[Hirsch]

Quote:

Originally posted by kuma Hirsch, Within all the OTL you've auditioned, how do they differ from one anothe sonic character wise? And what other SET fone amps did you try besides EAR? Thanks.

Actually, the SET phone amps I have are the Supra and HAP-03 (if the HAP-03 is push-pull, then I'm thinking about this wrongly). IIRC, the EAR is a push-pull amp, but I could be wrong. I'll have to look at the manual.

There is a commonality of sound between the Supra and the HAP-03 that's hard to describe. These are very different amps. What they do in common is simply put the listener into direct contact with the music. They are both very difficult to describe sonically, because the whole idea of a SET/OTL amp is for the amp to get out of the way. The sonics are reflective of the tube in use, and can vary wildly depending on tube choice. It's almost meaningless to talk about the "sound" of the amp without describing the particular tube in use.

Once you get to push-pull, and transformers, and feedback, the amp starts imposing its own colorations onto the sound, and the sonic signature of the amp becomes easier to define. The EAR is indeed a warm amp. Is it the transformer or the topology? I really can't know...if the EAR were SET, I'd suspect I'm hearing the transformer. I've got to RFTM

Feedback can also play a role. The RKV has a very strong sonic signature (pleasant), but the design uses a lot of feedback to control the characteristics of the tubes. Since the RKV is OTL, this is definitely not a transformer effect.

The more circuitry that gets introduced between the tube and the headphone, the easier it is to define the sound of the amp. IMO.

 

[Sean H]

Quote:

Originally posted by Hirsch The transformers have a strong effect in headphones as well. However, some of the best headphone amps are OTL. The RKV, the Singlepower amps, the MicroZOTL (sort of), the Earmax Pro, the HAP-03...all of these are OTL amps.

Uh huh, I see, poo poo'ing the MG Head OTL again I see. Just like I said in my PM. Let's get that on the list too, shall we.

 

[kuma]

Quote:

Originally posted by Hirsch There is a commonality of sound between the Supra and the HAP-03 that's hard to describe. These are very different amps. What they do in common is simply put the listener into direct contact with the music. They are both very difficult to describe sonically, because the whole idea of a SET/OTL amp is for the amp to get out of the way. The sonics are reflective of the tube in use, and can vary wildly depending on tube choice. It's almost meaningless to talk about the "sound" of the amp without describing the particular tube in use.

Thanks Hirsch.
Say, between RKV, Supra and HAP-03, which amp has most resolution?

Interesting you say RKV has an ability to dissappear in spite the heavy use of negative feed back. So far, the amps with heavy use of NFB sounds heavy handed. ( both push-pull and SET)

 

[Hirsch]

Quote:

Originally posted by kuma Thanks Hirsch. Say, between RKV, Supra and HAP-03, which amp has most resolution? Interesting you say RKV has an ability to dissappear in spite the heavy use of negative feed back. So far, the amps with heavy use of NFB sounds heavy handed. ( both push-pull and SET)

The Supra, with Sylvania VT-231's from the WWII era, has the highest resolution of the three, IMO. The HAP-03 has the least, although careful tube choice can help it a lot (I use an RCA cleartop 12AU7A and Raytheon steel pin 6922's).

Actually, the RKV does have a strong signature sound, which I do attibute to the feedback (or DC servo-control, as the designer puts it). It's still the best amp I've heard for the AKG K-1000. That pairing is made for each other.

 

[Hirsch]

Quote:

Originally posted by Sean H Uh huh, I see, poo poo'ing the MG Head OTL again I see. Just like I said in my PM. Let's get that on the list too, shall we.

LOL, my sum total listening time on an MG Head is still less than 15 min. I have no real idea where it belongs on any list

 

[Jon L]

Can you expand on what you hear with RKV plus K1000? What kind of "signature" does RKV have and why is it still the "best" with K1000?

RKV reportedly makes 2WPC, and I've tried a 2WPC 45SET with my K1000, but I don't think I have enough power for moderately high volume. RKV likely has the output impedance matched correctly, though...

 

[gbeard]

Quote:

Originally by Hirsch The Supra, with Sylvania VT-231's from the WWII era, has the highest resolution of the three, IMO. The HAP-03 has the least, although careful tube choice can help it a lot (I use an RCA cleartop 12AU7A and Raytheon steel pin 6922's). Actually, the RKV does have a strong signature sound, which I do attibute to the feedback (or DC servo-control, as the designer puts it). It's still the best amp I've heard for the AKG K-1000. That pairing is made for each other.

I think I am going to find out about the Supra soon

, and perhaps a better (or should I say Berning ) pairing with the AKG one of these days too, if somebody here will sell me a nice pair...

As far as SET amps go, they can be fabulous with all the ancillaries in synergy...

Cheers, g

 

[kuma]

Quote:

Originally posted by Jon L Can you expand on what you hear with RKV plus K1000? What kind of "signature" does RKV have and why is it still the "best" with K1000? RKV reportedly makes 2WPC, and I've tried a 2WPC 45SET with my K1000, but I don't think I have enough power for moderately high volume. RKV likely has the output impedance matched correctly, though...

Hey Jon L,

We'll be trying out K1000 with Jota this weekend finaly!

Probably try KR 52BX ( 30 watts) and KR 300BXLS ( 10 watts ).

 

[Hirsch]

Quote:

Originally posted by Jon L Can you expand on what you hear with RKV plus K1000? What kind of "signature" does RKV have and why is it still the "best" with K1000? RKV reportedly makes 2WPC, and I've tried a 2WPC 45SET with my K1000, but I don't think I have enough power for moderately high volume. RKV likely has the output impedance matched correctly, though...

I don't have the RKV anymore, and it's hard to come up with a good description from memory. I used to listen to that combo for hours at a time. When I sold my RKV, my usage of the K-1000 dropped precipitously. The RKV is a slightly dark amp, with powerful bass. Some people report rolled off highs, but they sounded fine to me.

 

[ddriveman]

Quote:

Originally posted by Jon L Can you expand on what you hear with RKV plus K1000? What kind of "signature" does RKV have and why is it still the "best" with K1000? RKV reportedly makes 2WPC, and I've tried a 2WPC 45SET with my K1000, but I don't think I have enough power for moderately high volume. RKV likely has the output impedance matched correctly, though...

Jon L,

I have a 3.5WPC 2A3SET with my K1000 and I also find it a little underpower. The difference for the RKV is that it makes 2WPC into 120 ohms which is the impedance of the K1000.
My 2A3SET and I believe yours too, makes their power output into 4/8/16 ohms speaker loads. When I convert my SET's 3.5WPC @ 8 ohm into 120 ohm, power drops to about 0.23WPC (if my calculations are right). The K1000 makes 112dB @ 1W. So 0.23W is about 96dB. But this assumes the amp is in full power, which is not practical to run. Hence at half power, then you have only 0.125W which translates to about 93dB. This is loud enough for most listening but not for all. Hence, the feeling of underpower.
Hope this helps.

 

[kuma]

Quote:

Originally posted by ddriveman Jon L, I have a 3.5WPC 2A3SET with my K1000 and I also find it a little underpower. The difference for the RKV is that it makes 2WPC into 120 ohms which is the impedance of the K1000. My 2A3SET and I believe yours too, makes their power output into 4/8/16 ohms speaker loads. When I convert my SET's 3.5WPC @ 8 ohm into 120 ohm, power drops to about 0.23WPC (if my calculations are right). The K1000 makes 112dB @ 1W. So 0.23W is about 96dB. But this assumes the amp is in full power, which is not practical to run. Hence at half power, then you have only 0.125W which translates to about 93dB. This is loud enough for most listening but not for all. Hence, the feeling of underpower. Hope this helps.

That's really cool. Would you mind giving me a rough estimate of power output at 30 watts and 10 watts @4 ohms?

K1000 did all right with 40 watts. ( @ 8ohm )

 

[ddriveman]

Kuma,

You can use the Ohm's Law calculator at this webpage:

http://www.angelfire.com/pa/baconbacon/page2.html

For tube amps, I assume a constant voltage. If assuming this, then 10W @ 4 ohm = 0.33W @ 120 ohm and 30W @ 4 ohm = 1W @ 120 ohm (More than enough for K1000).

For every 3dB increment/decrement you double/half the power. Hence, if 102dB @ 1w, then 99 dB @ 0.5W etc. I made a typo in my post, the K1000 has a sensitivity of 102 dB @ 1W

However, if you have a transistor amp, then you typically assume constant current though.

Anyway, have fun.

 

[kuma]

Quote:

Originally posted by ddriveman For tube amps, I assume a constant voltage. If assuming this, then 10W @ 4 ohm = 0.33W @ 120 ohm and 30W @ 4 ohm = 1W @ 120 ohm (More than enough for K1000).

This is very helpful.
I'll be using SET amps with KR 52BXL and 300BXLS. I have a feeling 300B won't make it. I see even 30 watts might be marginal.
My guess is with 300B, bass would go and with 52BX, trebles would go out to lunch...But, will see...

 

[ddriveman]

Kuma,

Actually a 300B SET could be the minimum needed. You would get 8WPC @ 8 ohm which translates to about 0.53WPC @ 120 ohm. Hence, at half power you would get about 96dB. Hence this could be enough. Hence, the reason why I am getting a LadyDay+ 300B (TJ mesh) SET kit amp built. Lets see.

 

[kuma]

Quote:

Originally posted by ddriveman Kuma, Actually a 300B SET could be the minimum needed. You would get 8WPC @ 8 ohm which translates to about 0.53WPC @ 120 ohm. Hence, at half power you would get about 96dB. Hence this could be enough. Hence, the reason why I am getting a LadyDay+ 300B (TJ mesh) SET kit amp built. Lets see.

The thing is, I don't have a 8 ohm tap on this amp. Only 4 ohm. So, I'd t hink I'll get less than 8 wpc, right?

I'm not familiar with LadyDay, but meshplate 300B is a very very nice bottle. I had a Sophia 300B meshplate based amp w. 274B rectifiers.