Quote from: bry melvin on June 08, 2010, 03:56:33 PM
There is a kit out to turn an epiphone valve JR into s standalone reverb (1 12ax7 and one el84)  You can get junior chassis on Ebay for about 50$.

This is probably the cheapest and easiest to build

sound.westhost.com  (elliot) has an SS reverb project.


The V JR project is probably very similar to my Vintage Guild amp (built in seperate reverb  amp  12ax7 and 6bm8 CTS 8" speaker)  That is a really nice California/surf sound reverb

Hello bry melvin,
                     Yes the ESP circuit does indeed work.  :tu:
I should know that as my *Maxiverb* unit is loosely based on his ideas.

I had quite a few conversations with Rod about it all and it's likely my interest prompted his addition of the *Booster circuit* that he added to his Reverb page.

I could not get enough drive to make mine work so in My Circuit I used a much higher voltage to run the booster and that makes all the difference.

most of the cirtcuits on the net are crap,,, believe me I've built most of them.

ESP circuit at least works straight up no mods. Stick it together on a bread board and instant reverb.
most of the others are either noisey or just plain gutless.

And what is really frightening is the *Recommended circuits* at *Accutronics site*
Are just plain useless. I kid you not.

As to running a Valve circuit,,, Well It's a toss up really as the cost will inhibit progress. (unless you already have a pile of Valve stuff lying around)
a SS version may work out cheaper.
Mine is a bit tricky to build because you still need a fair voltage,, i.e. 35-0-35 and 15-0-15 VDC to run it but still probably cheaper to build than an all Valve unit. :tu:
Cheers, Phil.

Thanks Mr, Fahey
Whoops I missed that one.
Good to know chaps like you are floating around to pick up the Fatal mistakes. :tu:
Personally I think this chap should quit while he is still breathing and hand it over to someone *Qualified*.
Phil.

Answer to your Q's is best coverd by you doing 2 things.
Read *Teemu's Book* http://www.ssguitar.com/index.php?topic=711.0
And build stuff and don't panic about those sorts of things.

It will slowly all come together.
When I started out I just kept reading screads of stuff,,, and over time all the bits I missed came together by just experimenting with simple low voltage stuff.

Hard to kill yourself with a 9Volt battery and a few fets. 0:)
Phil.

Hi f_b_ilies,
Ouch again!
You really need to consider learning the *Basics First* before jumping inside stuff you don't fully understand. (Now you are paying the price) 

Transformers work on AC Volts only, that's Alternating Current.
i.e. 240VAC @ 50hZ.   Or 50 times a second it alternates.
DC (Direct Current) does not alternate.

It's all AC until it passes the Diodes which transform the AC voltage to DC.
(Your *Diodes* are in that black square thing, should have 4 legs)

Your reading of 36 V *?* means little to us as you have not qualified if it's AC or DC your meter is reading.

Google *Rectification* I'm sure you will find something that may help you to understand the basic principle of converting AC to DC.

Your *36 volts* is likely to be the *Rectified DC* that powers the circuit.
A clue to this can be found by reading the working voltage on the side of those 2 large Electro Caps on the board. If they read 50Volts then you secondary DC will be *Below* that voltage.

Your secondary AC is likely to be around 25-0-25 VAC which will deliver the 37-0-37 VDC.
(This is a common voltage for amps in this class.)

In these circuits the VDC is *Split around Zero Volts*

So you have a *Positive Voltage and a Negitive* and Zero or common.
hence 3 wires 8|


Go here http://evatco.com.au/hamptchoke.htm

Click on
**Transformer Selection Guide**

If you are intending to learn *How stuff works* You will need Know this one day,,,
so Save it and print it out.
Phil.

Hi adamn,
Here's the schematic for my take on the Vtwin.

The Amp is long gone so don't hold me to exacts but I'm sure it won't take you long to find what works for you.

I deleted the optional bright cap (20pF) as the HiWatt Tone setup is already quite bright. If you are driving a SS poweramp then excessive treble will be harsh.

*Note the mistake* in the *Original Mesa drawing*
That being R24=270k is just insane,,, Try 27k, wink.

While bread board testing I found I did not need all the extra add on bits as it was built into a combo Amp chassis.
This makes it very straight forward to build.

The dirty channel was tested but frankly it sounded no better than some SS pedals.

Running this dirty channel Through to a Valve Amp may work better as a lot more high frequency hash is lost through some Valve Amp circuits but when driving into a SS poweramp you have to watch out for the dreaded diode hash.
Upon reflection a Cab sim circuit *After* that part might have been the go when working into SS pwr stage.
No matter cause you want the cleaner sounds. :tu:

My Valve part ran on 240VDC so try it out with 60VDC and see if it works.
My guess is you may need closer to 100 VDC,, but hey if it works for you then go with it.

Re the tone part;
Look if you want to replicate an *Exact* tone shape then just drop the HiWatt tone but IME you won't find a tone stack as powerful as the HiWatt.
Even the fabled *Dumble tone* circuit with all it's fancy switches is no match. 

Though it's No better than fender or marshall for treble and bass the *mid cut* ability of HiWatt tone just eats ALL the others.
I've built and tested most of them (side by side test) so I do know how they perform in the real world.

No other passive tone circuit I know of can pull the mid notch like HiWatt.

Note; All these tone circuits need to be looking into a BIG impeadence and the FET circuit on your link *Can't deliver the goods* It suffers great losses.
(been there done that).

It seems like a good idea but it became obvious to me that a simple opamp buffer works far better and minimises any loss (and potential noise) at this *Critical point*.

So don't delete the buffer opamp after the tone stack otherwise you will run into lots of trouble and the circuit will be wasted. 

Have fun with it all, Phil.

Quote from: f_b_ilies on June 08, 2010, 04:24:50 AM


Let me ask you, in theory, what happens with the output voltage of a transformer, if we double the input? Say we have a transformer 110V->15V and we plug it into 220V, will we get double on the output (30V)? If so, that's bad news for my amp, unless there is some kind of 3rd level protection there (in case neither the fuse nor the transformer blow).

Oh dear  Yes absolutley,,, when you double the primary it doubles the secondary VAC, So yep you likely fried the whole thing.
An that's usually everything $expensive$
Phil.

Hi adamn,
              First Q/ Are you wanting clean,, inbetween rattle rock tones,,
or full on metal?

IMExperience, The valves are being wasted setup like this.
My suggestion, Google *Mesa Boogie Vtwin schematic*

It will likely run on the 60 VDC you have and it's about the best tube preamp on the planet.

I only ever built the *Clean section* and of course it should obvious that you do not need all the extra stuff.
Makes for an easy project.

If the Vtwin schematic is hard to understand I can search through my old files and find the setup I built many years back.
Good on you for having a go at something that is not easy to do. :tu:
Phil.

Hi Enzo,
          Appreciate the input but my answer was based on the high likelihood that the owner is chasing a ***MUCH MUCH MUCH better Reverb*** and unknowingly assumes that the *TANK itself* is where the mojo (Killer tank slapping) reverb comes from.

Sadly this is Not the case.

A Big tank Will/maybe/if your lucky
(and the imp of both ends matches, cross your fingers)

Now even if he is that lucky,,,,then some improvement/difference will no doubt be heard.

But sadly no killer tank slapping reverb will be forthcoming.

I, just like Wiskytown once thought that it can't be that hard to get a better reverb sound.  Well didn't I have a lot to learn.
10 Years latter and a very very long story
I have a *Stand Alone Tank slapping Reverb Unit* that I built myself.

Those little *current drive opamp* tricks used in 90% of SS Amps (and a lot of Tube Amps) these days are just so dead pan (pun) gutless when compared to a pro unit.

All the same if wiskytown finds a cheap bargin tank and want's to swap it then go for it, he could get lucky but outlaying for a brand new unit is likely money wasted.

Wiskeytown, FWIW, The digital ones do a fine job but still no tank slap
(BTW, impossible to do with digital teck)

It is very hard to replicate the signature sound of a well thought out Tank Rev unit.
You can purchase *Dedicated Stand alone Analog tank units* and these will always work better than combo mounted units as the vibration issue is ever present inside the back of a speaker cab.
Cheers guys, Phil.

Hi wiskeytown,

The Rev Mojo (Or lack thereoff) is to be found in the circuitry, *Not the Tank*.

Finding a better Reverb circuit will be a lot easier and more rewarding that trying to match a Different tank to existing circuit.

You would be well advised to search for an outboard reveb setup instead of trying to mod existing setup.
Have fun, Phil

Hi JMFahey,
                Very good,, very funny,, I'll pay that one, LOL.
I live on the north side of the fence,, the Dingo side.

BTW Not ALL of Australia looks like this,, Though the centre is very much a no mans land in places.
Some roads out there you can drive at 140 MPH for hours,,,  DEAD Flat straight.
It's quite errie at night.
Cheers Phil.

Well good to know it works well, Obviously you've got it covered with PSU. :tu:
Phil.

Quote from: rowdy_riemer on May 18, 2010, 08:52:58 AM
Cool, thx for the info. I'll definitely give this a shot. BTW, I just picked up a stereo eq yesterday at the thrift store. Only $5.

Arrh, That's what we like to hear,,, *Cheap*
I just mount 6.5 sockets in the back panel and install internal jumpers across to the RCA sockets otherwise it's a pain to work with RCA

The other channel is obviously not used,, So a spare eq for something else maybe.
Just watch out for the top line models with the *stereo wide function*.
I have one like that and it does funny things when engaged as you are only using one side and hence mono signal.

If you happen to have a rack processor (with stereo out) or similar gear you can now do all the fancy time effext *post Power tube* into a stereo power Amp and two speaker boxes.

I think you will have a lot of fun with it.
Cheers Phil.

Attn *rowdy_riemer*
Re "suggestions for a re-amping setup"
----
Good Your little 5watt is a perfect candidate for soaking and ReAmping:)

Attenuators look appealing as it's a simple add on but they are very limiting.

I've found them painfully frustrating till I understood you can bypass most of the issues surronding the losses with attenuators by simply running a soak and tapping the signal off to another Amp.
(The 2 ideas are very similar and it often gets confusing)
The *Second Amp* drives the speaker (The UA does this all in one box)

A simple resistive load soaks the power tubes and via simple voltage division is converted back to line level.
Run this soaked output through a simple Graphic and into a SS power Amp of your chosen wattage and you will be way ahead for a very small outlay.

Now you can go crazy and not annoy the folks next door.

The pics should tell you most of it but may require some explaintion.
The load resistor for your 5Watt amp need only be 10Watt (you can go smaller but the cooler things run the better)
The box here runs only warm with my little 10Watt Amp.

The ground Lift will come in handy as you will no doubt have a second amplifier that is also grounded ,,trust me this sw will come in handy.

The Load R;
Assuming 8 Ohm output from tube amp then an 8 Ohm resistor will make for a very flat compressed output.
running 24 Ohms delivers a far more realistic dynamic response but will still need tonal adjustment to make up for losses.

Sadly there is probably no *perfect system* there will always be some loss when implimenting these things.

SS or Valves, you will loose some realisum when you turn the SPL down to very low levels but Any loss is far out weighted by the amount of tricks you get to do with this.
Have fun, Phil.

Quote from: J M Fahey on May 16, 2010, 02:38:49 PM

QuoteKinda different from that "sweet soft clipping" prejudice. Hard, square waveish clipping and awful amount of crossover distortion.

+1
I don't know why that old wive's tale of "tubes clip rounded, SS clips square"  and "tube has even harmonics, SS has odd ones" is still being sickeningly repeated over and over, zillions of times, specially by people who should know better, I mean famous name factories, boutique builders and "tube gurus".
Just for kicks, scope the output of a Plexi when overdriven by 10/15dB , loaded by a real world speaker, 4x12" welcome.
It will be like nothing you ever imagined; "complex dirt" indeed.
"Rounded sinewave" my 4ss !!!

I read somewhere that half wave clipping followed by square wave compression is what happens.
In my limited building of Valve gear
Triode preamps do deliver the aysimetrical wave but it's the power stage square wave thing that is most usefull.

As I've just been revisting B May it 's interesting to note that with just a simple one triode preamp (which by itself can't do very much distortion) You only need to send the thing a bigger signal swing and Presto! all the magic power tube stuff just jumps straight out.
Phil.

Quote from: rowdy_riemer on May 16, 2010, 11:27:13 PM

QuoteWorth a mention is Speakers.
I'll tell you a little story;
My friend of many years came to me with his Teck21 Trademark60.
He simply asked if there was any way to make it sound like my gear.
I won't bore you with details but he was stunned at the result.

I simply replaced the speaker with a far *LESS Efficent* speaker.

I like the sound of my little 5W amp, but I sure wouldn't mind a less efficient speaker if for no other reason than to make it quieter.
BTW, next time I go to a thrift store, I think I'll pickup whatever old eq they have. :tu:

Hi, Can I enquire if the little 5Watt Amp is a Valve unit?
If so you can do some tricks by ReAmplifying it and then run it through the cheap Graphic (you will no doubt find at a junk sale) then into a second amp.
I've done that trick to a simple Valve Amp, with great results.
No one wants those old HiFi type EQ's anymore so they tend to sell dirt cheap. :tu:
Phil.