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Amp Kits [message #8732] Sun, 23 January 2005 08:41 Go to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
The difficulty with providing kits for electronics lies in the choices the manufacturer needs to make in order to provide for some measure of profitability. In a tube amp kit; the most expensive aspect of sales is not the parts but the need to provide for aftermarket customer support, which is particularly involved in the case of kits. The parts of a tube amp; other than the transformers and chassis are not pricey and therefor have a limited profit possibility. At the 5-600$ point there is very little room for maximising profit potential; in fact the only flexible option is parts and the only parts that offer a serious cushion whithin which to float is the transformers. How much can you save on a capacitor or resistor. So therefor the manufacturer must by definition cut costs on the iron; which is the most important part of a tube amp.
Case in point; Bottlehead started as a group of guys selling kits in order to fund their own purchases. It helped that one of their members was a transformer winder. They did not need to make a big margin to survive. So they could sell cheap with decent iron. Once a kit is built with marginal transformers, no amount of tweaking will ever get the amp to the next level. That is the drawback to all tube amp kits as I see it. Even with economies of scale they still cannot sell enough to enable a serious transformer set to be feasible. So you are doomed before you start to mediocre performance.
There are rumours; unsubstatiated but from a good source that Magnequest wishes to leave the DIY community entirely due to low profit and high maintainence. I think we will see more of that as the year progresses.

Re: Amp Kits [message #8733 is a reply to message #8732] Sun, 23 January 2005 14:32 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)
You really should check out that Stoetkit, if you haven't already. Heart makes their own transformers and chassis, and I understand they make them as an OEM for a lot of other manufacturer's too. So that lets them bring a top-notch product to the market at an entry-level price.

Also, Douglas (Tnuctipun), here and over in the Group Build forum, has contacts with another transformer winder. I don't know much about the details, but I understand that the quality is very good.

Re: Amp Kits [message #8734 is a reply to message #8733] Sun, 23 January 2005 15:38 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
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Registered: May 2009
Illuminati (13th Degree)
I reviewed the Stoetkit from FSA audio and was impressed what one could hear for the price; which was very affordable at about 700$ for a tube integrated amplifier kit that looks beautiful.

However; the issue of transformer quality boils down to one of simple economics. They are labor intensive to build; they require large amounts of material and extensive attention to quality control. Not to mention they are heavy and expensive to ship. They are design dependant; ie. they are usually specific to each design so as a result they are small batch items. They have an inordinate effect on the sound of tube circuits, poorly regulated and constructed examples result in poor sound period. Well constructed units are expensive. Quality units are big and heavy and rely on the quality of the raw materials used to construct them for their sound.
There are no exceptions to this rule. With transformers; Quality=money. And you can't design around poor transformers. Cheap trans are not good; good trans are not cheap.
My point was the cost of good iron prohibits designers from making money on inexpensive amp kits. So by definition they must compromise on the transformers and no amount of tweaking passive parts can overcome that limitation.

Re: Amp Kits [message #8735 is a reply to message #8734] Sun, 23 January 2005 17:31 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
Hey Hey!!!,
While not exactly exceptions, there are wys around expensive TX's. The manufacturing costs are a major factor in stuff like vlave output transformers. For power Iron, it is a fine line between spending more money researching how cheap you can go v. getting something a bit on the big side for a bit more money.

For example NC winders v. 'by hand'. let alone the antics of what must be built like an electronic card shuffler to stack the lams v. 'by hand'. THe NC machine can be told how to handle TFE wrapping, or what ever the wire gage is, and it will do it quite well. Contrast this with soe knuckle-head who has either run out of pot the day before or has been indulging in the weed whilst winding your TX. I think I'll stick with the NC machine. Just need to tell it how to interleave, so get a good model and take it apart if you're in a big hurry. The R&D which would have to get spent on a new design makes things more expensive again.

Anybody have a Harman Kardon Citation II with a toasty opt? Think Homer SImpson's cloning hammock, put the bad one in( along with some money for the winder ) and out pop two new copies. Or one of the properly useful UTC Linear Standard series....name your fav, it can be copied and modified for new circuits. Put the tap for U-L just where you need it for what ever vlave you decide to use...
regards,
Douglas

Re: Amp Kits [message #8736 is a reply to message #8735] Sun, 23 January 2005 18:30 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
What about Acrosound Iron. There seems to be quite complete directions from the original winders on the net. Any thoughts. BTW The Citation II;
I was never a big fan. On a personal level I thought the V sounded better. Don't think they used the same Iron. Then again lot of people like the II better so who know's? I like the big trannies on the old Eico 20's.

Re: Amp Kits [message #8737 is a reply to message #8735] Sun, 23 January 2005 18:34 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)
Hi Douglas,

Did you happen to see that Stoetkit John and I were talking about? It's a UL P-P amp that develops 9 watts. The transformers are nice and they come with attractive metal covers, mounted on the chassis. This little amp looks great and sounds great too. As entry level tube amp kits go, it's definitely one of my favorites.

Wayne

Re: Amp Kits [message #8738 is a reply to message #8736] Sun, 23 January 2005 19:13 Go to previous messageGo to next message
PakProtector is currently offline  PakProtector
Messages: 935
Registered: May 2009
Illuminati (2nd Degree)
hey 'block,
can you direct me to this mass of information on the Acro OPT's? I have a TO330 and 300 waiting for an appropriate project( and their sacrifice to the cloning process at Heyboer ). I have my suspicions about the 300, the 330 seems to be a bit more complex...
regards,
Douglas

Re: Amp Kits [message #8740 is a reply to message #8738] Mon, 24 January 2005 06:52 Go to previous messageGo to next message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
It is probably the same sites you have already accesed. I would ask have you tried a patent search? I believe it is still free from the patent office but you do need the original patent no. Sowter makes a copy; you probably know all this so excuse me if I am redundant. There was a article in Sound Practices that told of winding your own and I believe they used an Acro. I'll check unless you already have. Sorry could not be more help. J.R.

transformers [message #8742 is a reply to message #8732] Tue, 25 January 2005 09:47 Go to previous messageGo to next message
akhilesh is currently offline  akhilesh
Messages: 1275
Registered: May 2009
Illuminati (3rd Degree)
Based on my limited knowledge, output trannies are very important in the standard direct coupled SET mode. Output trannies for parallel feed amps (like doc bottlehead's) are much less important. Output trannies for PP are also less important, though for UL they may make soem difference. POwer trannies i think make much less difference, assuming they are a hammond or above.

Bottom line, i think output trannies matter only in the direct coupled mode SET config...the good ones sell for about $600 a pair!
Even the James trannies in my custom SET 45 sell for about $200-$250 a pair.

The output trannies in a parafeed config like the bottleheads would sell for much less (they are much less critical and their mfg requirements are much less)..my guess would be $20-$50 a pair.
thanx
akhilesh

Re: transformers [message #8743 is a reply to message #8742] Tue, 25 January 2005 19:14 Go to previous messageGo to previous message
Manualblock is currently offline  Manualblock
Messages: 4973
Registered: May 2009
Illuminati (13th Degree)
Sorry to disagree but power trannies require very good regulation and high permeability and low internal resistance in order that they are able to provide adequate current when needed and that they do not roll off the frequency extremes. There are no tube functions where a transformer is not very important, not even Parrallel circuits.

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