RH84-weak sound

Rookie builder need help. Waiting for my UL OPT's and power transfo to build a Kegger SEUL amp,
so figured to throw together a rh84. "for practice"
problems are:
very weak/low sound, if increase volumn on preamp it starts clicking, and the louder you go, the louder and faster the clicking gets, until it turns into a screaming/screeching whail.
if you start up amp w/ out the pre-inputs connected, these sounds/screeching starts immediately. Rechecked all wiring, twice. rechecked all resistor and cap values, twice. Have tried a different set of tubes.
tube pin violtages:
6bq5
1: 8.3
2: -27.8
3. 4.0
7: 321
9: 278

12at7
1: 196.6
2: .6
3: 1.28
I know the B+ is a little high, at this measurement, I am using a Variac, and it does the same thing at 300V.
Also the 250ohm resistor from pin three to grd on 12at7 is 240.
270ohm 5 watt pin 3 6bq5 is only 250 ohm. this is what i had, and the difference is almost within the 5% tolerance.

any help thoughts would be most appreciated.
I can upload some pics tonight.
Is my mistake right in front of my face?

Thanks in advance Stu

I can't say that I know what it is that you may have wired wrong.

But I can see an issue, that -27.8v at pin 2 (grid) of the EL84 is not
suppose to be there and it'll making your tube draw very little current.
(without that voltage you should see 7-11v on pin 3(cathode) of EL84)

Pin 1 on the EL84 shouldn't be connected to anything either, no voltage.

It is obvious that the EL84 is not drawing enough current, actually with that negative votlage it should not be amplifying anything at all...

Sorry, but I have to say that the layout is a mess, and most probably there is contact between the legs of two or more components.

This is a case of "dismantle everything and start all over again".

It is a pity if that discourages you from building an RH amp... but there is no amp you will be able to build with success unless you improve on the layout strategy

Looks like your RCA inputs are not isolated from the chassis. Last pic upper right had corner where the speaker wire is hooked up? Could be speaker outs too, either way when I build I use isolated jacks for both. meaning there's plastic washers between the jacks and chassis and then run a ground back to the star ground (or ground return).

Part of the "art" of doing point to point is the layout. What I like to do is create a ground wire - bare 18guage I make from a piece of copper.

Here's a pic from my last build (this is not completed in the pic yet) notice the copper wire with caps attached - that's the ground "buss" wire going back to the star ground - I only use one ground point and thats at the left side of the wire buss which is attached to a bolt holding the power transformer to the chassis (notice BOTH center taps from the transformer attached there too) - that's the ONLY place that is actually grounded other than the 3rd prong on my IEC power socket (earth ground). You did a good job with your heater wires, that's pretty important to reduce hum. You could re-arrange your terminal strips and add a bare copper ground wire going between 2 of the terminal strips (be sure to not use the center loop on the terminal strip as it's attached to the chassis and would be another ground point). There are of course MANY ways to do it. I like the star ground way, keeps the hum issues to a minimum which can be a pita to track down, and all my components are lined up and easy to follow once I get into issues. Don't be discouraged ... I've only put together one amp that worked the fist time .... if you do your layout so it's easy to follow then trouble shooting probable hook up issues are easier to figure out. Pretty much my goal every time I build an amp is to not get jolted by electricity, after that everything else is the "fun" part. Hope that helps .... Why don't you try posting a pic a little farther away from your circuit so we can see the whole underside of the amp?? Ripping everything apart probably not needed, my first point to point looked like yours and it was the amp that worked first time.... go figure.

yeah.......

I cris-crossed the coupling caps.:tears: what a dope........
worse thing is I looked at them several times, and knew they didn't look right, just didn't see it until tonight.

but it plays now, very nice I might add.
This was a trial run of sorts, to keep busy and make sure I can follow directions.
I have two weeks to go for my Edcor Iron for a "Kegger SEUL". :thmbsp:
I can't wait.
I am plannig to try and keep that one a neat as possible, altho I have found in my limited experience, the less wire you use, the quieter the amp is.

Thanks for the wisdom offered. Another rookie built amp sings.

my two cents Stu

srb02 said:

yeah.......

I cris-crossed the coupling caps.:tears: what a dope........
worse thing is I looked at them several times, and knew they didn't look right, just didn't see it until tonight.

but it plays now, very nice I might add.
This was a trial run of sorts, to keep busy and make sure I can follow directions.
I have two weeks to go for my Edcor Iron for a "Kegger SEUL". :thmbsp:
I can't wait.
I am plannig to try and keep that one a neat as possible, altho I have found in my limited experience, the less wire you use, the quieter the amp is.

Thanks for the wisdom offered. Another rookie built amp sings.

my two cents Stu

Click to expand...

Nice.... glad that worked out for you. Sometimes you can look at something wrong and you just don't "see" it. Kinda like in that pic I posted - there's a cap in there backwards! I couldn't get the voltages right until BANG goes the cap. Bad cap?? nah I just f'd it up.. look look look didn't see it but I can see it in the pic.

You're gonna love the Keg-miester SEUL build. That pic I posted is one in it's infancy... Listening to it now. Mighty fine.

What Edcor trannys you getting?? I bought a pair of CXSE-25-4-5K (using with 4ohm speakers) they are HUGE - right at 400v on the plate w/KT-88s. I've tried that circuit with a bunch of different drivers and output tubes ... it's all good. You're in for a surprise me thinks.

I liked the first one I built with 6L6 and swapped in 807s and liked that the best, so I bought a quad of the super 6BG6 tubes and am going to re-wire my first one and try parallel 6BG6 supers.

The hardest part for the Kegger SEUL is getting LEDs with 1.6-1.7vF ... I've probably got 200 LEDs or more laying around that are either too low or too high vF. I've found the IR-LEDs are closer than any of the red LEDs and they sound (or not sound) great. Once you get all your parts together if you need a set of IR-LEDs let me know, I'll send ya a set (I just got a new batch). Takes me longer to test LEDs (and its BORING) than it does to wire everything up.
Cheers,
Bob

If you are trying to keep the wiring to a minimum, you should, at the very least, use heat-shrink tubing on the component leads to insulate them and prevent the very short-circuit you experienced. $10 of heat shrink and an extra 45 minutes of time during assembly can save you a lot of hassle later.

-D

srb02 said:

I have two weeks to go for my Edcor Iron for a "Kegger SEUL". :thmbsp:
I can't wait.
Another rookie built amp sings.

Click to expand...

The amp sings because it's an RH amp
It's a pity you are so into SEUL... but you will most probably have a better insight in the amp you will be building after the RH experience.
I suggest you keep this amp as a "reality check"...

Hey Stu! Glad you are choosing to build the Kegger SEUL. You are going to be very happy.

As far as the detail and sound stage of the SEUL. With the right loudspeakers it will blow the RH amp out of the water.

Scott

scott17 said:

Hey Stu! Glad you are choosing to build the Kegger SEUL. You are going to be very happy.

As far as the detail and sound stage of the SEUL. With the right loudspeakers it will blow the RH amp out of the water.

Scott

Click to expand...

Which RHamp is it supposed to blow out of the water? What power are we comparing?

Have you ever built one (RHamp)?

You seem very confident, is it because you know from experience, or because of buddy support?

scott17 said:

Hey Stu! Glad you are choosing to build the Kegger SEUL. You are going to be very happy.

As far as the detail and sound stage of the SEUL. With the right loudspeakers it will blow the RH amp out of the water.

Scott

Click to expand...

bobrown14 said:

Click to expand...

Some like to watch, while others are at it...

I think properly built either design will make you happy.

Alex you've picked up on some of my trolling habits!

The important part, whichever you build... is to follow the instructions/schematic to the letter. Then when you are finished you can compare them and find out which you prefer.

Mixing and matching might get you something less impressive.

I think if I were going to run the output in pentode mode I'd be doing a seperate G2 supply or running some form of regulation....however in the interest of science I'll build up one of Alex's amps as designed and give it a listen.

My biggest mistake when I built Keggers SEUL is deviating form the plan....which was well thought out IMO.

Alex Kitic said:

Some like to watch, while others are at it...

Click to expand...

I hear that... been listening to my Keggerized version for a few weeks now!
Already got another build going & gathering parts.

:thmbsp::thmbsp:

rage said:

The important part, whichever you build... is to follow the instructions/schematic to the letter. Then when you are finished you can compare them and find out which you prefer.

however in the interest of science I'll build up one of Alex's amps as designed and give it a listen.

Click to expand...

I cannot ask for more: give it a try and check for yourself. I can only promise you are in for a surprise if you build it properly

Well, after a while, it would be interesting to read about what happened afterwards.
I have the impression that too many threads remain unfinished (and eventual dilemmas unsolved).

What did srb02 build in the end? Was he satisfied with his builds?

update:
Can't stop listening to this thing, as it is by far one of the sweetest sounding amp I've heard to date. (Rookie, so my listening is limited).

I have also cobbled together the 330v version of this 6v6 SE amp:http://mail.audiokarma.net/forums/showthread.php?t=382218&page=3,
as a simple rectifier tube change fixed voltages. To me, very nice, better bass, alittle less top end.

To build the SEUL version, I have to disassemble this amp totaly for the parts.
Can't bring myself to do that, (What would I listen to) so I have shelved that idea for now. Will come back to it at a later date.

And ordered a complete set of iron (Edcor) for a KT88 amp, w/ UL taps. Am planing to start w/ a pr of KT88's.
Maybe to ambitious for a Rookie builder, but HEY, nothing ventured, nothing gained.

And I'm sure I'll need some help with this build.

anyway
AS always, my 2 cents
and thanks
Stu