Newcomer, Melbourne, Australia

[phatt]

Headscratch?,, I'm not sure this is right.

Better minds will reply I'm sure but in my understanding you have not established a correct reference voltage?
It would just float ? xP
Phil.

Ed: My guess you would need a voltage divider from HT to ground to create a reference voltage that is fixed?

Ed 2 forget that,, I missed the ground reference,,, long day

[nodz]

With 256V in and the voltage divider of 100k and 220k resistors, should give an elevated voltage of approx 80v.   :dbtu:   Hopefully, with this set up, providing I get the hardware wiring right, this should be a fairly quiet supply. Ideas initially taken from audiophile circuits.

[nodz]

Did a stock check of the parts required, off to Jaycar tomorrow to buy a couple of resistors and a few hardware bits and pieces.  Hopefully come Monday afternoon will have a working PS.  Not boxed up but a working PS, none the less.

[Roly]

Did a stock check of the parts required, off to Jaycar tomorrow to buy a couple of resistors and a few hardware bits and pieces.  Hopefully come Monday afternoon will have a working PS.  Not boxed up but a working PS, none the less.

:dbtu:

[nodz]

Got everything required, except the case.  Was thinking, that as I am building a modular unit, I might have to use something like 19" rack cases

[phatt]

Yeah but Unless you use those flat donut transformers you will have to use a full height case?

I assume this is for some kind of preamp setup in which case you'll likely want plenty of control over parameters.
Which often leads to many knobs on the front and many modification before you are happy.
I'd  go cheap as you can get before outlaying on powder coated silk screen fronts.
Phil.

[nodz]

Building in a modular fashion over a period of time, so would like everything to match.  19" racks is probably the way to ensure that the cases are always available.  Agree with you about the height, even with using toroidal transformers, still think you will need at least 2U cases.  I want to build a PS, preamp, reverb unit, overdrive unit and power amp in separate cases.  I don't think the reverb tank will fit in the 19" case either, so I might struggle with them.

Edit:  Just had a look at the Accu Bel site for the different types of tank, the outer dimensions of the long tanks are 16.75" so a 19" rack should be alright.

[phatt]

This is a stand alone reverb unit,,, fits into a half rack case,, and I doubt you will ever need nor want for much better Reverb than what this little mongrel can produce. winky

full story here;
http://www.ssguitar.com/index.php?topic=2773.15

Adding pic of my PhAbbTverb.
Phil.

[nodz]

Very nicely done.  However, I was going to build a stand alone tube reverb, using a single tube, similar to these

http://www.el34world.com/Forum/index.php?topic=7957.0

Don't know how they'll go.

Going to use an effects loop bypass unit, so that it's not in circuit all the time like the units shown.

http://www.beavisaudio.com/techpages/PedalHacker/

The one with the 3PDT and indicator light.

[phatt]

Hi Nodz,

Yep I understand the attraction of glass but as I have discovered once you dig deep enough you don't need it.

Having spent years working on this I am fully aware that there is little interest in SS reverb stuff.

Mainly because a lot of Modern Valve Amps use pathetic SS reverb circuits and I can certainly understand the casual observer thinking He might need a Real Valve reverb and assumes SS is no good for reverb.
But as I've found this is just not so.
Too late the damage is done and SS rev gets the thumbs down.

The Big names just shoe horn in any cheap *Untested* SS circuit as long as it works the average kid will not know the difference.
If Amp makers actually paid for brains instead of advertizing space A SS reverb can work as well as any Glass power device.

Heck I did it!!! and I'm just a back yard hobby novice,  go figure?? :lmao:

Don't get me wrong I love Valve gear and would love to own a lot of famous gear but I'll never have the funds.

Somehow I always knew a SS reverb could work as well as any Valve driven device and after years of failed attempts I was with help able to produce such a beast. <3)

Try looking at some of these as options;
http://sound.westhost.com/project34.htm

Rod Elliot was a huge help while I struggled to come to terms with reverb circuits.
As should be evident from my Reverb circuits I used his mixer setup as it worked straight up, unlike most of the *Claimed to work* stuff found on the net.
All I did was improve the Driver setup as that is the critical part of tank verbs.
If the drive end is weak then forget the rest as you will be forever searching.

Re those ideas you linked;
I'd err a bit as I don't think an AX7 would have what it takes to drive the tank. (if that is the one you refer?)
An AT7 has ~ x10 the grunt of AX7 as can be evidenced by looking at fender circuits where the AT7 has the plates strapped to drive the tank Tr.

Better minds here can explain the indepth details if you need help with that.

Re the loop;
The Tverb has both a true bypass (Front panel) as well as the mute foot switch (back panel).
Depending how you setup the whole chain of events The mute is all you may need.
I only use the true bypass as a back up in case of trouble with a rig setup.

Phil.

[Roly]

The amateur has several ace-in-the-hole advantages over the big boys, not least because we are personally attached to the results, and you just can't buy that at any price.  We don't have the time or cost pressures, or accountants second guessing technical or sonics matters.  We have the luxury of time to ponder, think and think again, research what others have done, experiment and tinker, let it brew on the back burner, perhaps for years.  There is nothing I could do as a professional designer I can't do in my home workshop.

Take a look at freeware, put together by enthusiasts, and it's very often better than anything you can buy.

James Lovelock, CH, CBE, FRS, Ph.D is a fair dinkum scientist (who once remarked that to do creative work you have to get as far away from the nearest airport, freeway and city as possible) and he did two really remarkable things; firstly he devised the ionisation detector that lifted the sensitivity of gas chromatography by a factor of ten in a single stroke; secondly he used that invention to discover how widespread chlorofluorocarbons were, which directly led to the discovery of the effect they were having on the ozone layer - and he did it as an independent in his own workshop in his cottage in rural Devon.


Yes, a reverb line doesn't require a lot of drive power, but it does require some, and the 12AX7 is a bit light-on in that respect.  There are still a number of small power pentodes available which would be a more logical choice, however I agree with Phil that solid-state is a serious contender.  The tank itself utterly swamps any subtle "tube tonality" that might be in the reverb sidechain.

[nodz]

Having spent years working on this I am fully aware that there is little interest in SS reverb stuff.

Yeah, I totally agree with this, especially in the audiophile area, although a lot of the newer generations are turning away from valve, due to the cost of the valves, PT and OPT.  Much easier to get a 18-0-18V, 300VA toroidal that can deliver the requirements of a 50W chip amp etc.

I have no problems with SS per se, I was predominantly raised in the SS era and all my amateur radio homebrew stuff, including the audio amps etc has been SS.  I have two practice amps and both are SS, so I am not averse to it 

Mainly because a lot of Modern Valve Amps use pathetic SS reverb circuits and I can certainly understand the casual observer thinking He might need a Real Valve reverb and assumes SS is no good for reverb.  But as I've found this is just not so.  Too late the damage is done and SS rev gets the thumbs down.  The Big names just shoe horn in any cheap *Untested* SS circuit as long as it works the average kid will not know the difference.  If Amp makers actually paid for brains instead of advertizing space A SS reverb can work as well as any Glass power device.

Again you raise a valid point.  Many of the modern amps, use poor quality SS reverb circuits.  The stomp boxes and amp modellers can be as bad, if not worse.  I must admit that I like the idea of both SS and valve reverb, as long as they have the spring tanks and are not computer modelled, although some of the top end amps are starting to improve.

Don't get me wrong I love Valve gear and would love to own a lot of famous gear but I'll never have the funds.

How right you are.  $2500+ for a Fender twin reverb reissue.  I will never own any of this type of gear either.  So bang for the buck when I make my own is important.  As I said the amp itself will be modular and I was thinking of putting it in racks.  The reasoning behind this is I can put all the racks in a case and I can develop bits and pieces of gear as I go along.  I will probably build the 10W 12AQ5 PA to start with but later I might try one of the 50W chip amps for an SS PA.  So an SS reverb is not ruled out either.

Try looking at some of these as options;
http://sound.westhost.com/project34.htm
Rod Elliot was a huge help while I struggled to come to terms with reverb circuits.  As should be evident from my Reverb circuits I used his mixer setup as it worked straight up, unlike most of the *Claimed to work* stuff found on the net.

I am familiar with the ESP stuff.  I was looking at building the solid state preamp and the 60W? amp at one point.

I'd err a bit as I don't think an AX7 would have what it takes to drive the tank. (if that is the one you refer?)
An AT7 has ~ x10 the grunt of AX7 as can be evidenced by looking at fender circuits where the AT7 has the plates strapped to drive the tank Tr.

Yeah, I noticed this and was then toying with the idea of going with somethig like the 6BM8 pentode/triode set up.

Re the loop;
The Tverb has both a true bypass (Front panel) as well as the mute foot switch (back panel).
Depending how you setup the whole chain of events The mute is all you may need.
I only use the true bypass as a back up in case of trouble with a rig setup.

Will check this out.  As I said, open to suggestions and there are no hard and fast criteria with the actual final configuration. 

Cheers

[nodz]

The amateur has several ace-in-the-hole advantages over the big boys, not least because we are personally attached to the results, and you just can't buy that at any price.  We don't have the time or cost pressures, or accountants second guessing technical or sonics matters.  We have the luxury of time to ponder, think and think again, research what others have done, experiment and tinker, let it brew on the back burner, perhaps for years.  There is nothing I could do as a professional designer I can't do in my home workshop.

This is how my design has progressed.  It originally started, with a single tube preamp and a SE PA for about 4W out.  Over a period of time, it has become quite a developed design, moving to PI with prescence control, I/P drive and O/P volume for the preamp, a PP 10W PA and also with the reverb and O/D ideas being added.  So the thing is still fairly amorphous  :cheesy:

Yes, a reverb line doesn't require a lot of drive power, but it does require some, and the 12AX7 is a bit light-on in that respect.  There are still a number of small power pentodes available which would be a more logical choice, however I agree with Phil that solid-state is a serious contender.  The tank itself utterly swamps any subtle "tube tonality" that might be in the reverb sidechain.

As mentioned in the above post, was thinking of going to something like a 6BM8 pentode/triode device.  However, I will seriously look at the SS option.  If I'm building modular, it might very well be easier with respect to the power supply and componenty and provide me with the necessary tonal device I'm after.

[nodz]

BTW do you have a circuit diagram for the PS?
Is it a 15-0-15V, 20VA troidal transformer centre tapped that you have rectified and then used the +, - connects of the rectifier to get the +15V, -15V as per Image 1 (although this diagram is for 25-0-25 to give +/- 35V)
or have you used each secondary and rectified and then filtered as per Image 2
or have you used a 18-0-18V transformer and rectified and regulated with something like a 7815, 7915 pair as per Image 3?

[nodz]

Also while tooling around the net, I found an SS reverb circuit but using discrete components rather than ICs.
Design originally came from a Heathkit TA-27, 20W amplifier with tremelo and reverb.