Upgrading caps and resistors on a Little Bear T11

the thin end of the wedge
metal_gear14
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Upgrading caps and resistors on a Little Bear T11

Post by metal_gear14 » 08 Nov 2019 17:34

To start, I want to say that I'm very happy with my Little Bear T11 preamp. Others online seem to be satisfied with it, and still others are going the extra mile and modding the heck out of em. I read a few posts online of people modding their T10s and T11s and getting a better sound out of them, so I became intrigued.

What I want to do is I want to upgrade the hardware on my T11, but the problem is I have zero electrical and soldering experience. I don't even know what brand, how many, or exactly what types of caps/resistors I need to improve the sound on my T11. I would like to purchase everything I need online, then I'll take everything to a local hardware electrician and have him put it all together. I'd also hate to show up and not be able to explain what exactly it is I want done to my amp, so please, can someone give me a list of caps and resistors that YOU would use and maybe a T11 schematic and a rough idea of what it is i'm trying to get done here. I'm willing to spend a little extra on decent hardware so Mundorf, Russian PIOs, or what have you. With an online tutorial I'd be willing to do the whole thing myself, but without it, i'm afraid i'll just end up frying something. Much thanks! I appreciate any help coming my way.

T68
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Re: Upgrading caps and resistors on a Little Bear T11

Post by T68 » 08 Nov 2019 23:09

+1 om this! I would really appreciate an "upgrade little bear t10/11 for dummies" guide sort of thing :-).

mamakasou
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Re: Upgrading caps and resistors on a Little Bear T11

Post by mamakasou » 09 Nov 2019 08:45

I have used the Vishay MKT/MKP series of capacitors as upgrade for coupling duties, with good results.
Vishay 1% metal film resistor as well. Also some PRP and Takman metal films.

But, when you're willing to go that route, it's a very good idea to make some effort in learning at least the basics regarding electronics. It certainly makes things a lot easier and a lot more interesting.

I'd suggest you try watching some helpful video tutorials out there on how things work.
When it comes to general tube stuff, I 'd definitely recommend you watch some related videos by Uncle Doug.

Example:
https://www.youtube.com/watch?v=l-u8J-yh9ZA

metal_gear14
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Re: Upgrading caps and resistors on a Little Bear T11

Post by metal_gear14 » 11 Nov 2019 02:21

download/file.php?id=31666&mode=view

^That's of the T10 but should work just the same for T11

Some guy on another forum recommended these caps:

FOUR 4X Mundorf MCap Supreme Aluminum Capacitor 0.47 uf 0.47 .47 600VDC MFD

https://www.ebay.com/itm/FOUR-4X-Mundor ... 6537!US!-1

Also I stumbled upon this youtube video of this guy who ruined his T10 v2.5 trying to mod it himself:

https://www.youtube.com/watch?v=sXQTm84pz44&t=136s

Thanks Mamakasou, Just now subscribed to Uncle Doug. I'll be watching some of his videos soon.

billshurv
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Re: Upgrading caps and resistors on a Little Bear T11

Post by billshurv » 11 Nov 2019 11:36

I'm going to be a little contentious here, but component rolling unless something is very old, or was built on a shoestring is unlikely to bring anything other than a hole in the bank account. A T11 is £150. Spending that much again on a few capacitors is not likely to be a good use of funds.

rewfew
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Re: Upgrading caps and resistors on a Little Bear T11

Post by rewfew » 11 Nov 2019 13:50

Echo that sentiment. It's only audiophile nervousa. This condition is contagious from reading forums where meaningful enthusiasts express sonic breakthroughs from a capacitor, resistors, diode change. Even a few cm's of wire. The circuit itself is unfazed with this modification. It all takes place in the mind of the intrepid hobbyist from their surgical amendment to the device. And there are many, more than willing vendors, purveyors of exotic and expensive mod's to keep the contagion going full circle. The circuit itself, how it's devised, is the sum total of what you hear. Good parts to make it work reliably are all that is needed. The exotic add on's are sorcerers, magicians recipes.

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Re: Upgrading caps and resistors on a Little Bear T11

Post by Big B5515 » 12 Nov 2019 00:14

I after working with my T10 a few years back, I kind of feel the same way on the last two comments. Unless the lower gain RIAA filter circuit is desired, the only other change aside from maybe shielding that made a worth while difference in my experimentation was cutting a trace, and adding a wire to allow all tube heater current to bypass signal carrying ground traces, pretty much solving it's AC hum issue.

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Re: Upgrading caps and resistors on a Little Bear T11

Post by mamakasou » 12 Nov 2019 07:49

To my ears, rolling capacitors and even resistors in a circuit, can affect the sound.
But the differences can be so minor that for a lot of people, the effort and money aren't justified.
Others might have different opinion on the matter and might be willing to experiment.

Usually, a small improvement can be made by omitting the DC blocking caps near input/output.
But this cannot always be done, as there are serious risks.
In case of tube circuits, the risk is greater, since DC voltage (B+ plate voltage) can be pretty high (x100s of volts(, so be careful!

It can only be done, when there isn't any DC offset at the input/output the amp.

A safer way to experiment, would be to use a polypropylene capacitor in place of an electrolytic, or to change film capacitors with higher values ones (capacitance & voltage rating).

aardvarkash10
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Re: Upgrading caps and resistors on a Little Bear T11

Post by aardvarkash10 » 12 Nov 2019 08:45

component rolling - colour me skeptical.

caps rolled between the thighs of siberian virgins will sound no different to those rolling off the end of a japanese production line, but will tend to be less consistent in pretty much every parameter you can measure.

If you want to "improve" the device, do what engine builders have done for decades. Blueprint it.

By that I mean match every component as closely as possible to the spec shown in the schematic. Buy 10 of each resistor, measure (and match) them then fit the single (or pair) that most closely meet the specs. Repeat this for every passive component.

When you've finished with the passives, do the same with the tubes. Ideally, get dynamically matched tubes.

Then go to your nearest record store and spend all your money on new vinyl.

mamakasou
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Re: Upgrading caps and resistors on a Little Bear T11

Post by mamakasou » 12 Nov 2019 10:11

aardvarkash10 wrote:
12 Nov 2019 08:45
component rolling - colour me skeptical.

caps rolled between the thighs of siberian virgins will sound no different to those rolling off the end of a japanese production line, but will tend to be less consistent in pretty much every parameter you can measure.

Yeah and it can be a crapshoot with choosing to upgrade.
Price just doesn't equate better sound, in most cases.

Especially with a lot of 'boutique' type of components it's obvious that they are ridiculously priced.
And the sonic gains-if any, usually aren't in par or justified.

If I had the time and money to spend on it, I'd prefer trying some well-documented industrial components from the big boys, like some Z-Foil resistor by Vishay or some Sprague orange drop caps.

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Re: Upgrading caps and resistors on a Little Bear T11

Post by mamakasou » 12 Nov 2019 10:22

Actually, I have some pairs of large Soviet PIO capacitors and I've been thinking to try the on my stock Little Bear P3 tube buffer.

The original Chinese tubes are another point that I could change with Soviet equivalents, just for the fun of it.

It also looks like they've used a type of carbon composition resistances on that board and I might be changing them to some Vishay Dale or Roederstein metal-film ones.

The potentiometer that came on it, is also a cheap chinese knock - off of 50kΩ ALPS RK09 so I might change that too.
There is an excellent ALPS RK27 chinese knock off that I have tried and tested and I might just use that in its place.

You can get these RK27 on the web for around 10 bucks, but be careful because there are a couple different qualities.
One good and one not so good.

PioneerFan
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Re: Upgrading caps and resistors on a Little Bear T11

Post by PioneerFan » 12 Nov 2019 13:30

If anyone is going to go through this effort, on what essentially constitutes a new device, why not simply design your own from scratch? Or, simply go with a beefier power supply, which should make a difference.

rewfew
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Re: Upgrading caps and resistors on a Little Bear T11

Post by rewfew » 12 Nov 2019 15:59

PioneerFan wrote:
12 Nov 2019 13:30
If anyone is going to go through this effort, on what essentially constitutes a new device, why not simply design your own from scratch? Or, simply go with a beefier power supply, which should make a difference.
Many, many hobbyist's don't have the experience or knowledge to design a whole circuit constituting something like a low noise phono preamp. But the audio forums are full of these cut and paste improvements. It's understandable that the enthusiasm to maybe improve your gear with only the where with all of learning to solder seems like a plausible and fun adaptation to the hobby. A power supply upgrade is worthwhile up to a point. But a phono preamp doesn't draw like a power amplifier. So a big beefy power supply isn't necessary, and would just be there, never reaching it's potential. DIY is a great means of obtaining really nice gear. There are many fine kit designers out there. But this tweaking mumbo jumbo is money down a rat hole. A good design just needs good soldering skill.

PioneerFan
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Re: Upgrading caps and resistors on a Little Bear T11

Post by PioneerFan » 12 Nov 2019 16:03

Buying a preamp and removing parts you paid for seems like a bit of money down the proverbial rathole, too.

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Re: Upgrading caps and resistors on a Little Bear T11

Post by Big B5515 » 12 Nov 2019 16:47

I just wouldn't be replacing resistors, or other original parts that are in reasonable tolerance between channels, or wasting big money on fancy brands even if I did try different coupling capacitors. While I did not have a way to compare the two side by side, I do think the lower gain 40db RIAA circuit discussed in the other long thread refined things a bit with minimal expense. A well planned, hard wired version built from scratch might not not be a bad idea, if someone really wanted to make serious improvements. My findings were shortcomings related to circuit board design, and the quality of it's conductive layer.

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