[Gallic Dweller]

Maybe not, this comment was made after I had listened to only one side. After another 2 sides it was gone. Even before I've changed the Chinese polyester o/put caps the bass is really deep and tight. The Stereo Coffee preamp was a good buy, not using the ridiculous volume on the D/V is an excellent move.

 

[wwmhf]

The Stereo Coffee preamp is an interesting idea similar to what I have been thinking to do. I have bought the following passive preamp and want to use it with the DV:

https://www.ebay.com/itm/Finished-R...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

Need time, where is it?

 

[Gallic Dweller]

wwmhf,
that looks very interesting and it comes ready built. Just disconnect the volume and preamp inside the D/V, make a new chassis earth to the input PCB and think about using better quality signal wiring.

 

[wwmhf]

wwmhf,
that looks very interesting and it comes ready built. Just disconnect the volume and preamp inside the D/V, make a new chassis earth to the input PCB and think about using better quality signal wiring.

Thanks for the suggestion of connection between the ground of the DV and the volume control. My signal wires are top-notch because I make almost all of them.

 

[Gallic Dweller]

The signal wiring is so important. Just desolder the original earth and scrape enough paint from a point on the nearby vented part of the chassis.

 

[SWIN]

Posting some inside pictures of the DV 336 SE.

Nice build quality, very easy to repair.

Quite like the Bottlehead Crack in circuit layout, but this is much beefier and have substantially bigger and better coupling capacitors, that's those big orange blobs.

The Crack uses only a very small 160 V 100 uF electrolytic cap.

All in all a nice little amp.

Will try to post a up to date schematic, with voltages.

 

[wwmhf]

Thanks for sharing those pictures. An up to date schematic with voltages will be great!

 

[Gallic Dweller]

Posting some inside pictures of the DV 336 SE.

Nice build quality, very easy to repair.

Quite like the Bottlehead Crack in circuit layout, but this is much beefier and have substantially bigger and better coupling capacitors, that's those big orange blobs.

The Crack uses only a very small 160 V 100 uF electrolytic cap.

All in all a nice little amp.

Will try to post a up to date schematic, with voltages.

Very nice photos. Not sure about your comment on the o/put caps though - bigger does'nt have to mean better, they are only 30uF per side, not so good if your cans are low Ohms. A schematic will be useful and especially voltages. Others have measured the voltages at the o/put caps @ 70V be nice to see if you find the same. Changing these unknown Chinese o/put caps should make a very good h/amp into an even better one.

Some have said their D/V runs very hot, mine does'nt. Having disconnected the pot there is very slight hum which does'nt increase if I turn the volume to max on my Stereo Coffee preamp. It does'nt interfere with the music at all, ironically it's only slightly annoying when I'm not playing any music.

 

[SylvesterH]

Hi,

How many hours can it be safely use the amp without overheating?
Has anyone some experience on this subject?

 

[MelonHead]

It surely depends on the environmental temperature and the surrounding space as well as the heat dissipation of the exact tubes. It happened a few times when I incidentaly left my 336SE on during a whole night which was 16 hours cumulated with the listening session, but I have not recognized any extreme heat.
Btw: I don't know whether my resistor problem, which caused the mute in the left channel has anything in common with the few long runs, so take my perception with a grain of salt.

 

[SylvesterH]

Thanks a lot. The amp is in a well ventilated space and the ambient temperature is around 22-23 C.

 

[ThermalAlchemy]

Hi,

How many hours can it be safely use the amp without overheating?
Has anyone some experience on this subject?

Don’t worry about heat unless you’re in a climate of 80°F plus you can do the conversion for Celsius . You simply fix the overheating problem with a six-inch 12 V computer fan and run it at 6 V no higher than 7 V is more than adequate enough of the air movement to cool off part face either sideways into the side vents and tubes or from underneath your cabinet facing up into the vents underneath. By running a computer fan at half the voltage it’s usually near dead quiet by being 6 inches in diameter at that speed is more than enough airflow to cool the components .

 

[Gallic Dweller]

Don’t worry about heat unless you’re in a climate of 80°F plus you can do the conversion for Celsius . You simply fix the overheating problem with a six-inch 12 V computer fan and run it at 6 V no higher than 7 V is more than adequate enough of the air movement to cool off part face either sideways into the side vents and tubes or from underneath your cabinet facing up into the vents underneath. By running a computer fan at half the voltage it’s usually near dead quiet by being 6 inches in diameter at that speed is more than enough airflow to cool the components .

I'v e been using computer fans beneath hybrid amps for years, so it was obvious to use the same method with the D/V. I had a slate box made when I lived in Spain - no bottom or rear plate and lined with bitumen sheeting. I'm going to use the same method beneath my Parasound Zamp.

I have to say that my D/V does'nt run at all hot. I use a Tung Sol RP 6F8G and a Russian and a GE o/put tube.

 

[wwmhf]

Using a quiet fan for a tube amp seems to be a good idea. I do not use a fan for my DV 336 amp, but I use a fan for my DV 339 amp. DV 339 can generate more heat than DV336, and I really like how the fan works for reducing the temp of DV 336.

 

[Gallic Dweller]

There were white papers written in the 1950s' about heat and the effect on caps and resistors - reduce the heat exposure to caps and resistors by 10C and double the life. You see so many comments about how mosfets sound better when hot but never any trials to justify these statements. To be valid experiments should need to be done in cooling mosfets and compare hearing tests.

the power resistors in the D/V also get hot, changing them for Mills or other quality resistors is really easy and yes the PSU components do affect the sound.