owner had totally gutted the amp and modded it beyond recognition with all new iron. Rather than make it just an...
by BungleSim
Mon Jan 16, 2023 12:48 pm
Forum: Technical Discussion
Topic: Hiwatt DR201 OT - Tube Town vs TAD
Replies: 9
Views: 984

Re: Hiwatt DR201 OT - Tube Town vs TAD

I'm a regular customer of Tube Town and I even used the mentioned set of transformers in a bass amp with pleasing results. In my opinion Tube Town is a very serious store without all that voodoo / snake oil stuff TAD will tell (and charge) you. Thank you for answering my question directly! I really...
by BungleSim
Fri Jan 13, 2023 1:18 pm
Forum: Technical Discussion
Topic: Hiwatt DR201 OT - Tube Town vs TAD
Replies: 9
Views: 984

Hiwatt DR201 OT - Tube Town vs TAD

I'm building a Hiwatt DR103 type of amp for my friend/guitar player in my band. We're into big, loud amps and I've been curious about KT88 tubes so I'm thinking about sticking a DR201 OT in the amp and using 4X KT88s to get 200W out. The price of a DR201 OT from Tube Town is pretty good at 110 EUR ,...
by BungleSim
Fri Apr 09, 2021 1:32 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

...Anyway, I have put a 4.7K resistor across the standby switch ... Merlin suggests 47k, but as your HT voltage is so high, I’d increase that, eg 100k. Thank you for pointing this out because I was just going to post how when the standby switch is opened the HT only drops to about 475V and doesn't ...
by BungleSim
Thu Apr 08, 2021 7:45 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

Phil, I see your rationale, but I think it’s standard terminology for a switch, when ‘closed’, to allow current to pass, and for it to stop current flow when it’s ‘open’. Other common switch terminology is ‘make’ and ‘break’, perhaps that’s a bit less open to misunderstanding? Basically, in every w...
by BungleSim
Thu Apr 08, 2021 6:19 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

I guess maybe the terminology is confusing me. Closed in my head meant 'shut off' The scope seems to show that the voltage dropped drastically, spiked a few times, then dropped again, like caps were discharging and then the voltage was gone. Since there's no mark of what the actual bottom and top v...
by BungleSim
Thu Apr 08, 2021 5:33 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

pompeiisneaks wrote: Thu Apr 08, 2021 5:31 pm I'd think seeing when it opens is more helpful, as the spikes likely come when an amps caps are pulling large inrush current to charge up, but maybe I've misunderstood the potential fault?

~Phil
But aren't the caps charging when the switch closes, not opens?
by BungleSim
Thu Apr 08, 2021 5:14 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

Here's a measurement of the cathode of D5 while the the standby switch is being closed. This was done with a 100X scope.
PXL_20210408_165712269.NIGHT.jpg
by BungleSim
Thu Apr 08, 2021 1:40 pm
Forum: Technical Discussion
Topic: Bassman style amp blowing rectifier diodes
Replies: 28
Views: 2904

Re: Bassman style amp blowing rectifier diodes

If it was PIV related then some options could be to use 2x 1N5408 or UF5408 in series, and add a C-RC snubber across the HV secondary, and replace the standby switch if the amp has been in service for some time (as the contacts may have degraded). I don't think I can fit double the diodes, but I'm ...