I've got two S-500s. They're good on low frequencies, but get somewhat cloudy or veiled at higher frequencies. I tend to use them on my woofers or subs most of the time.
Adding film caps--I used a handful of 4uF polypropylene caps I had on hand--as bypasses to the power supply caps went a long way towards opening up the mids and highs. At one point, I added enough extra power supply capacitance to bring each amp up to a quarter-Farad...helped very nicely with the subs I was running at that time.
There are some tantalum caps in the front end that I replaced with polyester caps, not so much as a sound quality issue (they're part of current sources, as I recall), but because one of the tantalum caps failed. Film caps tend to last a while.
I'll try to roust a brain cell or two and remember what else I've done.
Grey
Adding film caps--I used a handful of 4uF polypropylene caps I had on hand--as bypasses to the power supply caps went a long way towards opening up the mids and highs. At one point, I added enough extra power supply capacitance to bring each amp up to a quarter-Farad...helped very nicely with the subs I was running at that time.
There are some tantalum caps in the front end that I replaced with polyester caps, not so much as a sound quality issue (they're part of current sources, as I recall), but because one of the tantalum caps failed. Film caps tend to last a while.
I'll try to roust a brain cell or two and remember what else I've done.
Grey
I noticed that too, nice unit for bass but not the best for mid/highs.
I am using a Pooge2 modified DH200 for the mid/highs right now. Figured it was a good time to recap my S350e now, as it "came apart"
Mods would be very easy now. Once this one is done, I can move onto the S500e, as funds permit.
I am using a Pooge2 modified DH200 for the mid/highs right now. Figured it was a good time to recap my S350e now, as it "came apart"
Mods would be very easy now. Once this one is done, I can move onto the S500e, as funds permit.Attachments
Thanks for the welcome!
Definitely a cool start to our winter, an excellent reason though to work on various indoor projects such as audio/electronics.
I really like the older Threshold amps, and ended up picking up all 3 for less than the cost of a new S300 way back then.
I might have a spare Threshold amp to part with later on too.
I am thinking of putting the money into parts to build a musical concepts equipped Hafler amp.
Definitely a cool start to our winter, an excellent reason though to work on various indoor projects such as audio/electronics.
I really like the older Threshold amps, and ended up picking up all 3 for less than the cost of a new S300 way back then.
I might have a spare Threshold amp to part with later on too.
I am thinking of putting the money into parts to build a musical concepts equipped Hafler amp.
I have a S300mk2 sitting in a cupboard. Quite useless sonically, even for bass. The heatsinks and casing are probably the only redeemable parts and it may nicely house a 30-40W class A amp.
The only reason i haven't reused the casing already is the power tranny. If i could figure a way to non-destructively remove the potting i would rewind the secondaries to a lower voltage. Any suggestions how to do this?
The only reason i haven't reused the casing already is the power tranny. If i could figure a way to non-destructively remove the potting i would rewind the secondaries to a lower voltage. Any suggestions how to do this?
Seems a shame to cannibalize a decent amplifier like that, especially considering it is still worth about $1000 US or more on the used market in North America. I'm sure someone out there would love to have it, and then you can use the money to buy the parts or equipment you need. Your location might be a issue though, I imagine shipping costs would be a little bit pricey. The DH series Hafler amps are not the most revealing amplifiers either in stock form, but boy do they come alive when upgraded. I wonder if the same is true for the Threshold amps? I did notice the 500e has much tighter, sharper and more defined bass than the 300 Series II, the 300 sounded kind of muffled and rumbley (word?) in comparison. Just out of curiosity, do you know what the secondary voltage on that torroid is? Chances are someone could also use that as is too.
msb64 said:
When i last looked they seemed to go for around $700-800. I can't get a nice case and heatsinks for this amount. Plus i hate any kind of metal work. Most other types of work too
I would very gladly reuse the transformer though. I think it outputs around 62v per rail dc so maybe 43v ac. I tried some half-hearted passive parts upgrades and none brought a worthwhile improvement. Bypassing the main filter caps sounded outright bad with a wide range of bypass values. Replacing the NFB polycarbonate decoupling cap with a polyprop sounded marginally better. I guess good main filter caps will have a more substantial effect but that's a couple of hundred spent on a probably lost cause. If i get the energy to break the transformer potting i might turn it into an F5. The Threshold internals may be of use to someone looking for a nice PA amp.
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I ended up replacing all of the electrolytics in my S350e, and added Vishay MKP1837 .01 mfd bypass caps, it did make a very noticable difference in the top end. I will be hanging on to this unit now as a backup unit for mid/highs.
I also have an S300 MK2 that I replaced the electrolytics in, as well as adding Vishay MKP1837 and some used Wondercap bypass caps, and I also increased the large ps caps from 29K mfd to 45K mfd caps that I had on hand. I brought it over to my buddies Infinity RS1 system and it easily outperformed his stock S300 amps. About 6 people were on hand to compare the units, and all picked the tweaked MK2 as superior in sound performance.
The Vishay MKPs are nice inexpensive bypass caps that anyone should be able to afford. The Wondercap Ultimas though are no longer available, so I am going to order some Sonicap Gen1s and Gen2s to try out.
I also have an S300 MK2 that I replaced the electrolytics in, as well as adding Vishay MKP1837 and some used Wondercap bypass caps, and I also increased the large ps caps from 29K mfd to 45K mfd caps that I had on hand. I brought it over to my buddies Infinity RS1 system and it easily outperformed his stock S300 amps. About 6 people were on hand to compare the units, and all picked the tweaked MK2 as superior in sound performance.
The Vishay MKPs are nice inexpensive bypass caps that anyone should be able to afford. The Wondercap Ultimas though are no longer available, so I am going to order some Sonicap Gen1s and Gen2s to try out.
Strange opposite of my experience with my 500-2 ..
In my current system it tends to be very detailed open and dynamic on the top , a bit over damped and too much control on the bass . i have the system bi-amped with the threshold on the top ..
Hmmm will give the 4 uf bypass a try to see if it steps up ...
Thanks for the update , could you be more specific on the sonic changes after the mods were done on the s300 ....
regards ,
It is a little harder for me to exactly define all the differences the cap changes made, as I find that my friends system to be not as open and revealing as my setup. I do not agree with his choice of interconnects and his source transport/dac is extremely dated and could be a lot better even with a modest investment. I also prefer the sound of my Betas over his RS1Bs. When I listen to his setup, I can't help but think to myself "that is not the way it is supposed to sound" I tested the MK2 at his place because he has 2 stock S300s that I thought would be the closest to the MK2, to make a comparison. That being said, here is what I found to be different.
The larger ps main caps had a significant improvement in bass response in the Mark2, the bass was much more effortless and sounded like it had a faster attack. The late 80s 4.7 mfd Wondercaps may have also contributed to this as well. The Vishay .01 bypass caps definitely helped in the top end, I have tried them in several Threshold amps now and like the results. I am so happy with them, I have also installed them in my tube dac and tube preamp as well. The transition between upper bass and lower mids seem to pick up as well, but again it is hard to distinguish in his system.
With the exception of the Vishay .01 mfd caps, all the other caps I had on hand already and were used. Someone had mentioned that there probably wouldn't be any significant gains to be had with the MK2, and I decided to find out for myself. I found that there were some gains to be had with the simple component upgrades, and I found the difference to be significant.
If I get a chance, I will compare the S300MK2 against the S350e again, now that changes have been made to each.
I have tried the S300MK2, S350e and S500e in various places in my system when they were all in stock configuration. I found that the S350e sounded the best by far to power the mid/high towers and the S500e did the best job on powering the bass towers. The S350e is a very interesting amp, nice build quality, and the ps is in some ways beefier than the older S500e, more capacitance and also has dual rectifiers. I have not touched my S500e yet. I plan on replacing all electrolytics in that one as well, increase the main caps and add some bypass caps.
I apologize if my description of the sonic changes is lacking. I find that detecting changes as well as identifying if the changes are good or bad is fairly easy for me, but I find that accurately describing the sonic changes to be the most difficult part.
I tested the MK2 at his place because he has 2 stock S300s that I thought would be the closest to the MK2, to make a comparison. That being said, here is what I found to be different.The larger ps main caps had a significant improvement in bass response in the Mark2, the bass was much more effortless and sounded like it had a faster attack. The late 80s 4.7 mfd Wondercaps may have also contributed to this as well. The Vishay .01 bypass caps definitely helped in the top end, I have tried them in several Threshold amps now and like the results. I am so happy with them, I have also installed them in my tube dac and tube preamp as well. The transition between upper bass and lower mids seem to pick up as well, but again it is hard to distinguish in his system.
With the exception of the Vishay .01 mfd caps, all the other caps I had on hand already and were used. Someone had mentioned that there probably wouldn't be any significant gains to be had with the MK2, and I decided to find out for myself. I found that there were some gains to be had with the simple component upgrades, and I found the difference to be significant.
If I get a chance, I will compare the S300MK2 against the S350e again, now that changes have been made to each.
I have tried the S300MK2, S350e and S500e in various places in my system when they were all in stock configuration. I found that the S350e sounded the best by far to power the mid/high towers and the S500e did the best job on powering the bass towers. The S350e is a very interesting amp, nice build quality, and the ps is in some ways beefier than the older S500e, more capacitance and also has dual rectifiers. I have not touched my S500e yet. I plan on replacing all electrolytics in that one as well, increase the main caps and add some bypass caps.
I apologize if my description of the sonic changes is lacking. I find that detecting changes as well as identifying if the changes are good or bad is fairly easy for me, but I find that accurately describing the sonic changes to be the most difficult part.
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I have a Ta300, this amp is only 75% cost of s350e, it announced when Nelson left Threshold but in fact the circuit is same as S350e, the main different is having a less powerful transformer and a half of total capacitance. I'm planning to replace the transformer and capacitors.
Can someone tell me what is the rail voltage and bias setting of S350e
Can someone tell me what is the rail voltage and bias setting of S350e
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