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  #21  
Old 18th July 2019, 06:49 PM
Black Stuart Black Stuart is offline
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Default Re: Headphone Amps and choices

Martin,
getting rid of the hum problem is easy and a necessity.

Re. the pot - as a first attempt why not try pre-attenuation see - www.goldpt.com/mods.html. This is dead easy to do, just choose the appropriate Rs for the 250K pot, cheapos to start with. If it works fine, whatever flavour you like.

The pot is easy to remove, be careful to note any earthing contact points, always good to take pics to refer back to.

Replacing - 2 options (1) a shunted Alps Blue or an SMT resistor stepped att. @ $15.99 approx. I have no actual experience of this type but many have and like it very much.

Whatever, this is a must do mod unless you want hum issues with lots of different valves

Re.valves - I use what I have found to be an end game - the Tung Sol RP 6F8G/6SN7. However I was lucky and bought 5 used 6F8G for $70 way back, I'm still using the first one I tried. The Russian 1578 is ahead top and bottom but the mids are not quite right used as o/put tubes with a 6F8G is for me the perfect blend. None of these are cheap now. Many sellers in the eastern bloc are scamming with cheapo Russian valves - caveat emptor. I have more of these two valves than I will ever need and shall be selling off some of each in the autumn.

The o/put valve is more problematical I use a Svetlana which is cheap enough but there are others that are supposed to be much better and much more expensive. Some sayn the DV runs hot, I have not found this but then I use a computer fan under the DV which sits on a slate box which has no back plate allowing input and o/put of air.

I have an original Joni Mitchell - Herija LP and a remastered version which is definitely better. Played through the DV - what to say - Joni is 3D and Jaco's bass floats in and out through the whole LP like a shaman - not to believe.

Cheapest is Drop/Massdrop but check out an untampered s/hand version on Headfi/ebay - enjoy.
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  #22  
Old 18th July 2019, 06:51 PM
Black Stuart Black Stuart is offline
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Default Re: Headphone Amps and choices

Whoops,
the hum issue is separate but see the Fitz or Floyd mod on Headfi.
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  #23  
Old 20th July 2019, 12:21 AM
Pingushome Pingushome is offline
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Default Re: Headphone Amps and choices

Quote:
Originally Posted by Black Stuart View Post
Whoops,
the hum issue is separate but see the Fitz or Floyd mod on Headfi.
Thanks for the info, all noted.
I’ll order the DV next month I hope

All the best
Martin
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  #24  
Old 8th August 2019, 12:13 AM
Black Stuart Black Stuart is offline
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Default Re: Headphone Amps and choices

Martin,
the DV comes with 3 per side o/put caps that are unknown Chinese, not bad but can be bettered, again take a look at what others have done on the Headfi threads.

From experience I don't like desoldering and resoldering PCBs. When I bought a Bada h/amp I decided that by destroying cheap caps I didn't like but keeping the legs I could solder to these meaning I didn't have to remove the PCB, so much easier.

The DV has a PCB which holds the o/put caps amongst other components. I removed this PCB and wish I hadn't. It was a devil to remove and even worse to re-instate because the Tx wiring is so short. The preamp components are also on the PCB but can be removed easily.

The Chinese o/put caps have very thin legs so be careful and take your time, this will be far simpler than removing the PCB.

I've just received what I am sure will be my final set of h/phones - a pair of Oppo PM2 - they are superb but they are only 32 Ohm unlike my Beyers. The supplied o/put caps are only 30uF per side.
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  #25  
Old 8th August 2019, 07:02 PM
Pingushome Pingushome is offline
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Default Re: Headphone Amps and choices

Hi Stuart,

Picked up a S/H one just waiting for it to arrive, if dpd can find it. They seem to have lost track of it.

Been reading the forums and was thinking of eventually doing the full RG job new power caps resistors and upgrading other caps.
Noticed on “superbestaudiofriends” web site some one suggests replacing the resistors on the cathode bias with led’s instead of the “Fitz mod”. Not sure what that does or how/why it work (if it does). Beyond my techy grade sorry
I already have a stepped att. spare so whether that or shunt pot not sure.
I’ll have to wait and see if anyone has played with it first, then decide where to go.

Thanks for the advise I’ll post on here when it comes.

Nice new cans btw read the write ups very good indeed.

Anyone else any thoughts pls feel free to chip in all help very welcome

All the Best
Martin
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  #26  
Old 9th August 2019, 03:52 PM
Black Stuart Black Stuart is offline
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Default Re: Headphone Amps and choices

Martin,
the LED mod is really simple, desolder the resistors and replace with the LEDs. I do hope the DV turns up. You will not regret my suggestion to not take out the PCB, just make sure all the debris is removed from the chassis.

Re. the o/put caps check out - www.bennic.com/en/filmcap - FPP (pure copper leads) UPP (pure silver leads). Apparently the 5% are just as accurate as the 1% (Dayton). 220uF should be fine.

I think the PSU caps are an optional change. Well worth changing the first resistor for Z foils, especially as you are going to get rid of supplied pot.

Only ever had one no-show in over 20 years of buying online - a s/hand CD from Germany and I've bought from all over the world. Just received in the post today a £1.99 s/hand copy of Back To Black - Amy had a voice in a generation - crap father/crap boyfriends - esta la vida.
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  #27  
Old 10th August 2019, 09:31 PM
Pingushome Pingushome is offline
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Default Re: Headphone Amps and choices

Ha ha ha well we’ll see Stuart.
After four days of lies and obfuscations from DPD group the parcel has allegedly been found but as yet not moved from the pick up point .
I’ve noted you’re comments so when it eventually arrives I’ll take a look.
Martin
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  #28  
Old 12th August 2019, 09:42 PM
Pingushome Pingushome is offline
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Default Re: Headphone Amps and choices

Well it arrived and to the minute of the advised time exactly. Well only four days late but exactly to the minute 10.32hrs well done DPD
Sounds very good no hum at all and good upgraded valves.

............ Now where’s my screwdriver and iron
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  #29  
Old 13th August 2019, 08:02 AM
bob orbell bob orbell is offline
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Default Re: Headphone Amps and choices

If it sounds good, why not leave it alone and listen to it for some time, by diving in to it immediately, you will never know if the mods you have been told about are successful, and may be you will like it as is, the way the manufactures intended it to be. Bob
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  #30  
Old 13th August 2019, 11:15 AM
Black Stuart Black Stuart is offline
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Default Re: Headphone Amps and choices

Bob,
you havn't been paying attention - the volume control is a joke, there is only one point at which you can listen comfortably. Below this point there is no sound and above you would soon go deaf.

Martin seems to be lucky, he has no hum, if he tries different tubes and still has no hum then the old adage applies - if it ain't broke, don't fix it.
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