Guy77 wrote: ↑Fri Jun 19, 2020 1:47 pm
Congrats on your new build rootz! Let us know which is your favorite our of the 2 amps or maybe each is very special in its own way!
I know a lot of the power transformers from twin reverb amps from the 60's and 70's ran very hot as well, couldn't keep hand on power transformers for more than a few secs and they ended up lasting several decades and then some. These are huge chucks of iron and can take a lot of heat.
I would definitely go for the 240v tap on the transformer this should cool things a bit.
I am planning a second Overdrive Reverb build and this time I will be using Marshall 100 watt power transformers.
Cheers!
Guy
I might take the heat. I still think it’s to hot though. Adding a fan using Martins suggestions is simple enough and I’ll test with that.
An overdrive reverb with Marshall transformers sounds like a marvellous idea! Are you going to build something based on a 183 or hrm? You could use El34’s of course! Maybe even make the pi more Marshall than the usual Dumble. Really looking forward to your ideas.
Guy77 wrote: ↑Fri Jun 19, 2020 1:47 pm
Congrats on your new build rootz! We will eventually need to know which is your favorite our of the 2 amps or maybe each is very special in its own way!
I know a lot of the power transformers from twin reverb amps from the 60's and 70's ran very hot as well, couldn't keep hand on power transformers for more than a few secs and they ended up lasting several decades and then some.
Cheers!
Guy
exactly. the hot Peavey trannies I have are 30 years old and going strong despite the heat. I haven't got round to installing a fan yet either.
i would love to add reverb to one of my ODS. that is something I'm going to look into after seeing your builds.
m
Thanks for your insights Marcus. Erwin also used the same peavey iron on a HRM. Runs hot, but still goes strong after 12 years.
Adding reverb to an existing amp might not be that simple. I remember a post from redplate where he incorporated reverb into a Dumbleator. That might be an idea. If you want to do something new or an overhaul of sorts I’ve got plenty ideas that prove themselves via Guy and my amps.
I didn't describe it very well. In the pic you posted, its the earth lug between the tube socket and rectifier board. Must be all good if its working
I have a set of these transformers as well. But my power transformer looks bigger what's the part number on yours?
I might take the heat. I still think it’s to hot though. Adding a fan using Martins suggestions is simple enough and I’ll test with that.
An overdrive reverb with Marshall transformers sounds like a marvellous idea! Are you going to build something based on a 183 or hrm? You could use El34’s of course! Maybe even make the pi more Marshall than the usual Dumble. Really looking forward to your ideas.
Hi rootz. I wanted to get a higher plate voltage and the Marshall power transformer will get me closer to around 470v, this is higher than what the Hammond twin transformer will get me. I prefer the sound of 6L6 so I will stick to those tubes and I will use a output transformer with about a 2.2k primary. Thank you for the info on your transformer.
This time I will try to pull the reverb just before v1b with a 68K resistor . This is the same way that the ODRS #13 and JM/Wonderland amp do it and then I will mix the clean/overdrive and the reverb with a "tweed mixer" similar to yours and the JM amp. It will take 6 preamp tubes in total to do it this way. I will do it with the classic tone stack, its my favorite tone stack and probably a low plate/high plate version.
It will be later in August when I will be doing it and I will post the results.
Your idea about keeping the reverb in a dumbleator circuit sounds like an excellent idea too. I added an external dumbaltor to an ODS build I did 5 years ago and really liked the sound of it!
Thanks for sharing the info on your first build. I really like the sounds from my amp too !
Excited to hear feedback on how your build sounds!! I am sure it will be another winner!
Low volume home recording with an iPhone. I tried to capture how deep this reverb sounds. I think I made the right decision to put the master after the reverb section. Mid boost was on during most of the recording.
Yes the reverb sounds amazing with the Master after the reverb! I really like how the overdrive sounds with this high plate version and the higher voltage transformer!
Did you use the 2.2meg /68K voltage divider before sending the signal to the tweed mixer, like you did in your previous build?
I left mine with a 470k/68k divider.
Edited.... I see now from your schematic you used the 1meg/68k divider. Nice!
She is a winner! Congrats rootz!
Guy
Last edited by Guy77 on Sat Jul 04, 2020 2:35 pm, edited 1 time in total.
rootz wrote: ↑Sat Jun 20, 2020 10:06 am
Here is some feedback Guy
Low volume home recording with an iPhone. I tried to capture how deep this reverb sounds. I think I made the right decision to put the master after the reverb section. Mid boost was on during most of the recording.
Congrats; it's a wonderful sounding amp. I like the singing quality the OD has in combination with the reverb.
Thanks Guy! It’s not really much higher voltage than the layout of #102 or 183 that can be found in the files section. I rewired it to the 240V tap on the power transformer, so my B+ is down to 475v now. Heaters are now at 6.15V. Does it run cooler? No, I chose the same bias point, so plate dissipation will remain the same.
The tweed mixer is not the same as in the other amp. The general idea is the same, but I combined the local feedback on the dry side with the voltage divider you mention. It is now 470k series resistance, 470k grid leak after that and a 1 meg feedback resistor. Much like ODRS 60 iirc. The gain of the dry mixer is only 6dB, so it very clean. This strays a bit away from the Wonderland topology.
I want to thanks Martin for the guide about the Fet setup with two 9V batteries. So simple to do. I landed on a 3k3 source resistor. A bit higher than I expected, but if it works, it works. I adjusted the lower resistor from the 150k/8k2 voltage divider to 22k. I get about 18V that way, the drain is at a bit above 9V.
I also went with Martin’s suggestion to power the fans from the heaters of the power tubes. The fans are supplied with 8.5V dc. Fans? Yes, there are now two of them spinning on a low speed and pushing hot air out through the front panel. The amp now stays pretty cool.
It surprises me how loud a 100 Watt amp is. This is so much louder and bolder than the 2x6v6 amp I did last year. You can hear all this power, even when it’s on low playing volume. Strange huh? I also have the impression this amp feeds back much easier than my other one. Even on low volume I can hear the sustain is there in spades.
Thanks for the update rootz. I was just looking at the #60 schematic and it is just as you described it 470k series resistor and then the 470k grid leak. I will have to try that combo. I have an 8meg local feedback resistor on my dry mix side, your 1meg must clean it up nicely!
Here is a little clip of mine with first no reverb and then half reverb and then full reverb, there are pauses between each change. Its on the overdrive channel.
These are beautiful sounding amps!
Thanks rootz!
Guy
ODSR_Reverb2.m4a
You do not have the required permissions to view the files attached to this post.
Sounds great Rootz . Plenty of reverb available there and seems to have no negative effect on the OD at all.
would be great if you could post a layout /schematic for this amp? The one thing I Miss with my ODS amps is just being able to dial in some Spring reverb. Having to lug around a dumbleator and pedals sometimes is just a PIA.
congratulations on a great build, you must be very happy.
I am very happy for you. This is a very nice and so much of a personal/DIY build. I liked to see (& ear) that...
rootz wrote: ↑Sat Jun 20, 2020 3:01 pm
It surprises me how loud a 100 Watt amp is. This is so much louder and bolder than the 2x6v6 amp I did last year. You can hear all this power, even when it’s on low playing volume. Strange huh?
My old man used to say that the power was not necessarily to be used to make more noise, rather to reproduce the amplitude of the signal. That's what you hear, I believe...
