Is a 50v Presence cap too small for 100 watt amp

[rootz]

Tony, am I understanding you correctly, when I say a reverb should best be implemented like it's in the loop. If so, that is one thing I certainly agree with.

[talbany]

Tony, am I understanding you correctly, when I say a reverb should best be implemented like it's in the loop. If so, that is one thing I certainly agree with.

Rootz
Thats correct!. Take a look at something like a Hot Rod Deluxe
Tony

[Guy77]

Or maybe I am just perceiving it that way

You are not the only one This was a problem we (VVT Amps)ran into when we were prototyping adding reverb into our Dumble style amps years ago way before any ODSR or SSS info was available. We incorporated a similar parallel type 2 tube reverb set up as the Bloomfield where we mixed it back in at the master volume, We could not keep it balanced..Now before everyone loses their minds here it did work O.K however being an amp company selling amps to the general public we thought it was not up to our standards and didn't want to deal with any complaints about not having a perfectly balanced amp w/reverb..(Perhaps this is why Dumble tried different methods of implicating reverb into the O.D.S Topology). I will however say that the best sounding better balanced method done by some of the other well known highly respected builders ( I cannot mention) sets it up Post OD gets sent through the tank and mixed back in just before the Master. (Same basic technique as Dumbleator)
Again this is not knocking Two Rock or and other Pre O.D mixing method since some people might even like the slight difference in reverb mix in O.D this would work out wonderful for you.
Now keep in mind this is what we experienced and is my own opinion agree or disagree with me, however your perception is everything regardless as to what math or modeling and my opinion tells you or anyone else..IMO

Tony

Yes very true Tony. We all perceive sound differently and like different sounds. This is definitely the reason we have so many amps to choose from these days! The few customers I have are also very diverse with the particular sound they are after and no two are the same.

Cheers

G

[rootz]

Haha yes Guy, some people don’t even like ‘the Dumble sound’! I do, but as with food, art and many other things I like more flavours than one.

Tony, the HRD has a loop like reverb indeed. It is, and I might be conservative here, the best place to use time based effects IF you want the most consistency out of them. Now there are many guitarist who’d disagree and use eg phaser in front of a distorting amp. You know who I mean.

Then again, utilising reverb like it’s in a loop might nog be enough. The TR CRS V3 did that, more or less (post master volume), but it still did not compensate for differences in output levels of the preceding stages when switching from clean to OD and/or engaging PAB or FET. Many amps do these days! Dual controls, like I advocated earlier, is a way to do it. Another would be one I saw in a Tone King iIRC. They made different input setups for the reverb driver tube that switches with channels. Much less mids in the reverb for the higher gain channel. Couple that with a dual return control and you gain all the versatility at the expense of a pot, knob, relay and some extra wire.

Now there are some more design short comings TR could have dealt with in the CRS V3. 12ax7 reverb driver, not a great choice. High end losses in a couple of places due to loading by the reverb circuit. Adding a good amount of new harmonics with the mixer they chose.

By the way, I never ever liked the OD sounds TR got from any of their Dumble inspired (don’t fall for their marketing: we designed it from the ground up by ear, it’s beside the truth and well just marketing) circuits. Until the Bloomfield drive that is! Finally they managed to build something that has a great clean sound and does not sound lifeless to my ears in OD.

[talbany]

Tony, the HRD has a loop like reverb indeed. It is, and I might be conservative here, the best place to use time based effects IF you want the most consistency out of them.

Rootz
Just so we are clear I am not talking about the buffer/Return amp (Blank those out)I am talking about how the reverb was implemented and where its mixed. Look at it from pin 4 coming off the relay would be the master vol.
You can use either TL072 or convert it into a tube driven style reverb and there you go
Now will it be perfectly balanced? probably not but it will be better balanced than the Pre OD method because your mixing the signal after the O.D just before the P.I..
BTW.This will work using the line out on an ODS style amp as is using the poweramp in jack on the Deluxe

HRD_PreAmp-Verb-1a-144.jpeg

Tony

[335rat]

Has anyone tried to use this HRD reverb/loop in an ODS-build?

I have translated a Fender Super 60 to an ODS#124 style amp on the original pcb. Then there already are a similar reverb and loop circuit as on the HRD that I have tried to use, but I can't get it to work ok. I think the signal loss is too big and it feels like the amp doesn't have the full power. I have changed the Master volume to 100k like it's in the HRD otherwise there will be no reverb. The reverb/loop is inserted after the master but before the PI like it was on the original Super60 and where it is on the ODS.
Does anyone know what more I have to change or maybe the HRD circuit is better in this place?
I can't find out why it does not work in the ODS when it worked in the Super 60. Maybe it's the lack of the third gainstage?

Attatch The Super60 reverb/loop and amp schematics

Thanks!

[talbany]

Has anyone tried to use this HRD reverb/loop in an ODS-build?

I have translated a Fender Super 60 to an ODS#124 style amp on the original pcb. Then there already are a similar reverb and loop circuit as on the HRD that I have tried to use, but I can't get it to work ok. I think the signal loss is too big and it feels like the amp doesn't have the full power. I have changed the Master volume to 100k like it's in the HRD otherwise there will be no reverb. The reverb/loop is inserted after the master but before the PI like it was on the original Super60 and where it is on the ODS.
Does anyone know what more I have to change or maybe the HRD circuit is better in this place?
I can't find out why it does not work in the ODS when it worked in the Super 60. Maybe it's the lack of the third gainstage?

Attatch The Super60 reverb/loop and amp schematics

Thanks!

In the above HRD Schematic I posted has been used in several popular Dumble ODS Style amps..i don't think they would appreciate me mentioning their names so I won't..I have not personally implemented this style loop/reverb so i cannot recommend any mods or improvements. I did play through them and was impressed at how balanced the reverb performed given it was an ODS style amp It also wouldn't surprise me if the HRD circuit was tweaked as well.
Sorry can't help you?
Tony

[335rat]

Thank you!

Then it's worth to give it a try to see what I can do with it.

[neskor]

Hi.
Anybody built his amp or have a layout for this Bloomfield clone?

[Guy77]

Hi.
Anybody built his amp or have a layout for this Bloomfield clone?

Hi. There is a schematic that rootz was kind enough to do for us and also some hand drawings I made and some more info. further down on page 4.

https://ampgarage.com/forum/viewtopic.p ... 5&start=45

Very nice sounding amp.

Guy

[neskor]

Looking at the pictures of a real Bloomfield drive and rootz schematic I can see couple of small differences.
1. Mixing resistor shoul be 270K
2. Snubbers caps in OD channel, not in original amp
3. No Deep switch in schematic
4. No 1nF cap on 220K in Reverb circuit
5. 110K /110K + 10K pot in schematic of PI, 120K/110K no pot in original
6. Bright cap should be 180pF
7. 50/100W power switch is different, I can see only one 1R/5W resistor on that switch on original
I draw layout by hand on a piece of paper but it will be nice to have in a proper form here for future use, if somebody knows how to do that

Thank you so much Guy77 and rootz for this great topic!

[jazzbass]

Did you find out by any chance what are the values and the role of the capacitor and the trimmer on the pab relay board?

Hi

I will check the cap values on my next visit to the amp. I believe the cap and trimmer are part of what's called a "treble bleed" circuit for the Overdrive channel.

Cheers
Guy

Hi Guy and Dimitris, I think they have the same function as Kemdrix's Texas Tea in the Joezee amp, a volume adjustable PAB.

Un abbraccio, Franco

[jazzbass]

Did you find out by any chance what are the values and the role of the capacitor and the trimmer on the pab relay board?

Hi

I will check the cap values on my next visit to the amp. I believe the cap and trimmer are part of what's called a "treble bleed" circuit for the Overdrive channel.

Cheers
Guy

Hi Guy and Dimitris, I think they have the same function as Kemdrix's Texas Tea in the Joezee amp, a volume adjustable PAB.

Un abbraccio, Franco

No, it doesn't really look like a Kemdrix Texas Tea, I tried to insert it as per the diagram between the contacts of the PAB relay NC and the eath but what I get is not a decrease in the volume of the sound but a less aggressive sound a little less " wild", it softens the top end a little.

A question for Guy, I've read the discussion on these pages several times and I'm wondering if the diagram on page 4 made by rootz is the definitive one or did you make changes and/or progress in the construction of the amplifier.
I ask you this because I have decided that this will be my next construction with my little experience I would not be able to improve or make changes to the project.

Thanks and a hug.
Franco

[Guy77]

Hi

I will check the cap values on my next visit to the amp. I believe the cap and trimmer are part of what's called a "treble bleed" circuit for the Overdrive channel.

Cheers
Guy

Hi Guy and Dimitris, I think they have the same function as Kemdrix's Texas Tea in the Joezee amp, a volume adjustable PAB.

Un abbraccio, Franco

No, it doesn't really look like a Kemdrix Texas Tea, I tried to insert it as per the diagram between the contacts of the PAB relay NC and the eath but what I get is not a decrease in the volume of the sound but a less aggressive sound a little less " wild", it softens the top end a little.

A question for Guy, I've read the discussion on these pages several times and I'm wondering if the diagram on page 4 made by rootz is the definitive one or did you make changes and/or progress in the construction of the amplifier.
I ask you this because I have decided that this will be my next construction with my little experience I would not be able to improve or make changes to the project.

Thanks and a hug.
Franco

Ciao Franco, the way you describe the effect of that trimmer on the PAB is correct. Regarding the final schematic, yes page 4 is the final schematic.

Cheers
Guy

[jazzbass]

Ciao Franco, the way you describe the effect of that trimmer on the PAB is correct. Regarding the final schematic, yes page 4 is the final schematic.

Cheers
Guy
[/quote]

Ciao Gaetano,

Thanks for the reply, I need some advice, I built a Steel String Special (rootz, a great friend) and was wondering if I could use that lay out an equal chassis and boards and with the proper modifications build the other amp?

Thanks, a hug.

P.S. Can I add you as a "friend"?

Franco