Possible group buy of Lundahl input/phase splitter transformers.

[Shoog]

Hi all,
I am currently dragging together parts for a Tabor clone and mainly need a nice input/phase splitter transformer. I would also like to upgrade my 6080 amp with currently uses toroidals as parafeed phase splitters.
Whilst scanning Ebay I came across this auction;

http://cgi.ebay.co.uk/Calrec-Vintage...QQcmdZViewItem


This has 16 x Lundahl LL1517. The 1517 is described as a linestage output transformer/splitter, but to my mind that simply means that its a bit beefier and a bit more lossy than the traditional interstage transformer (am I wrong ??). Should make an excellent candidate for a parafeed interstage and has excellent specs.

Anyway I need four transformers and if I go for this auction I will get 16, which makes 5 spare pairs. Once postage and VAT was factored in the auction should cost about £143.00, which would give a price of about £18.00 per pair + onward postage. The same transformers from Lundahl would cost about £100.00 a pair + postage.

So if anyone is interested in going ahead with this get in touch and if there is enough interest I will arrange a group buy. If there is more than 5 people interested there are two other auctions up at the same time, so a potential of 20 pairs in all.

Shoog

[nemestra]

Hi Shoog,

I'll take half (one board's worth) i.e. 8 transformers. I would prefer the whole board so I take the responsibility of demounting them.

Thanks,

James

[Shoog]

Sounds good to me. I'll wait to see if one or two more come onboard before I commit. I was thinking of angle grinding the boards up so that there was no chance of heat damage.

Shoog

[korneluk]

I'll take a panel of 8 transformers as well.

-- josé k.

[Shoog]

Hi Jose,
Initially i would like to try to keep this with Britian/Europe - to simplify postage issues. If it grows beyond one set and I can get more than one set then i will get back to you.

Shoog

[planet IX]

Hi Shoog,
I'm also interested in one board.

Regards, Boris

[dsavitsk]

Originally posted by Shoog
Hi Jose,
Initially i would like to try to keep this with Britian/Europe - to simplify postage issues.

If you do go outside the borders, I'd be in for a pair as well.

[Poindexter]

I'm with dsavitsk; I'll take a pair, if it comes to my 'hood.

Hau'oli Makahiki Hou,

Poinz

[andyjevans]

Have you checked that this transformer will handle enough current and/or voltage for what you want? May be marginal - I've used a 1540 and that's pushing it at 5 or 6 volts.

[Shoog]

I have been doing some extensive searching on this transformer. There is precious little useful information out there. Two things I have established is;

1- it is specifically designed for solid state output duties, which means that it expects a very low impedance drive. In this case many tubes might not satisfy. It also means that it it is designed to drive a 600ohm input, which might means that the need for low impedance drive may be much relaxed when presented with a >10K load. Would ringing become an issue then ??
I have heard of it been used in the "SlowBlow" Mic preamp (a SRPP design) as an output transformer, so it seems it can be done.

2- in terms of voltage capability the data sheet says
Max output level before saturation (sec. in series 600ohm) +24dBU @ 30hz.
dBU relative to what ???

The LL1540 is a line input transformer, so will be designed for much lower drive levels than the LL1517.

So there are still a few questions to be resolved before pushing on. We have 7days to find the answers so there is no panic.
Can I suggest that if I do go ahead with this I will be reluctant to order more than one set for braking, so maybe someone in America could arrange for another set to go that way directly.

Shoog