ModWright SWL 9.0 SE Signature Pre

machone

I bought this from jetmaker737 here on the forum. Thanks Rick!

As many have said a tube pre with ss amp is a great combo so now my journey continues with tubes. BTW I know zero about tubes except they get hot.

Away I unpacked it, installed the tubes and powered it up with no problems. While I had the cover off I Dynamated it.

I did not get a good listen the first night so Tuesday night I sat down and began to play some familiar tunes.

Wow! The first thing that popped into my mind is it is very dynamic and is so at low or high volumes. Great imaging with a very natural sound with no fatigue. I played Abby Road at a decent volume and it really set me back in my seat! I am sure this is going to be fun!

One thing is there is more noise than I am used to hearing through my system. The Hafler 110 pre is totally silent and the ModWright has some hum/hash. Is this normal for this unit or could it be tubes?

stangman67

My tube pre has some hiss as well. I think it just comes with the territory. The key thing is as long as it is not present when the music is actually playing. It bothers me a bit but once music is playing it is not noticeable

SCompRacer

One thing you could check for hum is chassis ground. I purchased my first ModWright SWL 9.0 SE used. It had a hum. I contacted the seller and he was very apologetic. Claimed he forgot about it. He used a cheater plug to lift the ground when he first got it.

I called Dan and he suggested I check the chassis ground. He said some of the pre's were assembled without the powder coat being ground off where the ground wire attached to chassis. This was at the IEC plug. IIRC they had the ground between the IEC and chassis? I ground the powder coat off, reattached ground/IEC and it was totally quiet after that. Worth a look.

Of course power down, remove power plug before checking.

Mike Reeter

Tube Gear and Tubes "can" be noisy, nature of the Beast. I always Mute my Preamp between tracks or changing sources.

machone

SCompRacer wrote: »

One thing you could check for hum is chassis ground. I purchased my first ModWright SWL 9.0 SE used. It had a hum. I contacted the seller and he was very apologetic. Claimed he forgot about it. He used a cheater plug to lift the ground when he first got it.

I called Dan and he suggested I check the chassis ground. He said some of the pre's were assembled without the powder coat being ground off where the ground wire attached to chassis. This was at the IEC plug. IIRC they had the ground between the IEC and chassis? I ground the powder coat off, reattached ground/IEC and it was totally quiet after that. Worth a look.

Of course power down, remove power plug before checking.

Interesting.
I contacted ModWright and Dan responded with two things.
1. It could be time for tubes.
2. It could be an internal ground issue.

Thanks scomp
Either way I will find it and yes I will disconnect power

machone

This preamp continues to impress!! I will give details later.

I have done some troubleshooting to find the source of the hum. Mind you it is slight but I can hear it from my seating position without music.

1. I tried a 2 conductor power cable without safety ground and the same.
2. I changed the tubes and the same.
3. I disconnected all sources and the same.

So last night I used a paper towel tube to see if the hum was localized to one driver and found that it is not coming from the tweeters or stereo drivers but it is coming from the sda drivers. So I disconnected the SDA cable from the Dreadnought and the hum stopped. I don't remember this as an issue with the Hafler pre so why with the ModWright? Magnetic field of the ModWright interfering with the Dread? Maybe tonight I will move the Dread to a different position.

You guys ever run into this before?

F1nut

That is a strange one. I don't think the Dreadnought is close enough to your pre amp for that to be the issue, but try moving it anyway.

mikeyb128

I think it depends on the tubes you have. I use some 40’s RCA grey glass 6SN7’s and they are dead quiet, you have to put your ear an inch from the tweeter to hear anything. I also have some 59 Sylvania GTB tubes and you can hear hiss from my seat, compared to the exact same tubes from Baldwin (screened for organ use) are as quiet as the RCA’s, not to mention I like them better, and they were dirt cheap, like 100 bucks for 5 NOS matched set.

I haven’t had an SS pre in so long, I really can’t remember how quiet they really are.

mikeyb128

Be careful if you have any streamers or WiFi related components near your pre, I recall my EE minimax had hum when in the proximity of my Auralic streamer!

machone

Thanks guys.
I will move the dreadnought and cables to see if it has an affect.
Strange to be isolated to the SDA circuit

machone

Ok the hum is not just in the sda circuit. It is in the stereo drivers also but very faint. If I hook up the Halfer pre the hum is still there in the same proportions stereo to sda but barely perceptible and a non-issue.
So for whatever reason the modwright has more hum. The hum does not change with volume.
BTW moving the dreadnought had no affect on the hum.
Try another set of tubes?

marvda1

try disconnecting and reconnecting all your rca cables.

F1nut

Try what SCompRacer suggested.

machone

Fixed it!
It was the ground at the IEC. The lead was sandwiched between the IEC flange and the case and making poor contact.
Unfortunately the nut was galled on the screw so I had to grind off the head to get it apart. It was impossible to get access between the IEC and the case to remove the paint without removing several components so opted to move the lead to a new ground screw.
I reattached the IEC with a new screw and nut. Then drilled new hole and installed the new grounding post.
Thanks for your help!

Jetmaker737

I'm glad you got that fixed! The pre never gave me any hum but as I said in our PM's this unit was boxed and moved when I relocated to a different state. I never thought to test it prior to sale. So maybe between my move and shipping to you it got jarred and brought the issue out. Again, glad to see it's all fixed!

machone

I have been enjoying the Modwright!

I am using inputs for:
1. CD
2. Tuner
3. TV
4. Blueray
5. Phono pre from the Hafler (to be replaced in the future).

Yes, five because the monitor can be used as the fifth input.

I am currently using two GE 5687 tubes and a fat base Great Britain F31 5AR4 Mullard rectifier. BTW I don't know jack about tubes except they really get hot!

Anyway it sounds great. I needed a good power cable so I built some DIY cables using VH Audio recipes. I used my Hafler 500 amp to burn in the preamp cable and to my surprise it bested the cable I have been using for a couple of years so I built another PC for the Hafler 500.




Now that the cables are settling in I decided to pull out my IFI Purifier2 and give it a try. I took it off the system last year when I was installing four dedicated 20 amp circuits.



The IFI is inserted at the DAC end of the USB cable coming from the computer and plugged into the Marantz. Now that I have a more resolving system the IFI is very noticeable. I have switched back a forth with and without it in the system and with it the bass is tighter and the background is blacker. Voices are very natural and everything seems smoother but also faster. I think it is staying.

Hey Skip, the IFI Purifier2 is one piece that would be a great candidate for a trial. It is only a little over $100 and is easy to ship and trial. I believe a lot of you guys might find it worth the listen.

halo

@machone

I had three pairs of tubes with my ModWright modified Sony NS9100ES:

• Tung Sol 5687
• Amperex 7119
• GE 7044

My favorites were the Amperex 7119.

You don't have a lot of choices for rolling tubes but that may be a good thing.

Enjoy!

msg

So how do you actually ground it with that auxiliary lug? Are you just running a wire to some other piece of gear?

machone

It's just grounded inside the case for now but
I was moving the ground anyway so I made sure I could add a wire to the outside to tie into another piece of gear in the future.

machone

Just rolled tubes.
Got a pair of 5687 military Raytheon bronze plates from Brent Jessee.
Sweet!

pitdogg2

machone wrote: »

Just rolled tubes.
Got a pair of 5687 military Raytheon bronze plates from Brent Jessee.
Sweet!

boy the boxes look great... how about a picture of the tubes

machone

Fake Tubes.............

decal

Love the Z.Z. Top photo !!!!!!!!!!!!!!!!!!!!!!!

machone

decal wrote: »

Love the Z.Z. Top photo !!!!!!!!!!!!!!!!!!!!!!!

Macon Ga back in the early 70s.

machone

"Got a pair of 5687 military Raytheon bronze plates from Brent Jessee."

I so I have been burning in these new tubes.

Initially I liked what I heard but as they burned in I lost the emotional connection with the music. Imagining was ok but that special air, focus and depth just was not there.

While listening to the beginning of DSOTM I noticed the heart beat was muddied. So I decided to move the speakers away from the wall 1" and bingo the magic is back in spades!

I guess the new tubes have better bass performance and the muddied bass was masking the overall system.

I went from wondering if I was going deaf to beautiful music!

SCompRacer

They may be harder to find now, but 6900's worked really well in ModWright gear.

A 6900 is like a 5687 on steroids. It was used in ICBM warheads. Max altitude 80,000 feet, 500G impact load, 50G vibration acceleration. It's job, to survive until target reached and detonated. In audio applications, near twice the transconductance of a 5687. Incredible detail and dynamics.

The 6900 is constructed from Nonex glass, which is quite heavy. It also uses a Tungsten stem seal construction like many of the high-powered transmitting tubes do. The 3 spacers are made from ceramic. Each of these ceramic spacers has the equivalent thickness of about 4 of the typical spacers used in other 9-pin tubes, stacked together. Also the use of ceramic spacers eliminated one of the common sources of tube failure, which is the evolution of gas from other less costly materials such as mica which is commonly used for spacers.

The ceramic spacers along with the use of of multi-pillar supports locked together via 12 welded eyelets, contribute to a sturdier structure. Special alloy snubbers, which maintain their position, retain their spring properties at high temperatures.

Bendix first made the 6900, then MU engineering purchased Bendix tube division and rebranded old stock and manufactured tubes with the Bendix tooling. I had both the Bendix and the MU6900, could not notice any SQ difference between them.

Back in the day a pair of Bendix 6900 would fetch $600 or more while MU could be had for $300 a pair. Until folks figured it out, then the MU went way up in price.

pitdogg2

Those are pretty cool Rich

machone

Brent Jessee lists them for 600 a pair but is out of stock. Maybe that's a good thing?

pitdogg2

Rich has posted pictures of these tubes before, so yes I looked before and I believe Brent Jesse had been out for a long time. I would think these were very limited in the first place.

machone

I am sure they are great but I can buy a lot of stuff with $600.

schwarcw

I still have the Modwright Sony 9100 ES CD player. I have some Gold Brand Sylvania 5687s, with gold pins. Got it from Scompracer years ago and still going strong!