its more of a design issue. but what do you expect for a $270 amp. They went to a lot of work making it look pretty. As it does look like the more expensive amps.
It would work good for a guitar amp sine they start distorting about 1/2 way up.
It would work good for a guitar amp sine they start distorting about 1/2 way up.
When I get enough money to burn, I might buy one of these just to see how cheap they actually are. Btw it probably uses the cheap $5 usb audio interface that is barley mid-fi (20-20Khz)
From the DIYAudio viewpoint I'd regard the Peach as a nicely made SE kit, containing most of the important parts required to create a good SE amplfier in a neat box, complete with packing case.
I have not used the USB interface, or the phono but I suspect they are the cheapest possible. The advantage of them however is that you get the selector switch and front panel markings for them 😉
To make my amp out of the Peach I changed all three signal tubes, added a MOSFET for the screen regulation, changed the top-plate and added two regulator tubes.
I also added a mini transformer for the top SRPP filaments, used all new signal components (threw away old PCB) and changed the Chinese FU50s for Russian GU50s, and tweaked the bias circuit to give enough volts to bias the GU50s as pentodes.
I've ended up with a professional looking amp that rocks, so I do like the Sweet peach 😉
I have not used the USB interface, or the phono but I suspect they are the cheapest possible. The advantage of them however is that you get the selector switch and front panel markings for them 😉
To make my amp out of the Peach I changed all three signal tubes, added a MOSFET for the screen regulation, changed the top-plate and added two regulator tubes.
I also added a mini transformer for the top SRPP filaments, used all new signal components (threw away old PCB) and changed the Chinese FU50s for Russian GU50s, and tweaked the bias circuit to give enough volts to bias the GU50s as pentodes.
I've ended up with a professional looking amp that rocks, so I do like the Sweet peach 😉
OK, Not had a chance to put the meter across yet (if nothing else the bass comes through loud indeed and even moderate volume would be annoying to the neighbours). I'll pick a day when they are out.
In the meantime, I thought I would start on the job of changing the caps. I had a look at Rapid but couldn't find any 0.1mf polypropylene caps available. Being a little distrustful of ebay for I had a search. Are these suitable?:
Class X2 capacitors
If not, any suggestions for where else (I can go to Maplins but begrudge the huge mark-up!)
If they are suitable, what else do you recommend changing at the same time? (specific will help - struggling a little with some of the shorthand on here).
BTW - thanks for the wealth of info so far. It will hopefully turn a so so amp into a class act in the near future.
Dave
In the meantime, I thought I would start on the job of changing the caps. I had a look at Rapid but couldn't find any 0.1mf polypropylene caps available. Being a little distrustful of ebay for I had a search. Are these suitable?:
Class X2 capacitors
If not, any suggestions for where else (I can go to Maplins but begrudge the huge mark-up!)
If they are suitable, what else do you recommend changing at the same time? (specific will help - struggling a little with some of the shorthand on here).
BTW - thanks for the wealth of info so far. It will hopefully turn a so so amp into a class act in the near future.
Dave
No, those are ceramic type safety caps based on the link name and are not suitable for this use.
There must be suppliers of parts for diy who are on the net there in the UK.. Alternately you could check with askjanfirst here: Ask Jan First ® ; electron tubes and more, Partsconnexion in Canada, or Michael Percy in the US..
Note that there are plenty of reputable sellers on eBay.. Looking at their feedback ratings will tell you a lot. I purchase a good % of my tubes, caps and resistors from various vendors mostly in Eastern Europe, the UK, Hong Kong, and Germany..
The linked page describes them as polypropylene. They look like rectangular film caps, not ceramics. X and Y caps are available in several different technologies.
Yes, I use eBay for many components, all have been fine.
The advantage is free/cheap postage, fast delivery and a huge range!
These are (identical to) the ones I bought:
CAPACITOR: 0.1UF/1000V Axial POLYPROPYLENE | eBay
They are quite long but solder in fine.
If going for Wima go for a reputable source, although if the price is high enough they are probably genuine,
WIMA MKP-10 0.1uF 630V Polypropylene Capacitor, x2 PCS | eBay
or get the sweet shaped ones:
0.1uF 630V Polypropylene Capacitors Qty 5 VALVE RADIO | eBay
OK, Just a bit of an update.
I have measured the AC on the output with my multi-meter. A bit difficult to be precise as (obviously) the readings jump around:
at just below the distortion I get between 4.2 and 5v ac
distortion (esp female vocals) starts to appear in the 5 - 5.5v ac stage.
The Speaker impedance is running at 6.2 ohm (tested in isolation not connected to amp).
Do these figures sound about right?
Next, I have ordered 2 sets of replacement caps for the coupling:
some like for like WIMA (But 400v) and some K40 PIO Russian caps. Neither have got here yet but I will replace, run in and report my findings.
Dave
I have measured the AC on the output with my multi-meter. A bit difficult to be precise as (obviously) the readings jump around:
at just below the distortion I get between 4.2 and 5v ac
distortion (esp female vocals) starts to appear in the 5 - 5.5v ac stage.
The Speaker impedance is running at 6.2 ohm (tested in isolation not connected to amp).
Do these figures sound about right?
Next, I have ordered 2 sets of replacement caps for the coupling:
some like for like WIMA (But 400v) and some K40 PIO Russian caps. Neither have got here yet but I will replace, run in and report my findings.
Dave
Given the difficulty of measuring audio AC with a normal meter they look about right, or maybe a little low. However, assuming that your meter averages over a short period they could be fine, as music peaks will be higher.
You are starting to see clipping at about 4W. The spec claims 10W (but these are Chinese watts). You would need to do sine wave testing, preferably with an oscilloscope, to see where the real onset of clipping is. If the amplifier meets its spec this would happen at about 7-8V rms, or 10-11V peak. You will not be able to tell the difference as this is only about 4dB higher.
Changing capacitors won't change this, unless one is faulty (which I doubt).
You are starting to see clipping at about 4W. The spec claims 10W (but these are Chinese watts). You would need to do sine wave testing, preferably with an oscilloscope, to see where the real onset of clipping is. If the amplifier meets its spec this would happen at about 7-8V rms, or 10-11V peak. You will not be able to tell the difference as this is only about 4dB higher.
Changing capacitors won't change this, unless one is faulty (which I doubt).
True, but if they are using the same capacitors that they put in mine then they are muffling and distorting the sound severely. The effect of changing mine wasn't subtle...
You mentioned earlier---
'Fake capacitors'
You really think this was the case....?😱
They had Wima written on them, then were either fake Wima or recycled. Recycled usually consists of an indian toddler laying the PCB on an open fire and pulling the components off - so this may have had an effect. Either way they were hardly capacitors as they lost the treble.
I have had a couple of issues,
With standard caps or X type being sold as (Hi End)...and its not until you come across this with a lable under a label that you believe its real..
Orange drop 716 (cheap) are quite good not 715 they have steel lead outs...
Regards
M. Gregg
With standard caps or X type being sold as (Hi End)...and its not until you come across this with a lable under a label that you believe its real..
Orange drop 716 (cheap) are quite good not 715 they have steel lead outs...
Regards
M. Gregg
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I haven't tried mine yet but if you connect the USB to a Windows PC / laptop it should detect it as a soundcard and just work. The USB interface is one chip then it goes through some cheap electrolytics which you could easily improve.
When I get a moment I will investigate the USB audio chip in the amp but I would assume it is a standard one.
My amp sounds pretty good without mods but I concur with you on the soft and perhaps fuzzy treble so first to go will be those coupling capacitors. My amp is an EL34B version, just got it from the UK seller on the bay and very cheap now. The bass is surprisingly solid and deep, out of the box.
It might be worth drawing out the circuit diagram of the phono board as with a new IC and possible cap upgrades it might be reasonable, though not seriously good enough for this amp.
Cheers, Paul.
When I get a moment I will investigate the USB audio chip in the amp but I would assume it is a standard one.
My amp sounds pretty good without mods but I concur with you on the soft and perhaps fuzzy treble so first to go will be those coupling capacitors. My amp is an EL34B version, just got it from the UK seller on the bay and very cheap now. The bass is surprisingly solid and deep, out of the box.
It might be worth drawing out the circuit diagram of the phono board as with a new IC and possible cap upgrades it might be reasonable, though not seriously good enough for this amp.
Cheers, Paul.
Another update
I have now swapped out the stock Wima MKS4 coupling caps for Wima MKP10 400v 0.1uF. I am still running them in but looks good so far - I must confess to a healthy dose of scepticism when I first read Globulator's post but I take it all back - £6 worth of known genuine caps make a hell of a difference!
I still have a small issue with the treble headroom on some female vocals but, my God, what a difference to the mid-range. It wasn't bad before but now it really sings - so much depth and clarity. Solo guitar tracks (both electric like Satriani's 'Always with me' and acoustic {John Williams' Cavatina and anything by Doyle Dykes!} ) are especially crisp now - with eyes closed and speakers positioned well you could be next to them.
I will try the bypass caps on the electros next (improve my treble issue maybe?) and also remove the input caps but wanted to identify the change made by each mod rather than all at once.
Interestingly, I also replaced the chinese 6N1 and 6n3's with Russians but I'm afraid the difference is negligible (if anything the Chinese tubes sound marginally better - clarity wise). I'll do a couple of swap overs to see if I can prove to myself that anything changes.
My biggest remaining issue is having to live with small bookshelf speakers - the bass from the sweet peach can overwhelm them so easily - but I'm stuck on this one (it was hard enough convincing the missus to accommodate the industrial design of the amp!) for now.
Thanks to both Globulator and frapa02 (Paul) for the excellent input both on here and the 'making sense of the sweet peach' thread - it really has opened my eyes (ears) to the differences a few simple mods can make.
Dave
I have now swapped out the stock Wima MKS4 coupling caps for Wima MKP10 400v 0.1uF. I am still running them in but looks good so far - I must confess to a healthy dose of scepticism when I first read Globulator's post but I take it all back - £6 worth of known genuine caps make a hell of a difference!
I still have a small issue with the treble headroom on some female vocals but, my God, what a difference to the mid-range. It wasn't bad before but now it really sings - so much depth and clarity. Solo guitar tracks (both electric like Satriani's 'Always with me' and acoustic {John Williams' Cavatina and anything by Doyle Dykes!} ) are especially crisp now - with eyes closed and speakers positioned well you could be next to them.
I will try the bypass caps on the electros next (improve my treble issue maybe?) and also remove the input caps but wanted to identify the change made by each mod rather than all at once.
Interestingly, I also replaced the chinese 6N1 and 6n3's with Russians but I'm afraid the difference is negligible (if anything the Chinese tubes sound marginally better - clarity wise). I'll do a couple of swap overs to see if I can prove to myself that anything changes.
My biggest remaining issue is having to live with small bookshelf speakers - the bass from the sweet peach can overwhelm them so easily - but I'm stuck on this one (it was hard enough convincing the missus to accommodate the industrial design of the amp!) for now.
Thanks to both Globulator and frapa02 (Paul) for the excellent input both on here and the 'making sense of the sweet peach' thread - it really has opened my eyes (ears) to the differences a few simple mods can make.
Dave
MKS are polyester. MKP are polypropylene. Polyester can be a bit non-linear, so fine for radio sets and guitar amps but not for critical positions in hi-fi. Changing caps like this won't increase the power output, which was the original question, but it may reduce distortion below the clipping level. The 'muddled' sound which some find with MKS is probably due to intermodulation, which can be more annoying than similar levels of harmonic distortion.
Glad you got them changed out and can now hear the sound of this Peach!
I bypassed all my poly and oil caps with Silver Mica after I discovered what a difference swapping the caps made!
I bypassed all my poly and oil caps with Silver Mica after I discovered what a difference swapping the caps made!
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