REVIEW: Decware Select Zen CSP2 Tube Headphone Amp - Page 30

Just curious, has anyone tried the 5Y3GT rectifier with 6DJ8 (ECC88) power tubes and had problems such as sparking at switch on, or noise (independent of volume setting) like you get with a tiring tube etc?

 

I use a Mullard old shield logo E88CC & tried a handful of 5Y3GT's, 5R4GY's, and 5U4G's. No problems. But I have heard the ECC88's are finicky and prefer not to use them due to the lower resiliency. 

Thanks Nick! I bought Mad Dude's near new CSP2+ from him last year, after it was checked and re-warranted by Decware. He had problems of the sort described above.

Last week I rolled two pairs of mid-60s RCA 6DJ8 into the power positions. One from each pair sparked. I put the first one down to a bad tube. Didn't know what to think of the second. Then last night I tried a pair of Amperex Orange Globes. No sparking, but lots of noise. Nevertheless, they sounded terrific with rock - much better than the stock 6N1Ps - but obviously no good for classical.

Disconcertingly, this mirrored Mad Dude's experience. However, remembering different rectifiers provide different voltage points, I decided to roll back (from MD's RCA 5Y3GT) to the stock 5U4G. Problem gone, though sound not quite as good.

Judging from your experience, this is a specific problem with MD's rectifier rather than with the 5Y3GT/6DJ8 combination. This one tube may have been MD's problem all along - and I must say it didn't occur to me to question the rectifier last week!

I'll try another 5Y3GT to confirm. Thanks again :-)

I have Buge Boys in there 6dj8 now and I have used the 5y3G with no issues but i prer the 5U4G and the bugle Boys.  No issue for me with the 6dj8

 

Ha! Awesome... he's a cool dude and wound up buying my Mapletree Signature Edition #250. "It's a small small Head-Fi world"

 

I briefly experienced one tube arcing incident when I swapped a 7308 in place of one 6N1P driver tube. I can't remember which rectifier was in place. Regardless, it only happened that one time & I've swapped other 6922's in the driver positions without incident. So.... not sure what the issue was.

 

In my experience, it wasn't worthwhile to swap out the 6N1P drivers. I used three Mullard old shield E88CC's but the sound was similar enough that I reverted back to the 6N1P's as drivers and kept the one Mullard up front. Better to roll the rectifier than triple the expense of a good signal tube.

 

Favorite rectifiers (so far) that I actively use: Brimar 5R4GY for pure midrange beauty and RCA 5Y3GT black base red label for more detail without sacrificing midrange and lower extension

 

I also recommend the RCA 5U4G black base as a low cost Brimar alternative... good all-round

 

Didn't like: Tung Sol 5Y3GT had a "hi fi" tonality extended at both ends but otherwise meh

Sylvania 5Y3GT red label a bit steely w/not enough lushness in the midrange

RCA 5R4GY brown base too sloppy in the lower end & so-so detail retrieval

Philips 5R4GYS impressively detailed but neither sweet nor lush and suffered from unacceptably light bass

Edited by Nick Dangerous - 2/12/13 at 7:20pm

Thanks Frank - listening to them with the (Chinese) 5U4G right now, and indeed no problems.

Later going to try the Tung Sol 5Y3GT from my Taboo in there to confirm (a) it's problem free (if so, then Mad Dude had a bad NOS 5Y3GT) and (b) I still think it sounds better than the 5U.

Of course, the 5U4G not being NOS - whereas I'm sure yours is - is another factor. Right now I only have these tubes stock - three of them!

Followup: I rolled in my Tung Sol 5Y3GT, fully confident there would be no problem.

Alas, two distinct sparks in one of the power tubes . The power tubes were worse than with the RCA 5Y3GT, where I 'only' got hissing.

So, given Nick and Frank have had few or no problems with the 5Y3GT/6DJ8 combination, I think my CSP2 is partly faulty, much as MadDude found. (Nick, I take your point about the ECC88s being finicky though).

Still, they sound terrific with the 5U4G - and the Taboo sounds fantastic fed by the CSP2 in this form too.

That's a positive gain. The second is I know a bit more than MadDude did about the nature of the problem.

Nick, thanks for your extensive notes - really helpful! As the 5U4G is obviously 'the one for me' ATM, I'll follow up your RCA recommendation.

Btw, like you I previously concluded the two power tubes weren't worth changing, and had only been experimenting with the driver (an Amperex 6DJ8 BB right now)...except...the power tube change actually has made a big difference to the Taboo., e.g. the drumming and bass work in Led Zeppelin is now so textured and detailed I really 'get' how much Bonham and Jones contributed to Zep's sound. They were more than just a tight rhythm section - they were playing tunes in the engine room just as much as Plant and Page were up front.

Oh, and been following your experiences of the Concero with interest.

I use the Sylvania 5U4G and also have a Tungsol 5u4G all NOS. I have been using the Sylvania the bass is outstanding as well as the mids and treble. The Bugle Boys are special tubes and really bring to life the CSP2 but there are also good alternatives with the Sylvania 6DJ8,Genelex 6922 and the Matsusita 6922. IfgI were you I would swap out the tubes and makes sure you buy from reputable tube dealers. I use Jim Mcshane for new production tubes and Chris Johnson for NOS at Parts Connexion. He had selected and matched the bugle boys for no noise and is reasonable too.  I think you limiting the CSP2 with the stock tubes/ You will notice a major difference when swapping them out. If your problem continues you need to send the amp in.

Edited by Frank I - 2/13/13 at 5:26am

+1 on the Genalex 6922's. I have one in the front driver slot. Talked to Steve and he thought it was a good fit with the stock 6N1P's in the L/R positions. I really liked the Jan Sylvania 5U4G but the USAF-596 has wonderful tight bass.

Thanks guys. Yes, the tubes I've bought myself (Upscale, Tubemonger etc) have generally worked out. I don't really know where MadDude got his - presumably European sources.

Decware checked this amp on its way to me, but I think they didn't have the crucial information (problem specifically happens with non-6N1P in the power positions and with 5Y3GT rectification). For sure, the stock set-up has no problems, and this is the configuration they use to test, I understand.

Earlier in this thread, when MadDude had the original problem, there was an interesting comment concerning the design of the CSP2.

/start speculation/ I actually suspect part of the secret of these amps' performance is that they "push the envelope". That is, they're getting a little close to the edge of instability. /end speculation/ I used to be a programmer, and the best performing code was not generally the safest, clearest or most maintainable code!! Add to this the uncertainty inherent in the quality of the tubes, as Frank highlights, and well...

All of this is something I'm happy to live with because of the performance, although I agree my unit will probably need repair at some point - definitely so if I ever sell it. Gotta love the lifetime warranty!

Have the csp2 and taboo. Csp2 tubes are three 6922/CV2493 nos Mullards and an RCA 5Y3GT mid 1950s rectifier. The taboo has two EL84 nos mullards, a sylvania 5751, and the same rectifier as in the csp2. The only headphones that are great marches with the csp2 are the hd800 and T1. Anything with lower impedance (including the akg701) sound like crud and badly distort, especially with large orchestral pieces (Mahler) and choral works (dies irae from Verdi's requiem). The T1s have never sounded better...truly magical pairing. The Taboo is pretty good with almost everything else (and does great too with the T1 and hd800). The LCD 2 sounds amazing out of the taboo. There is a small problem with low impedance high sensitivity cans such as Fostex th900 and ath3000anv...a slight hum at louder volumes. By the way, the taboo is a disaster with the HE-6...maybe if you plug them to the speaker terminals would you get the supposed watts of power.

Frank I found his taboo couldn't drive the HE6 iirc. It seems insane power is needed, beyond the taboo's two watts plus into 50 ohms. I've heard some think the 4w (50 ohm) schiit lyr isn't enough. Most seem to use speaker amps of 50w (8 ohms) or more, translating to 8w 50 ohms assuming a near-zero output impedance.

I suspect the new taboo has more power, but enough??

Agree csp2/t1 and taboo/lcd2 are terrific pairings.

The Taboo could only drive small jazz and folk with the he6 but demanding music would make the he6 clip. I would not try to use the Taboo with the he6. I do not believe the power is sufficient  and is very stressful on the taboo.

I truly feel that if you have the cps2 and the Taboo you don't really need another amp unless you want to: (1) go on a quest for El Dorado and the Holy Grail in trying to find an adequate amp for the HE-6s; or (2) you want to go the Stax route in the search for musical nirvana. By the way, it seems odd that while the EF-6 amp was specifically designed to drive the HE-6, it fails miserably in that regard since it starts to clip and distort in big orchestral climaxes. Although the Schiit lyr is better, it still clips a little. In my quest for the holy grail I've ordered the Ray Samuels Dark Star to drive the He-6...if it fails like all the others, I vow to destroy the HE-6s with a sledge hammer and then check into the local insane asylum...in my opinion, headphones were not intended to be driven through speaker terminals.

 

Yep...Looking forward to El Dorado in May!.....