Cheap 300Bs should i stay away

colin.hepburn · Post by **colin.hepburn** » Thu Sep 08, 2011 5:38 pm

Hi All
Just wanted some members thoughts
Has anyone any experience of these cheap 300Bs or should I stay away from cheap 300Bs
http://www.ebay.co.uk/itm/2x-Matched-Gu ... 483cb3faac

pre65 · Post by **pre65** » Thu Sep 08, 2011 5:51 pm

I've got a pair of Chinese 300b and I use them every now and then. I don't think they are bad personally, although the EH gold grids are a tad better.

Just remember, in my opinion it's important to get any DHT filament supply exactly right. Straight AC or DC will do, but it's not the best.

A current/voltage module like Tentlabs do, or even the DHT supply that Mike H developed will be best.

That's my opinion,or my theory.

Of course, on 833a, I don't follow my own advice.

JackOfAll · Post by **JackOfAll** » Thu Sep 08, 2011 6:02 pm

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colin.hepburn · Post by **colin.hepburn** » Thu Sep 08, 2011 6:21 pm

JackOfAll wrote:Colin,

Before you go buying 300B's, talk to me. I have many pairs that I bought for a 300B headphone amp project that never made it past the breadboard stage and into a chassis. What are you after? Just the cheapest possible, or something in particular?

Hi Clive
I am just thinking of getting some different valves to try in the EL34 mainly the cheap Russian ones for now and the cheap 300B is an option i aim thinking about for my next amp as well a 2A3s/ 6B4G looking for a small selection of different valve to play with

JackOfAll · Post by **JackOfAll** » Thu Sep 08, 2011 6:38 pm

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pre65 · Post by **pre65** » Thu Sep 08, 2011 6:48 pm

Clive, those DIY hi-fi modules, are they the old type, or the new type ?

JackOfAll · Post by **JackOfAll** » Thu Sep 08, 2011 6:54 pm

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pre65 · Post by **pre65** » Thu Sep 08, 2011 7:02 pm

I think the early ones could be configured as current source, or voltage source.

What does the writing on the PCB say ? (all of it)

JackOfAll · Post by **JackOfAll** » Thu Sep 08, 2011 7:36 pm

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pre65 · Post by **pre65** » Thu Sep 08, 2011 7:45 pm

The ones I have say copyright 2010 on the board, have blue screw connectors and the diodes are raised up quite a bit. I think these are what I call the later type.

I would buy another pair like these.

EDIT I don't believe mine have a jumper either.

EDIT 2 No, mine has the jumper, I looked with the light on. Never noticed that when I fitted them.

EDIT 3 I'm confused now cos DIY hi fi supply seem to list both types on their web site. The ones like yours with the green terminal blocks and the ones like mine with blue terminal blocks.

http://www.diyhifisupply.com/catalog/102

colin.hepburn · Post by **colin.hepburn** » Thu Sep 08, 2011 8:06 pm

JackOfAll wrote:
colin.hepburn wrote: I am just thinking of getting some different valves to try in the EL34 mainly the cheap Russian ones for now and the cheap 300B is an option i aim thinking about for my next amp as well a 2A3s/ 6B4G looking for a small selection of different valve to play with
Colin, PM me a phone number and I'll give you a call later this evening. 300B's..... VCS Heater supplies..... cant offer you the Tent modules, but I have several new pairs of the diyhifisupply modules. £25 for a pair.

I'm holding onto the transformers/choke for the 6H30 headphone build, so if you want me to add to the list of items.......

Clive You Have PM

Paul Barker · Post by **Paul Barker** » Thu Sep 08, 2011 8:22 pm

How many heater supplies can you sell me Clive? Site unseen regardless of fart about jumpers? I#ll take as many as you can spare.

pre65 · Post by **pre65** » Thu Sep 08, 2011 8:35 pm

colin.hepburn wrote: Clive You Have PM

Colin, you sent that PM to me by mistake.

colin.hepburn · Post by **colin.hepburn** » Thu Sep 08, 2011 8:37 pm

pre65 wrote:
colin.hepburn wrote: Clive You Have PM
Colin, you sent that PM to me by mistake.

oops sorry philip

JackOfAll · Post by **JackOfAll** » Thu Sep 08, 2011 9:05 pm

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Cheap 300Bs should i stay away

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