hello,
I just finished building my hybrid amp following this schematic:
http://www.head...osae/MHHAv2.gif

Everything sounds fine, but when checking the filament voltage it is only 5.4v and not 6.3 like it should be......
I am using the KS117 with the 220ohm resistor as the CCS, every other part is the same. Could someone give me some ideas to what could be wrong? Btw i'm not using batteries in my circuit.

Thanks

[Edited by pho_boi on 06-25-2005 at 07:38 AM.]

Not sure if the CRD affects the filament voltage either :(

[Edited by pho_boi on 06-25-2005 at 07:51 AM.]

maxw,
The CRD part do not affect the filament voltage.

I am using a Electro Harmonix 6922EH tube, which should still be 300ma for the heater current.

[Edited by pho_boi on 06-25-2005 at 11:11 AM.]

here are some pics of it so far without caseing:

http://users.on....ng/IMGP0784.JPG

http://users.on....am/IMGP0785.JPG

http://users.on....am/IMGP0786.JPG

Regarding the CCS:
If you use the 6922: it has 300mA heater current.
So, theoretically the proper resistor value is 8.33 Ohm.
But since the 6922 is a parallel heated type of tube more
important would be the voltage across the heater.
It should not exceed 6.3VDC for more than 5%.
So please double check. You may adjust both CCS resistors equally
until you reach near 6.3VDC. Maybe than the current exceeds
300mA but thats ok for that tube (as for all constant voltage heated
tubes).

The whole thing is vice-versa if you use constant current heated tubes such as 7DJ8 or PCC88. But no-one seems to do here (except me).

I've been following along and trying to learn more about circuits and such, before I try my hand at anything. Was curious what the two caps, etc... at the output are for (I don't see them in the V.2 schematic? (Sorry guys, real noob question I'm sure, but that's how to get steered in the right direction.)

[Edited by Blooze on 06-28-2005 at 01:23 PM.]

Also available from mouser:
The replacement from NTE http://www.mouse...e_pcodeid=52600
Or the one from fairchild http://www.mouse...e_pcodeid=51229

And ummmm. what transistor?

---

quote:

Hey everyone, I got it to work properly now. Just changed the resistor value to roughly 7ohm and used a different regulated 24v power supply.

here are some pics of it so far without caseing:

http://users.on...ng/IMGP0784.JPG

http://users.on...am/IMGP0785.JPG

http://users.on...am/IMGP0786.JPG

---

Nice one! Go Jaycar parts
Hey, a question: what were your other voltage measurements compared with the ones stated on the diagram?

---

quote:

If you dont mind, what did you use for the 317 and the transistor?
I'm about 95% sure I connected my circuit correctly, but I'm about 5% sure I'm using the correct parts, not that I see that it doesnt work at all.

---

The 317 is a voltage regulator, its full name is LM317 and its very common and cant really be mistake for anything else.
By transistor I assume you mean the MOSFET, IRF610. \"IRF610\" is its name.

[Edited by maxw on 07-13-2005 at 10:40 AM.]

I am a newbie in tube amp. Recently I found the layout of multi-hybrid from
http://www.headp..._sijosae&no=207
and had built one (I choose this version because I cannot source CRD's component here)
Now, it can come out sound now correctly ^_^ except that the sound level is not balance in left/right channel

I had tested it with connecting both left/right channel to left out of my radio,
but, the sound of left/right is not at same loudness.

Here's some question:
- May I ask if there's way to ture the balance?
- What's the use of trimmer 22K?
- What's the use of the battery? I had omitted them.

Sorry for that asking so many question here....
I build the amp before I discover this forum :-0

Using resistors on the input can tune the balance however then the left and right channels will be amplified differently and the distortion signature changes. The source of the imbalance other then picking incorrect components is usually the volume pot, which is less accurate at the first 1/5th turn, but should be more closely balanced in the centre. Using audio grade pots or simply buying several untill you find one with good balance is the best way to do it.

Remember just because a part says 5% tollerance doesn't mean you can't get a nicely matched one.

Thanks for reply first!

But, can you further explain the how to use pot?

And, may I ask why the figure at sijosae's web:
http://headphone...ae/TubeTest.gif
The gain of 6922 is not same at LR channel? I m exactly using Philips JAN 6922 and exactly right channel is louder than left one. I don't know Korean so can't see the building notes there.

I had slightly(sorry bad english) match the component of the amp. I use some cheapy 1% metal resistors, and had prepared double quatity of them for matching. All resistor had matched within 1% differences between 2 channels. The input cap is 0.217/0.215uf. Though, I had not match the mosfet and output E cap. (Though, I m not confidence if this is not source of im-balance)

siuguyguy which pot do you mean? How to further use the bias pot, or the volume pot? I'm going to assume the latter.

The differences in gain are manufacturing faults. The raw fact is that tubes, pots, resistors, etc all can only be manufactured to certain tollerences. DAC chips have really tight tollerances but as soon as you get through countless resistors, capacitors, transistors, or in this case volume pots and tubes the differences between left and right begin to vary. Tubes and pots I believe are the most missmatched components, but often transistors are too.

In this circuit the missmatches can be fixed by finding a pot with equal and opposite missmatches which would be the best option sound quality wise, or by using resistors either before the pot, between the pot and the input capcitor, or after the output capacitor to even the sound. I'm not sure about other areas of the circuit. You just need to be careful that interactions between the resistor doesn't affect the pot or the heapdhones.

---

quote:

Hi groups,

I am a newbie in tube amp. Recently I found the layout of multi-hybrid from
http://www.head..._sijosae&no=207
and had built one (I choose this version because I cannot source CRD's component here)
Now, it can come out sound now correctly ^_^ except that the sound level is not balance in left/right channel

I had tested it with connecting both left/right channel to left out of my radio,
but, the sound of left/right is not at same loudness.

Here's some question:
- May I ask if there's way to ture the balance?
- What's the use of trimmer 22K?
- What's the use of the battery? I had omitted them.

Sorry for that asking so many question here....
I build the amp before I discover this forum :-0

---

Just adjust the two trimmers (not the 22k one) until it sounds right, trust me! If you adjust them so the anode voltages are identical the balance between left and right is usually not right so adjust them while listening and you will get them within about 1.5V of each other and the balance will be good. This is how it was for me anyway

More photos and eagle files I used here:
http://max8888.orcon.net.nz/hybrid.htm

Z'