JJaudio 6080 SET tube amp

[Gradofan2]

Quote:

Originally Posted by phergus_25 I actually am not too sure as to what to look for, so give me something to look at and I'll do it. With the tubes I have read a good bit about the diff ones and they actually made some swap in military grade tubes that are suposidly better than any 12ax7s, bidding on some right now. I couldnent hear any hiss on on the AKGs, forgot to check with the Grados but I'll do that when I get home. I did notice that the stage seems really black if that makes anysince compared to the LD. Its like its more silent than the LD, kinda weird. For the transformers I posted a thread in the DIY forum to see if anyone can kinda "un build" it to try and find out what its all for. When I get home it will have been going for ~24 hours, so Im excited to see of any changes. -greg

Just look for brand names on the caps - if you can see any - like you noted on the Wima's, or the Alps POT. You may not see any on the other components (e.g. resistors, transformers, etc.). I was just curious if the caps were known brands like the Rubycons, MCaps, Auricaps, Blackgates, etc.

 

[phergus_25]

Quote:

Originally Posted by Gradofan2 Just look for brand names on the caps - if you can see any - like you noted on the Wima's, or the Alps POT. You may not see any on the other components (e.g. resistors, transformers, etc.). I was just curious if the caps were known brands like the Rubycons, MCaps, Auricaps, Blackgates, etc.

I'll take a look later on, Im actually enjoying listining as I type. After about 30 hours the bass is tightning up and I think Im getting alittle better imaging and depth.
-greg

 

[Fitz]

Just got a chance to hear this amp and poke around under the hood...

The electrolytics used in it were an assorted bunch from Nippon Chemi-Con, Rubycon, and Elna. The Nippon Chemi-Con and Rubycon were used as the B+ caps, and the Elnas were on the 12AX7's cathodes. The coupling capacitors between the two stages were the Wimas, with a larger pair on the preamp outputs. The main output coupling capacitors are an unknown film cap with any markings rubbed off or hidden on the side that's glued down.

Resistors and transformers didn't have any distinguishing features that I noticed. I didn't look too extensively at the power supply, but it looked like the small "transformer" inside the chassis is actually a choke.

I'll post my impressions on it later..

 

[phergus_25]

Today me and Fitz got to get togeather and do alittle investigation on the new amp. I'll let him express his ideas, but I think that this amp will become well established as a great amp for higher Ohm cans. With the AD2ks the bass was all mangled, same with the W5ks. However, when you bust out the K501s its a quite synergistic pair. [yea i kinda made that word up]
When fitz gets the scamatic drawn up we should be be able to do some comparisons to the Woo 3.
I should be getting a new set of pre amp tubes here soon, so impressions to come on taht as well.
-greg

 

[Gradofan2]

Quote:

Originally Posted by phergus_25 Today me and Fitz got to get togeather and do alittle investigation on the new amp. I'll let him express his ideas, but I think that this amp will become well established as a great amp for higher Ohm cans. With the AD2ks the bass was all mangled, same with the W5ks. However, when you bust out the K501s its a quite synergistic pair. [yea i kinda made that word up] When fitz gets the scamatic drawn up we should be be able to do some comparisons to the Woo 3. I should be getting a new set of pre amp tubes here soon, so impressions to come on taht as well. -greg

So... the amp does well with mid to high impedence phones, but not low impedence phones - is that correct?

 

[phergus_25]

Quote:

Originally Posted by Gradofan2 So... the amp does well with mid to high impedence phones, but not low impedence phones - is that correct?

IMO its not horrible with low impedence cans, but it deffinitly dosent do what it does for the higher ones. Fitz was saying it had to do with the output caps, they are film so there is no way they are verry high. With it being known that with lower impedence cans its not the best, I am confident to say that it is a real winner for high impedence cans, expecially with its current price of around $200.
-greg

 

[Gradofan2]

Quote:

Originally Posted by phergus_25 IMO its not horrible with low impedence cans, but it deffinitly dosent do what it does for the higher ones. Fitz was saying it had to do with the output caps, they are film so there is no way they are verry high. With it being known that with lower impedence cans its not the best, I am confident to say that it is a real winner for high impedence cans, expecially with its current price of around $200. -greg

Does Fitz have a mod in mind that would make it drive Grados well?

 

[Fitz]

Quote:

Originally Posted by Gradofan2 So... the amp does well with mid to high impedence phones, but not low impedence phones - is that correct?

Correct. I imagine increasing the size of the output coupling capacitors would help to alleviate the problem.

 

[Fitz]

Quote:

Originally Posted by Gradofan2 Does Fitz have a mod in mind that would make it drive Grados well?

At some point we're going to try out some of the leftover 330uF caps I have, to see how it goes.

 

[phergus_25]

I really am enjoying this combo. I cant wait to get these old Sylvania tube and see how much of an upgrade they are over the provided EHs.
There was a slight improvment with just the power tube being replaced momentairly with a NOS russian tube Fitz had. So I think it will really take well to tube uprgades.
-greg

 

[Fitz]

Some brief thoughts before I go to sleep...


The Good:

* Soundstage is very smooth and seamless. It has good coherency, and leans towards the more intimate side.

* It excels with mid to high impedance phones; it had no trouble driving the K501 to its full potential.

* The sound is very "tubey", making the mids very lush and smooth.

* All the tubes are readily available in both current production and NOS, with more options for the driver tubes than you could imagine.

* The synergy with the K501s is unbelievable, they sounded better than I ever remember them being in my own setup.


The Bad:

* Limited ability to provide sub-bass for low impedance phones. This can potentially be fixed by modding. (Untested as of yet, but based off my experience with the Darkvoice's similar output stage)

* With the stock tubes, the amp just squeaks by to have enough power at very high volumes. During complex passages with the volume as high as I could bear for long enough to test, the tubes occasionally started to overdrive. It was relatively subtle and only at very high volumes, but stood out more in a back and forth comparison. (The amp has yet to be tried with different driver tubes than the provided EHs)

* The sound is very "tubey", which may not suit some people's tastes.


The Skinny:

Great sounding amp with amazing K501 synergy and a tuberoller's dream. Not very good stock for low impedance phones but has a lot of potential for modding. With the rising price of the Darkvoice THA336i and the reliability issues with the LD2+, this is a nice tube amp that won't break the bank.

 

[LeChuck]

I've read that OTL designs are just plain out not great at driving low impedance cans, so maybe it's just in the nature of the design.

 

[Fitz]

Quote:

Originally Posted by LeChuck I've read that OTL designs are just plain out not great at driving low impedance cans, so maybe it's just in the nature of the design.

Tell that to the guy whose favourite amp for his low impedance phones is an OTL.

 

[phergus_25]

Great summary. I'm glad you enjoyed it and thanks for point out some things I was unable to hear/understand.
-greg
Quote:

Originally Posted by Fitz Some brief thoughts before I go to sleep... The Good: * Soundstage is very smooth and seamless. It has good coherency, and leans towards the more intimate side. * It excels with mid to high impedance phones; it had no trouble driving the K501 to its full potential. * The sound is very "tubey", making the mids very lush and smooth. * All the tubes are readily available in both current production and NOS, with more options for the driver tubes than you could imagine. * The synergy with the K501s is unbelievable, they sounded better than I ever remember them being in my own setup. The Bad: * Limited ability to provide sub-bass for low impedance phones. This can potentially be fixed by modding. (Untested as of yet, but based off my experience with the Darkvoice's similar output stage) * With the stock tubes, the amp just squeaks by to have enough power at very high volumes. During complex passages with the volume as high as I could bear for long enough to test, the tubes occasionally started to overdrive. It was relatively subtle and only at very high volumes, but stood out more in a back and forth comparison. (The amp has yet to be tried with different driver tubes than the provided EHs) * The sound is very "tubey", which may not suit some people's tastes. The Skinny: Great sounding amp with amazing K501 synergy and a tuberoller's dream. Not very good stock for low impedance phones but has a lot of potential for modding. With the rising price of the Darkvoice THA336i and the reliability issues with the LD2+, this is a nice tube amp that won't break the bank.

 

[Gradofan2]

Quote:

Originally Posted by LeChuck I've read that OTL designs are just plain out not great at driving low impedance cans, so maybe it's just in the nature of the design.

Yes... as I understand it from WooAudio, that's accurate, depending upon how much current the particular amp is able to provide to the phones.

If it can provide sufficient current, an OTL design, apparently is fine... but, if it can't then the phones tend to clip / distort at certain frequencies at higher volume levels.

That's why WooAudio recommends their WA2 amp (OTL amp with more current / head room) for low impedence phones, or better yet, their "transformer coupled" amps the WA4 and new WA6, which provide more current for low impedence phones.