[jp11801]

PS back on topic anyone else have a sig 30 besides the OP and me, I'd love to hear your thoughts?

Also for those more electrically inclined if I had my akg 340s recabled to a 4 pin xlr and connected to the pigtail for the k1000 to the sig 30 would that cause "worlds to collide" or should it be ok since electrets like power and the 340s are tought to drive anyway?

 

[philodox]

Well, you will probably get more than enough current, but I am not sure what voltage swing the sig30 puts out. I know that when we connected my K340's to a T-amp it had tons of authority and slam, but sounded kind of closed in and limited in the upper and lower registers.

 

[hugz]

Does anyone know how hard it would be to allow the f2 to work as a headphone amp?

Since mine's DIY I can do whatever i want to it as long as i can afford it. A firstwatt would probably be far cooler to power my headphones than pretty much any other headphone amp.

I get the feeling that the usual two issues are impendence and power. impendence mismatching shouldn't be a big issue since it's current drive and ignores voice coil impendence. 5w is a bit too powerful for headphones.. but is almost managable? I've used a headphone amp that claims to be 1.5w RMS. 5w is only 5db louder than 1.5w

 

[nightfire]

Quote:

Originally Posted by hugz /img/forum/go_quote.gif Does anyone know how hard it would be to allow the f2 to work as a headphone amp? Since mine's DIY I can do whatever i want to it as long as i can afford it. A firstwatt would probably be far cooler to power my headphones than pretty much any other headphone amp. I get the feeling that the usual two issues are impendence and power. impendence mismatching shouldn't be a big issue since it's current drive and ignores voice coil impendence. 5w is a bit too powerful for headphones.. but is almost managable? I've used a headphone amp that claims to be 1.5w RMS. 5w is only 5db louder than 1.5w

Well depending on the impedance and sensitivity the gain on the f2 may be too high. You can fix this with some resistors in series (say, 300-500ohms).

 

[GASTAN]

Would
Aleph 5 work ? (it's 50W)

 

[randytsuch]

There is an article on 6moons about someone who adapted an aleph30 for headphones. He changed the output transistors, and rebiased it for lower output, but that is a different topology. Maybe a future project for me.

Could you just lower the bias current? Seems too easy, so I am probably missing something. I am not sure how the output transistor's distortion will change with a lower output, I know that is an issue with the Alephs, and I think that is one of the reasons the guy who made the alelph for cans changed the transistors.

Randy

 

[nightfire]

Quote:

Originally Posted by randytsuch /img/forum/go_quote.gif There is an article on 6moons about someone who adapted an aleph30 for headphones. He changed the output transistors, and rebiased it for lower output, but that is a different topology. Maybe a future project for me. Could you just lower the bias current? Seems too easy, so I am probably missing something. I am not sure how the output transistor's distortion will change with a lower output, I know that is an issue with the Alephs, and I think that is one of the reasons the guy who made the alelph for cans changed the transistors. Randy

Yup. That's what I did on my F1; I lowered the bias from 2A a side to 1.2, for my K1000.

It seemed to improve the sound quality due to lower gain (I had to set my lavry to 2 or 3 before - now 10 is a good listening volume) with a higher S:N ratio. But I didn't make any measurements; it's purely qualitative.

 

[jp11801]

Quote:

Originally Posted by philodox /img/forum/go_quote.gif Well, you will probably get more than enough current, but I am not sure what voltage swing the sig30 puts out. I know that when we connected my K340's to a T-amp it had tons of authority and slam, but sounded kind of closed in and limited in the upper and lower registers.

first impressions are pretty good connecting the 340s to the RWA amp I'll let you know after a few more lps and beers

 

[hugz]

Quote:

Originally Posted by nightfire /img/forum/go_quote.gif Yup. That's what I did on my F1; I lowered the bias from 2A a side to 1.2, for my K1000. It seemed to improve the sound quality due to lower gain (I had to set my lavry to 2 or 3 before - now 10 is a good listening volume) with a higher S:N ratio. But I didn't make any measurements; it's purely qualitative.

By this do you mean that the amp had less noise? I was under the impression that the firstwatt series of amplifiers had practically no noise. Maybe headphones brings it out.

Do you think lowering the bias brought it into headphone amp territory, or is it still very much a speaker amp? Have you tried connecting speakers since the change? (assuming you have access to xover-free speakers)

 

[jp11801]

ok it's official the RWA sig 30 is also great at powering the akg340s!! After about 2 hours of running through my normal list of records I love the 340s are at least as good as the k1000s. This amp is turning into a swiss army knife. I'll be at the national with it so feel free to stop by and check it out. Also I have a few headfiers in the area that I invite to listen to it and post comments.

Witht he sig 30 and the 340s there is great extension both low and high the mids they are famous for are still there and dynamics are amazing I had a little fun with an slp meter and the cans and they showed a pretty wide range with the rat shack meter

 

[nightfire]

Quote:

Originally Posted by hugz /img/forum/go_quote.gif By this do you mean that the amp had less noise? I was under the impression that the firstwatt series of amplifiers had practically no noise. Maybe headphones brings it out. Do you think lowering the bias brought it into headphone amp territory, or is it still very much a speaker amp? Have you tried connecting speakers since the change? (assuming you have access to xover-free speakers)

Well the real F1 introduces no detectable background noise (though my clone did because of my transformer placement).

However in any case, the more input signal you can get the better. The resistors in the attenuator circuit on the DA10 would conceivable create noise, the cables might, etc. So anything that allows you to drive a higher voltage should be better...

In my case the hum I was hearing from the transformer disappeared. It was barely audible to begin with.

I haven't tried speakers at all, but my change should have brought the gain to ~0.4 amps per input volt instead of the standard 0.6. That should mean a maximum output of about 6 watts I guess.

But if I were to use it as a speaker amp I'd bring the bias back up again.

 

[krmathis]

Sorry for going a bit off-topic.
But I wonder if anyone have heard the Red Wine Audio Signature 30 powering a pair of Stax 'phones through a Pro energizer?

 

[smeggy]

Quote:

Originally Posted by krmathis /img/forum/go_quote.gif Sorry for going a bit off-topic. But I wonder if anyone have heard the Red Wine Audio Signature 30 powering a pair of Stax 'phones through a Pro energizer?

Damn, it's like you were reading my mind

 

[bobcn]

Deleted

 

[hugz]

Quote:

Originally Posted by hugz /img/forum/go_quote.gif Does anyone know how hard it would be to allow the f2 to work as a headphone amp?

Quote:

Originally Posted by nightfire /img/forum/go_quote.gif Well depending on the impedance and sensitivity the gain on the f2 may be too high. You can fix this with some resistors in series (say, 300-500ohms).

Since this thread has been bumped back to the first page, I may as well point out that I added 47 ohms of parallel resistance (just because thats pretty much all i have on hand atm) and now use the f2 as a headphone amp. Still just playing around with it though.

btw as per my earlier posts... i put massive resistors in series like i said I would to test out if it ruins the sound quality, however the big resistors seem to absorb some of the amp's power in heat (or something), reducing the volume slightly and making it all a pain to tell by myself if its affected the quality or not. Hypothetically the current flow should remain the same regardless and the sound should be unchanged, but that has yet to be seen

i might play around with it some more with headphones though, since I find them better for critical listening.

(and sorry for being a bit flame-ish earlier on)