An amp for k501

[Xander]

Quote:

Originally posted by Tim D Nick, you say out of the six you listed in that price range you recommend three. But what are the other three since I never saw the six listed? The Headroom Little was one amp I've tried with AKG501's as well. Course Neruda likes to tell me that I need an SAC amp to hear its glory and everything else sucks bigtime.

pfft, Neruda speaks the truth.

 

[kwkarth]

Hey man, don't knock it till you've tried it!

 

[Daniel Pumphrey]

Hi,

I would recommend the Meier Corda and my reason is the fact that it can be easily upgraded with better opamps.
I just recently built a new amp using the BB OPA 627 and Buf 634 and this is The amp for the 501. The 501 is very inefficient compared to almost any other available in it's price range. Sure it sounds fine with some amps and I have heard almost all of them, but this combination turns the 501 into a new creature altogether.
The Meier Corda is easily modified to take the above chips by replacing one resistor per side. Other chips can also be tried at will with this design. Also I believe you will really like the amp stock too.
The OPA 627 was used in the top Headroom amp of last year, (I don't know about the newest amps), but not in combination with the Buf 634 which really is a great match. I don't know of a commercial amp which uses this combination, but it can't be beat for the 501. Maybe others will disagree, but they have not heard this combination as it is only available in DIY at the moment. I just wish they could hear this amp with the 501.

Dan

 

[legoman]

Quote:

Originally posted by Daniel Pumphrey Hi, I would recommend the Meier Corda and my reason is the fact that it can be easily upgraded with better opamps. I just recently built a new amp using the BB OPA 627 and Buf 634 and this is The amp for the 501. [...] The OPA 627 was used in the top Headroom amp of last year, (I don't know about the newest amps), but not in combination with the Buf 634 which really is a great match. I don't know of a commercial amp which uses this combination, but it can't be beat for the 501. Maybe others will disagree, but they have not heard this combination as it is only available in DIY at the moment. I just wish they could hear this amp with the 501. Dan

Ok, so it is merely an issue of changing some socketed opamps and one resistor?

What is the material cost of the mod (on top of the Corda amp)?

 

[Neruda]

I don't know how much the buffer costs, but each opa624 is in the vicinity of $20 I believe.

 

[nick danger]

Well,

To say that optimal listening conditions existed at the headroom gathering would be incorrect. I did hear the Corda and it didn't work for me under those conditions. The 501s are very open and it was pretty noisy and I needed more quiet (or higher volume).

That said the three that I mentioned sounded good enough and were powerful enough to ease through the noise. Listening to the 501s in a quieter setting may have allowed a better showing for the Corda.

I for one can't wait to see THE amp from Daniel Pumphrey!

Nick

 

[Daniel Pumphrey]

The OPA 627 Opamp is 14.00 each from Digikey, maybe a little more with a recent price increase. There is a 20.00 version which is not really an improvement over the other. There is also a Metal Can Military version which Is expensive.
The buf 634 8 Pin Dip is around 5.00. There are three other versions in different packages, but these would be difficult to use in a Dip amp board like the Meier has.
The Meier has a resistor before the second opamp which can be changed to a straight wire, or a much smaller value like 50 ohms. 50 ohms is about equal to most cable impedences.
There are a few other opamps I am going to try with the Buf 634 buffer soon, but I can't imagine an improvement over the 627. There are some 2107 opamps I just got which are supposed to be dual low powered versions of the 627 but these are not easily found except in Metal can at 45.00 each. A little high for my budget and not really an improvement.
I have heard many amps Headroom, Creek, Grado, Meier Szekeres, Pro Studio Amps, and about every type of Cmoy design and nothing has sounded like this combination yet. It is a startling improvement in every way. The bass which has been an area of concern with the 501 is much more present with this new amp. So I now believe this was not a problem with the 501, these phones simply needed more power. The highs are more extended with this new amp too. Overall changes are so distinct that Any listener will immediately hear the difference. This is not a subtle improvement unless you already own the Top headroom amp, or something equivalent.

The recommendation of the Meier amp is based on knowledge of it's circuit. It has a regulated power supply which can provide the needed voltage and current for these opamps. The 627 needs +-15V to operate at potential and the Meier has the power. The buf 634 can operate with less voltage but absolutely "rocks" in full bandwidth mode and +-15 volts with a supply with real current. The Corda is a well built amp in every respect and is also available as a Kit. I am not talking about the Porta Corda. There is a big power supply difference between these. The Corda is a home amp.
Dan

 

[kwkarth]

Sounds very interesting Dan'l!

 

[Neruda]

Quote:

Originally posted by Daniel Pumphrey The bass which has been an area of concern with the 501 is much more present with this new amp. So I now believe this was not a problem with the 501, these phones simply needed more power.

EXACTLY!

 

[Shak]

Thank you all very much! You're so helping, it's great.

I found a dealer for Creek in Israel which sells the OBH-11SE
for about 410$ US!!!

On the other hand:
I found realy good deal on the Creek OBH-11SE for about 300$US
(including all-shipment etc.) (at stoneaudio)

BUT: I've checked the costums rates and they actually know the brand and type! they charge 70% !!! (about 170$ more!)

So , I guess I'll have to wait for someone to go abroad (and come back) and pass it as personal stuff..

or, anyone has a solution? I have no patience...

 

[legoman]

Quote:

Originally posted by Shak [...] or, anyone has a solution? I have no patience...

DIY? But I am not sure whether any of the designs on Headwize adequately drive the power hungry 501s.

 

[Daniel Pumphrey]

I am working on several designs which will drive the 501. One is actually pretty simple and is intended for any portable device. It simply boosts the current of the actual headphone out from a portable. This is a good solution for portables which have no lineout and allows them to easily drive Any headphone including the Sennheiser and AKG. Many portables have good specs but lack the power to drive better phones.
The other is an amp for the Etymotic phones. After several experiments I have concluded that even the ER4-P needs more power than many portables have. The bass response suffers when driven by a portable with less than 25ma output. Many portables just can't make these phones sound as good as they are capable, and likewise many amps have too much power for the ER4-p and exhibit hiss as well as other problems with over sensitive inputs. This causes volume imbalances also.
Dan

 

[carlosgp]

What about Musical Fidelity X-CANS V2 with AKG 501?