Another MET1 on the forum - NO problems

[jeffreybehr]

Jeffrey: I followed your sugestion about buying a bunch of 6135 and I have a couple of Sylvania comming. We'll se how they behave Previous GE 6c4's were terrible.
Also found your post on audiogon about Watford and it looks like it's they have original m8080 for 15GBP. Tubeworld also carries pairs of m8080 for $80. I still don't know how much CJ charge for them?

Thanks again for your help

YW again.

The 'M8080s' I find at Watford are Mullard CV4058s, also marked 6100, a known equivalent, and 7410, a number I know nothing about. My perhaps-commercially-labeled Mullard M8080s are also marked what appears to be exactly the same on the back. Here's a pic of some of my M8080s/CV4058s/6135s/6C4s.

From the left--2 RCA 6C4s, whose triodes look just like those in a 12AU7, which I understand is the 'same' tube but a twin-triode and having 9 pins; a Sylvania Gold Box GB-6135; 2 GE 5-star-labeled 6135s; and a pair of Mullard 8080s. I understand the 6135 to be a ruggedized version of the 6C4.


This image is 1000 pixels wide on Photobucket; there's also one 2000 pixels wide if you wish to see or download it.
http://i89.photobucket.com/albums/k220/ ... 5s6C4s.jpg

Good luck with your 6135s.

[Mr_BT]

So far I've played with:

Sylvania 6135, GE 6C4WA, GE6C4

Sylvania seems to have no microphonics or hiss and actually sounds pretty darn good. GE 6C4WA is the most resistant to microphonics (even popping slightly with fingernail gives not much of audible effect), however it's hissssing. The last of the three is the worst: horrible microphonics and goddamn noisy.

Since the beginnig of my tube jurney I've menaged to gather some exerience. Tube dampers may be tricky, e.g.: Sylvanias doesn't like them at all. With GE6C4WA doesn't make any difference. Original Mullards are the trickiest. On some m8080's it takes four dampers to almost tame microphonics to tolerable levels.

Jeffrey:
I've noticed on photo of your MET1 you have some different dampers than originals. What is this? Does it work better than just a silicon o-rings?


It looks like chance of succes with m8080 are 50/50. Out of original six only three were without problems. Out of 2 I recently received from CJ only one is fine.

I'll try hunting for the tubes from your photo. But for now I think I'll settle down with three mullards on F,L,C; two sylvanias 6135 on rears and GE6WA on SW.

Long story short: I made a peace with my MET1 and really, really love it.

Thanks to admin, Jeffrey and Lew Johnson for assistance with my problems.(alphabetical order

[jeffreybehr]

So far I've played with:

Sylvania 6135, GE 6C4WA, GE6C4

Sylvania seems to have no microphonics or hiss and actually sounds pretty darn good. GE 6C4WA is the most resistant to microphonics (even popping slightly with fingernail gives not much of audible effect), however it's hissssing. The last of the three is the worst: horrible microphonics and goddamn noisy. Since the beginnig of my tube jurney I've menaged to gather some exerience. Tube dampers may be tricky, e.g.: Sylvanias doesn't like them at all. With GE6C4WA doesn't make any difference. Original Mullards are the trickiest. On some m8080's it takes four dampers to almost tame microphonics to tolerable levels.

Jeffrey:
I've noticed on photo of your MET1 you have some different dampers than originals. What is this? Does it work better than just a silicon o-rings?

It looks like chance of succes with m8080 are 50/50. Out of original six only three were without problems. Out of 2 I recently received from CJ only one is fine. I'll try hunting for the tubes from your photo. But for now I think I'll settle down with three mullards on F,L,C; two sylvanias 6135 on rears and GE6WA on SW. Long story short: I made a peace with my MET1 and really, really love it.

Thanks to admin, Jeffrey and Lew Johnson for assistance with my problems.(alphabetical order

BT, you're very welcome, and I'm pleased you're happy with your MET1.

On tubes, your experience with M8080s is not as good as mine--EVERY M8080 I've tried has been quiet, nonmicrofonic, and great sounding.

The tube dampers are from Herbies'...http://herbiesaudiolab.net/preamp.htm ...SS-7 size, but mine have slightly different damping pads on them. If I bought more, I'd buy the regular SS-7s with the whitish, squishy pads. The overall sounds seems slightly smoother...less edgy...with the Herbies rings. But as you can see in the pic, I believe in overkill, that if a little is good, more is better.

On the mix of tubes, if I had only 4 excellent M8080s, I'd use them in pairs and only in the front-L&R channels, then another very good one in the center channel, and just-good-enough ones in the Surround and SW channel. I've been listening to 2 new-to-me pairs of Sylvania G(old)B(ox)-6135s in the fronts, and both pairs are highly nonmicrofonic and quite nice sounding. At almost $40 delivered for the pair, 6135s are no longer inexpensive!

Enjoy your MET1, and when you want to improve its transparency, you know whom to e-mail.

[Mr_BT]

Just ordered some SS-7 tube dampers from herbies. We'll see....

"Enjoy your MET1, and when you want to improve its transparency, you know whom to e-mail."
Jeffrey, if by saying that you mean grabbing soldering iron and start breathing flux fumes I'm all over it However without your guidance I don't think I'll be successful. Out of curiosity, what was your total cost of caps upgrade and where did you buy it from?

P.S. a quick search brought www.soniccraft.com as a good source of most parts. Did you use excactly the same values of caps as originals?

[jeffreybehr]

Just ordered some SS-7 tube dampers from herbies. We'll see....

"Enjoy your MET1, and when you want to improve its transparency, you know whom to e-mail."
Jeffrey, if by saying that you mean grabbing soldering iron and start breathing flux fumes I'm all over it However without your guidance I don't think I'll be successful. Out of curiosity, what was your total cost of caps upgrade and where did you buy it from?

P.S. a quick search brought http://www.soniccraft.com as a good source of most parts. Did you use excactly the same values of caps as originals?

I think you'll enjoy the results of the Herbies dampers.

I got ALL my parts from Sonic Craft. I started doing business with SC years ago, and its owner, Jeffrey Glowacki, has turned into a friend. I did my upgrades a few years ago with, sometimes, preproduction caps he had lying around and was happy to sell to me at a substantial discount from the new-cap retail price. Right now, the 2uF SoniCap Platinum ('SCP'; Teflon-alloy-film) cap retails for a rather high price of $280; you'll need at least 2 depending on how many channels you wish to improve. For the PowerSupply, the combination of a Jupiter HT and small SCP retails for about $100; you'll need 2 combos. The SCP is certainly one of the best-sounding caps available, but another, less-expensive way to do it would be with the excellent MultiCap RTX (polystyrene) 2/200 coupler bypassed with a small...say 0.33uF...SCP. That combo retails for $121 per channel. The PS combo could be a 0.82/400* MCRTX and a 0.047/400 SCP; that combo retails for $77...times 2 = $154.

The original output-coupling caps are 4.15uF 'propylene-and-'styrene combos. The value YOU need depends on the impedance each channel is driving. My 2uF caps achieve a below-2Hz filter point with the 500K load resistor in parallel with the input impedances of the poweramps** it's driving. I can help you with these calculations if you wish.

The MET1 sounds very good as is; with better output-coupling and powersupply-bypass caps, it'll sound excellent.

* 400VDC-rated caps are required here.
** The improved McC DNA-750s and the Crown CDi-2000 subwoofer amp.

[Mr_BT]

when it rains, it pours......

I think I'll have to put the modification on hold for some time. The reason is always the same....money. It's kinda expensive but It's still less by more than twice the cost I may end up paying to fix my martin logan speakers....

I enjoyed my multichannel system for how long? two weeks?......

Jeffrey,
calculations I'd appreciate your help with:

output coupling caps:

input impedance of my amplifiers is 47.5kohm as measured by stereophile: "The speaker inputs offered an input impedance almost identical to the specified 50 ohms, at 49.5 ohms, while the line-level input impedances were 47.5k ohms (unbalanced input and each leg of the balanced input) at low and midrange frequencies, dropping slightly and inconsequentially to 40k ohms at 20kHz."

What are Power Supply bypass caps values?



I'd rather have all the info ready for caps purchase and I don't think I'll be going with compromized/cheaper options

Thanks
Bart

[Mr_BT]

Hello,

Some more tubes tested and I think we have a WINNER!!!!


Being worried about future tubes availability for the MET1 preamp began a hunt for a "perfect tube" to supply myself for a long time relationship with my lovely multichannel preamplifier.

Evertything what jeffreybehr said is 100% accurate. Most of a tubes easily available are useless.....
Either microphonic, noisy or both.....

But I believe we have a winner it this competition:
PHILIPS M8080!!!! six out of six trouble free!!!! and I got it really cheap $6.50 each. So after testing first batch of six I decided to buy another six.
They look identical to (and probably are) original MULLARD M8080.

From the rest of the bunch the Sylvanias 6135 turned to be the most reliable. Three out of five survived for maybe two months as rear and SW channels but became unbearably noisy after that period.

Original Mullards M8080 were dicey 50/50.... one noisy and two or so microphonic.

From three 5-star GE 6c4wa only one after a couple of weeks is still working fine. Rest become noisy....

Next step will be caps upgrade for MET1 preamp (as jeffreybehr instructed).......

[jeffreybehr]

But I believe we have a winner it this competition:
PHILIPS M8080!!!! six out of six trouble free!!!! and I got it really cheap $6.50 each. So after testing first batch of six I decided to buy another six.
They look identical to (and probably are) original MULLARD M8080.

From the rest of the bunch the Sylvanias 6135 turned to be the most reliable. Three out of five survived for maybe two months as rear and SW channels but became unbearably noisy after that period.

Original Mullards M8080 were dicey 50/50.... one noisy and two or so microphonic.

From three 5-star GE 6c4wa only one after a couple of weeks is still working fine. Rest become noisy....

Next step will be caps upgrade for MET1 preamp (as jeffreybehr instructed).......

Your and my experiences with HIGH-quality tubes for the MET1 are LOTS different. Yours go to hell in months, while mine last for 2 years before I get around to changing them. Wow. Maybe you just hear better than I.

Output-coupling-cap values:
The load your coupling caps are driving is 500K (within the preamp) paralleled with call-it-49K, or c. 45K**. One rule of thumb for high-pass-filter-point-for-excellent-sounding-bass is 3 octaves below lowest audible frequency, = 2.5Hz (assuming 20Hz); another is 2Hz or below. I'm plenty happy with 2.5Hz or below...so...with a 45K load, 1.5uF gives us 2.4Hz and 2uF gives us 1.8Hz. YOU get to choose what value you want, but clearly one doesn't need the original 4.15uF when driving 47K. 2uF SoniCap Platinums (SCPs) are now $280 each, while V-Cap TFTF* 2uFs are $345. Of course there are other 5-star-quality caps out there; YOU get to make YOUR choice and spend YOUR money. The 'affordable' combination of a 2uF RTX ($45) plus a, say, 0.33uF SCP ($76) (= $242 for 2 channels) will sound more transparent than the original 4uF 'propylene bypassed with a 0.15uF 'styrene, as will a Mundorf Silver/Oil 2.2uF at $70 (= $140 for 2 channels) will.

BTW there's nothing magic or mysterious about these calculations. The standard high-pass filter formula is F = 159155/RC, where F = frequency in Hertz, R = load resistance in Ohms, and C = capacitance in microFarads.

I'll have to look at what values I used for the PS-bypass caps.

BTW I bought on eBay a half-dozen of those Phillips Mullard M8080s; thx for mentioning them.


* = Teflon-film, tin-foil
** See http://www.1728.org/resistrs.htm .

[Mr_BT]

Jeffrey,
As usual, Thank You for support, help, guidance


Finally decided to approach this carefully and go with Mundorf 2.2uf (cheap option) simply because I don't know what to expect. If I'm happy with caps change I will think of upgradig to SCPs. Also, why not to experiment with a few caps and have all the fun last longer? .

Two Mundorf 2.2uF are on its way from sonicraft and should be here Thursday and I may have some spare time to install it overv this weekend.
Will report results.

If it's not asking too much I'd like to know the PS caps values you used. From you photos available online it's difficult to tell (low res).

Thanks again,

[jeffreybehr]

Jeffrey,
As usual, Thank You for support, help, guidance You are very welcome.

Finally decided to approach this carefully and go with Mundorf 2.2uf (cheap option) simply because I don't know what to expect. If I'm happy with caps change I will think of upgrading to SCPs. If you find, after a couple-hundred hours of break-in, that the Mundorf Silver/Oils (MSOs) sound better than the originals, I suggest you merely add a 0.33uF SCP in parallel with the MSOs. Doing so will add some 'air', some transparency, that the MSOs don't have.

Also, why not to experiment with a few caps and have all the fun last longer? .
I've had my solderingpencil in mine plenty-enough times and had some trouble with the double-sided, plated-thru-holes board, and you too might decide that ONCE is enough!

Two Mundorf 2.2uF are on its way from Sonic Craft and should be here Thursday and I may have some spare time to install it over this weekend.
Will report results.

If it's not asking too much I'd like to know the PS caps values you used. From you photos available online it's difficult to tell (low res).

Found my notes on the PS caps. In the initial high-Voltage filter, I removed Cs 33, 92, and 93 (all in parallel) and installed a 2.2uF Jupiter HT and a 0.01 SCP. Doesn't matter which of these 2 goes in which of the 3 positions. In the final HV filter (= regulator output), I removed Cs 41 and 94 and installed a 2.2 Jupiter HT and a 0.22 SCP. If J-Glo doesn't have a single 0.22 SCP left, use a 0.33uf SCP.

I just posted a 2000-pixel-wide image of the completed preamp.
http://s89.photobucket.com/user/jeffrey ... sort=3&o=0

[Mr_BT]

You just scared me off with 200h of brake-in time so I had to change my strategy:

- Mundorf caps are going to Power supply together with small SCPs 0.33 and 0.01uF
- For L and R channel I'll have Multicap RTX 2.0uF with SCP 0.33uF
All parts ordered and awaiting delivery.

Jeffrey,
How did you secure the caps in vertical position? Did you use glue, silicon etc? Any tips?

[Mr_BT]

I think I see double sided adhesive under caps?

[jeffreybehr]

You just scared me off with 200h of brake-in time so I had to change my strategy:

- Mundorf caps are going to Power supply together with small SCPs 0.33 and 0.01uF
- For L and R channel I'll have Multicap RTX 2.0uF with SCP 0.33uF
All parts ordered and awaiting delivery.

How did you secure the caps in vertical position? Did you use glue, silicon etc? Any tips?

BT, did you talk to J-Glo about your cap selections? He knows a LOT about how various caps sound in various applications.

Two layers of double-sided plastic-foam tape on the bottom of the cap.

[Mr_BT]

No, I did not talk to him.
Why? Would there be any problem with Mundorfs in PS?
Based on my brief online research many people use them in power supplies.

[Mr_BT]

Thanks to Jeffreybehr for being a mastermind of this operation.
Thanks to Mr. Jameson for for giving me courage and steady hand while holding soldering iron over $7500 piece of electronics.
Here it is up and running:

[jeffreybehr]

Way to go, BT; that was fast. I hope everything sounds great...at least as good as the preamp did while all its parts were thoroughly broken in. For break-in, I'd leave the preamp on with some source of continuous music playing thru those front channels. (The poweramp does NOT need to be turned on, but the preamp needs to be driving it the 'right' amount of current flow.) I think you'll be around half-way there at around 100 hours, but those Teflon-alloy-film-and-foil SoniCap Platinums will take maybe a couple weeks before they sound their best.

Who's Mr. Jameson?

[Ray]

Fantastic Job!

Thanks to Jeffreybehr for being a mastermind of this operation.
Thanks to Mr. Jameson for for giving me courage and steady hand while holding soldering iron over $7500 piece of electronics.
Here it is up and running:

[Mr_BT]

Who's Mr. Jameson?

Irish Whiskey

Modified unit indeed sounds differently. First impression (first two hour after modification) is quite satisfactory: spaciousness, transparency and instruments upper range extensions were improved. Lower end was kinda thin but after about 10h I can say it's improving. Final impressions will be posted at 100h brake-in.
All in all, it was worthy modification and it will get even better. I can't wait

Jeffrey,
I wonder about your power supply caps selection values ? Original values were 1x1uF and 3x0.25uF.
Also I didn't quite pay attention to shorter lead (shield) of SCP. Read online after that it can be omitted without any problems. What do you think about it?

P.S. I found your DNA-750 moddification thread at audiocircle. Well.....it's inspiring . Thinking of modding my Musical Fidelity 750k's

[Mr_BT]

Fantastic Job!

Thanks Ray!

[jeffreybehr]

Who's Mr. Jameson?

Irish Whiskey AHA!!!!!!!!!!

Modified unit indeed sounds differently. First impression (first two-hour after modification) is quite satisfactory: spaciousness, transparency and instruments upper range extensions were improved. Lower end was kinda thin but after about 10h I can say it's improving. Final impressions will be posted at 100h brake-in.
All in all, it was worthy modification and it will get even better. I can't wait

Jeffrey,
I wonder about your power supply caps selection values ? Original values were 1x1uF and 3x0.25uF. Those values were recommended by J-Glo; I just bought and installed them.

Also I didn't quite pay attention to shorter lead (shield) of SCP. Read online after that it can be omitted without any problems. What do you think about it? I think that having it connected as J-Glo recommends might make a tiny difference in sound quality, but that difference is HIGHLY unlikely to be one that I could hear. If you're confident, turn what ever is 'backwards' around; I sure wouldn't.

P.S. I found your DNA-750 moddification thread at audiocircle. Well.....it's inspiring . Thinking of modding my Musical Fidelity 750k'ssize] Getting a schematic would be a start; I wouldn't even start an improvement project without one.