[Headamp] upgrading a Lehmann BCL clone

[Cidious]

Yeah I also like the Pureisms. Thinking of putting them back. They are just a bit more detailed it seems.

Next to that I ordered my self some SIL sockets, 2 new boards and a shitload of components. Also ordered myself 20 gain switches hahaha.

I will definitly keep updating my thread to share my findings and my learning process.


Thanks for all the help so far! It is REALLY appreciated!

 

[Cidious]

What about these puppies?

Amtrans AMCO | Hifi Collective

http://www.hificollective.co.uk/sites/default/files/amtrans_caps_0.pdf

Any use for these? Maybe I could use the 22nf version for the signal path replacing the EROs?

Any ideas on these caps?

 

[Cidious]

Populating a new PCB this week.

Got 2 pcb's. The rev7 I posted earlier was not in stock so I will build that later.

For now I am deciding which PCB to pick.

Silver colored contacts.. I assume tinned. Even though it was a little bit more expensive than the other I don't think the contacts are silver plated for roughly $5. 2 OZ PCB.

I marked the most notable (but still insignificant) difference between the two PCB's for as far I could find. The four smaller resistors made place for two big ones like in the original Lehmann BCL design. What resistors should I use for this position? 3R 1W? and what type will be good for the power supply?

This is the PCB revision I already populated. It's near 1:1 with the Lehmann BCL too. Can mount polystyrene caps here next to the opamp but I will go for Amtrans AMCH anyway. Also 2 OZ.


When I gathered all my parts I will make a list and a few pictures of all the parts before I start soldering.

 

[Cidious]

Will go with the first pcb. Even ordered a new case for it.. it is actually saying lehmann bcl including logo on the front.. CHEEKY! The pcb also says Lehmann.. this is China haha. Ah well I am not buying it to make a profit out of the device or selling it as an original.. just personal use, so my conscious is clear for now .

The 63V Mundorf caps didn't fit my other case. Just 1 or 2 mm to high. Let's hope they fit in my new case. Else I will send them back and get the 40V version. The 63Vs have better specs that make the upgrade from the Vishay BCs a bit more justified..

Also looking in to using Amtrans AMCO caps for opamp and input caps bypass. I can make them fit with 22nf value. Have to read more up on this to let it make sense.

Will use Kiwame resistors for all the output positions. Amtrans has some nice 2W resistors but they are also $7.50 here.. amtrans seems to be quite expensive.. Amtrans took over a Riken resistor factory if I'm not mistaken. They are highly valued. I think Kiwame will be sufficient though at $1.20 each..

Also still have to find some good 3R 2W resistors between the big Mundorf caps. I guess I could just go with metal film and don't need carbon here or would carbon still be preferred even if not in signal path?

 

[Cidious]

I have a question.

Since I modified the power supply with the diode and the 2 10uf caps I got a strong hissing in all of the music on the background.

I think it maybe is because of the diodes.. Like I mentioned I didn't get the red glass ones but black ones. The package said fairchild. So I assumed they would be kind of good. The packaging was quite professional too.. But maybe there was something not totally right with them. I did match them and stuff so I only had 2mv offset on both channels which was really good.

I have been looking around on some audio DIY shops on Taobao and found some German ITT 400V diodes.. Could I use these? Or are they serious overkill?

Any clues on this?

Also the progress:

Chosing. picked the silver looking one. I think the contacts are nickelplated, which is harder than gold. A lot of contacts on the other PCB went bad with some soldering. Really thin material. So witch a little bit of care and the harder nickel this choice will probably pay of in better connections. I also liked the layout of the input bypass caps a bit better. Now I can use larger caps there.

Gathering parts. Paired everything I could pair. Parts are still coming in.

Soldered some basics on there. WIMA MKP10 0.1uf 400V. Mundorf MCap MKP input caps, Amtrans AMCH 100pf caps, Vishay ERC/RNC55 resistors for signal path. Vishay MSR125 for power path. They send me some YEAGO 1% resistors for next to the LEDs.. Never heard of them.. put them in there.. They measured quite accurate so I guess they will do fine there.. If people doubt then please tell me what to use instead.

My opamps and the adapter. Got some OPA111AM, OPA111VM, OPA627BP, OPA2604(AP I think) and an AD8620AR. Seems like I can do some rolling opamps.

 

[Cidious]

Also the Kiwame resistors are hard to get in the 10R value.. would 3/4 watt be enough for the output? I could get the Amtrans AMRG 3/4 watt. They are a bit cheaper. But I don't know if it would be enough.

 

[ClaveFremen]

Also still have to find some good 3R 2W resistors between the big Mundorf caps. I guess I could just go with metal film and don't need carbon here or would carbon still be preferred even if not in signal path?

I would stick to metal films... carbon films are always colored, in a nice and pleasant way, but still not neutral.

I think it maybe is because of the diodes.. Like I mentioned I didn't get the red glass ones but black ones. The package said fairchild.

It's possible, particularly if they're high wattage type.

Do you have access to RS Components or similar?

I have been looking around on some audio DIY shops on Taobao and found some German ITT 400V diodes.. Could I use these? Or are they serious overkill?

Pay attention to the power rating, higher the required wattage, higher the biasing current...

Try to get the red glasss BZX85, those will work for sure.

They send me some YEAGO 1% resistors for next to the LEDs.. Never heard of them.. put them in there.. They measured quite accurate so I guess they will do fine there.. If people doubt then please tell me what to use instead.

If they're YAGEO they are pretty good quality but with a very thick sound.

 

[Cidious]

Thanks for your response.

Will look into everything.

I do have access to RS components. But it takes a long time to get stuff from there and the VAT is kind of harsh here..

What voltage may the resistors be? I can find 12V, 15V but not 13V in the red glass color. (Edit: I have found them. What power rating is preferable? The ones I got were 1W)

I honestly thought the Vishay Dale ERC55 were carbon film resistors.. whoops.. they weren't. If I had have known I would have populated the whole board with them.

I see you have chosen more 'common' resistors near the transistors. 1.5K and 47R they are I think. I have populated these places with Vishay MSR125. But the 1.5Ks look different from the ones on my other board... which are supossed to have the same ones from the same shop.. darker in color.

Now I feel I should have gone with the good Vishay dales I got my hands on. But I don't fancy soldering everything out again. These small holes are a nightmare to suck the solder out. I don't want to damage the board. Are the resistors in this place notable for the sound signature?

 

[ClaveFremen]

Thanks for your response.

You're welcome

What voltage may the resistors be? I can find 12V, 15V but not 13V in the red glass color. (Edit: I have found them. What power rating is preferable? The ones I got were 1W)

BZX85 usually are 1.3W zeners

I see you have chosen more 'common' resistors near the transistors. 1.5K and 47R they are I think. I have populated these places with Vishay MSR125. But the 1.5Ks look different from the ones on my other board... which are supossed to have the same ones from the same shop.. darker in color.

I've used Philips/BC MRS25.

Color could be different if they're from the Philips era or BC or Vishay.

The big 1W resistors are all Vishay/Beyshlag MBE0414

These small holes are a nightmare to suck the solder out. I don't want to damage the board. Are the resistors in this place notable for the sound signature?

Less than those in direct signal path but you will still hear them... BTW their ''thick" sound could be beneficial since the Lehmann is so dead neutral, give them a try.

BTW I solved all problems related to desoldering using a chinese desoldering station, a good investment.

 

[Cidious]

https://item.taobao.com/item.htm?spm=a230r.1.14.132.CUeHPh&id=526507715383&ns=1&abbucket=3#detail Like this?

 

[Cidious]

From the package list they send me with some basic components its says

0.6W 金属膜电 3R3 Vishay MRS25 1%
0.6W 金属膜电 47R Vishay MRS25 1%
0.6W 金属膜电 1K5 Vishay MRS25 1%
0.6W 金属膜电 4K7 Vishay MRS25 1%
0.6W 金属膜电 56K Vishay MRS25 1%
1W 金属膜电阻 10R Vishay MBE0414 1%
2W 金属膜电阻 47R 国巨YAEGO 金属膜 1%

I am still doubting if I will use the 1W 10R output resistors or replace them with something more fancy.

But the thing is. The 1.5K's are definitely different from the ones I've had before from the same shop.. maybe they are fakes? Not sure. I will ask them. See what they come up with.

 

[ClaveFremen]

https://item.taobao.com/item.htm?spm=a230r.1.14.132.CUeHPh&id=526507715383&ns=1&abbucket=3#detail Like this?

No, that one is for SMD desoldering, you should search for the vacuum ones.

Later I will post a link.

0.6W 金属膜电 56K Vishay MRS25 1%
1W 金属膜电阻 10R Vishay MBE0414 1%
2W 金属膜电阻 47R 国巨YAEGO 金属膜 1%

I am still doubting if I will use the 1W 10R output resistors or replace them with something more fancy.

The original Lehmann use Vishay MBE0414 also for the 47R.

But the thing is. The 1.5K's are definitely different from the ones I've had before from the same shop.. maybe they are fakes? Not sure. I will ask them. See what they come up with.

They seems legit, MRS25 from recent production batches are pale blue while thee ones from BC/Philips era are darker.

 

[ClaveFremen]

Later I will post a link.

Someone like AOYUE 474A++ or like this:

Hot selling High quality Desoldering Station of Ningbo ZD, View Desoldering Station, ZD Product Details from Ningbo Zhongdi Industry & Trade Co., Ltd. on Alibaba.com

I have this one:

110-130V/220-240V High quality Soldering Desoldering Station in digital of Ningbo ZD, View soldering desoldering station, ZD Product Details from Ningbo Zhongdi Industry & Trade Co., Ltd. on Alibaba.com

 

[Cidious]

I will think that over. Depending on how many time I will have for projects this year.

Btw I am looking into using PRP resistors for the output path. But I can not find 2W versions for the pre amp output. would 1W be sufficient for this position? I see other people using them.. but just want to make sure.

 

[ClaveFremen]

Btw I am looking into using PRP resistors for the output path. But I can not find 2W versions for the pre amp output. would 1W be sufficient for this position? I see other people using them.. but just want to make sure.

MBE0414, used by Lehmann in all those positions, are 1W rated so I suppose that the 1W rating is enough.

PRPs could be a nice choice too, be aware that they sound a bit ticker and with a tiny hint of harshness.

 

[Cidious]

I don't like harshness because I already have harsh headphones.

The black Dale resistors, they are carbon film aren't they?

And what about the orange CPFs?

I really have a hard time finding proper resistors for the 3R 2W positions on the board.. the board seller says they need to be 2W.. I somehow doubt it.. but maybe he's right.. don't really know.. the thing is that I can only find the black Dales in 2W or chinese crap

Can also get the Red RA resistors for the output positions. I think I will try them. And keep looking for some 3R 2W metal film resistors in between the big power caps.

 

[basi]

I don't like harshness because I already have harsh headphones.

The black Dale resistors, they are carbon film aren't they?

And what about the orange CPFs?

I really have a hard time finding proper resistors for the 3R 2W positions on the board.. the board seller says they need to be 2W.. I somehow doubt it.. but maybe he's right.. don't really know.. the thing is that I can only find the black Dales in 2W or chinese crap

Can also get the Red RA resistors for the output positions. I think I will try them. And keep looking for some 3R 2W metal film resistors in between the big power caps.

If u dont like harshness then put a smaller capacitor near opa 2134.Instead of 470Uf try 47uf or smaller.

 

[Cidious]

I am not using opa2134 anymore. Inferior opamp. And I have panasonic pureism 220uf or Elna Silmic II 100uf for this position. Also I ordered a shitload of mkp and polystyrene caps to try in between the radial opamp caps ranging from 0.022uf to 0.1uf. Soldered some sockets into place to do quick solder free comparisons.

Got some 3.01R Vishay Dale 2W resistors. For the positions in between the big power caps.

Got RA resistors for the output positions.

 

[Cidious]

Prices in yuan. As you can see they are not THAT expensive. so I just ordered some. Have sockets soldered at these positions so I will clean the pins and try them in the positions of the input bypass caps and the opamp bypass caps.

Very curious what they can do vs the standard Wima caps.

The Shin Shins and Soshins look promissing also in size.. Japanese stuff..

Also got some panasonics and other brands I've never heard about. Can't harm trying them.

 

[Cidious]

Also did some PSU caps shopping. Even ordered some Bipolar caps.. not sure what to do with them yet.. but this shop had quite and inventory sooo.. I decided that more is better.. I will try them for the PSU and do A/B-X comparisons.

Also decided not to use radial electrolytes for the small 10uf LM317 mod but ordered some genuine Spraque 10uf 35V tantalums to put in this position for the charge en decharge WAY faster than the slow Elna Silmic IIs. Lets see if they will do good there.

Also ordered some german ITT 13V 1W Zener diodes to match. Will test them against the advised BZX85 13Vs that I still have a matched pair of lying around from the previous modifications. Then I'll know if the background noise came from the diodes or not. Also have the 1.1K resistors to compare with.

Will be a lot of A/B comparisons, but I am confident to select the best parts after that.

Will do comparisons with 3 sets of cans. Beyerdynamic DT1770, DT770 and Mr Speakers Mad Dog headphones. All headphones use custom designed cables. Mostly Canare and Mogami with genuine top-range Neutrik or Amphenol connectors.
I will also test the pre-amp function on my active QMS Q5 studio monitor loudspeakers (Which are pretty amazing considering they are a Chinese manufactured and designed product at less than $350 for a pair . Blow Audioengine A5+ out of the water in A/B comparison on all fronts also (b)eat M-Audio AV-40s easily to my ears. For this price it's really not comparable.)