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KrellClone KSA100-MKII 1000VA toroidal transformer for dual mono GB

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As discussed in the original Krell KSA-100mkII thread (http://www.diyaudio.com/forums/showthread.php?s=&threadid=78129), I decided to start GB for toroidal transformers for the project to get better pricing from Toroid Corporation of Maryland (www.toroid.com). This is transformer for dual mono version of the amplifier.
Transformer should have electrostatic and magnetic shield and have following windings:
Primaries: 110/120 – dual for 110, 120 220 and 240V mains
2*38V*12A(under full 12A load)/39.5V(no load) – output stage
2*10V*12A(under full 12A load)/10.5V(no load) – output stage extra, for those who’d like to experiment with LC power supply, drive higher impedance load, etc
2*65V*0.8A – “main board” – everything else in audio path (LTP - driver), for regulated PSU
2*15V*0.25A - for protection, soft start windings, etc

I didn’t get final quote, but I’d expect prices in $220 range per transformer (shipment is extra) if 10 or more ordered.

Preliminary specs without 4 extra windings and tap on primaries attached. I'm going to send request for final quote tomorrow morning (3/11/2008 EST time).

I'd like to place an order no later then the end of the next week.


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Also for KRELL Clone KSA-50 mkII

;) Be aware of this transformer is well suited for the KSA-50 clone project too ;)

You have the opportunity to wire it for approx. 29V AC secondary and a universal mains voltage of 110, 120 220, 230 and 240V primary.

This transformer, 1.2 kVA for to be correct is perfect for a 2 ch. stereo amp, but it could also serve as a mains transformer for a 4 ch. bi-wired speaker system (active crossover) if speaker has 8 ohms impedance. Otherwise you will need two transformers for to bi-wire 4 ohms speaker (2 x 2 channels). :rolleyes:

Regards :cool:
Final quotes from toroid.com:

Pricing, Terms and Conditions
Prices are FOB, Salisbury, MD. Terms and conditions as per enclosed form 228 apply unless otherwise agreed upon in writing. Our product warranty is 36 months as per paragraph 8 in the enclosed form 228. Quote is good for 60 days

Quantity- Price ($) each
2- $410.43
5- $302.32
10- $260.97

Delivery time: 1-5 prototypes can ship in 2-3 weeks or less after approval of data sheet. Production volume as agreed upon, shipping currently 4-5 weeks or less after prototype approval, depending on quantity ordered.

Auxiliary secondary windings are 10V*0.8A instead of 15V - it seams cheaper to use thicker gauge, that change wire. 10VAC will give unregulated 12VDC each.

I'd like to make an order by Friday, March 21st.


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I'm planning to use 2. Each of the transformers are capable of continues 12A on main secondaries.

Shipping can be arranged - I'm not sure about price. They will be shipped from Salisbury, MD or from Salisbury, MD to Gaithesburg, MD 20878 to ... or from Salisbury, MD to Alexandria, VA 22314.
Not sure which route will work better for Europe.
I can re-ship using any locally available carrier of your choice.

Weight of each is 22lb
Fix said:
USPS @ $175 with insurance and 45 LBS

Fedex and UPS were Expensive.

I've mailed Floedstrom and asked if he is doing a GB in Europe, but put me up for 2 for the moment.
I used Lufthansa cargo back in 2000. They charged about $4 per kg of cargo to ship from Moscow (SVO) to Washindton (IAD). You may try to do something simillar. I'm not sure about taxes and etc
Fix said:
Looked at the data sheet, and do I really need 2 of them ?
Since there are 2x of every output.

If not needed two, why use two ?

If I want to build the KSA 100 Clone at original specs, is one trafo enough ?

Wasn't the original at 500Va / channel ?
According to the original thread MKII had 900VA per channel. I don't remember all details, but the main reasons for that power raiting are 4Ohm speakers, and fact that transformer produces current only at relatively short time of a full period.

For less demanding load you could probably use one of these
"2x" is actually for "+" and "-" rails
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