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Old 13th January 2003, 04:42 PM   #11
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Default Thank you for your advice

Thanks for the input...Yeah I am very aware that I can be killed by the voltages involved. Many of the posts that I have seen stress this. It does scare me, but I have read enough to see that I have to be VERY CAREFUL, especially with discharging caps and not "experimenting" with charged devices or plugged-in circuits.

Now on to the fun stuff:
I wish to build an amp with about 15W-20W output. Topology is whatever is least costly, with the potential for good results. Looks like right now PP. Thoughts?

Next questions?
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Old 13th January 2003, 04:59 PM   #12
dhaen is offline dhaen  Europe
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It does scare me
Well that's good. You'll respect it.

These are my idea's that first come to mind:

15-20 Watts:

Low budget: Push pull.
You might get this power out of a pair of triode connected pentodes such as EL34 or 6550.

High budget: PSE
Parallel connectd 300B

Mid budget: PSE
Parallel connected 6550
But you might prefer the Push Pull....

Everyone else will have their own ideas...

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Old 13th January 2003, 05:18 PM   #13
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Default Hummm.....

Some basic issues before we get looking for a schematic? ?

Given: Speakers: (relatively inefficient) Wharfedale Diamond 8.2 (86 dB/1W/1m)

Comments above:
1)10W will be enough to start with
2) Unless you're living in a tiny room 10W is too few for comfort

Who is right here? I'm a bit of a beginner myself but I go for more horsepower. I think you are asking to be disappointed with any SE project you can do as a first time project (not par optubes) Therefore, we are looking for a PP schematic.

I do no think the general advice in the link below is far off re power requirements.

Tstrong, we are dealing with exponential not linear relations. If a SET is not enough a few more watts does not amount to much. It takes almost 10 times the watts (10 dB) to sound twice as loud. So a 80W amp is only twice as loud as a 8W amp. Going from an 8w to 15 w may seem like a lot but it really isnít.

Don't we have to answer the power issue before we look for schematics? If the speakers are going to be kept I would say go for 30-50w min. That is just IMHO

Said above by Tstrong: My budget is moderate...Less than say $200 for all the parts.

I haven't studied this price range much. But, generally when I see an amp worth building for this amount it is by working with what is on hand. Parts put together from various sources w/ a fair amount of salvaged parts (taken for next to nothing from old consoles off ebay or something) but I am not that experienced here. Can you put together a listenable PP for $200 having to pay retail for parts?

Iíve heard this amp
( ) kit for $140 and while it is an ok first project or something I would say save a couple hundred more bucks up for your project if you are trying to make something you plan on keeping.

One you get to that price range there are lots of fairly good kits available.

Gabe, who posts here, has a kit in the 15 w range if that is what you are looking at but it is about twice your budget.

I would agree with Frank and suggest a kit the first time out. There is enough to keep straight the first time like not killing yourself as Dhaen mentions. If you get a kit the physical layout has also been considered which is another thing Dhaen mentions.

Another idea is to watch ebay for an old dyna st-70 or Eico and mod it but this would put you over your budget too.

Iíd really have to look for a good PP at $200. No one has come up with one yet maybe because it is quite hard to do.

Any fool can ask more questions than seven sages can answer.
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Old 13th January 2003, 05:24 PM   #14
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Default OK...

I like the idea of the PSE using 6550's...I understand from other posts, that I can eventually chain multiple tubes (albeit with other modifications) to achieve higher outputs.

OK...that settled, I am ready to move to the next step...Fully understanding the schematics, like for instance, I can never fully understand how different areas of the circuit are powered...I can see that the power transformer has multiple windings, but when the schematic has different sections (ie, not shown all wired together), I get somewhat confused. I'd like to get that down prior to beginning any project..
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Old 13th January 2003, 05:31 PM   #15
dhaen is offline dhaen  Europe
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Slow down!
There are issues with expandability, that complicate.
Read Ryder's comments well.
I had not noticed how low your budget was, until he reminded me.


Could Tony be the person to try your resource guide on, or is it too early yet?
I've been looking through. It's good so far.

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Old 13th January 2003, 05:45 PM   #16
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Default OK, sorry

OK, I know that I am moving quickly, but...Trust me I know that I may have some issues with expanding the project later, but I am no so worried about that right now...

I have the DIY Resource guide already and have been looking through it, to great positive effect.

Any other resources?
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Old 13th January 2003, 06:00 PM   #17
HDTVman is offline HDTVman  United States
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Tony, I have one of the S-5 (11BM8) amps that I built just for fun and it sounds nice, not the greatest amp in the world but very good for the price.

Ryder is right about the amout of power you will need for the speakers your talking about. I live in the Chicago area and if you would like we could get together and you could find out what an 8 watt PP tube amp sounds like with your speakers.

I would also suggest that you look around for an old tube intergrated amp. They can often be rebuilt and sound very good or be a source of cheep parts. I could bring one of these to try too.

It's up to you, email me if you would like to do this.


PS week ends are best for me.
What ever makes the tunes flow
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Old 13th January 2003, 06:06 PM   #18
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Default Good response

Thanks HDTV! I will likely take you up on the offer...Let me check my schedule...

I am reviewing information from Ryder's guide and looking in particular about things showing circuits and their connections to the various components.

If you have any advice in this area, your suggestions would be appreciated
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Old 13th January 2003, 06:09 PM   #19
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Default Some trouble reading schematics


Here is a little different amplifier, and it is very clearly drawn.

Hopeing it would help to someone.

Best regards,
Kristijan Kljucaric
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File Type: gif 6c33c-amp.gif (13.2 KB, 263 views)
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Old 13th January 2003, 06:11 PM   #20
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... and here is the Power Supply.
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File Type: gif 6c33c-aps.gif (23.4 KB, 266 views)
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