• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Completely new to building amplifiers

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#23
Frank and others..

I will make the changes and post the amplifier section of the KT88
mono block Quicksilver amplifier next week as I am off that week and will have the time to do it. This may serve as an interesting topic as well as a good building tool to follow?

As I have nothing to compare the modified power supply to I must admit that I find it very smooth and also an am not hurting for bass response.🙂 🙂 🙂

If I had known the information existed for modifying a 8417 amp I probably would have purchased a used pair off ebay for less than I paid for these KT88 mono's. Either way I am very satisfied with the performance of these amps.


Joe
 
#25
Looking at it again, I'd build the GEC over the Quicksilver, with a couple of minor mods. I'd phase split before the 12AX7s with a Lundahl LL1544A, or similar Jensen trans, make it balanced in, and put a CCS in the tail of the first two stages down to an extra negative supply (-20V?). The last is just my preference for a real diff stage, rather than PP.
 
#27
Tube manuals

No, I do not have a tube manual. Where might I acquire such a thing? Do these include schematics?
Click to expand...

There are a few online:

1) Sylvania Tube Manuals (1943,49 and 1959)
http://www.montagar.com/~patj/electro.htm
2) RCA Radiotron Tube Manual, No. R-10 (Tim Reese’s site) http://www.nmr.mgh.harvard.edu/~reese/RC10/
3) RCA HB-3 Tube Manual (Pete Millett’s site) http://www.pmillett.addr.com/hb-3_tube_manual.htm
4) Karl R. Spangenberg, On Vacuum Tubes. (Ken Gilbert’ site) Used by grad students at Stanford studying vacuum tube design in the 40s. http://ken-gilbert.com/spang/spangenberg.html

These are in the outline of online tube info I sent you.
The first 25 pages of tghe R-10 is worth the read while you're waiting for F.
At least you can see what one is.


cheers
Craig Ryder
 
#32
PSE means Parallel Single Ended. By paralleling the output valves in an SET amp, it's possible to double or tripple the output power, though all do not approve.
Probably the "Push Pull" topology would be better for a starter amplifier. Easier, and much cheaper to get that power output.
Also, have a good think how much power you actually need.
Check on previous threads abou speaker efficiency vs power.
 
#33
60W

Hi,

I stand with D'haen here.

60W in single ended is going to require a lot of paralled tubes.

I'm not even sure there is such a beast out there.

Much easier to do with a simple PP of a pair of output tubes and improve the circuit by paying attention to the power supply (PSU)
and other "details".

Cheers,😉
 
#34
60W DIY

Tom: thank you!

Dhaen, fdegrove: So, it seems that the route to go is the push-pull way, for both simplicity and cost. I was under the impression that P-P led to poorer performance, (as it does in some solid-state amps) but I wonder if I should even worry about that for the time being?

fdegrove: You say that improving the 'details'such as the power supply, would sweeten the experience of the P-P tube amp. What else do you recommend?
 
#35
FIRST AMP

Hi,

What else do you recommend?
Click to expand...

Generally,paying attention to layout,passive components choice such as coupling caps,resistors,hook-up wire even the solder you use.

Once you've made your choice of amplifier circuit you'll see the advice flowing in from all sides,believe me.😎

Cheers,😉
 
#37
I was under the impression that P-P led to poorer performance
Click to expand...
Well, it's a bone of contention😉
Although I am an SET man myself, I'd be the first to admit that a mediocre SET sounds worse than a PP to anybody.

What I was trying to get over (please excuse my limited descriptive powers - after all, this is my native language:xeye: ), is that for high powers >15W, SET becomes cumbersome, and if not done perfectly, at great expense - mediocre.
Whereas PP (even though the component count may be greater) can achieve super results.

If, on the other hand you want something that sounds soft and warm: sell your speakers, buy some high efficiency ones, and build a 300B amp, and wallow in it - be happy🙂
 
#38
HANG ON....

Hi,

Tony,

OK! layout of the circuit pieces? and wiring? what would the board recommend?
Click to expand...

Hold your horses...

First things first:

1/PP amp 50-60W?Which one,Genalex or more like the Quicksilver?
Or something else perhaps?
There are at least a dozen schematics available on the net for that topology alone.

2/Sources for unusual compontents such as the OPT,choke(s) powerxformer,chassis,tubes etc.

3/After that we can discuss the finer details.

Back to you Tony,😉
 
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